Molecular linkage studies of bipolar disorders

Mental health symptoms and inflammatory markers among HIV infected patients in Tanzania

Background

HIV and mental disorders are predicted to be the leading causes of illness worldwide by the year 2030. HIV-infected patients are at increased risk of developing mental disorders which are significantly associated with negative clinical outcomes and propagation of new HIV infections. There is little evidence that links inflammation to development of mental disorders among HIV patients. Therefore, the main objective of this study was to evaluate if mental health symptoms were associated with biomarkers of inflammation in HIV infected subjects.

Methods

A cross-sectional study was conducted in Dar es Salam, Tanzania from March to May 2018. Standardized tools were used to collect data based on the World Health Organisation's (WHO) stepwise approach for non-communicable diseases (NCD) surveillance. A total of 407 HIV+ patients on antiretroviral therapy were recruited. The WHO stepwise approach for NCD surveillance was used to collect data together with anthropometric measurements. Mental health symptoms were determined based on self-reported thoughts of helplessness, suicide ideation, depression, despair, discouragement, and feelings of isolation. Enzyme-linked immunosorbent assay was used to test for inflammatory markers:- C-reactive protein (CRP), Iinterleukin-6 (IL-6), interleukin-18 (IL-18), soluble tumour necrosis factor receptor-I (sTNFR-I), and soluble tumour necrosis factor receptor-II (sTNFR-II). Bivariate and multi-variate analysis was conducted to examine the association between biomarkers and mental health symptoms.

Results

The prevalence of self-reported mental health symptoms was 42% (n = 169). Participants with self-reported symptoms of mental health had elevated CRP, were less likely to walk or use a bicycle for at least 10 minutes, were less likely to participate in moderate-intensity sports or fitness activities, and had poor adherence to HIV treatment (p < 0.005). CRP remained significant in the sex adjusted, age-sex adjusted, and age-sex-moderate exercise adjusted models. In the fully adjusted logistic regression model, self-reported mental health symptoms were significantly associated with a higher quartile of elevated CRP (OR 4.4; 95% CI 1.3–5.9) and sTNFR-II (OR 2.6; 95% CI 1.4–6.6) and the third quartile of IL-18 (OR 5.1;95% CI 1.5–17.5) as compared with those reporting no mental health symptoms. The significance of sTNFR-II and IL-18 in the fully adjusted model is confounded by viral load suppression rates at the sixth month.

Conclusion

High CRP and sTNFR II were important contributors to the prevalence of mental health symptoms. This study is among the minimal studies that have examined mental health issues in HIV, and therefore, the findings may offer significant knowledge despite the potential reverse causality. Regardless of the nature of these associations, efforts should be directed toward screening, referral, and follow-up of HIV patients who are at-risk for mental health disorders.

A hypothesis-driven pathway analysis reveals myelin-related pathways that contribute to the risk of schizophrenia and bipolar disorder

Schizophrenia (SZ) and bipolar disorder (BD) are both severe neuropsychiatric disorders with a strong and potential overlapping genetic background. Multiple lines of evidence, including genetic studies, gene expression studies and neuroimaging studies, have suggested that both disorders are closely related to myelin and oligodendrocyte dysfunctions. In the current study, we hypothesized that the holistic effect of the myelin-related pathway contributes to the genetic susceptibility to both SZ and BD. We extracted pathway data from the canonical pathway database, Gene Ontology (GO), and selected a 'compiled' pathway based on previous literature. We then performed hypothesis-driven pathway analysis on GWAS data from the Psychiatric Genomics Consortium (PGC). As a result, we identified three myelin-related pathways with a joint effect significantly associated with both disorders: 'Myelin sheath' pathway (P(SZ) = 2.45E-7, P(BD) = 1.22E-3), 'Myelination' pathway (P(SZ) = 2.10E-4, P(BD) = 2.53E-24), and 'Compiled' pathway (P(SZ) = 4.57E-8, P(BD) = 2.61E-9). In comparing the SNPs and genes in these three pathways across the two diseases, we identified a substantial overlap in nominally associated SNPs and genes, which could be susceptibility SNPs and genes for both disorders. From these observations, we propose that myelin-related pathways may be involved in the etiologies of both SZ and BD.

[Polymorphism in the Serotonin Transporter Gene (SLC6A4) and Emotional Bipolar Disorder in Two Regional Mental Health Centers from the Eje Cafetero (Colombia)]

INTRODUCTION

The indel polymorphisms in the promoting region and the 2(nd) intron polymorphisms in the serotonin transporter gene (SLC6A4) have been associated to bipolar disorder 1 (BD1) in several population studies. The objective was to analyze the genotypic and allelic frequencies in both gene regions in a study of cases and controls with individuals from Risaralda and Quindío (Colombia) so as to establish possible associations to BD1, and compare results with previous and similar studies.

METHODS

133 patients and 120 controls were studied. L and S indel polymorphisms in the promoting region were analyzed by PCR, together with VNTR STin2.10 and STin 2.12 VNTRs polymorphisms in the 2(nd) intron of the SL-C6A4 gene

RESULTS

Genotypic and allelic frequencies for the S and L polymorphisms were similar both in cases and controls. However, the LL genotype was significantly increased both in BD1 population (OR=1.89; CI95%=1.1-3.68), and when discriminated by gender. This particular genotype in general population is OR=2.22; IC95%=1.04-5.66 for women, and OR=1.62; IC 95%=0.71-4.39 for men. No significant genotypic and allelic differences were found for VNTR STin2.10 and STin 2.12. polymorphisms.

CONCLUSIONS

No association was found between polymorphisms of 5-HTTLPR polymorphisms and the 2(nd) intron of the serotonin transporting gene in general patients with BD1, nor when compared by gender. Our results are similar to those reported for Caucasian populations and differ from those of Asian and Brazilian populations.

Behavioral genetics of affective and anxiety disorders

As shown by clinical genetic studies, affective and anxiety disorders are complex genetic disorders with genetic and environmental factors interactively determining their respective pathomechanism. Advances in molecular genetic techniques including linkage studies, association studies, and genome-wide association studies allow for the detailed dissection of the genetic influence on the development of these disorders. Besides the molecular genetic investigation of categorical entities according to standardized diagnostic criteria, intermediate phenotypes comprising neurobiological or neuropsychological traits (e.g., neuronal correlates of emotional processing) that are linked to the disease of interest and that are heritable, have been proposed to be closer to the underlying genotype than the overall disease phenotype. These intermediate phenotypes are dimensional and more precisely defined than the categorical disease phenotype, and therefore have attracted much interest in the genetic investigation of affective and anxiety disorders. Given the complex genetic nature of affective and anxiety disorders with an interaction of multiple risk genes and environmental influences, the interplay of genetic factors with environmental factors is investigated by means of gene-environment interaction (GxE) studies. Pharmacogenetic studies aid in the dissection of the genetically influenced heterogeneity of psychotropic drug response and may contribute to the development of a more individualized treatment of affective and anxiety disorders. Finally, there is some evidence for genetic factors potentially shared between affective and anxiety disorders pointing to a possible overlapping phenotype between anxiety disorders and depression.

Phospholipid profile in the postmortem hippocampus of patients with schizophrenia and bipolar disorder: no changes in docosahexaenoic acid species

Previous studies with postmortem brain tissues showed abnormalities not only in n-3 long-chain polyunsaturated fatty acids (PUFA) but also in phospholipid metabolism in the cortex of individuals with schizophrenia and mood disorder. In this study we investigated whether there is similar abnormality in n-3 long-chain PUFAs and/or in phospholipid profile in the hippocampus of schizophrenia and bipolar disorder patients compared to unaffected controls. Using high-performance liquid chromatography/electrospray ionization-mass spectrometry (LC/MS), the phospholipid contents in the postmortem hippocampus from 35 individuals with schizophrenia, 34 individuals with bipolar disorder and 35 controls were evaluated. Unlike the previous findings form orbitofrontal cortex, we found no significant differences in either n-3 long-chain PUFA or total phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylcholine (PC). However, docosapentaenoic acid (n-6, 22:5n-6)-PS and 22:5n-6-PC were significantly lower in individuals with schizophrenia or bipolar disorder than the controls. When fatty acid contents were estimated from PS, PE and PC, 22:5n-6 was significantly lower in both patient groups compared to the controls. From these results we concluded that DHA loss associated with these psychiatric disorders may be specific to certain regions of the brain. The selective decrease in 22:5n-6 without affecting DHA contents suggests altered lipid metabolism, particularly n-6 PUFA rather than n-3 PUFA, in the hippocampus of individuals with schizophrenia or bipolar disorder.

Genetic research into bipolar disorder: the need for a research framework that integrates sophisticated molecular biology and clinically informed phenotype characterization

Research into the genetic basis of bipolar disorder (BD) has reached a turning point. Genome-wide association studies (GWAS), encompassing several thousand samples, have produced replicated evidence for some novel susceptibility genes; however, the genetic variants implicated so far account for only a fraction of disease liability, a phenomenon not limited to psychiatric phenotypes but characteristic of all complex genetic traits studied to date. It appears that pure genomic approaches, such as GWAS alone, will not suffice to unravel the genetic basis of a complex illness like BD. Genomic approaches will need to be complemented by a variety of strategies, including phenomics, epigenomics, pharmacogenomics, and neurobiology, as well as the study of environmental factors. This review highlights the most promising findings from recent GWAS and candidate gene studies in BD. It furthermore sketches out a potential research framework integrating various lines of research into the molecular biological basis of BD.

Bipolar disorder preceded by substance abuse: a different phenotype with not so poor outcome?

BACKGROUND

The co-occurrence of bipolar disorder and substance use is frequent. The question whether substance use precedes, induces or follows bipolar disorder is still unresolved. Substance use has been typically represented as a negative prognostic factor for the clinical course of bipolar illness and it has been associated with decreased compliance and treatment resistance. To extend these previous findings we examined the clinical course and outcome of patients with bipolar disorder I or II whose bipolar onset was preceded by substance/alcohol use.

METHODS

The impact of substance use as a predisposing or precipitating factor of a bipolar episode was evaluated by comparing a group of bipolar subjects whose mood symptomatology onset was preceded by substance/alcohol use (N=145) (SUBP) with a similar sized representative sample of bipolar patients (either substance users/abusers or not using substances) whose first mood episode was unrelated to substance use (N=144) (NSUBP). RESULTS; The analysis of clinical and socio-demographic variables revealed that patients in the SUBP group showed less severe psychopathology, as indicated by fewer total hypomanic and depressive episodes during the course of their illness. Depressive onset was less frequent amongst the SUBP group. SUBP patients, compared to NSUBP, were poorly compliant to treatment.

CONCLUSIONS

Bipolar disorder preceded by substance misuse may represent a clinically milder subtype of bipolar illness. This subtype would be less "primary" and might be more early targeted by primary prevention with programmes focused on substance misuse.

Multivariate genomewide linkage scan of neurocognitive traits and ADHD symptoms: suggestive linkage to 3q13

Family and twin studies suggest that a range of neurocognitive traits index the inherited liability to ADHD; however, the utility of such measures as endophenotypes in molecular genetic studies remains largely untested. The current article examined whether the inclusion of neurocognitive measures in a genomewide linkage analysis of ADHD could aid in identifying QTL linked to the behavioral symptoms of the condition. Data were from an affected sibling pair linkage study of DSM-IV ADHD conducted at Massachusetts General Hospital. The sample included 1,212 individuals from 271 families. ADHD symptoms were assessed with the K-SADS-E. The neurocognitive battery included Wechsler Intelligence Scales subtests, the Stroop, the Wisconsin Card Sorting Test (WCST), the Rey-Osterreith Complex Figure, a working memory CPT, the CVLT and WRAT-III subscales. Evidence for linkage was assessed using a simulation-based method that combines information from univariate analyses into the equivalent of a multivariate test. After correction for multiple trait testing, a region on chromosome 3q13 showed suggestive linkage to all neurocognitive traits examined and inattention symptoms of ADHD. The second highest peak occurred on 22q12 but showed linkage to a single subscale of the WCST. In univariate analysis, this region retained criteria for suggestive linkage to this measure after correction for multiple trait testing. Our primary findings raise the possibility that one or more genes on 3q13 influence neurocognitive functions and behavioral symptoms of inattention. Overall, these data support the utility of neurocognitive traits as ADHD endophenotypes, but also highlight their limited genetic overlap with the disorder.

Genetics of bipolar disorder

Bipolar disorder, especially the most severe type (type I), has a strong genetic component. Family studies suggest that a small number of genes of modest effect are involved in this disorder. Family-based studies have identified a number of chromosomal regions linked to bipolar disorder, and progress is currently being made in identifying positional candidate genes within those regions, À number of candidate genes have also shown evidence of association with bipolar disorder, and genome-wide association studies are now under way, using dense genetic maps. Replication studies in larger or combined datasets are needed to definitively assign a role for specific genes in this disorder. This review covers our current knowledge of the genetics of bipolar disorder, and provides a commentary on current approaches used to identify the genes involved in this complex behavioral disorder.

Schizoaffective disorder: diagnostic issues and future recommendations

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.

Disorders of thought are severe mood disorders: the selective attention defect in mania challenges the Kraepelinian dichotomy a review

Kraepelin said severe mental illness was due to 2 diseases subsequently characterized as disorders of thought vs disorders of mood, ie, the Kraepelinian dichotomy. Schizophrenia, traditionally considered the disorder of thought, has been defined by the presence of hallucinations, delusions, catatonia, and disorganization. Tangentiality, derailment, loose associations, and thought blocking are typically considered pathognomonic of schizophrenia. By contrast, the mood disorders have been characterized only as disorders of the emotions, though both depression and mania, when severe, are now recognized to include the same psychotic features traditionally considered diagnostic of schizophrenia. This article addresses disordered thinking in mania in order to clarify the relationship between schizophrenia and psychotic mood disorders. Normally, the brain's selective attention mechanism filters and prioritizes incoming stimuli by excluding from consciousness extraneous, low-priority stimuli and grading the importance of more relevant data. Because this "filter/prioritizer" becomes defective in mania, tangential stimuli are processed without appropriate prioritization. Observed as distractibility, this symptom is an index of the breakdown in selective attention and the severity of mania, accounting for the signs and symptoms of psychotic thinking. The zone of rarity between schizophrenia and psychotic mood disorders is blurred because severe disorders of mood are also disorders of thought. This relationship calls into question the tenet that schizophrenia is a disease separate from psychotic mood disorders. Patients whose case histories are discussed herein gave their written informed consent to participate in this institutional human subjects committee-approved protocol.

Genome-wide scan of bipolar disorder and investigation of population stratification effects on linkage: support for susceptibility loci at 4q21, 7q36, 9p21, 12q24, 14q24, and 16p13

Bipolar disorder (BPD) is a complex genetic disorder with cycling symptoms of depression and mania. Despite the extreme complexity of this psychiatric disorder, attempts to localize genes which confer vulnerability to the disorder have had some success. Chromosomal regions including 4p16, 12q24, 18p11, 18q22, and 21q21 have been repeatedly linked to BPD in different populations. Here we present the results of a whole genome scan for linkage to BPD in an Irish population. Our most significant result was at 14q24 which yielded a non-parametric LOD (NPL) score of 3.27 at the D14S588 marker with a nominal P-value of 0.0006 under a narrow (bipolar type I only) model of affection. We previously reported linkage to 14q22-24 in a subset of the families tested in this analysis. We also obtained suggestive evidence for linkage at 4q21, 9p21, 12q24, and 16p13, chromosomal regions that have all been previously linked to BPD. Additionally, we report on a novel approach to linkage analysis, STRUCTURE-Guided Linkage Analysis (SGLA), which is designed to reduce genetic heterogeneity and increase the power to detect linkage. Application of this technique resulted in more highly significant evidence for linkage of BPD to three regions including 16p13, a locus that has been repeatedly linked to numerous psychiatric disorders.

The effect of previous psychotic mood episodes on cognitive impairment in euthymic bipolar patients

OBJECTIVES

Cognitive dysfunctions in several domains were proposed to be trait markers of bipolar patients. The aim of this study was to evaluate the effect of previous psychotic features on neuropsychological measures, including sustained attention, in remitted bipolar patients.

METHODS

The study participants were 40 euthymic psychotic, 25 non-psychotic bipolar I patients and 30 healthy control subjects. Participants were assessed with a battery of neuropsychological tests targeting attention, executive functions, psychomotor speed, verbal learning and memory.

RESULTS

Euthymic psychotic bipolar patients performed worse than controls on most of the measures, after controlling for the confounding effects of education, age and residual symptoms. Non-psychotic patients were also impaired on tasks of attention, fluency and psychomotor speed. 'Number of Wisconsin Card Sorting Test (WCST) categories' achieved was the only measure on which psychotic patients performed significantly worse compared to non-psychotic patients. Differences among patient groups were not explained by illness severity measures. The duration of illness was related to slowness in psychomotor speed tasks. Verbal memory deficits may be related to serum lithium levels and age of onset of disease.

CONCLUSIONS

Deficits in cognitive flexibility may be a candidate for being a trait marker of psychotic features among bipolar patients. However, verbal fluency, psychomotor speed and sustained attention deficits may be candidates for vulnerability indicators of bipolar disorder in general.

Schizoaffective disorder merges schizophrenia and bipolar disorders as one disease--there is no schizoaffective disorder

PURPOSE OF REVIEW

Schizoaffective disorder was named as a compromise diagnosis in 1933, and remains popular as judged by its place in the International Classification of Diseases and the Diagnostic and Statistical Manual of Mental Disorders, its frequent use in clinical practice, and its extensive discussion in the literature. Some, however, have questioned the validity of schizoaffective disorder as separate from psychotic mood disorder. We examined the literature to assess the rationale for the continuation of schizoaffective disorder as a legitimate diagnostic category.

RECENT FINDINGS

The diagnosis of schizoaffective disorder depends on the disease specificity of the diagnostic criteria for schizophrenia; however, the psychotic symptoms for schizophrenia, traditionally held as specific, can be accounted for by psychotic bipolar. Further, the interrater reliability for diagnosing schizoaffective disorder is very low. A recent and expanding body of comparative evidence from a wide range of clinical and basic science studies, especially genetic, reveals multiple similarities between schizoaffective disorder, schizophrenia and psychotic bipolar.

SUMMARY

Schizoaffective disorder unifies schizophrenia and bipolar, blurring the zones of rarity between them and suggesting that schizoaffective disorder is not a separate, 'bona-fide' disease. Patients diagnosed with schizoaffective disorder likely suffer from a psychotic mood disorder. The diagnosis of schizoaffective disorder, which can result in substandard treatment, should be eliminated from the diagnostic nomenclature.

The schizophrenias, the neuroses and the covered wagon; a critical review

OBJECTIVE

In order to compare their validity, this review applies scientific standards for sustaining the neuroses, the schizophrenias and bipolar disorders as separate "bona-fide" psychiatric diseases. The standards for disease validation demand specific and unique symptoms.

METHOD

We review a wide variety of clinical and basic science comparisons between schizophrenia and psychotic bipolar in a select English-language literature.

RESULTS

Like covered wagons, the neuroses once served us well but became obsolete and were discarded or reorganized based on what was known about commonalities of symptoms, causation and pharmacological responsivity. Bipolar patients meet unique and specific diagnostic criteria and demonstrate consistent results across a variety of scientific disciplines. Neither the neuroses nor the schizophrenias have such unique or disease specific diagnostic criteria. Psychotic mood disorders account for the DSM diagnostic criteria for schizophrenia. A recent, selected but diverse basic science literature demonstrates surprising similarities between schizophrenia and psychotic bipolar which should not exist if these disorders are distinct.

CONCLUSIONS

Like the neuroses, there is stigma, confusion and misunderstanding about the condition called schizophrenia, resulting in substantial negative impact on bipolar patients misdiagnosed as having schizophrenia. The psychoses, including the schizophrenias, likely are explained by a single disease, psychotic bipolar disorder, that has demonstrated a wide spectrum of severity of symptoms and chronicity of course, not traditionally recognized.

Chromosomal fragile site expression in Turkish psychiatric patients

Chromosomal aberrations associated with psychiatric disorders may suggest regions in which to focus a search for genes predisposing to psychosis by a linkage strategy. Identification of these may be especially important given the unknown pathophysiology and the probable genetic heterogeneity of psychiatric disorders. In this study, the frequencies of folate sensitive fragile sites (FS) were compared among psychiatric disorders (e.g., schizophrenia, bipolar disorder, and other psychosis) and normal individuals. The rate of FS expression in the patients was considerably higher than in the controls. Sites 1p22, 1q21, 1q32, 2q31, 3p14, 3p25, 5q22, 5q31, 6p21, 6q21, 6q25, 7q22, 7q32, 8q22, 10q21, 11q23, 12q24, 13q32, 14q24, 16q22, 17q21, Xp22 and Xq26 were expressed more frequently in the patients. Thirty possible relevant chromosomal sites were identified in schizophrenia: 1q21, 1q32, 2p13, 2q21, 3p14, 3p25, 3q21, 5q22, 5q31, 6p21, 6q25, 6q26, 7q21, 7q22, 7q32, 8q22, 9q21, 10q21, 11q23, 12q24, 13q32, 14q24, 16q22, 17q21, Xp22, Xq22, and Xq26. Possible relevant sites were also identified in bipolar disorder: sites 1p36, 1q21, 1q32, 3p14, 3p25, 5q31, 7q22, 7q32, 11q23, 12q24, 13q32, 14q24, Xp22, and Xq26. Sites in the other psychosis group were: 1p22, 1p32, 1p36, 1q21, 1q32, 2q31, 3p14, 3p25, 5q31, 6p21, 6q21, 6q25, 6q26, 7q22, 7q32, 8q22, 10q21, 11q23, 12q13, 12q24, 13q32, 16q22, 16q24, 17q21 and Xq26. Among patient groups, there were significant differences in bands 1p32, 2p13, 2q21, 2q31, 3p14, 3p25, 5q31, 6q21, 6q26, 7q22, 7q32, 9q21, 11qq23, 12q13, 12q24, 16q24, and Xq22 between schizophrenic and bipolar patients. These regions were more frequently expressed in schizophrenic patients than in bipolar patients. The 1p22, 1p32, and 16q24 regions were significantly more frequently expressed in the other psychosis group than in the bipolar group. These interesting regions, which may harbor important genes for psychosis, have produced strong support for linkage in the majority of genome scan projects.

Association study of adenosine A2a receptor (1976C>T) genetic polymorphism and mood disorders and age of onset

Evidence suggests that the adenosine A2a receptor (A2aAR) may be implicated in the pathogenesis of mood disorders. We tested the hypothesis that the A2aAR 1976C>T genetic variant confers susceptibility to mood disorders by comparing 192 mood disorder patients and 216 normal controls. The distribution of the A2aAR genotypes and alleles did not differ significantly comparing the two groups, suggesting that it is unlikely that the A2aAR 1976C>T polymorphism plays a major role in the development of mood disorders.

Schizoaffective disorders are psychotic mood disorders; there are no schizoaffective disorders

Schizoaffective disorder (SA D/O), introduced in 1933 by Dr. Jacob Kasanin, represented a first, modest change in our concept about the diagnoses of psychotic patients away from the beliefs of E. Bleuler, i.e., that hallucinations and delusions define schizophrenia, and toward the recognition of a significant role for mood disorders. SA D/O established a connection between schizophrenia and mood disorders, traditionally considered mutually exclusive, a connection that has strengthened progressively toward the diagnostic unity of all three disorders. A basic tenet of medicine holds that if discrepant symptoms can be explained by one disease instead of two or more, it is likely there is only one disease. The scientific justification for SA D/O and schizophrenia as disorders distinct from a psychotic mood disorder has been questioned. The "schizo" prefix in SA D/O rests upon the presumption that the diagnostic symptoms for schizophrenia are disease specific. They are not, since patients with severe mood disorders can evince any or all of the "schizophrenic" symptoms. "Schizophrenic" symptoms mean "psychotic" and not any specific disease. These data and a very low interrater reliability for SA D/O suggest that the concepts of SA D/O and schizophrenia as valid diagnoses are flawed. Clinically SA D/O remains popular because it encompasses both schizophrenia and psychotic mood disorder when there is a diagnostic question. We present a review of the literature in table form based on an assignment of each article assigned to one of five categories that describe the possible relationships between SA D/O, schizophrenia and psychotic mood disorders. We conclude that the data overall are compatible with the hypothesis that a single disease, a mood disorder, with a broad spectrum of severity, rather than three different disorders, accounts for the functional psychoses.

Early onset bipolar disorder: possible linkage to chromosome 9q34

OBJECTIVES

Bipolar disorder (BD) is characterized by manic and depressive states that onset at various times in life. Research shows that early onset forms of BD are associated with a stronger genetic loading for the illness. We hypothesized that using age at onset to look at subsets of BD families in a genetic linkage analysis would prove useful in separating etiologically homogeneous BD sub-groups and subsequently identifying genetic susceptibility regions.

METHODS

We used the wave-I National Institute of Mental Health (NIMH) Genetics Initiative BD sample, which includes 540 individuals from 97 families with BD, in an ordered-subsets linkage analysis with age at onset of mania as the subset-identifying covariate. This analysis was performed using GENEHUNTER-PLUS followed by the ordered-subsets analysis program. This program generates empirical p-values for the subset with the largest LOD score to determine whether this value was significantly higher than the baseline LOD score using all families.

RESULTS

Three chromosomal regions resulted in LOD scores above 2.0: 2.21 (6q25), 3.21 (9q34), and 2.16 (20q11). The largest increase in LOD score was observed on chromosome 9q34 between markers D9S290 and D9S915 in the subset of 58 families that had mania onset before age 20. Families with a minimal mania onset less than 20 years had a significantly greater number of psychiatric comorbidities (p = 0.02) and a marginal increase in depressive symptoms (p = 0.10).

CONCLUSIONS

Further investigation into chromosomal region 9q34 is necessary to determine whether this region may harbor a gene specific to families with a minimal age at onset of less than 20.

Bipolar affective disorder: advances in genetics and mood-stabilising medication

The lifetime prevalence of bipolar affective disorder is between 1 % and 2%. This educational review paper focuses on two areas of interest and relevance to trainees preparing for the membership examination of the Royal College of Psychiatrists: (a) advances in the genetics of bipolar affective disorder; and (b) mood-stabilising medication in bipolar affective disorder.

Excitement and confusion on chromosome 6q: the challenges of neuropsychiatric genetics in microcosm

The search for genes that are implicated in the pathogenesis of schizophrenia (SCZ), bipolar disorder (BPD) and other complex neuropsychiatric phenotypes has yielded a plethora of positive findings, but has also engendered a substantial degree of confusion. Exciting findings include positive linkage results in a number of chromosomal regions and the identification of several genes that have been associated with SCZ and to a lesser extent with BPD. Confusing aspects include the difference between studies in localization of linkage peaks in the same chromosomal regions, raising the possibility that these regions may harbor more than one gene, the fact that positive linkage findings as well as associated genes appear in several cases to be shared by more than one disorder, and the failure to identify thus far the precise pathogenic variants in associated genes. Recent findings of linkage and association studies on chromosome 6q illustrate the current status of neuropsychiatric genetics in intriguing microcosm. Positive findings from linkage and association studies are reviewed in order to identify approaches that may help to settle apparent contradictions and allow an interpretation of the results that may prove useful in application to findings from other chromosomal regions. Not only SCZ and BPD but also other psychiatric and neurological phenotypes are considered. Taking a topographic approach, we identify five foci of positive findings on chromosome 6q and suggest that each may harbor gene(s) that confer susceptibility to SCZ or BPD or may modify their onset or clinical course. We further suggest that in searching for these genes the possibility that they may be implicated in more than one disorder should be taken into account. We also discuss the potential contribution of rare genetic variants identified in homogeneous, isolated populations to the subsequent identification of common variants in the same gene that contribute to disease susceptibility in outbred populations.

Family, twin, adoption, and molecular genetic studies of juvenile bipolar disorder

Juvenile bipolar disorder (JBD) has been a subject of significant research and debate. Phenotypic differences between JBD and adult-onset bipolar disorder have led researchers to question whether or not similar neuropathologic mechanisms will be found. While much is known about the genetic and environmental contributions to the adult-onset phenotype, less is known about their contributions to JBD. Here, we review family, twin, adoption, and molecular genetic studies of JBD. Behavioral genetic data suggest both genetic and environmental contributions to JBD, while molecular genetic studies find linkage to age of onset of bipolar disorder to chromosomes 12p, 14q, and 15q. Additionally, changes associated with symptom age of onset have been recently reported in the brain-derived neurotrophic factor (BDNF) and glycogen synthase kinase 3-beta (GSK3-beta) genes. We contend that further progress in discovering the precise genetic and environmental contributions to JBD may depend on advances in phenotypic refinement, an increased appreciation of comorbid conditions, and more investigation of the longitudinal course of the disorder.

Schizophrenia: update on genetics, cognitive behavioural therapy and early intervention

There have been considerable advances in the understanding of schizophrenia in recent years. This educational review paper focuses on three areas of interest and relevance to trainees preparing for the membership examination of the Royal College of Psychiatrists (MRCPsych): (a) recent advances in the genetics of schizophrenia; (b) advances in cognitive behavioural therapy in schizophrenia; and (c) advances in early intervention strategies for schizophrenia. Relevant papers and systematic reviews are discussed, and recommendations for further reading are provided.

A genome-wide scan of symptom dimensions in bipolar disorder pedigrees of adult probands

Although twin and adoption show bipolar disorder (BP) has a strong genetic component, few chromosomal regions have been consistently implicated by molecular genetic studies. To address this issue, we sought to determine if quantitative dimensions of bipolar disorder symptoms would be useful for detecting genes that underlie the susceptibility to bipolar disorder. Subjects were 520 individuals diagnosed with bipolar I, bipolar II or schizoaffective disorder, bipolar type who had participated in the NIMH genetics initiative for bipolar disorder. We constructed symptom scores from 29 psychiatric symptoms recorded in the Diagnostic Interview for Genetic Studies (DIGS). Principal components factor analysis followed by a varimax rotation was used to extract symptom dimensions. Factor scores were calculated for all genotyped individuals in the sample, regardless of affection status. Heritable factors were used in a variance-components linkage analysis, which utilized the exact likelihoods of allele-sharing identical-by-descent for each pair of relatives within each pedigree. The principal components factor analysis resulted in five independent dimensions: depressed state, psychosis, sleep disturbances, psychomotor acceleration, and irritability. Two factors were significantly heritable: depression (h2=0.53, p<0.001) and irritable vs. euphoric mania (h2=0.35, p=0.03). These were subsequently used in a linkage analysis that resulted in LOD scores of <2.0, which are not statistically significant. The five constructs developed through factor analysis appear to be consistent with previous factor analyses. Notably, only the dimensions associated with the type of mood disturbance showed high heritability, which suggests that careful measurements of depression, euphoria and irritability may be particularly useful in clarifying the genetic etiology of bipolar disorder in future studies.

The common variants/multiple disease hypothesis of common complex genetic disorders

Unlike simple rare Mendelian disorders, the genetic basis for common disorders is unclear. A general model of the genetics of common complex disorders is proposed which emphasizes the shared nature of common alleles in related common disorders, such as schizophrenia and bipolar disorder, Type II diabetes and obesity, and among autoimmune diseases. This model, the common variants/multiple disease hypothesis, emphasizes that many disease genes may not be disease specific. Common deleterious alleles, found at a relatively high frequency in the population may play a role in related clinical phenotypes in the context of different genetic backgrounds and under different environmental conditions.

Family, twin, and adoption studies of bipolar disorder

Family, twin, and adoption studies have been essential in defining the genetic epidemiology of bipolar disorder over the past several decades. Family studies have documented that first-degree relatives of affected individuals have an excess risk of the disorder, while twin studies (and to a lesser extent, adoption studies) suggest that genes are largely responsible for this familial aggregation. We review these studies, including the magnitude of familial risk and heritability estimates, efforts to identify familial subtypes of bipolar disorder, and the implications of family/genetic data for validating nosologic boundaries. Taken together, these studies indicate that bipolar disorder is phenotypically and genetically complex.

Genetic linkage and association studies in bipolar affective disorder: a time for optimism

Genetic research on complex diseases is beginning to bear fruit, with the successful identification of candidate susceptibility genes in diabetes, asthma, and other illnesses. Similar success is on the horizon for bipolar affective disorder (BPAD), but significant challenges remain. In this review, we outline the basic concepts of linkage and association mapping for complex phenotypes. We point out important caveats inherent in both approaches, and review guidelines on the interpretation of linkage statistics and significance thresholds. We then apply these concepts to an evaluation of the present status of genetic linkage and association studies in BPAD. The challenges posed by locus heterogeneity, phenotype definition, and sample size requirements are given a detailed treatment. Despite these challenges, we argue that the way ahead remains firmly rooted in linkage studies, complemented by association studies in linked regions. This is the only truly genome-wide approach currently available; it has succeeded in other complex phenotypes, and it is the surest strategy for mapping susceptibility genes in BPAD. Once these genes are identified, genetic mapping methods will yield to the other methods of 21st-century molecular biology as we begin to elucidate the pathophysiology of BPAD.

Examination of IMPA1 and IMPA2 genes in manic-depressive patients: association between IMPA2 promoter polymorphisms and bipolar disorder

Manic-depressive (bipolar) illness is a serious psychiatric disorder with a strong genetic predisposition. The disorder is likely to be multifactorial and etiologically complex, and the causes of genetic susceptibility have been difficult to unveil. Lithium therapy is a widely used pharmacological treatment of manic-depressive illness, which both stabilizes the ongoing episodes and prevents relapses. A putative target of lithium treatment has been the inhibition of the myo-inositol monophosphatase (IMPase) enzyme, which dephosphorylates myo-inositol monophosphate in the phosphatidylinositol signaling system. Two genes encoding human IMPases have so far been isolated, namely myo-inositol monophosphatase 1 (IMPA1) on chromosome 8q21.13-21.3 and myo-inositol monophosphatase 2 (IMPA2) on chromosome 18p11.2. In the present study, we have scanned for DNA variants in the human IMPA1 and IMPA2 genes in a pilot sample of Norwegian manic-depressive patients, followed by examination of selected polymorphisms and haplotypes in a family-based bipolar sample of Palestinian Arab proband-parent trios. Intriguingly, two frequent single-nucleotide polymorphisms (-461C>T and -207T>C) in the IMPA2 promoter sequence and their corresponding haplotypes showed transmission disequilibrium in the Palestinian Arab trios. No association was found between the IMPA1 polymorphisms and bipolar disorder, neither with respect to disease susceptibility nor with variation in lithium treatment response. The association between manic-depressive illness and IMPA2 variants supports several reports on the linkage of bipolar disorder to chromosome 18p11.2, and sustains the possible role of IMPA2 as a susceptibility gene in bipolar disorder.

Methylomics in psychiatry: Modulation of gene-environment interactions may be through DNA methylation

Fine-tuning of neuronal connections during development is regulated through environmental interactions. Some fine-tuning occurs through changes in gene expression and/or epigenetic gene-specific DNA methylation states. DNA methylation occurs by transfer of a methyl group from S-adenosyl methionine to cytosine residues in the dinucleotide sequence CpG. Although CpG sequences spread throughout the genome are usually heavily methylated, those occurring in CpG islands in the promoter regions of genes are less methylated. In most cases, the extent of DNA methylation correlates with the extent of gene inactivation. Other known epigenetic mechanisms include histone deacetylation and chromatin remodeling, RNA inhibition, RNA modification, and DNA rearrangement. Exposure memory expressed as epigenetic DNA modifications allows genomic plasticity and short-term adaptation of each generation to their environment. Environmental factors that affect DNA methylation include diet, proteins, drugs, and hormones. Induced methylation changes may produce altered gene response upon subsequent hormonal stimulation. The gene-specific DNA methylation state may be preserved upon transmission through mitosis and meiosis. An increasing amount of data implicates a role for DNA methylation in multi-factorial psychiatric disorders. For example, L-methionine treatment can exacerbate psychosis; while valproate, a drug producing hypomethylated DNA, reduces such symptoms. Hypermethylation of the promoter region of the RELN gene correlates with reduced gene expression. This gene's protein Reelin, which is necessary for neuronal migration and synaptogenesis, is reduced in schizophrenia and bipolar disorder, suggesting hypermethylation of the promoter region in these disorders. Some evidence implicates methylation of the promoter regions of the DRD2 and HTR2A genes in schizophrenia and mood disorders as well. DNA methylation usually increases with age, although hypomethylation of the promoter region of the amyloid A4 precursor gene during aging may play a role in Alzheimer's disease. More studies are needed to define the role of methylomics and other epigenetic phenomena in the nervous system.

Association of neural cell adhesion molecule 1 gene polymorphisms with bipolar affective disorder in Japanese individuals

BACKGROUND

Although the pathogenesis of mood disorders remains unclear, heritable factors have been shown to be involved. Neural cell adhesion molecule 1 (NCAM1) is known to play important roles in cell migration, neurite growth, axonal guidance, and synaptic plasticity. Disturbance of these neurodevelopmental processes is proposed as one etiology for mood disorder. We therefore undertook genetic analysis of NCAM1 in mood disorders.

METHODS

We determined the complete genomic organization of human NCAM1 gene by comparing complementary deoxyribonucleic acid and genomic sequences; mutation screening detected 11 polymorphisms. The genotypic, allelic, and haplotype distributions of these variants were analyzed in unrelated control individuals (n = 357) and patients with bipolar disorder (n = 151) and unipolar disorder (n = 78), all from central Japan.

RESULTS

Three single nucleotide polymorphisms, IVS6+32T>C, IVS7+11G>C and IVS12+21C>A, displayed significant associations with bipolar disorder (for allelic associations, nominal p =.04, p =.02, and p =.004, respectively, all p >.05 after Bonferroni corrections). Furthermore, the haplotype located in a linkage disequilibrium block was strongly associated with bipolar disorder (the p value of the most significant three-marker haplotype is .005).

CONCLUSIONS

Our results suggest that genetic variations in NCAM1 or nearby genes could confer risks associated with bipolar affective disorder in Japanese individuals.

Schizophrenia—an evolutionary enigma?

The term 'schizophrenia' refers to a group of disorders that have been described in every human culture. Two apparently well established findings have corroborated the need for an evolutionary explanation of these disorders: (1) cross-culturally stable incidence rates and (2) decreased fecundity of the affected individuals. The rationale behind this relates to the evolutionary paradox that susceptibility genes for schizophrenia are obviously preserved in the human genepool, despite fundamental reproductive disadvantages associated with the disorders. Some researchers have therefore proposed that a compensatory advantage must exist in people who are carriers of these genes or in their first-degree relatives. Such advantages were hypothesised to be outside the brain (e.g. greater resistance against toxins or infectious diseases), or within the social domain (e.g. schizotypal shamans, creativity). More specifically, T.J. Crow has suggested an evolutionary theory of schizophrenia that relates the disorders to an extreme of variation of hemispheric specialisation and the evolution of language due to a single gene mutation located on homologous regions of the sex chromosomes. None of the evolutionary scenarios does, however, fully account for the diversity of the symptomatology, nor does any one hypothesis acknowledge the objection that the mere prevalence of a disorder must not be confused with adaptation. In the present article, I therefore discuss the evolutionary hypotheses of schizophrenia, arguing that a symptom-based approach to psychotic disorders in evolutionary perspective may improve upon the existing models of schizophrenia.

Targeted psychosocial interventions for bipolar disorder

Pharmacotherapy is the foundation of treatment for bipolar disorder, but research suggests that adjunctive psychosocial interventions that are manualized, reproducible, time-limited, empirically supported, and strategically target a number of critical domains, can efficiently provide additional benefits. Psychoeducation as an adjunct of pharmacotherapy may be beneficial, but questions remain about the utility of this treatment for patients who are already compliant with medication treatment. Family educational interventions have demonstrated encouraging results in relapse prevention, but follow-up data are limited and application to patients who have limited social networks may be problematic. Reports on interpersonal and social rhythm therapy in patients with bipolar disorder are scarce, and what is available shows no differential effect on time to remission or relapse, but a significant impact on subsyndromal symptoms. Follow-up data suggest that patients receiving cognitive behavior therapy have significantly fewer bipolar episodes, shorter episodes, fewer hospitalizations, and less subsyndromal mood symptoms. It is unclear, however, if cognitive behavior therapy is superior to other active psychosocial treatments and whether its mechanism in patients with bipolar disorder is through changing dysfunctional cognitions or simply enhancing early symptom detection. Psychotherapies should be considered early in the course of illness to improve medication compliance and to help patients identify prodromes of relapse in order to take steps for prevention. In addition, some strategies may have a beneficial effect on residual symptoms, particularly symptoms of depression, and thus help move patients toward a more comprehensive functional recovery.

Psychotic bipolar disorders: dimensionally similar to or categorically different from schizophrenia?

For over a century, clinicians have struggled with how to conceptualize the primary psychoses, which include psychotic mood disorders and schizophrenia. Indeed, the nature of the relationship between mood disorders and schizophrenia is an area of ongoing controversy. Psychotic bipolar disorders have characteristics such as phenomenology, biology, therapeutic response, and brain imaging findings, suggesting both commonalities with and dissociations from schizophrenia. Taken together, these characteristics are in some instances most consistent with a dimensional view, with psychotic bipolar disorders being intermediate between non-psychotic bipolar disorders and schizophrenia spectrum disorders. However, in other instances, a categorical approach appears useful. Although more research is clearly necessary to address the dimensional versus categorical controversy, it is feasible that at least in the interim, a mixed dimensional/categorical approach could provide additional insights into pathophysiology and management options, which would not be available utilizing only one of these models.

Genome-wide linkage survey for genetic loci that influence the development of depressive disorders in families with recurrent, early-onset, major depression

In this report, we describe the results of the first genome-wide linkage survey for genetic loci that influence the development of unipolar Mood Disorders in 81 families identified by individuals with Recurrent, Early-Onset, Major Depressive Disorder (RE-MDD). Model-free linkage analysis was performed using genotypes for 392 highly informative polymorphisms with an average spacing of 9 cM. The highest maximum LOD score observed, 8.19 (genome-wide adjusted P << 0.0001), occurred for Recurrent Major Depressive Disorder (R-MDD) at D2S2321 (205 cM), located 121 kb proximal to CREB1. Nineteen chromosomal regions contained linkage peaks that reached genome-wide statistical significance (genome-wide adjusted P < 0.05) and ten of these were "highly significant" (adjusted P < 0.001). Six of the 19 linkage peaks were revealed only when the analysis included covariates to control for the effects of sex and linkage to CREB1. Sex-specific susceptibility loci were common and preferentially affected the vulnerability of women to developing unipolar Mood Disorders. Five loci revealed evidence of interaction with the CREB1 locus in determining susceptibility (epistasis). A systematic candidate gene analysis is presented and potential overlaps of the linkage regions for unipolar Mood Disorders with those reported for other psychiatric disorders are discussed. The findings suggest that genes whose products participate in cellular signaling pathways that converge on CREB, as well as the target genes whose expression they regulate, may also harbor alleles that affect the development of Mood Disorders and related conditions.

Epigenetics and bipolar disorder: New opportunities and challenges

Despite significant effort, understanding of the molecular causes and mechanisms of bipolar disorder (BD) remains a major challenge. Numerous molecular genetic linkage and association studies have been conducted over the last two decades; however, the data are quite inconsistent or even controversial. This article develops an argument that molecular studies of BD would benefit significantly from adding an epigenetic (epiG) perspective. EpiG factors refer to modifications of DNA and chromatin that "orchestrate" the activity of the genome, including regulation of gene expression. EpiG mechanisms are consistent with various non-Mendelian features of BD such as the relatively high degree of discordance in monozygotic (MZ) twins, the critical age group for susceptibility to the disease, clinical differences in males and females, and fluctuation of the disease course, including interchanges of manic and depressive phases, among others. Apart from the phenomenological consistency, molecular epiG peculiarities may shed new light on the understanding of controversial molecular genetic findings. The relevance of epigenetics for the molecular studies of BD is demonstrated using the examples of genetic studies of BD on chromosome 11p and the X chromosome. A spectrum of epiG mechanisms such as genomic imprinting, tissue-specific effects, paramutagenesis, and epiG polymorphism, as well as epiG regulation of X chromosome inactivation, is introduced. All this serves the goal of demonstrating that epiG factors cannot be ignored anymore in complex phenotypes such as BD, and systematic large-scale epiG studies of BD have to be initiated.

Genetics and genomics of behavioral and psychiatric disorders

Psychiatric conditions are to some degree under genetic influences. Despite the application of advanced genetic and molecular biological technologies, the genetic bases of the human behavioral traits and psychiatric diseases remains largely unresolved. Conventional genetic linkage approaches have not yielded definitive results, possibly because of the absence of objective diagnostic tests, the complex nature of human behavior or the incomplete penetrance of psychiatric traits. However, recent studies have revealed some genes of interest using multifaceted approaches to overcome these challenges. The approaches include using families in which specific behaviors segregate as a mendelian trait, utilization of endophenotypes as biological intermediate traits, identification of psychiatric disease phenotypes in genomic disorders, and the establishment of mouse models.

Schema-focused cognitive therapy for bipolar disorder: reducing vulnerability to relapse through attitudinal change

OBJECTIVE

Acceptance of, and adaptability to illness, are major determinants of adherence to treatment and functional recovery. This paper addresses the major psychosocial factors associated with bipolar disorder and the role of psychological interventions in symptom management and adaptability to the illness experience. A new model is presented highlighting the role of developmental experiences and temperament in determining reactions to bipolar disorder. The authors propose that by addressing reactions to the illness experiences and effects on self-concept through schema-focused cognitive therapy, functional recovery is more likely to occur among those patients functioning below expectation.

METHOD

A systematic review of the current literature including an Index Medicus/MEDLINE search was conducted, focusing on risk factors, cognitive vulnerabilities and triggers associated with bipolar disorder. Psychological treatments available for the treatment of bipolar disorder are reviewed and details of a novel schema-focused cognitive model for this condition are presented. Traditional models of adaptation to chronic illness are outlined and incorporated into the proposed model. Schema-focused cognitive therapy is proposed as an approach to help patients reduce cognitive vulnerability to relapse in addition to adopting effective mood management strategies.

RESULTS AND CONCLUSIONS

There is a need for psychological treatments which reduce the risks associated with poor functionality in patients with bipolar disorder. Schema-focused cognitive therapy specifically targets the temperament, developmental experiences and cognitive vulnerabilities that determine adjustment to illness. This proposed treatment, combined with pharmacotherapy, may offer new psychotherapeutic options for the future.

Population isolates: their special value for locating genes for bipolar disorder

OBJECTIVES

Population isolates offer several advantages for those hoping to identify predisposition genes for bipolar disorder (BP). In this review article, the rationale for performing gene mapping studies in this type of population and the results of genetic mapping studies performed to date in population isolates are presented.

METHODS

This article begins with a brief review of the concepts involved in mapping genes for BP. The concept of populations that show some degree of historical isolation and their special utility for certain types of gene mapping is presented. Methods of statistical analysis particularly relevant for gene mapping of complex diseases like BP are presented. Finally, several BP gene studies conducted to date in several population isolates are reviewed.

RESULTS

Genetic mapping studies of BP have occurred thus far in several isolates or sub-isolates, including the Amish population, Costa Ricans, Finnish, and Canadians (in Quebec), and significant linkage scores have been identified in the latter three isolates.

CONCLUSIONS

Possible greater homogeneity and greater consistency of diagnosis are factors that have been cited in several studies of BP done in isolates to date. Another special advantage of working in certain types of population isolate is their appropriateness for using certain types of association or linkage disequilibrium-based approaches at both the genome screening and fine mapping stages. These tests include mapping by linkage disequilibrium analyses, an approach that allows mapping to occur at the population, rather than the pedigree, level.