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Liu YL, Wang SC, Hwu HG, Fann CSJ, Yang UC, Yang WC, Hsu PC, Chang CC, Wen CC, Tsai-Wu JJ, Hwang TJ, Hsieh MH, Liu CC, Chien YL, Fang CP, Faraone SV, Tsuang MT, Chen WJ, Liu CM. Haplotypes of the D-Amino Acid Oxidase Gene Are Significantly Associated with Schizophrenia and Its Neurocognitive Deficits. PLoS One 2016; 11:e0150435. [PMID: 26986737 PMCID: PMC4795637 DOI: 10.1371/journal.pone.0150435] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 02/13/2016] [Indexed: 01/01/2023] Open
Abstract
D-amino acid oxidase (DAO) has been reported to be associated with schizophrenia. This study aimed to search for genetic variants associated with this gene. The genomic regions of all exons, highly conserved regions of introns, and promoters of this gene were sequenced. Potentially meaningful single-nucleotide polymorphisms (SNPs) obtained from direct sequencing were selected for genotyping in 600 controls and 912 patients with schizophrenia and in a replicated sample consisting of 388 patients with schizophrenia. Genetic associations were examined using single-locus and haplotype association analyses. In single-locus analyses, the frequency of the C allele of a novel SNP rs55944529 located at intron 8 was found to be significantly higher in the original large patient sample (p = 0.016). This allele was associated with a higher level of DAO mRNA expression in the Epstein-Barr virus-transformed lymphocytes. The haplotype distribution of a haplotype block composed of rs11114083-rs2070586-rs2070587-rs55944529 across intron 1 and intron 8 was significantly different between the patients and controls and the haplotype frequencies of AAGC were significantly higher in patients, in both the original (corrected p < 0.0001) and replicated samples (corrected p = 0.0003). The CGTC haplotype was specifically associated with the subgroup with deficits in sustained attention and executive function and the AAGC haplotype was associated with the subgroup without such deficits. The DAO gene was a susceptibility gene for schizophrenia and the genomic region between intron 1 and intron 8 may harbor functional genetic variants, which may influence the mRNA expression of DAO and neurocognitive functions in schizophrenia.
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Affiliation(s)
- Yu-Li Liu
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli 35053, Taiwan
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei 10051, Taiwan
| | - Sheng-Chang Wang
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli 35053, Taiwan
| | - Hai-Gwo Hwu
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei 10051, Taiwan
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei 10051, Taiwan
| | | | - Ueng-Cheng Yang
- Institute of Bioinformatics, National Yang-Ming University, Taipei 112, Taiwan
| | - Wei-Chih Yang
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Pei-Chun Hsu
- Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei 10051, Taiwan
| | - Chien-Ching Chang
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Chun-Chiang Wen
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei 10051, Taiwan
| | - Jyy-Jih Tsai-Wu
- Department of Medical Research, National Taiwan University Hospital, Taipei 10051, Taiwan
| | - Tzung-Jeng Hwang
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei 10051, Taiwan
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei 10051, Taiwan
| | - Ming H. Hsieh
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei 10051, Taiwan
| | - Chen-Chung Liu
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei 10051, Taiwan
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei 10051, Taiwan
| | - Yi-Ling Chien
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei 10051, Taiwan
| | - Chiu-Ping Fang
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli 35053, Taiwan
| | - Stephen V. Faraone
- Medical Genetics Research Center and Department of Psychiatry and Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, United States of America
| | - Ming T. Tsuang
- Harvard Institute of Psychiatric Epidemiology and Genetics, and Departments of Epidemiology and Psychiatry, Harvard University, Boston, Massachusetts, 02115, United States of America
- Institute of Behavioral Genomics, University of California San Diego, San Diego, California 92093, United States of America
| | - Wei J. Chen
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei 10051, Taiwan
| | - Chih-Min Liu
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei 10051, Taiwan
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei 10051, Taiwan
- * E-mail:
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Cella M, Hamid S, Butt K, Wykes T. Cognition and Social Cognition in non-psychotic siblings of patients with schizophrenia. Cogn Neuropsychiatry 2015; 20:232-42. [PMID: 25720746 DOI: 10.1080/13546805.2015.1014032] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Deficits in Social Cognition are common in people with schizophrenia. However, it is not clear if these deficits are a vulnerability marker and whether they are independent to cognitive difficulties. This study investigates these two issues in individuals with a genetic liability to psychosis. METHODS Twenty-one healthy siblings of patients with schizophrenia were compared with 21 healthy individuals on a range of cognitive and social cognitive measures. Significant differences in cognitive domains were controlled for when comparing the two groups on measures of social cognition. RESULTS Siblings of people with schizophrenia performed significantly worst on tests of theory of mind and social perception but not on affect recognition. Scores on tests of executive function, processing speed and general IQ were also lower in the sibling group. When controlled for differences in cognitive tests, the two groups still retained significant differences in theory of mind and social perception. However, executive function significantly contributed to theory of mind and processing speed to social perception differences. CONCLUSIONS These results further suggest that difficulties in some domains of social cognition are associated with a genetic vulnerability for schizophrenia. In these areas, cognitive difficulties account only partially for social cognition problems suggesting that these two domains may represent relatively independent liability factors.
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Affiliation(s)
- Matteo Cella
- a Department of Psychology , Institute of Psychiatry, King's College London , De Crespigny Park, SE5 8AF London , UK
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García-Montes JM, Noguera C, Alvarez D, Ruiz M, Cimadevilla Redondo JM. High and low schizotypal female subjects do not differ in spatial memory abilities in a virtual reality task. Cogn Neuropsychiatry 2015; 19:427-38. [PMID: 24655143 DOI: 10.1080/13546805.2014.896786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Schizotypy is a psychological construct related to schizophrenia. The exact relationship between both entities is not clear. In recent years, schizophrenia has been associated with hippocampal abnormalities and spatial memory problems. The aim of this study was to determine possible links between high schizotypy (HS) and low schizotypy (LS) and spatial abilities, using virtual reality tasks. We hypothesised that the HS group would exhibit a lower performance in spatial memory tasks than the LS group. METHODS Two groups of female students were formed according to their score on the ESQUIZO-Q-A questionnaire. HS and LS subjects were tested on two different tasks: the Boxes Room task, a spatial memory task sensitive to hippocampal alterations and a spatial recognition task. RESULTS Data showed that both groups mastered both tasks. Groups differed in personality features but not in spatial performance. These results provide valuable information about the schizotypy-schizophrenia connections. CONCLUSION Schizotypal subjects are not impaired on spatial cognition and, accordingly, the schizotypy-schizophrenia relationship is not straightforward.
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Thermenos HW, Keshavan MS, Juelich RJ, Molokotos E, Whitfield-Gabrieli S, Brent BK, Makris N, Seidman LJ. A review of neuroimaging studies of young relatives of individuals with schizophrenia: a developmental perspective from schizotaxia to schizophrenia. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:604-35. [PMID: 24132894 DOI: 10.1002/ajmg.b.32170] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 04/24/2013] [Indexed: 11/08/2022]
Abstract
In an effort to identify the developing abnormalities preceding psychosis, Dr. Ming T. Tsuang and colleagues at Harvard expanded Meehl's concept of "schizotaxia," and examined brain structure and function in families affected by schizophrenia (SZ). Here, we systematically review genetic (familial) high-risk (HR) studies of SZ using magnetic resonance imaging (MRI), examine how findings inform models of SZ etiology, and suggest directions for future research. Neuroimaging studies of youth at HR for SZ through the age of 30 were identified through a MEDLINE (PubMed) search. There is substantial evidence of gray matter volume abnormalities in youth at HR compared to controls, with an accelerated volume reduction over time in association with symptoms and cognitive deficits. In structural neuroimaging studies, prefrontal cortex (PFC) alterations were the most consistently reported finding in HR. There was also consistent evidence of smaller hippocampal volume. In functional studies, hyperactivity of the right PFC during performance of diverse tasks with common executive demands was consistently reported. The only longitudinal fMRI study to date revealed increasing left middle temporal activity in association with the emergence of psychotic symptoms. There was preliminary evidence of cerebellar and default mode network alterations in association with symptoms. Brain abnormalities in structure, function and neurochemistry are observed in the premorbid period in youth at HR for SZ. Future research should focus on the genetic and environmental contributions to these alterations, determine how early they emerge, and determine whether they can be partially or fully remediated by innovative treatments.
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Affiliation(s)
- H W Thermenos
- Harvard Medical School, Boston, Massachusetts; Massachusetts Mental Health Center, Division of Public Psychiatry, Boston, Massachusetts; Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts
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Faraone SV, Seidman LJ, Buka S, Goldstein JM, Lyons M, Kremen WS, Glatt SJ. Festschrift celebrating the career of Ming T. Tsuang. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:551-8. [PMID: 24132890 DOI: 10.1002/ajmg.b.32194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 07/23/2013] [Indexed: 01/25/2023]
Affiliation(s)
- Stephen V Faraone
- Departments of Psychiatry and of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, New York
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Stone WS, Giuliano AJ. Development of liability syndromes for schizophrenia: where did they come from and where are they going? Am J Med Genet B Neuropsychiatr Genet 2013; 162B:687-97. [PMID: 24132901 DOI: 10.1002/ajmg.b.32185] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 06/21/2013] [Indexed: 01/24/2023]
Abstract
Three decades after Paul Meehl proposed the term "schizotaxia" to describe a conceptual framework for understanding the liability to schizophrenia, Ming Tsuang et al. at Harvard University reformulated the concept as a clinical syndrome with provisional research criteria. The reformulated view relied heavily on more recent data showing that many non-psychotic, un-medicated biological relatives of individuals with schizophrenia showed difficulties in cognitive and other clinical functions that resembled those seen in their ill relatives. The reformulation raised questions about both whether and when liability could be assessed validly in the absence of psychosis, and about the extent to which symptoms of liability are reversible. Both questions bear on the larger issue of early intervention in schizophrenia. This article reviews the efforts of Tsuang et al. to conceptualize and validate schizotaxia as one such syndrome of liability. Towards this end, liability is considered first more generally as an outcome of interactive genetic and environmental factors. Liability is then considered in the context of endophenotypes as a concept that is both broader and is potentially more specific (and predictive) than many DSM or ICD diagnostic symptoms. Liability syndromes are then considered in the context of their proximity to illness, first by reviewing prodromal syndromes (which are more proximal), and then by considering schizotaxia, which, as it is currently formulated, is pre-prodromal and, therefore, less proximal. Finally, challenges to validation and future directions for research are considered.
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Affiliation(s)
- William S Stone
- Department of Psychiatry, Massachusetts Mental Health Center, Division of Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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Landgraf S, Osterheider M. "To see or not to see: that is the question." The "Protection-Against-Schizophrenia" (PaSZ) model: evidence from congenital blindness and visuo-cognitive aberrations. Front Psychol 2013; 4:352. [PMID: 23847557 PMCID: PMC3696841 DOI: 10.3389/fpsyg.2013.00352] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 05/30/2013] [Indexed: 12/12/2022] Open
Abstract
The causes of schizophrenia are still unknown. For the last 100 years, though, both “absent” and “perfect” vision have been associated with a lower risk for schizophrenia. Hence, vision itself and aberrations in visual functioning may be fundamental to the development and etiological explanations of the disorder. In this paper, we present the “Protection-Against-Schizophrenia” (PaSZ) model, which grades the risk for developing schizophrenia as a function of an individual's visual capacity. We review two vision perspectives: (1) “Absent” vision or how congenital blindness contributes to PaSZ and (2) “perfect” vision or how aberrations in visual functioning are associated with psychosis. First, we illustrate that, although congenitally blind and sighted individuals acquire similar world representations, blind individuals compensate for behavioral shortcomings through neurofunctional and multisensory reorganization. These reorganizations may indicate etiological explanations for their PaSZ. Second, we demonstrate that visuo-cognitive impairments are fundamental for the development of schizophrenia. Deteriorated visual information acquisition and processing contribute to higher-order cognitive dysfunctions and subsequently to schizophrenic symptoms. Finally, we provide different specific therapeutic recommendations for individuals who suffer from visual impairments (who never developed “normal” vision) and individuals who suffer from visual deterioration (who previously had “normal” visual skills). Rather than categorizing individuals as “normal” and “mentally disordered,” the PaSZ model uses a continuous scale to represent psychiatrically relevant human behavior. This not only provides a scientific basis for more fine-grained diagnostic assessments, earlier detection, and more appropriate therapeutic assignments, but it also outlines a trajectory for unraveling the causes of abnormal psychotic human self- and world-perception.
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Affiliation(s)
- Steffen Landgraf
- Department for Forensic Psychiatry and Psychotherapy, District Hospital, University Regensburg Regensburg, Germany ; Berlin School of Mind and Brain, Humboldt Universität zu Berlin Berlin, Germany
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Sponheim SR, Sass SM, Noukki AL, Hegeman BM. Fragile early visual percepts mark genetic liability specific to schizophrenia. Schizophr Bull 2013; 39:839-47. [PMID: 22446567 PMCID: PMC3686444 DOI: 10.1093/schbul/sbs041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Disruption of visual percepts by a subsequent stimulus (ie, backward masking) has been consistently noted in schizophrenia, with some evidence that this fragility in early perception is present in people with genetic liability for the disorder. Given the potential of backward masking paradigms to mark neural processes that confer risk for schizophrenia, it is important to test the diagnostic specificity of abnormalities in visual perception. To more fully assess whether masking visual stimuli reveals a marker of genetic liability (ie, endophenotype) specific to schizophrenia, we tested 44 people with the disorder, 29 people with bipolar disorder, 56 first-degree biological relatives of people with schizophrenia, 26 first-degree biological relatives of people with bipolar disorder, and 43 nonpsychiatric control participants using a magnocellular-biased visual backward masking procedure that included target-to-mask onset asynchronies ranging from 0 to 80 ms. Relatives of people with schizophrenia who were without schizophrenia spectrum disorders exhibited impaired performance compared with nonpsychiatric control participants and relatives of people with bipolar disorder when a visual mask interrupted early perception (eg, 27 ms). A similar vulnerability of early processes was noted in people with schizophrenia, yet they also had impaired performance when masks occurred at later time points (ie, 80 ms). Performance deficits were not attributable to intellectual function, measures of attention and memory, symptomatology, or medication dosage. Bipolar patients and their relatives failed to exhibit deficits on the backward masking task. Fragility of early visual percepts appears to mark genetic liability specific to schizophrenia and may serve as an endophenotype for the disorder.
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Affiliation(s)
- Scott R. Sponheim
- Minneapolis Veterans Affairs Health Care System, One Veterans Drive, Minneapolis, MN 55417,Departments of Psychiatry and Psychology, University of Minnesota, Minneapolis, MN,To whom correspondence should be addressed; tel: 612-725-2074, fax: 612-727-5964, e-mail:
| | - Sarah M. Sass
- Department of Psychology, University of Texas at Tyler, Tyler, TX
| | - Althea L. Noukki
- Wisconsin Resource Center, Department of Health Services, Madison, WI
| | - Bridget M. Hegeman
- Minneapolis Veterans Affairs Health Care System, One Veterans Drive, Minneapolis, MN 55417
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Lin SH, Liu CM, Hwang TJ, Hsieh MH, Hsiao PC, Faraone SV, Tsuang MT, Hwu HG, Chen WJ. Performance on the Wisconsin Card Sorting Test in families of schizophrenia patients with different familial loadings. Schizophr Bull 2013; 39:537-46. [PMID: 23196712 PMCID: PMC3627779 DOI: 10.1093/schbul/sbs141] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Despite the consistent presence of performance deficits on the Wisconsin Card Sorting Test (WCST) in schizophrenia patients, whether poorer performance is also present in their nonpsychotic relatives is not certain. This study aimed to estimate both the recurrence risk ratio (λs) and the heritability of WCST scores in simplex and multiplex families, respectively, and to examine the influence of familial loading on these estimates. Participants were patients with schizophrenia and their nonpsychotic first-degree relatives from 168 simplex families and 653 multiplex families as well as 440 normal comparisons. On the basis of adjusted z scores, both the λs at a series of cutoff points and heritability estimates based on variance component modeling in the nonpsychotic relatives of schizophrenia patients were estimated. The WCST deficits in schizophrenia patients were more prominent in multiplex families than in simplex ones. Among relatives, WCST deficits were limited to parents of multiplex families for most WCST scores and siblings from multiplex families for total errors, perseverative responses, and perseverative errors. Pertaining to λs, the estimates for multiplex families (highest estimates ranging from 7.9 to 11.0) were greater than those for simplex ones (<2.5). Nevertheless, the heritability estimates were very similar between simplex (ranging from 0% to 17%) and multiplex (ranging from 0% to 21%) families, with the latter having slightly greater values than the former. There is only a small-to-modest familial aggregation on part of WCST scores in families of schizophrenia patients, and this may limit its use as endophenotypic markers to schizophrenia susceptibility.
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Affiliation(s)
- Sheng-Hsiang Lin
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chih-Min Liu
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Tzung-Jeng Hwang
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ming H. Hsieh
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Po-Chang Hsiao
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan
- Genetic Epidemiology Core Laboratory, Research Center for Medical Excellence, National Taiwan University, Taipei, Taiwan
| | - Stephen V. Faraone
- Department of Psychiatry and Behavioral Sciences, Medical Genetics Research Center, SUNY Upstate Medical University Syracuse, NY
| | - Ming T. Tsuang
- Departments of Epidemiology and Psychiatry, Harvard Institute of Psychiatric Epidemiology and Genetics, Harvard University, Boston, MA
- Center for Behavioral Genomics, Department of Psychiatry, University of California, San Diego, CA
| | - Hai-Gwo Hwu
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan
- Department of Psychology, College of Science, National Taiwan University, Taipei, Taiwan
| | - Wei J. Chen
- Department of Psychiatry, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
- Genetic Epidemiology Core Laboratory, Research Center for Medical Excellence, National Taiwan University, Taipei, Taiwan
- Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
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Yang HC, Liu CM, Liu YL, Chen CW, Chang CC, Fann CSJ, Chiou JJ, Yang UC, Chen CH, Faraone SV, Tsuang MT, Hwu HG. The DAO gene is associated with schizophrenia and interacts with other genes in the Taiwan Han Chinese population. PLoS One 2013; 8:e60099. [PMID: 23555897 PMCID: PMC3610748 DOI: 10.1371/journal.pone.0060099] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 02/22/2013] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Schizophrenia is a highly heritable disease with a polygenic mode of inheritance. Many studies have contributed to our understanding of the genetic underpinnings of schizophrenia, but little is known about how interactions among genes affect the risk of schizophrenia. This study aimed to assess the associations and interactions among genes that confer vulnerability to schizophrenia and to examine the moderating effect of neuropsychological impairment. METHODS We analyzed 99 SNPs from 10 candidate genes in 1,512 subject samples. The permutation-based single-locus, multi-locus association tests, and a gene-based multifactorial dimension reduction procedure were used to examine genetic associations and interactions to schizophrenia. RESULTS We found that no single SNP was significantly associated with schizophrenia. However, a risk haplotype, namely A-T-C of the SNP triplet rsDAO7-rsDAO8-rsDAO13 of the DAO gene, was strongly associated with schizophrenia. Interaction analyses identified multiple between-gene and within-gene interactions. Between-gene interactions including DAO*DISC1 , DAO*NRG1 and DAO*RASD2 and a within-gene interaction for CACNG2 were found among schizophrenia subjects with severe sustained attention deficits, suggesting a modifying effect of impaired neuropsychological functioning. Other interactions such as the within-gene interaction of DAO and the between-gene interaction of DAO and PTK2B were consistently identified regardless of stratification by neuropsychological dysfunction. Importantly, except for the within-gene interaction of CACNG2, all of the identified risk haplotypes and interactions involved SNPs from DAO. CONCLUSIONS These results suggest that DAO, which is involved in the N-methyl-d-aspartate receptor regulation, signaling and glutamate metabolism, is the master gene of the genetic associations and interactions underlying schizophrenia. Besides, the interaction between DAO and RASD2 has provided an insight in integrating the glutamate and dopamine hypotheses of schizophrenia.
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Affiliation(s)
- Hsin-Chou Yang
- Institute of Statistical Science, Academia Sinica, Taipei, Taiwan
| | - Chih-Min Liu
- Department of Psychiatry, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Li Liu
- Division of Mental Health and Substance Abuse Research, National Health Research Institutes, Taipei, Taiwan
| | - Chia-Wei Chen
- Institute of Statistical Science, Academia Sinica, Taipei, Taiwan
| | | | - Cathy S. J. Fann
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Jen-Jie Chiou
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan
| | - Ueng-Cheng Yang
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan
| | - Chun-Houh Chen
- Institute of Statistical Science, Academia Sinica, Taipei, Taiwan
| | - Stephen V. Faraone
- Medical Genetics Research Center and Departments of Psychiatry and Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, New York, United States of America
| | - Ming T. Tsuang
- Harvard Institute of Psychiatric Epidemiology and Genetics, and Departments of Epidemiology and Psychiatry, Harvard University, Boston, Massachusetts, United States of America
- Institute of Behavioral Genomics, University of California San Diego, La Jolla, California, United States of America
| | - Hai-Gwo Hwu
- Department of Psychiatry, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan
- Institute of Epidemiology, College of Public Health, National Taiwan University, Taipei, Taiwan
- Department of Psychology, College of Science, National Taiwan University, Taipei, Taiwan
- Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
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Tsuang MT, Stone WS, Faraone SV. Conceptualization of the liability for schizophrenia: clinical implications. DIALOGUES IN CLINICAL NEUROSCIENCE 2012. [PMID: 22034209 PMCID: PMC3181581 DOI: 10.31887/dcns.1999.1.3/mtsuang] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Historically, the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnostic criteria for schizophrenia have emphasized several features, including symptoms of psychosis, a dissociation of symptoms from their etiology, a reliance on clinical symptoms, and a categorical approach to classifying the disorder. Although these emphases are quite useful, they have limitations. We review these here, and stress the importance of incorporating recent data on the genetic /biological and neurodevelopmental origins of schizophrenia into current conceptions of the disorder. We also review “schizotaxia, ” which is a concept thai embodies this point of view, occurs before the onset of psychosis, and is hypothesized to represent the liability for schizophrenia. If our hypothesis on this point is correct, the identification of schizotaxic individuals will eventually facilitate the development of prevention strategies by identifying a premorbid (but clinically significant) condition for schizophrenia. Moreover, the identification of biological or neuropsychological components of schizotaxia will provide more specific bases for developing novel treatment interventions. Our initial attempts to develop protocols for the assessment and treatment of schizotaxia are encouraging, and will be reviewed.
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Affiliation(s)
- M T Tsuang
- Harvard Medical School Department of Psychiatry at the Massachusetts Mental Health Center and Brockton / West Roxbury Veterans Affairs Medical Center and Harvard Institute of Psychiatric Epidemiology and Genetics, USA; Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
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Neurocognitive and clinical dysfunction in adult Chinese, nonpsychotic relatives of patients with schizophrenia: Findings from the Changsha study and evidence for schizotaxia. Asian J Psychiatr 2012; 5:83-92. [PMID: 22773937 PMCID: PMC3388535 DOI: 10.1016/j.ajp.2011.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many first-degree relatives of patients with schizophrenia demonstrate deficits in neurocognitive, social, clinical and other dimensions, in the absence of psychosis. Based on a reformulation of Meehl's concept of "schizotaxia" as a clinically meaningful syndrome reflecting liability to schizophrenia, we proposed research criteria in relatives focused on negative symptoms and neurocognitive deficits. Here we assess validity of the syndrome in a sample of Chinese adult relatives by assessing measures of concurrent validity, and by using cluster analysis to test the hypothesis that relatives could be grouped into distinct schizotaxic and non-schizotaxic subgroups based on our diagnostic criteria. Thirty community comparison subjects (CCS) and 189 relatives were evaluated with measures of clinical, cognitive, medical and social function at the Mental Health Institute, Second Xiangya Hospital of Central South University, Changsha (Hunan, China), as part of a larger study to identify and ameliorate symptoms of schizotaxia. Using modified research criteria based on negative symptoms and neurocognitive deficits, 103 relatives did not meet criteria for schizotaxia, and 86 did. The cluster analysis confirmed a two-group solution that corresponded to our non-schizotaxic and schizotaxic groups, but it increased the non-schizotaxic group to 135, and reduced the schizotaxic group to 53. Both schizotaxic groups, but especially the cluster-derived group, showed significant impairment in a variety of independent (i.e. non-criterion related) measures of clinical and social function. These findings provide additional validity for a liability syndrome, and for its utility as an intervention target for strategies aimed at ameliorating both its core and its associated symptoms.
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Recent developments in neuropsychological endophenotypes for schizophrenia: Development of the MATRICS battery, liability syndromes and the near future. CHINESE SCIENCE BULLETIN-CHINESE 2011. [DOI: 10.1007/s11434-011-4759-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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15
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Levy DL, Coleman MJ, Sung H, Ji F, Matthysse S, Mendell NR, Titone D. The Genetic Basis of Thought Disorder and Language and Communication Disturbances in Schizophrenia. JOURNAL OF NEUROLINGUISTICS 2010; 23:176. [PMID: 20161689 PMCID: PMC2821112 DOI: 10.1016/j.jneuroling.2009.08.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Thought disorder as well as language and communication disturbances are associated with schizophrenia and are over-represented in clinically unaffected relatives of schizophrenics. All three kinds of dysfunction involve some element of deviant verbalizations, most notably, semantic anomalies. Of particular importance, thought disorder characterized primarily by deviant verbalizations has a higher recurrence in relatives of schizophrenic patients than schizophrenia itself. These findings suggest that deviant verbalizations may be more penetrant expressions of schizophrenia susceptibility genes than schizophrenia. This paper reviews the evidence documenting the presence of thought, language and communication disorders in schizophrenic patients and in their first-degree relatives. This familial aggregation potentially implicates genetic factors in the etiology of thought disorder, language anomalies, and communication disturbances in schizophrenia families. We also present two examples of ways in which thought, language and communication disorders can enrich genetic studies, including those involving schizophrenia.
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Affiliation(s)
- Deborah L Levy
- Psychology Research Laboratory, McLean Hospital, Belmont, MA, USA
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Sung H, Ji F, Levy DL, Matthysse S, Mendell NR. The power of linkage analysis of a disease-related endophenotype using asymmetrically ascertained sib pairs. Comput Stat Data Anal 2009; 53:1829-1842. [PMID: 20160849 DOI: 10.1016/j.csda.2008.08.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A linkage study of a qualitative disease endophenotype in a sample of sib pairs, consisting of one disease affected proband and one sibling is considered. The linkage statistic compares marker allele sharing with the proband in siblings with an abnormal endophenotype to siblings with the normal endophenotype. Expressions for the distribution of this linkage statistic, in terms of the recombination fraction are derived and (1) the genetic parameter values (allele frequency and endophenotype and disease penetrance) and (2) the abnormal endophenotype rates in the population and in classes of relatives of disease affected probands. It is then shown that when either the disease or the abnormal endophenotype has additive penetrance, the expressions simplify to a monotonic function of the difference between abnormal endophenotype rates in siblings and in the population. Thought disorder is considered as a putative schizophrenia endophenotype. Forty sets of genetic parameter values that correspond to the known prevalence values for thought disorder in schizophrenic patients, siblings of schizophrenics and the general population are evaluated. For these genetic parameter values, numerical results show that the test statistic has>70% power (α = 0.0001) in general with a sample of 200 or more proband-sibling pairs to detect the linkage between a marker (θ = 0.01), and a locus pleiotropic for schizophrenia and thought disorder.
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Affiliation(s)
- Heejong Sung
- Genometric Section, IDRB, NHGRI, NIH, Baltimore, MD, USA
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17
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Malhi GS, Green M, Fagiolini A, Peselow ED, Kumari V. Schizoaffective disorder: diagnostic issues and future recommendations. Bipolar Disord 2008; 10:215-30. [PMID: 18199238 DOI: 10.1111/j.1399-5618.2007.00564.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Difficulties surrounding the classification of mixed psychotic and affective syndromes continue to plague psychiatric nosology. This paper addresses the controversy regarding the diagnostic validity of schizoaffective disorder (SAD), a diagnosis that is used in both DSM-IV and ICD-10 and one that encroaches on both schizophrenia (SCZ) and bipolar disorder (BD). METHODS A systematic synthesis of clinical and empirical literature, including evidence from cognitive, neurobiological, genetic, and epidemiological research, was undertaken with the aim of evaluating the utility of the SAD classification. RESULTS Distinctions between the diagnostic categories of SCZ, SAD and BD are not clearly demarcated by findings from neuropsychological, neuroimaging, molecular neurobiology, or genetic epidemiology studies. On the contrary, convergent evidence purports overlap across current diagnostic boundaries in the heritability and pathophysiology of psychotic and affective disorders. However, there are some disorder-specific findings. CONCLUSIONS Schizoaffective disorder is a prototypic boundary condition that epitomizes the pitfalls of the current categorical classification system. Future revisions to the DSM should consider the implementation of one of two alternative models to account for individuals presenting with mixed psychotic and affective symptoms. These include the views that (i) SAD is a comorbid set of symptoms that occur as a by-product of two separate disorders (SCZ and BD) or, that (ii) SAD exists as the mid-point on a continuum between SCZ and BD, such that the incorporation of these two disorders onto one dimension may be a suitable alternative. Hence the category SAD should be omitted in future revisions of DSM, allowing the development of meaningful nomenclature that rests upon further rigorous investigation of differences and similarities between disorders.
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Affiliation(s)
- Gin S Malhi
- Northern Clinical School, University of Sydney, Sydney, Australia.
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18
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Rommelse NN, Altink ME, Martin NC, Buschgens CJ, Faraone SV, Buitelaar JK, Sergeant JA, Oosterlaan J. Relationship between endophenotype and phenotype in ADHD. Behav Brain Funct 2008; 4:4. [PMID: 18234079 PMCID: PMC2267799 DOI: 10.1186/1744-9081-4-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 01/30/2008] [Indexed: 11/15/2022] Open
Abstract
Background It has been hypothesized that genetic and environmental factors relate to psychiatric disorders through the effect of intermediating, vulnerability traits called endophenotypes. The study had a threefold aim: to examine the predictive validity of an endophenotypic construct for the ADHD diagnosis, to test whether the magnitude of group differences at the endophenotypic and phenotypic level is comparable, and to investigate whether four factors (gender, age, IQ, rater bias) have an effect (moderation or mediation) on the relation between endophenotype and phenotype. Methods Ten neurocognitive tasks were administered to 143 children with ADHD, 68 non-affected siblings, and 120 control children (first-borns) and 132 children with ADHD, 78 non-affected siblings, and 113 controls (second-borns) (5 – 19 years). The task measures have been investigated previously for their endophenotypic viability and were combined to one component which was labeled 'the endophenotypic construct': one measure representative of endophenotypic functioning across several domains of functioning. Results The endophenotypic construct classified children with moderate accuracy (about 50% for each of the three groups). Non-affected children differed as much from controls at the endophenotypic as at the phenotypic level, but affected children displayed a more severe phenotype than endophenotype. Although a potentially moderating effect (age) and several mediating effects (gender, age, IQ) were found affecting the relation between endophenotypic construct and phenotype, none of the effects studied could account for the finding that affected children had a more severe phenotype than endophenotype. Conclusion Endophenotypic functioning is moderately predictive of the ADHD diagnosis, though findings suggest substantial overlap exists between endophenotypic functioning in the groups of affected children, non-affected siblings, and controls. Results suggest other factors may be crucial and aggravate the ADHD symptoms in affected children.
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Affiliation(s)
- Nanda Nj Rommelse
- Department of Clinical Neuropsychology, VU University Amsterdam, Van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands.
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19
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Faraone SV, Adamson JJ, Wilens TE, Monuteaux MC, Biederman J. Familial transmission of derived phenotypes for molecular genetic studies of substance use disorders. Drug Alcohol Depend 2008; 92:100-7. [PMID: 17766060 PMCID: PMC2273999 DOI: 10.1016/j.drugalcdep.2007.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 06/28/2007] [Accepted: 07/03/2007] [Indexed: 10/22/2022]
Abstract
Although family, twin, and adoption studies indicate that genes play a significant etiologic role in the development of substance use disorders (SUDs), detecting specific genes has been difficult due to uncertainties about how to define SUDs, genetic heterogeneity and variable phenotypic expression of SUD genotypes. We used data from families recruited into six contemporaneous studies of children and adults to derive candidate SUD phenotypes using principle factors factor analysis with varimax rotation. We previously found evidence of two SUD phenotypes in offspring: a psychopathology dimension and a cognitive impairment dimension. We found evidence for one SUD-related phenotype in adults that we term Psychopathology and Cognitive Impairment. Parental factor scores significantly predicted both offspring phenotypes, as well as parental SUD (OR=1.41, p<0.001) and offspring SUD (mother's phenotype: OR=1.34, p=0.04; father's phenotype: OR=1.33, p=0.01). Offspring phenotype predicted offspring SUD (psychopathology phenotype: OR=2.96, p<0.001; cognitive impairment: OR=1.33, p=0.04); in offspring, baseline psychopathology predicted SUD at follow-up assessments (OR=1.55, p=0.01). Results suggest that these candidate SUD phenotypes may be useful for genetic studies of SUD.
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Affiliation(s)
- Stephen V Faraone
- Department of Psychiatry, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY 13210, USA.
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20
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Abstract
To date, the diagnosis of mental disorders has been based on clinical observation, specifically: the identification of symptoms that tend to cluster together, the timing of the symptoms' appearance, and their tendency to resolve, recur or become chronic. The Diagnostic and Statistical Manual of Mental Disorders and the International Classification of Disease, the manuals that specify these diagnoses and the criteria for making them, are currently undergoing revision. It is thus timely to ask whether neuroscience has progressed to the point that the next editions of these manuals can usefully incorporate information about brain structure and function.
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Affiliation(s)
- Steven E Hyman
- Harvard University, Massachusetts Hall, Cambridge, Massachusetts 02138, USA.
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21
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Liu YL, Fann CSJ, Liu CM, Chang CC, Yang WC, Hung SI, Yu SL, Hwang TJ, Hsieh MH, Liu CC, Tsuang MM, Wu JY, Jou YS, Faraone SV, Tsuang MT, Chen WJ, Hwu HG. More evidence supports the association of PPP3CC with schizophrenia. Mol Psychiatry 2007; 12:966-74. [PMID: 17339875 DOI: 10.1038/sj.mp.4001977] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Calcineurin is a calcium/calmodulin-dependent protein phosphatase composed of two subunits, a regulatory subunit of calcineurin B (CNB) and a catalytic subunit of calcineurin A (CNA). PPP3CC is the gamma isoform of CNA located at the chromosome 8p21.3 region. To evaluate the association between PPP3CC and schizophrenia in the Taiwanese population, 10 single nucleotide polymorphism (SNP) markers across the gene were genotyped by the method of MALDI-TOF in 218 schizophrenia families with at least two affected siblings. One SNP (rs2272080) located around the exon 1 untranslated region was nominally associated with schizophrenia (P=0.024) and significantly associated with the expression of PPP3CC in lymphoblast cell line; the TT and TG genotype had significantly higher relative expression levels than the GG genotype (P=0.0012 and 0.015, respectively). In further endophenotype stratification, the single locus of rs2272080 and the haplotypes of both two-SNP haplotype (rs7833266-rs2272080) and seven-SNP haplotype (rs2461491-rs2469758-rs2461489-rs2469770-rs2449340-rs1482337-rs2252471) showed significant associations with the subgroup of schizophrenia with deficits of the sustained attention as tested by the continuous performance test (CPT, P<0.05) and the executive functioning as tested by the Wisconsin Card Sorting Test (WCST, P<0.05). The results suggest that PPP3CC gene may be a true susceptibility gene for schizophrenia.
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Affiliation(s)
- Y L Liu
- Division of Mental Health and Substance Abuse Research, National Health Research Institutes, Taipei, Taiwan
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22
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Rybakowski JK, Drozdz W, Borkowska A. Long-term administration of the low-dose risperidone in schizotaxia subjects. Hum Psychopharmacol 2007; 22:407-12. [PMID: 17597479 DOI: 10.1002/hup.863] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The term schizotaxia is currently defined as a syndrome of neuropsychological deficits and negative symptoms found in relatives of schizophrenic patients. The aim of this study was to assess the effect of long-term treatment with the low-dose risperidone on cognitive and social functioning in seven schizotaxia patients. There were four males and three females, aged between 17 and 44 years, first-degree (four patients) or second-degree (three patients) relatives of schizophrenic patients. Schizotaxia was recognized in them on account of neuropsychological and social function impairment. They all consented to risperidone administration, 1-2 mg/day. Duration of risperidone treatment has ranged between 3-7 years. In all subjects, the continuous treatment with risperidone brought about a marked improvement in their cognitive, social, and vocational functioning. Neuropsychological testing after 6-24 months showed significant improvement on such tests as Wisconsin Card Sorting Test (WCST), Trail Making Test (TMT), and Stroop Test. Discontinuation of treatment after 3-4 years did not cause deterioration of functioning.
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Affiliation(s)
- Janusz K Rybakowski
- Department of Adult Psychiatry, Poznan University of Medical Sciences, Poznan, Poland.
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23
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Szatmari P, Maziade M, Zwaigenbaum L, Mérette C, Roy MA, Joober R, Palmour R. Informative phenotypes for genetic studies of psychiatric disorders. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:581-8. [PMID: 17219386 DOI: 10.1002/ajmg.b.30426] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Despite its initial promise, there has been both progress and some set backs in genetic studies of the major psychiatric disorders of childhood and adulthood. Finding true susceptibility genes may be delayed because the most genetically informative phenotypes are not being used on a regular basis in linkage analysis and association studies. It is highly likely that using alternative phenotypes instead of DSM diagnostic categories will lead more rapid success in the search for these susceptibility genes. The objective of this paper is to describe the different types of informative phenotypes that can be employed in psychiatric genetic studies, to clarify their uses, to identify several methodologic issues the design and conduct of linkage and association studies that use alternative phenotypes and finally to suggest possible solutions to those difficulties. This is a conceptual review with a focus on methodological issues that may arise in psychiatric genetics and examples are taken from the literature on autism, schizophrenia, bipolar disorder, and alcoholism.
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Affiliation(s)
- Peter Szatmari
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada.
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24
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Faraone SV, Adamson JJ, Wilens TE, Monuteaux MC, Biederman J. Deriving phenotypes for molecular genetic studies of substance use disorders: a family study approach. Drug Alcohol Depend 2007; 88:244-50. [PMID: 17141426 DOI: 10.1016/j.drugalcdep.2006.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 10/31/2006] [Accepted: 11/01/2006] [Indexed: 11/18/2022]
Abstract
Although, family, twin, and adoption studies indicate that genes play a significant etiologic role in the development of substance use disorders (SUDs), the specific genes involved have been difficult to detect due, in part, to uncertainties about how best to define SUDs, the possibility of genetic heterogeneity and the variable phenotypic expression of SUD genotypes. The goal of the present work was to determine if phenotypes external to the diagnosis of SUD such as psychopathology and cognitive functioning would show evidence of utility as phenotypes for genetic studies of SUD. We did this by applying factor analysis to multiple measures collected from our family-study program and then determining if these factors were heritable and were co-familial with SUDs. We used data from families recruited into six contemporaneous studies of four psychiatric conditions in children and adults. We found evidence for two SUD related phenotypes. One was an index of Psychopathology and Psychosocial Impairment; the other was an index of school failure and cognitive dysfunction. Both factors showed evidence of heritability, longitudinal stability and familial association with Parental SUD but these findings were stronger for the index of school failure and cognitive dysfunction. Results provide some support for the idea that candidate SUD phenotypes such as psychopathology and cognitive functioning, which are external to the diagnostic criteria for SUDs, may be useful for genetic studies of SUD.
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Affiliation(s)
- Stephen V Faraone
- Department of Psychiatry, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
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25
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Braff DL, Freedman R, Schork NJ, Gottesman II. Deconstructing schizophrenia: an overview of the use of endophenotypes in order to understand a complex disorder. Schizophr Bull 2007; 33:21-32. [PMID: 17088422 PMCID: PMC2632293 DOI: 10.1093/schbul/sbl049] [Citation(s) in RCA: 346] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The genetics of schizophrenia has been approached utilizing a variety of methods. One emerging strategy is the use of endophenotypes in order to understand and identify the functional importance of genetically transmitted, brain-based deficits across schizophrenia kindreds. The endophenotype strategy is a topic of this issue of Schizophrenia Bulletin. Endophenotypes are quantitative, heritable, trait-related deficits typically assessed by laboratory-based methods rather than clinical observation. Endophenotypes are seen as closer to genetic variation than are clinical symptoms of schizophrenia, and are therefore closely linked to heritable risk factors. There has been a broad expansion of opportunities available to psychiatric neuroscientists who use the endophenotype strategy to understand the genetic basis of schizophrenia. In this context, genetic variation such as single nucleotide polymorphisms (SNPs) induces abnormalities in endophenotypic domains such as neurocognition, neurodevelopment, metabolism, and neurophysiology. This article discusses the challenges that abound in genetic research of schizophrenia, including issues in ascertainment, epistasis, ethnic diversity, and the potentially normalizing effects of second-generation antipsychotic medications on neurocognitive and neurophysiological measures. Robust strategies for meeting these challenges are discussed in this review and the subsequent articles in this issue. This article summarizes conceptual advances and progress in the measurement and use of endophenotypes in schizophrenia that form the basis of the multisite National Institute of Mental Health Consortium on the Genetics of Schizophrenia. The endophenotype strategy offers powerful and exciting opportunities to understand the genetically conferred neurobiological vulnerabilities and possible new strong inference and molecularly based treatments for schizophrenia.
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Affiliation(s)
- David L Braff
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, Mail Code 0804, La Jolla, CA 92093, USA.
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26
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Lin CCH, Su CH, Kuo PH, Hsiao CK, Soong WT, Chen WJ. Genetic and Environmental Influences on Schizotypy among Adolescents in Taiwan: A Multivariate Twin/sibling Analysis. Behav Genet 2006; 37:334-44. [PMID: 16967335 DOI: 10.1007/s10519-006-9104-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Accepted: 07/31/2006] [Indexed: 12/01/2022]
Abstract
This study aimed to examine the relative contribution of genes and environment to psychometrically measured schizotypy and the causes for the covariation between different dimensions of schizotypy in a total of 330 pairs of twins and 36 same-sex sib-pairs aged 12-16 and systematically recruited from junior high schools in Taipei. Twins' zygosity was determined by a combination of DNA typing and physical similarity. Schizotypy was measured using the Perceptual Aberration Scale (PAS) as well as the Schizotypal Personality Questionnaire (SPQ) and its three factors (Cognitive-perceptual Dysfunction, Disorganization, and Interpersonal Dysfunction). Univariate analyses of structural equation modeling using Mx program showed that scores on these schizotypal measures were substantially heritable (h (2) ranging from 41 to 49%), with some genetic effects being non-additive. Multivariate analyses revealed common genetic factors linking between various traits of schizotypy, with bivariate heritability ranging from 50 to 65%. The proportion of the genetic contributions not shared with the other measures of schizotypy ranged from 24% for the Disorganization to 49% for the PAS scores. We concluded that there exist both common and specific genetic factors between the various dimensions of schizotypy, and at least half of their correlations were genetic in nature.
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Affiliation(s)
- Chaucer C H Lin
- Department of Psychiatry, Buddhist Tzu Chi General Hospital and University, Hualien, Taiwan
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27
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Abstract
This study examined whether the probabilistic reasoning bias referred to as a "jumping-to-conclusions" (JTC) style of reasoning, which, according to previous research, is associated with particular psychotic symptoms such as delusions, represents a trait that can also be detected in nonpsychotic relatives of patients with schizophrenia and in nonpsychotic individuals with a high level of psychotic experiences. Participants were, in order of level of psychosis liability, 40 patients with schizophrenia or a schizoaffective disorder, 40 first-degree nonpsychotic relatives, 41 participants from the general population with above average expression of psychotic experiences, and 53 participants from the general population with an average level of psychotic experiences. A "jumping-to-conclusions" bias was assessed using the beads task. A dose-response relationship was found in the association between level of psychosis liability and JTC (defined as needing only a single bead to complete the beads task) (odds ratio [OR] linear trend = 1.59, 95% CI: 1.13-2.24), and, independently, alinear association was apparent between JTC and level of delusional ideation (OR linear trend = 2.59, 95% CI: 1.18-5.69). In addition, the association between psychosis liability and JTC was generally much stronger as the level of delusional ideation was higher. JTC is associated with liability to psychosis (trait), in particular if the psychosis phenotype is characterized by delusional ideation (state).
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Affiliation(s)
- Frank Van Dael
- Department of Psychiatry and Neuropsychology, Maastricht University, The Netherlands
| | | | | | | | | | - Lydia Krabbendam
- Department of Psychiatry and Neuropsychology, Maastricht University, The Netherlands
- To whom correspondence should be addressed; e-mail:
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Snitz BE, Macdonald AW, Carter CS. Cognitive deficits in unaffected first-degree relatives of schizophrenia patients: a meta-analytic review of putative endophenotypes. Schizophr Bull 2006; 32:179-94. [PMID: 16166612 PMCID: PMC2632195 DOI: 10.1093/schbul/sbi048] [Citation(s) in RCA: 481] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cognitive deficits may index genetic liability for schizophrenia and are candidate endophenotypes for the illness. In order to compare the degree of sensitivity among cognitive tasks to group differences between healthy relatives and controls and the influence of moderator variables, this review reports mean effect sizes for 43 cognitive test scores from 58 studies of cognitive performance in the unaffected adult relatives of schizophrenia patients. Results indicate reliable relative-control differences, in the small to medium effect size range, over a diverse array of tasks, with the largest effect sizes seen in complex versions of continuous performance tasks, auditory verbal learning, design copy tests, and category fluency. Three study design features were found to have significant effects on overall effect size magnitude: groups unmatched on education, groups unmatched on age, and asymmetric psychiatric exclusion criteria. After excluding studies with the latter 2 design features, reliable performance differences were still observed over a smaller subset of cognitive test variables, with the largest effect sizes seen in Trails B (d = 0.50) and performance measures from both simple (d = 0.56) and complex (d = 0.60-0.66) versions of continuous performance tasks. Four of the 6 largest effect sizes reflect tasks with high executive control demands in common, such as working memory demands, set shifting, and inhibition of prepotent responses. Cognitive deficits, particularly those tapping such executive control functions, should continue to prove valuable as endophenotypes of interest in the search for specific genetic factors related to schizophrenia.
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Affiliation(s)
- Beth E Snitz
- Department of Psychiatry, University of Pittsburgh, 3811 O'Hara Street, Pittsburgh, PA 15213, USA.
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29
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Doyle AE, Faraone SV, Seidman LJ, Willcutt EG, Nigg JT, Waldman ID, Pennington BF, Peart J, Biederman J. Are endophenotypes based on measures of executive functions useful for molecular genetic studies of ADHD? J Child Psychol Psychiatry 2005; 46:774-803. [PMID: 15972070 DOI: 10.1111/j.1469-7610.2005.01476.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Behavioral genetic studies provide strong evidence that attention-deficit/hyperactivity disorder (ADHD) has a substantial genetic component. Yet, due to the complexity of the ADHD phenotype, questions remain as to the specific genes that contribute to this condition as well as the pathways from genes to behavior. Endophenotypes, or phenotypes that are more closely linked to the neurobiological substrate of a disorder, offer the potential to address these two issues simultaneously (Freedman, Adler, & Leonard, 1999). Thus far, potential endophenotypes for ADHD have not been systematically studied. METHOD The current paper reviews evidence supporting the use of deficits on neurocognitive measures of executive functions for this purpose. RESULTS Such deficits are a correlate of ADHD and show preliminary evidence of heritability and association with relevant candidate genes. Nonetheless, studies that have assessed the familial and genetic overlap of neurocognitive impairments with ADHD have yielded inconsistent results. CONCLUSIONS In order for executive function deficits to be used as an endophenotype for ADHD, we recommend greater attention to the neurocognitive heterogeneity of this disorder and to the precision of measurement of the neuropsychological tests employed. We also discuss empirical strategies that may be necessary to allow such research to progress prior to full resolution of the pathophysiological basis of ADHD.
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Affiliation(s)
- Alysa E Doyle
- Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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30
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Stone WS, Faraone SV, Seidman LJ, Olson EA, Tsuang MT. Searching for the liability to schizophrenia: concepts and methods underlying genetic high-risk studies of adolescents. J Child Adolesc Psychopharmacol 2005; 15:403-17. [PMID: 16092907 DOI: 10.1089/cap.2005.15.403] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Conceptualizations of the liability for schizophrenia help guide the development of research protocols, which, in turn, provide empirical confirmations or disconfirmations of the conceptualization's tenets. This paper focuses on a conception of liability and its relationships to genetic adolescent high-risk studies. Specifically, the derivation and nature of a proposed multidimensional syndrome of liability to schizophrenia ("schizotaxia") are outlined, followed by a representative review of features reported in previous high-risk studies that may be related to schizotaxia, and a perspective on future high-risk investigations. Overall, genetic high-risk studies generally confirm the concept of liability in the offspring of parents with schizophrenia, as expressed by deficits or abnormalities in multiple dimensions. It is concluded that high-risk studies on the liability to schizophrenia provide an important tool with which to explore the etiology and development of schizophrenia, in part by contributing to the identification and validation of specific liability syndromes.
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Affiliation(s)
- William S Stone
- Harvard Medical School Department of Psychiatry, Massachusetts Mental Health Center, Boston, MA 02115, USA.
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31
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Doyle AE, Willcutt EG, Seidman LJ, Biederman J, Chouinard VA, Silva J, Faraone SV. Attention-deficit/hyperactivity disorder endophenotypes. Biol Psychiatry 2005; 57:1324-35. [PMID: 15950005 DOI: 10.1016/j.biopsych.2005.03.015] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Revised: 03/09/2005] [Accepted: 03/09/2005] [Indexed: 01/21/2023]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable disorder with a multifactorial pattern of inheritance. For complex conditions such as this, biologically based phenotypes that lie in the pathway from genes to behavior may provide a more powerful target for molecular genetic studies than the disorder as a whole. Although their use in ADHD is relatively new, such "endophenotypes" have aided the clarification of the etiology and pathophysiology of several other conditions in medicine and psychiatry. In this article, we review existing data on potential endophenotypes for ADHD, emphasizing neuropsychological deficits because assessment tools are cost effective and relatively easy to implement. Neuropsychological impairments, as well as measures from neuroimaging and electrophysiological paradigms, show correlations with ADHD and evidence of heritability, but the familial or genetic overlap between these constructs and ADHD remains unclear. We conclude that these endophenotypes will not be a quick fix for the field but offer potential if careful consideration is given to issues of heterogeneity, measurement and statistical power.
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Affiliation(s)
- Alysa E Doyle
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA.
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van Rijn S, Aleman A, Swaab H, Kahn RS. Neurobiology of emotion and high risk for schizophrenia: role of the amygdala and the X-chromosome. Neurosci Biobehav Rev 2005; 29:385-97. [PMID: 15820545 DOI: 10.1016/j.neubiorev.2004.11.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 10/28/2004] [Accepted: 11/12/2004] [Indexed: 11/18/2022]
Abstract
Abnormalities in emotion processing and in structure of the amygdala have consistently been documented in schizophrenia. A major question is whether amygdala abnormalities reflect a genetic vulnerability for the disease. In the present paper, we reviewed Magnetic Resonance Imaging (MRI) studies that reported amygdala measures in several high-risk populations: subjects from the general population with subclinical schizophrenia symptoms and relatives of schizophrenia patients. In addition, we reviewed the evidence regarding Klinefelter syndrome (characterised by an additional X-chromosome), which has also been related to an increased risk for schizophrenia. Overall, the evidence points to structural abnormalities of the amygdala in individuals at increased risk for schizophrenia. Although the genetic basis of amygdala deficits remains unclear, abnormalities (of genes) on the X-chromosome might play a role as suggested by the evidence from individuals with sex chromosome aneuploidies. We propose that amygdala abnormalities are an endophenotype in schizophrenia and may account for subtle emotional processing deficits that have been described in these high-risk groups.
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Affiliation(s)
- Sophie van Rijn
- Department of Psychiatry, Rudolf Magnus Institute for Neuroscience, University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht, The Netherlands.
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Sporn A, Greenstein D, Gogtay N, Sailer F, Hommer DW, Rawlings R, Nicolson R, Egan MF, Lenane M, Gochman P, Weinberger DR, Rapoport JL. Childhood-onset schizophrenia: smooth pursuit eye-tracking dysfunction in family members. Schizophr Res 2005; 73:243-52. [PMID: 15653267 DOI: 10.1016/j.schres.2004.07.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Revised: 07/09/2004] [Accepted: 07/12/2004] [Indexed: 11/19/2022]
Abstract
BACKGROUND Childhood-onset schizophrenia (COS), a severe form of the disorder, is of interest for etiologic studies. Smooth pursuit eye-tracking dysfunction (ETD) is a biological marker for schizophrenia. AIMS To compare familial eye-tracking abnormalities for COS and adult-onset schizophrenia (AOS). METHOD Eye-tracking performance for 70 COS parents, 64 AOS parents and 20 COS siblings was compared to their respective age-matched control groups. RESULTS COS and AOS parents had higher rate of dichotomously rated eye-tracking dysfunction than their respective controls (16% vs. 1% and 22% vs. 4%, respectively). COS parents and siblings also differed from controls on several continuous measures. However, scores for COS, AOS and control groups overlapped extensively. CONCLUSIONS Genetic factors underlying eye-tracking dysfunction appear more salient for COS. However, eye-tracking measures have to be used with caution for endophenotypic definition due to low predictive power. DECLARATION OF INTEREST The study was done at the National Institutes of Health.
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Affiliation(s)
- Alexandra Sporn
- Child Psychiatry Branch, National Institute of Mental Health, National Institute of Health, Bldg 10, Rm 3N202, Bethesda, MD 20892, USA.
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Subotnik KL, Asarnow RF, Nuechterlein KH, Fogelson DL, Thorpe TI, Payne DL, Giannini CA, Kuppinger HE, Torquato RD, Mintz J, Hwang SS, Gottesman II. MMPI Vulnerability Indicators for Schizophrenia and Attention Deficit Disorder: UCLA Family Study of Biological Parents of Offspring with Childhood-Onset Schizophrenia or ADHD. Behav Genet 2005; 35:159-75. [PMID: 15685429 DOI: 10.1007/s10519-004-1016-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2002] [Accepted: 08/15/2004] [Indexed: 11/29/2022]
Abstract
Minnesota Multiphasic Personality Inventory (MMPI) scores were examined for 50 parents of children with an onset of schizophrenia prior to 14 years of age, 153 parents of children with attention deficit hyperactivity disorder (ADHD), and 168 parents of community comparison children. The parents were participants in the UCLA Family Study. The mean scores on all standard MMPI scales were within normal limits for all three groups of participants. Parents of schizophrenia probands were significantly higher on scale Sc than parents of community comparison children. Previous research has shown that scale Sc may be associated with a genetic liability to developing schizophrenia. Thus, scale Sc shows promise as an indicator of a heightened risk for the development of schizophrenia. The parents of the ADHD probands were significantly higher on standard clinical scale Pd than community comparison parents. Mothers of both schizophrenia and ADHD probands shared some personality indicators of stress reactivity. Although this study, like all non-adoptee family studies, cannot disentangle genetic effects on the development of these personality characteristics from environmental effects, we speculate that the emotional distress resulting in higher levels of the MMPI characteristics seen in the patients' mothers reflects the impact of raising a psychiatrically ill offspring.
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Affiliation(s)
- Kenneth L Subotnik
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA 90095-6968, USA.
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Sitskoorn MM, Ebisch SJH, Appels M, Nuyen J, Kahn RS. Memory profiles in parents of patients with schizophrenia. Psychiatry Res 2004; 128:27-37. [PMID: 15450912 DOI: 10.1016/j.psychres.2004.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2003] [Revised: 04/09/2004] [Accepted: 05/22/2004] [Indexed: 11/22/2022]
Abstract
Recent research shows that categorizing patients with schizophrenia based on frontal-striatal and frontal-temporal memory profiles may yield neurobiologically meaningful disease subtypes. We hypothesize that parents of patients exhibit similar memory profiles. Both parents of 36 patients with schizophrenia (N = 72) and 26 healthy married control couples (N = 52) participated in this study. All subjects were physically healthy and had no history of neurological illness or alcohol/drug abuse. The presence of a psychiatric and/or personality disorder was assessed with the Comprehensive Assessment of Symptoms and History (CASH) interview, the Schedule for Affective Disorders and Schizophrenia-lifetime (SADS-L) interview and the Structured Interview for DSM-IV Personality Disorders (SIDP-IV), respectively. Cluster analysis of selected measures from the Dutch version of the California Verbal Learning Test (CVLT) delineated parents into two subgroups with distinct memory deficits and a third subgroup without impairments. Specific frontal-striatal and frontal-temporal subgroups, however, were not found. In addition, our results indicated that mothers seem to be more protected against the negative effects of genetic liability to schizophrenia than fathers. Furthermore, relatives with a higher level of intelligence may have more cognitive reserve to compensate for the negative impact of implied brain dysfunction on verbal memory than relatives with a low level of intelligence. Although the parents of patients with schizophrenia could be delineated into subgroups with primary memory deficits, frontal-striatal and frontal-temporal subgroups could not be unambiguously identified. The association that emerged between level of intelligence, gender and severity of memory impairment deserves further exploration.
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Affiliation(s)
- Margriet M Sitskoorn
- Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, PO Box 85500, 3508 GA, The Netherlands.
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Chen WJ, Chang CH, Liu SK, Hwang TJ, Hwu HG. Sustained attention deficits in nonpsychotic relatives of schizophrenic patients: a recurrence risk ratio analysis. Biol Psychiatry 2004; 55:995-1000. [PMID: 15121483 DOI: 10.1016/j.biopsych.2004.01.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Revised: 01/07/2004] [Accepted: 01/09/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND In nonpsychotic parents and siblings of schizophrenic patients, the recurrence risk ratios of sustained attention deficits, as measured by the continuous performance test (CPT), were examined with a series of cut-off points. METHODS Among 116 parents and 95 siblings of 91 schizophrenic probands in northern Taiwan, both undegraded and degraded sessions of the CPT were administered. Subjects' signal detection sensitivity of CPT performance (d') was standardized against a community sample without (unadjusted z score) or with (adjusted z score) adjustment for age, gender, and educational level. RESULTS Differences in the risk ratios between the parents and siblings that were based on the unadjusted z scores of CPT d' diminished markedly if the adjusted z scores were used. As the cut-off point in the adjusted z score decreased from -2.5 to -3.0, the risk ratio increased continually for both the undegraded (10.1-18.8 for parents, 10.0-16.7 for siblings) and degraded (12.4-102.7 for parents, 8.6-72.0 for siblings) test. CONCLUSIONS Stringent cut-off criteria of CPT deficits with adjustment for demographic features leads to recurrence risk ratios greater than those based on schizophrenia alone in both parents and siblings of schizophrenic patients.
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Affiliation(s)
- Wei J Chen
- Institute of Epidemiology, College of Public Health, National Taiwan University, Taipei, Taiwan
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Stassen HH, Bridler R, Hell D, Weisbrod M, Scharfetter C. Ethnicity-independent genetic basis of functional psychoses: a genotype-to-phenotype approach. Am J Med Genet B Neuropsychiatr Genet 2004; 124B:101-12. [PMID: 14681924 DOI: 10.1002/ajmg.b.20081] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The functional psychoses schizophrenia, schizoaffective disorder, and bipolar illness represent complex clinical syndromes that are characterized by phenotypic heterogeneity. Yet evidence from numerous studies suggests that (1) the prevalence of schizophrenia and bipolar illness is with 1% very similar across ethnicities, and (2) a strong genetic component is involved in the disorders' pathogenesis. Using data from different US-American ethnicities (77 families with a total of 17 unaffected and 170 affected sib pairs; 276 marker loci), we searched for ethnicity-independent oligogenic susceptibility loci for which the between-sib genetic similarity in affected sib pairs deviated from the expected values. Specifically, we addressed the question of the extent to which genetic risk factors and their interactions constitute multigenic inheritance of functional psychoses across populations and might constitute universal targets for treatment. Our novel multivariate genotype-to-phenotype search strategy was based on a genetic similarity function that allowed us to quantify the inter-individual genetic distances d(x(i), x(j)) between the allelic genotype patterns x(i), x(j) of any two subjects i, j with respect to n loci l(1), l(2), em leader l(n). Thus, we were able to assess the between-ethnicity, the within-ethnicity, and the within-family genetic similarities. The problem of ethnicity-independent vulnerability was addressed by treating the Afro-American families as "training" samples, while the non-Afro-American families served as independent "test" samples. We evaluated the between-sib similarities, which were expected to deviate from "0.5" in affected sib pairs if the region of interest contained markers close to vulnerability genes. The reference value "0.5" was derived from the parent-offspring similarities that are always 0.5, irrespective of the affection status of parents and offspring. We found 12 vulnerability loci on chromosomes 1, 4, 5, 6, 13, 14, 18, and 20, that were reproducible across the two samples under comparison and therefore, likely to constitute an ethnicity-independent, oligogenic vulnerability model of functional psychoses. The elevated vulnerability appeared to be unspecific and to act in such a way that exogenous factors become more likely to trigger the onset of psychiatric illnesses.
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Affiliation(s)
- H H Stassen
- Psychiatric University Hospital, Zurich, Switzerland.
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Appels MCM, Sitskoorn MM, Westers P, Lems E, Kahn RS. Cognitive dysfunctions in parents of schizophrenic patients parallel the deficits found in patients. Schizophr Res 2003; 63:285-93. [PMID: 12957707 DOI: 10.1016/s0920-9964(02)00342-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Schizophrenia is characterized by a global cognitive impairment, with varying degrees of deficit in all ability domains. Since genetic factors are important in the etiology of schizophrenia we investigated whether parents of schizophrenic patients also show cognitive deficits, particularly on those cognitive ability domains that are most severely affected in patients. Both biological parents of 37 patients with schizophrenia (N=74 subjects) and 28 comparable healthy married control couples (N=56 subjects) were included. A comprehensive and standardized cognitive battery was used including tests measuring verbal memory, executive functioning, language, attention, and psychomotor functioning. Parents of patients differed from control couples on those cognitive constructs that are generally considered to be most impaired in schizophrenic patients, i.e. global verbal memory, bilateral motor skill, continuous performance, and word fluency. In addition, parents differed significantly from control couples on some other cognitive constructs on which patients show a smaller but also significant difference compared to healthy controls, i.e. unilateral motor skill and digit span. Results suggest that the cognitive constructs on which patients show relatively most severe impairment may prove suitable as endophenotypic markers in schizophrenia.
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Affiliation(s)
- Melanie C M Appels
- Department of Psychiatry, University Medical Center, PO Box 85500, 3508 GA, Utrecht, The Netherlands.
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Sponheim SR, Iacono WG, Thuras PD, Nugent SM, Beiser M. Sensitivity and specificity of select biological indices in characterizing psychotic patients and their relatives. Schizophr Res 2003; 63:27-38. [PMID: 12892855 DOI: 10.1016/s0920-9964(02)00385-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Although studies have detailed biological abnormalities in schizophrenia patients and their first-degree biological relatives, few studies have directly compared the utility of biological indices in these individuals. METHODS Measures of global smooth-pursuit ocular motor (OM) function, low frequency and alpha band electroencephalogram (EEG) power, and nonspecific fluctuations (NSF) in electrodermal activity and visibility of the plexus in the nailfold were collected from 136 schizophrenia patients and 67 of their first-degree biological relatives, 71 affective disorder psychotic patients and 68 of their first-degree biological relatives, and 169 nonpsychiatric comparison subjects. We conducted receiver operator characteristic (ROC) analyses to determine how well each index differentiated the patient groups and the groups of first-degree relatives. RESULTS Smooth-pursuit ocular motor function, low frequency and alpha band EEG power, and nailfold plexus visibility differentiated schizophrenia patients from nonpsychiatric comparison subjects. Nailfold plexus visibility was the only measure that significantly differentiated schizophrenia patients from both nonpsychiatric controls and affective patients. Smooth-pursuit ocular motor function and the number of electrodermal nonspecific fluctuations differentiated relatives of schizophrenia patients from nonpsychiatric comparison subjects. CONCLUSION Increased nailfold plexus visibility may mark a process associated with abnormal brain development leading to schizophrenia. Smooth-pursuit dysfunction may mark genetic vulnerability that is relatively specific to schizophrenia.
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Affiliation(s)
- Scott R Sponheim
- Veterans Affairs Medical Center, 116B One Veterans Drive, Minneapolis, MN 55417, USA.
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Takahashi S, Cui YH, Kojima T, Han YH, Yu SY, Tanabe E, Yara K, Matsuura M, Matsushima E, Nakayama J, Arinami T, Shen YC, Faraone SV, Tsuang MT. Family-based association study of the NOTCH4 gene in schizophrenia using Japanese and Chinese samples. Biol Psychiatry 2003; 54:129-35. [PMID: 12873802 DOI: 10.1016/s0006-3223(02)01731-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND A family based association study in a British sample found the NOTCH4 gene to be associated with schizophrenia; however, all six replication studies failed to confirm the finding. METHODS We performed a family based association study of NOTCH4 and schizophrenia in 123 trios (16 Japanese and 107 Chinese). In addition to the original study's polymorphisms, we examined four new single nucleotide polymorphisms (SNPs)--SNPs_A, B, C and D--around SNP1 of the original study. We genotyped all samples for SNPs_A-D and for SNP1 and (CTG)n of the original study. RESULTS We found no significant associations between NOTCH4 and schizophrenia or its subtypes for all polymorphisms, regardless of gender. The finding remained negative when the Chinese sample was analyzed separately. Exploratory analyses suggested that SNP_A may be associated with early-onset schizophrenia and that SNP1 may be associated with schizophrenia characterized by numerous negative symptoms. CONCLUSIONS NOTCH4 is not a significant susceptibility gene for schizophrenia when clinical heterogeneity is ignored; however, NOTCH4 may be associated with early-onset schizophrenia or schizophrenia with many negative symptoms, but these findings should be interpreted cautiously.
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Affiliation(s)
- Sakae Takahashi
- Department of Psychiatry, Massachusetts Mental Health Center, Harvard Medical School, Boston, Massachusetts 02115, USA
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Abstract
Schizophrenia is a biologic disorder whose etiology involves a combination of genetic and environmental risk factors. In this review, the authors update the conceptual basis of schizotaxia, consider evidence for its validity, and look toward its likely evolution in the future.
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Affiliation(s)
- Ming T Tsuang
- Department of Psychiatry at the Massachusetts Mental Health Center, Harvard Medical School, 74 Fernwood Road, Boston, MA 02115, USA.
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Chen WJ, Faraone SV. Sustained attention deficits as markers of genetic susceptibility to schizophrenia. AMERICAN JOURNAL OF MEDICAL GENETICS 2003; 97:52-7. [PMID: 10813804 DOI: 10.1002/(sici)1096-8628(200021)97:1<52::aid-ajmg7>3.0.co;2-6] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This article reviews recent evidence regarding the potential of the visual sustained attention deficits as measured by the Continuous Performance Test (CPT) as an endophenotype of the genetic susceptibility to schizophrenia. Findings in community subjects indicate that sustained attention develops during the primary school ages, reaches its maximum around early adolescence, and declines with age after adulthood. The assertion that CPT performance deficits, and especially on the more difficult versions, are reliable and valid genetic susceptibility indicators of schizophrenia is supported by the following results: 1) CPT deficits are present in schizophrenic patients, are particularly associated with negative and disorganized symptoms, and deficits on the more difficult CPT versions are not amenable to neuroleptic treatment; 2) subjects with schizotypal personality features also exhibit CPT deficits, which are specifically associated with the negative factor of schizotypy; 3) a substantial proportion of nonpsychotic relatives of schizophrenic patients (19-34%) have CPT deficits, which can also be predicted from their probands' CPT performance. Thus, using a CPT deficits as an endophenotype of schizophrenia would not only provide a valuable measure of genetic risk, but would also greatly enhance our understanding of etiology, and may help identify susceptibility genes for schizophrenia.
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Affiliation(s)
- W J Chen
- Institute of Epidemilogy, College of Public Health, National Taiwan University, Taipei, Taiwan
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Affiliation(s)
- M T Tsuang
- Harvard Institute of Psychiatric Epidemiology and Genetics and Superintendent and Head, Harvard Department of Psychiatry at Massachusetts Mental Health Center, USA
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Calkins ME, Iacono WG. Eye movement dysfunction in schizophrenia: a heritable characteristic for enhancing phenotype definition. AMERICAN JOURNAL OF MEDICAL GENETICS 2003; 97:72-6. [PMID: 10813807 DOI: 10.1002/(sici)1096-8628(200021)97:1<72::aid-ajmg10>3.0.co;2-l] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The occurrence of ocular motor dysfunction in schizophrenia patients and their first-degree biological relatives is remarkably consistent, suggesting that abnormal smooth pursuit and saccadic oculomotion are heritable characteristics that can be used to identify gene carriers for schizophrenia. Saccadic system dysfunction probably reflects a generalized deficit in prefrontal cortical functioning, rather than a specific deficit in saccade system functioning. Although abnormal smooth pursuit has also been associated with impaired frontal functioning, it is unclear whether these two types of dysfunction arise from the same neural pathology. Therefore, deviant smooth pursuit and saccadic oculomotion may constitute unrelated factors identifying two different types of genetic risk. Alternatively, they may derive from a single risk factor that causes (a) both types of deficits to be expressed together or (b) each type to be expressed separately as pleiotropic manifestations of the underlying genotype. Although a full complement of pursuit and saccade measures has not been examined together in family studies of schizophrenia, there is obvious value in determining how these measures relate to one another in schizophrenia families and whether they can be used in combination to enhance phenotype definition to facilitate the search for schizophrenia susceptibility genes.
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Affiliation(s)
- M E Calkins
- Clinical Science and Psychopathology Research Traing Program , University of Minnesota, MN 55455-0344l, USA.
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Faraone SV, Seidman LJ, Kremen WS, Kennedy D, Makris N, Caviness VS, Goldstein J, Tsuang MT. Structural brain abnormalities among relatives of patients with schizophrenia: implications for linkage studies. Schizophr Res 2003; 60:125-40. [PMID: 12591577 DOI: 10.1016/s0920-9964(02)00304-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Several studies suggest that the nonschizophrenic relatives of schizophrenic patients exhibit structural brain abnormalities that may be manifestations of genes that predispose to schizophrenia. In this work, we examine the utility of such measures for linkage analyses. Subjects were 45 nonpsychotic first-degree adult relatives of schizophrenic patients and 48 normal controls. Sixty contiguous 3-mm coronal, T1-weighted 3D magnetic resonance images of the entire brain were acquired on a 1.5-T magnet. We used factor analysis to derive MRI-based phenotypes for analysis. The factor analyses produced three factors that significantly discriminated relatives from controls. We used a linear combination of the three factor scores to derive an MRI phenotype. A receiver operating characteristic (ROC) analysis of this phenotype estimated an area under the curve (AUC) statistic of 0.85. The phenotype also discriminated nonpsychotic relatives having two schizophrenic relatives from those having only one. The nonpsychotic relatives of schizophrenic patients show deviant values on MRI measures of brain structure and the distribution of these deviations among relatives and controls suggests that if these results can be replicated, an MRI-derived phenotype could be useful for genetic linkage and association analyses.
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Affiliation(s)
- Stephen V Faraone
- Harvard Medical School Department of Psychiatry at the Massachusetts Mental Health Center, Boston, MA, USA.
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Tsuang MT, Stone WS, Tarbox SI, Faraone SV. Treatment of nonpsychotic relatives of patients with schizophrenia: six case studies. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 114:943-8. [PMID: 12457391 DOI: 10.1002/ajmg.10363] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ming T Tsuang
- Harvard Medical School, Department of Psychiatry at Massachusetts Mental Health Center, Boston 02115, USA.
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Abstract
Because of the paucity of research on the OCSDs, it seems premature to cluster these putative disorders together in DSM, to combine delusional and nondelusional variants of OCSDs, or to classify OCSDs dimensionally. Further investigation of the OC spectrums is clearly needed. These constructs are powerful and useful heuristics with potential validity and clinical utility. The putative OC spectrum and its subspectrums have some apparent advantages over current conceptualizations of these disorders. They may prove more consistent with empirical evidence and ultimately may be shown to better reflect these disorders' pathogenesis. Importantly, they also may be more useful and valid guides for clinical practice.
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Affiliation(s)
- Katharine A Phillips
- Department of Psychiatry and Human Behavior, Brown University School of Medicine, Body Dysmorphic Disorder Program, Butler Hospital, Providence, RI 02906, USA.
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Myles-Worsley M, Park S. Spatial working memory deficits in schizophrenia patients and their first degree relatives from Palau, Micronesia. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 114:609-15. [PMID: 12210274 DOI: 10.1002/ajmg.10644] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Spatial working memory deficits associated with dorsolateral prefrontal dysfunction have been found in Caucasian samples of schizophrenia patients and their first-degree relatives. This study evaluated spatial working memory function in affected and unaffected members of multiplex schizophrenia families from the Republic of Palau to determine whether the spatial working memory deficits associated with schizophrenia extend to this non-Caucasian population. Palau is an isolated island nation in Micronesia with an elevated prevalence of schizophrenia and an aggregation of cases in large multigenerational families. Our objective was to evaluate the potential for spatial working memory function to serve as one of multiple endophenotypes in a genetic linkage study of these Palauan schizophrenia families. A spatial delayed response task requiring resistance to distraction and a sensorimotor control task were used to assess spatial working memory in 32 schizophrenia patients, 28 of their healthy first-degree relatives, and 19 normal control subjects. Schizophrenia patients and their relatives were significantly less accurate than normal control subjects on the spatial delayed response task but not on the sensorimotor control task. On both tasks, patients and relatives were slower to respond than the normal controls. There were no age or gender effects on accuracy, and working memory performance in schizophrenia patients was not significantly correlated with medication dosage. In summary, spatial working memory deficits that have been found in Caucasian schizophrenia patients and relatives were confirmed in this isolated Pacific Island family sample. These results suggest that spatial working memory deficits may be a potentially useful addition to the endophenotypic characterization of family members to be used in a comprehensive genome wide linkage analysis of these Palauan families.
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Affiliation(s)
- Marina Myles-Worsley
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA.
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Tsuang MT, Faraone SV. Diagnostic concepts and the prevention of schizophrenia. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2002; 47:515-7. [PMID: 12211878 DOI: 10.1177/070674370204700602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Tsuang MT, Stone WS, Faraone SV. Understanding predisposition to schizophrenia: toward intervention and prevention. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2002; 47:518-26. [PMID: 12211879 DOI: 10.1177/070674370204700603] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Early intervention to prevent schizophrenia is one of the most important goals of schizophrenia research. However, the field is not yet ready to initiate trials to prevent prodromal or psychotic symptoms in people who are at risk for developing the disorder. In this paper, we consider some of the major obstacles that must be studied before prevention strategies become feasible. METHOD AND RESULTS One of the most important hurdles is the identification of a syndrome or set of traits that reflects a predisposition to schizophrenia and that might provide potential targets for intervention. In a recent reformulation of Paul Meehl's concept of schizotaxia, we integrate research findings obtained over the last 4 decades to propose a syndrome with meaningful clinical manifestations. We review the conceptualization of this syndrome and consider its multidimensional clinical expression. We then describe preliminary research diagnostic criteria for use in adult, nonpsychotic, first-degree relatives of patients diagnosed with schizophrenia, based on negative symptoms and neuropsychological deficits. We follow this with evidence supporting the validity of the proposed syndrome, which mainly includes social dysfunction and response to a low dosage of one of the newer antipsychotic medications. CONCLUSIONS Continued progress toward the eventual initiation of prevention strategies for schizophrenia will include sustained efforts to validate the traits reflecting a predisposition to develop the disorder (for example, schizotaxia), follow-up studies to confirm initial findings, and the identification of potentially useful preventive interventions.
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Affiliation(s)
- Ming T Tsuang
- Harvard Medical School Department of Psychiatry, Massachusetts Mental Health Center, 74 Fenwood Rd, Boston, MA 02115, USA.
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