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Schmitt LM, Shaffer RC, Hessl D, Erickson C. Executive Function in Fragile X Syndrome: A Systematic Review. Brain Sci 2019; 9:E15. [PMID: 30654486 PMCID: PMC6356760 DOI: 10.3390/brainsci9010015] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 01/09/2019] [Accepted: 01/11/2019] [Indexed: 12/17/2022] Open
Abstract
Executive function (EF) supports goal-directed behavior and includes key aspects such as working memory, inhibitory control, cognitive flexibility, attention, processing speed, and planning. Fragile X syndrome (FXS) is the leading inherited monogenic cause of intellectual disability and is phenotypically characterized by EF deficits beyond what is expected given general cognitive impairments. Yet, a systematic review of behavioral studies using performance-based measures is needed to provide a summary of EF deficits across domains in males and females with FXS, discuss clinical and biological correlates of these EF deficits, identify critical limitations in available research, and offer suggestions for future studies in this area. Ultimately, this review aims to advance our understanding of the underlying pathophysiological mechanisms contributing to EF in FXS and to inform the development of outcome measures of EF and identification of new treatment targets in FXS.
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Affiliation(s)
- Lauren M Schmitt
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
| | - Rebecca C Shaffer
- Division of Developmental and Behavioral Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
| | - David Hessl
- MIND Institute, Department of Psychiatry and Behavioral Sciences, University of California, Davis, CA 95616, USA.
| | - Craig Erickson
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
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Sandoval GM, Shim S, Hong DS, Garrett AS, Quintin EM, Marzelli MJ, Patnaik S, Lightbody AA, Reiss AL. Neuroanatomical abnormalities in fragile X syndrome during the adolescent and young adult years. J Psychiatr Res 2018; 107:138-144. [PMID: 30408626 PMCID: PMC6249038 DOI: 10.1016/j.jpsychires.2018.10.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/01/2018] [Accepted: 10/19/2018] [Indexed: 10/28/2022]
Abstract
Abnormal brain development and cognitive dysfunction have been reported both in children and in adults with fragile X syndrome (FXS). However, few studies have examined neuroanatomical abnormalities in FXS during adolescence. In this study we focus on adolescent subjects with FXS (N = 54) as compared to age- and sex-matched subjects with idiopathic intellectual disability (Comparison Group) (N = 32), to examine neuroanatomical differences during this developmental period. Brain structure was assessed with voxel-based morphometry and independent groups t-test in SPM8 software. Results showed that the FXS group, relative to the comparison group, had significantly larger gray matter volume (GMV) in only one region: the bilateral caudate nucleus, but have smaller GMV in several regions including bilateral medial frontal, pregenual cingulate, gyrus rectus, insula, and superior temporal gyrus. Group differences also were noted in white matter regions. Within the FXS group, lower FMRP levels were associated with less GMV in several regions including cerebellum and gyrus rectus, and less white matter volume (WMV) in pregenual cingulate, middle frontal gyrus, and other regions. Lower full scale IQ within the FXS group was associated with larger right caudate nucleus GMV. In conclusion, adolescents and young adults with FXS demonstrate neuroanatomical abnormalities consistent with those previously reported in children and adults with FXS. These brain variations likely result from reduced FMRP during early neurodevelopment and mediate downstream deleterious effects on cognitive function.
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Boutet I, Collin CA, MacLeod LS, Messier C, Holahan MR, Berry-Kravis E, Gandhi RM, Kogan CS. Utility of the Hebb-Williams Maze Paradigm for Translational Research in Fragile X Syndrome: A Direct Comparison of Mice and Humans. Front Mol Neurosci 2018; 11:99. [PMID: 29643767 PMCID: PMC5882825 DOI: 10.3389/fnmol.2018.00099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 03/13/2018] [Indexed: 11/26/2022] Open
Abstract
To generate meaningful information, translational research must employ paradigms that allow extrapolation from animal models to humans. However, few studies have evaluated translational paradigms on the basis of defined validation criteria. We outline three criteria for validating translational paradigms. We then evaluate the Hebb–Williams maze paradigm (Hebb and Williams, 1946; Rabinovitch and Rosvold, 1951) on the basis of these criteria using Fragile X syndrome (FXS) as model disease. We focused on this paradigm because it allows direct comparison of humans and animals on tasks that are behaviorally equivalent (criterion #1) and because it measures spatial information processing, a cognitive domain for which FXS individuals and mice show impairments as compared to controls (criterion #2). We directly compared the performance of affected humans and mice across different experimental conditions and measures of behavior to identify which conditions produce comparable patterns of results in both species. Species differences were negligible for Mazes 2, 4, and 5 irrespective of the presence of visual cues, suggesting that these mazes could be used to measure spatial learning in both species. With regards to performance on the first trial, which reflects visuo-spatial problem solving, Mazes 5 and 9 without visual cues produced the most consistent results. We conclude that the Hebb–Williams mazes paradigm has the potential to be utilized in translational research to measure comparable cognitive functions in FXS humans and animals (criterion #3).
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Affiliation(s)
- Isabelle Boutet
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | | | | | - Claude Messier
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | | | - Elizabeth Berry-Kravis
- Pediatrics, Biochemistry, and Neurology, Rush University Medical Center, Chicago, IL, United States
| | - Reno M Gandhi
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Cary S Kogan
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
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Rigoulot S, Knoth IS, Lafontaine M, Vannasing P, Major P, Jacquemont S, Michaud JL, Jerbi K, Lippé S. Altered visual repetition suppression in Fragile X Syndrome: New evidence from ERPs and oscillatory activity. Int J Dev Neurosci 2017; 59:52-59. [DOI: 10.1016/j.ijdevneu.2017.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/31/2016] [Accepted: 03/17/2017] [Indexed: 12/13/2022] Open
Affiliation(s)
- Simon Rigoulot
- Departement de PsychologieUniversité de MontréalMontrealCanada
- Neuroscience of Early Development (NED)MontrealCanada
- Centre de Recherche en Neuropsychologie et Cognition (CERNEC)MontrealCanada
- Research Center of the CHU Ste‐Justine Mother and Child University Hospital Center, Université de MontrealQuebecCanada
- International Laboratory for Brain, Music and Sound Research (BRAMS)MontrealQuebecCanada
| | - Inga S. Knoth
- Neuroscience of Early Development (NED)MontrealCanada
- Centre de Recherche en Neuropsychologie et Cognition (CERNEC)MontrealCanada
- Research Center of the CHU Ste‐Justine Mother and Child University Hospital Center, Université de MontrealQuebecCanada
| | - Marc‐Philippe Lafontaine
- Departement de PsychologieUniversité de MontréalMontrealCanada
- Neuroscience of Early Development (NED)MontrealCanada
- Centre de Recherche en Neuropsychologie et Cognition (CERNEC)MontrealCanada
- Research Center of the CHU Ste‐Justine Mother and Child University Hospital Center, Université de MontrealQuebecCanada
| | - Phetsamone Vannasing
- Research Center of the CHU Ste‐Justine Mother and Child University Hospital Center, Université de MontrealQuebecCanada
| | - Philippe Major
- Research Center of the CHU Ste‐Justine Mother and Child University Hospital Center, Université de MontrealQuebecCanada
| | - Sébastien Jacquemont
- Research Center of the CHU Ste‐Justine Mother and Child University Hospital Center, Université de MontrealQuebecCanada
| | - Jacques L. Michaud
- Research Center of the CHU Ste‐Justine Mother and Child University Hospital Center, Université de MontrealQuebecCanada
| | - Karim Jerbi
- Departement de PsychologieUniversité de MontréalMontrealCanada
- Centre de Recherche en Neuropsychologie et Cognition (CERNEC)MontrealCanada
- International Laboratory for Brain, Music and Sound Research (BRAMS)MontrealQuebecCanada
- Centre de Recherche de l'Institut Universitaire en Santé Mentale de Montréal (CRIUSMM)
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM)
| | - Sarah Lippé
- Departement de PsychologieUniversité de MontréalMontrealCanada
- Neuroscience of Early Development (NED)MontrealCanada
- Centre de Recherche en Neuropsychologie et Cognition (CERNEC)MontrealCanada
- Research Center of the CHU Ste‐Justine Mother and Child University Hospital Center, Université de MontrealQuebecCanada
- International Laboratory for Brain, Music and Sound Research (BRAMS)MontrealQuebecCanada
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Enriquez-Barreto L, Morales M. The PI3K signaling pathway as a pharmacological target in Autism related disorders and Schizophrenia. MOLECULAR AND CELLULAR THERAPIES 2016; 4:2. [PMID: 26877878 PMCID: PMC4751644 DOI: 10.1186/s40591-016-0047-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 01/25/2016] [Indexed: 01/01/2023]
Abstract
This review is focused in PI3K’s involvement in two widespread mental disorders: Autism and Schizophrenia. A large body of evidence points to synaptic dysfunction as a cause of these diseases, either during the initial phases of brain synaptic circuit’s development or later modulating synaptic function and plasticity. Autism related disorders and Schizophrenia are complex genetic conditions in which the identification of gene markers has proved difficult, although the existence of single-gene mutations with a high prevalence in both diseases offers insight into the role of the PI3K signaling pathway. In the brain, components of the PI3K pathway regulate synaptic formation and plasticity; thus, disruption of this pathway leads to synapse dysfunction and pathological behaviors. Here, we recapitulate recent evidences that demonstrate the imbalance of several PI3K elements as leading causes of Autism and Schizophrenia, together with the plausible new pharmacological paths targeting this signaling pathway.
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Affiliation(s)
- Lilian Enriquez-Barreto
- Institut de Neurociències, Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Miguel Morales
- Institut de Neurociències, Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
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Scherr JF, Hahn LJ, Hooper SR, Hatton D, Roberts JE. HPA axis function predicts development of working memory in boys with FXS. Brain Cogn 2016; 102:80-90. [PMID: 26760450 PMCID: PMC4724243 DOI: 10.1016/j.bandc.2015.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 11/18/2015] [Accepted: 12/10/2015] [Indexed: 11/22/2022]
Abstract
The present study examines verbal working memory over time in boys with fragile X syndrome (FXS) compared to nonverbal mental-age (NVMA) matched, typically developing (TD) boys. Concomitantly, the relationship between cortisol-a physiological marker for stress-and verbal working memory performance over time is examined to understand the role of physiological mechanisms in cognitive development in FXS. Participants were assessed between one and three times over a 2-year time frame using two verbal working memory tests that differ in complexity: memory for words and auditory working memory with salivary cortisol collected at the beginning and end of each assessment. Multilevel modeling results indicate specific deficits over time on the memory for words task in boys with FXS compared to TD controls that is exacerbated by elevated baseline cortisol. Similar increasing rates of growth over time were observed for boys with FXS and TD controls on the more complex auditory working memory task, but only boys with FXS displayed an association of increased baseline cortisol and lower performance. This study highlights the benefit of investigations of how dynamic biological and cognitive factors interact and influence cognitive development over time.
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Affiliation(s)
- Jessica F. Scherr
- Department of Psychology, 1512 Pendleton Street, University of South Carolina, Columbia, SC, 29208, USA
| | - Laura J. Hahn
- Department of Psychology, 1512 Pendleton Street, University of South Carolina, Columbia, SC, 29208, USA
| | - Stephen R. Hooper
- Departments of Allied Health Sciences and Psychiatry, 1028 Bondurant Hall, University of North Carolina School of Medicine, Chapel Hill, NC 27599-4120, USA
| | - Deborah Hatton
- Department of Special Education, Box 228 Peabody College, Vanderbilt University, Nashville, TN, 37203, USA,
| | - Jane E. Roberts
- Department of Psychology, 1512 Pendleton Street, University of South Carolina, Columbia, SC, 29208, USA
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Kirk HE, Gray K, Riby DM, Cornish KM. Cognitive training as a resolution for early executive function difficulties in children with intellectual disabilities. RESEARCH IN DEVELOPMENTAL DISABILITIES 2015; 38:145-160. [PMID: 25561358 DOI: 10.1016/j.ridd.2014.12.026] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 12/13/2014] [Accepted: 12/15/2014] [Indexed: 06/04/2023]
Abstract
Core executive functions (EF) such as attention, and working memory have been strongly associated with academic achievement, language development and behavioral stability. In the case of children who are vulnerable to cognitive and learning problems because of an underlying intellectual disability, EF difficulties will likely exacerbate an already compromised cognitive system. The current review examines cognitive training programs that aim to improve EF, specifically focusing on the potential of this type of intervention for children who have intellectual disabilities. We conclude that despite considerable discrepancies regarding reported intervention effects, these inconsistencies can be attributed to flaws in both program and study design. We discuss the steps needed to address these limitations and to facilitate the advancement of non-pharmaceutical interventions for children with intellectual disabilities.
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Affiliation(s)
- H E Kirk
- School of Psychological Sciences, Monash University, Melbourne, Australia.
| | - K Gray
- Centre for Developmental Psychology & Psychiatry, Department of Psychiatry, School of Clinical Sciences, Monash University, Melbourne, Australia
| | - D M Riby
- Department of Psychology, Durham University, England, United Kingdom
| | - K M Cornish
- School of Psychological Sciences, Monash University, Melbourne, Australia.
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Kazdoba TM, Leach PT, Silverman JL, Crawley JN. Modeling fragile X syndrome in the Fmr1 knockout mouse. Intractable Rare Dis Res 2014; 3:118-33. [PMID: 25606362 PMCID: PMC4298642 DOI: 10.5582/irdr.2014.01024] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 11/28/2014] [Indexed: 11/05/2022] Open
Abstract
Fragile X Syndrome (FXS) is a commonly inherited form of intellectual disability and one of the leading genetic causes for autism spectrum disorder. Clinical symptoms of FXS can include impaired cognition, anxiety, hyperactivity, social phobia, and repetitive behaviors. FXS is caused by a CGG repeat mutation which expands a region on the X chromosome containing the FMR1 gene. In FXS, a full mutation (> 200 repeats) leads to hypermethylation of FMR1, an epigenetic mechanism that effectively silences FMR1 gene expression and reduces levels of the FMR1 gene product, fragile X mental retardation protein (FMRP). FMRP is an RNA-binding protein that is important for the regulation of protein expression. In an effort to further understand how loss of FMR1 and FMRP contribute to FXS symptomology, several FXS animal models have been created. The most well characterized rodent model is the Fmr1 knockout (KO) mouse, which lacks FMRP protein due to a disruption in its Fmr1 gene. Here, we review the behavioral phenotyping of the Fmr1 KO mouse to date, and discuss the clinical relevance of this mouse model to the human FXS condition. While much remains to be learned about FXS, the Fmr1 KO mouse is a valuable tool for understanding the repercussions of functional loss of FMRP and assessing the efficacy of pharmacological compounds in ameliorating the molecular and behavioral phenotypes relevant to FXS.
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Affiliation(s)
- Tatiana M. Kazdoba
- MIND Institute, Department of Psychiatry and Behavioral Sciences, University of California, Davis, School of Medicine, Sacramento, CA, USA
- Address correspondence to: Dr. Tatiana M. Kazdoba, MIND Institute, Department of Psychiatry and Behavioral Sciences, University of California, Davis, School of Medicine, Sacramento, Research II Building 96, 4625 2nd Avenue, Sacramento, CA 95817, USA. E-mail:
| | - Prescott T. Leach
- MIND Institute, Department of Psychiatry and Behavioral Sciences, University of California, Davis, School of Medicine, Sacramento, CA, USA
| | - Jill L. Silverman
- MIND Institute, Department of Psychiatry and Behavioral Sciences, University of California, Davis, School of Medicine, Sacramento, CA, USA
| | - Jacqueline N. Crawley
- MIND Institute, Department of Psychiatry and Behavioral Sciences, University of California, Davis, School of Medicine, Sacramento, CA, USA
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9
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de Esch CE, Zeidler S, Willemsen R. Translational endpoints in fragile X syndrome. Neurosci Biobehav Rev 2014; 46 Pt 2:256-69. [DOI: 10.1016/j.neubiorev.2013.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/07/2013] [Accepted: 10/09/2013] [Indexed: 01/01/2023]
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Francis SM, Sagar A, Levin-Decanini T, Liu W, Carter CS, Jacob S. Oxytocin and vasopressin systems in genetic syndromes and neurodevelopmental disorders. Brain Res 2014; 1580:199-218. [PMID: 24462936 PMCID: PMC4305432 DOI: 10.1016/j.brainres.2014.01.021] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 11/08/2013] [Accepted: 01/15/2014] [Indexed: 10/25/2022]
Abstract
Oxytocin (OT) and arginine vasopressin (AVP) are two small, related neuropeptide hormones found in many mammalian species, including humans. Dysregulation of these neuropeptides have been associated with changes in behavior, especially social interactions. We review how the OT and AVP systems have been investigated in Autism Spectrum Disorder (ASD), Prader-Willi Syndrome (PWS), Williams Syndrome (WS) and Fragile X syndrome (FXS). All of these neurodevelopmental disorders (NDD) are marked by social deficits. While PWS, WS and FXS have identified genetic mutations, ASD stems from multiple genes with complex interactions. Animal models of NDD are invaluable for studying the role and relatedness of OT and AVP in the developing brain. We present data from a FXS mouse model affecting the fragile X mental retardation 1 (Fmr1) gene, resulting in decreased OT and AVP staining cells in some brain regions. Reviewing the research about OT and AVP in these NDD suggests that altered OT pathways may be downstream from different etiological factors and perturbations in development. This has implications for ongoing studies of the therapeutic application of OT in NDD. This article is part of a Special Issue entitled Oxytocin and Social Behav.
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Affiliation(s)
- S M Francis
- University of Minnesota, Department of Psychiatry, Minneapolis, MN, USA
| | - A Sagar
- University of California at Irvine, Department of Psychiatry and Human Behavior, USA
| | - T Levin-Decanini
- University of Minnesota, Department of Psychiatry, Minneapolis, MN, USA
| | - W Liu
- Northwestern University, Feinberg School of Medicine, Chicago, IL, USA
| | - C S Carter
- University of North Carolina, Department of Psychiatry, Chapel Hill, NC, USA
| | - S Jacob
- University of Minnesota, Department of Psychiatry, Minneapolis, MN, USA.
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de Diego-Otero Y, Calvo-Medina R, Quintero-Navarro C, Sánchez-Salido L, García-Guirado F, del Arco-Herrera I, Fernández-Carvajal I, Ferrando-Lucas T, Caballero-Andaluz R, Pérez-Costillas L. A combination of ascorbic acid and α-tocopherol to test the effectiveness and safety in the fragile X syndrome: study protocol for a phase II, randomized, placebo-controlled trial. Trials 2014; 15:345. [PMID: 25187257 PMCID: PMC4168067 DOI: 10.1186/1745-6215-15-345] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 07/18/2014] [Indexed: 01/18/2023] Open
Abstract
Background Fragile X syndrome (FXS) is an inherited neurodevelopmental condition characterised by behavioural, learning disabilities, phisical and neurological symptoms. In addition, an important degree of comorbidity with autism is also present. Considered a rare disorder affecting both genders, it first becomes apparent during childhood with displays of language delay and behavioural symptoms. Main aim: To show whether the combination of 10 mg/kg/day of ascorbic acid (vitamin C) and 10 mg/kg/day of α-tocopherol (vitamin E) reduces FXS symptoms among male patients ages 6 to 18 years compared to placebo treatment, as measured on the standardized rating scales at baseline, and after 12 and 24 weeks of treatment. Secondary aims: To assess the safety of the treatment. To describe behavioural and cognitive changes revealed by the Developmental Behaviour Checklist Short Form (DBC-P24) and the Wechsler Intelligence Scale for Children–Revised. To describe metabolic changes revealed by blood analysis. To measure treatment impact at home and in an academic environment. Methods/Design A phase II randomized, double-blind pilot clinical trial. Scope: male children and adolescents diagnosed with FXS, in accordance with a standardized molecular biology test, who met all the inclusion criteria and none of the exclusion criteria. Instrumentation: clinical data, blood analysis, Wechsler Intelligence Scale for Children–Revised, Conners parent and teacher rating scale scores and the DBC-P24 results will be obtained at the baseline (t0). Follow up examinations will take place at 12 weeks (t1) and 24 weeks (t2) of treatment. Discussion A limited number of clinical trials have been carried out on children with FXS, but more are necessary as current treatment possibilities are insufficient and often provoke side effects. In the present study, we sought to overcome possible methodological problems by conducting a phase II pilot study in order to calculate the relevant statistical parameters and determine the safety of the proposed treatment. The results will provide evidence to improve hyperactivity control and reduce behavioural and learning problems using ascorbic acid (vitamin C) and α-tocopherol (vitamin E). The study protocol was approved by the Regional Government Committee for Clinical Trials in Andalusia and the Spanish agency for drugs and health products. Trial registration ClinicalTrials.gov Identifier: NCT01329770 (29 March 2011)
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Affiliation(s)
- Yolanda de Diego-Otero
- Unidad de Gestión Clínica de Salud Mental, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Civil, Pabellón 2 bajo, Plaza del Hospital Civil S/N, 29009 Málaga, Spain.
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Petrinovic MM, Künnecke B. Neuroimaging endophenotypes in animal models of autism spectrum disorders: lost or found in translation? Psychopharmacology (Berl) 2014; 231:1167-89. [PMID: 23852013 DOI: 10.1007/s00213-013-3200-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 06/26/2013] [Indexed: 11/26/2022]
Abstract
RATIONALE Autism spectrum disorder(s) (ASDs) is a neurodevelopmental disorder characterized by stereotyped behaviours and impairments in communication and social interactions. This heterogeneity has been a major obstacle in uncovering the aetiology and biomarkers of ASDs. Rodent models with genetic modifications or environmental insults have been created to study particular endophenotypes and bridge the gap between genetics and behavioural phenotypes. Translational neuroimaging modalities with their ability to screen the brain noninvasively and yield structural, biochemical and functional information provide a unique platform for discovery and evaluation of such endophenotypes in preclinical and clinical research. OBJECTIVES We reviewed literature on translational neuroimaging in rodent models of ASDs. The most prominent models will be described and the respective neuroimaging endophenotypes will be discussed with reference to human data. A perspective on future directions of translational neuroimaging in animal models of ASDs will be given. RESULTS AND CONCLUSIONS To date, we experience a proliferation of rodent models which recapitulate specific liabilities identified in ASDs patients. Translational neuroimaging in these models is emerging but is skewed towards magnetic resonance imaging (MRI) modalities. Volumetric and structural assessments of the brain are dominating and a host of endophenotypes have been reported that allude to findings in ASDs patients but with only few to converge among the models. Caveats of current studies are the diverging biological conditions related to genetic background and age of the animals. It is anticipated that longitudinal and functional assessments will gain much importance and will help elucidating mechanistic relationship between behavioural and structural endophenotypes.
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Affiliation(s)
- Marija M Petrinovic
- F. Hoffmann-La Roche AG, pRED, Pharma Research and Early Development, DTA Neuroscience, Building 68, Room 327A, Grenzacherstrasse 124, 4070, Basel, Switzerland
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Fragile X syndrome: a preclinical review on metabotropic glutamate receptor 5 (mGluR5) antagonists and drug development. Psychopharmacology (Berl) 2014; 231:1217-26. [PMID: 24232444 DOI: 10.1007/s00213-013-3330-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Fragile X syndrome (FXS) is considered the leading inherited cause of intellectual disability and autism. In FXS, the fragile X mental retardation 1 (FMR1) gene is silenced and the fragile X mental retardation protein (FMRP) is not expressed, resulting in the characteristic features of the syndrome. Despite recent advances in understanding the pathophysiology of FXS, there is still no cure for this condition; current treatment is symptomatic. Preclinical research is essential in the development of potential therapeutic agents. OBJECTIVES This review provides an overview of the preclinical evidence supporting metabotropic glutamate receptor 5 (mGluR5) antagonists as therapeutic agents for FXS. RESULTS According to the mGluR theory of FXS, the absence of FMRP leads to enhanced glutamatergic signaling via mGluR5, which leads to increased protein synthesis and defects in synaptic plasticity including enhanced long-term depression. As such, efforts to develop agents that target the underlying pathophysiology of FXS have focused on mGluR5 modulation. Animal models, particularly the Fmr1 knockout mouse model, have become invaluable in exploring therapeutic approaches on an electrophysiological, behavioral, biochemical, and neuroanatomical level. Two direct approaches are currently being investigated for FXS treatment: reactivating the FMR1 gene and compensating for the lack of FMRP. The latter approach has yielded promising results, with mGluR5 antagonists showing efficacy in clinical trials. CONCLUSIONS Targeting mGluR5 is a valid approach for the development of therapeutic agents that target the underlying pathophysiology of FXS. Several compounds are currently in development, with encouraging results.
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14
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Giampetruzzi A, Carson JH, Barbarese E. FMRP and myelin protein expression in oligodendrocytes. Mol Cell Neurosci 2013; 56:333-41. [PMID: 23891804 DOI: 10.1016/j.mcn.2013.07.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 06/19/2013] [Accepted: 07/21/2013] [Indexed: 11/15/2022] Open
Abstract
Fragile X syndrome (FXS) is caused by lack of expression of fragile X mental retardation protein (FMRP), the product of the Fmr1 gene. In many cases FXS is associated with abnormalities in CNS myelination. Although FMRP is expressed in oligodendrocyte progenitor cells and immature oligodendrocytes (OLGs) previous studies have not detected it in mature, myelin-producing OLGs. FMRP represses translation of myelin basic protein (MBP) RNA in vitro and is believed to prevent premature MBP expression in immature OLGs. Lack of FMRP in FXS could lead to premature myelination and/or myelin abnormalities. Here we show that FMRP is expressed in mature, MBP-positive OLGs of rodents and in MBP-positive human OLGs. We confirm that FMRP is a translational repressor of MBP mRNA in vitro, but at concentrations likely too high to be physiologically relevant in vivo. We find MBP expression in cultured Fmr1 KO OLGs to be similar to wild type, and expression of MBP and other myelin proteins in brain homogenates of the Fmr1 KO mouse to be similar to wild type before, during, and after the period of active myelination. These results suggest that while FMRP is expressed in mature OLGs, myelin abnormalities caused by lack of FMRP expression in FXS are not recapitulated in rodents.
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Affiliation(s)
- Anthony Giampetruzzi
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3401, USA.
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Hallahan BP, Daly EM, Simmons A, Moore CJ, Murphy KC, Murphy DDG. Fragile X syndrome: a pilot proton magnetic resonance spectroscopy study in premutation carriers. J Neurodev Disord 2012; 4:23. [PMID: 22958351 PMCID: PMC3443443 DOI: 10.1186/1866-1955-4-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 08/13/2012] [Indexed: 11/10/2022] Open
Abstract
Purpose There is increasing evidence that neurodevelopmental differences in people with Fragile X syndrome (FraX) may be explained by differences in glutamatergic metabolism. Premutation carriers of FraX were originally considered to be unaffected although several recent reports demonstrate neuroanatomical, cognitive, and emotional differences from controls. However there are few studies on brain metabolism in premutation carriers of FraX. Methods We used proton magnetic resonance spectroscopy to compare neuronal integrity of a number of brain metabolites including N-Acetyl Aspartate, Creatine + Phosphocreatinine, Choline, myoInositol, and Glutamate containing substances (Glx) in 17 male premutation carriers of FraX and 16 male healthy control individuals. Results There was no significant between-group difference in the concentration of any measured brain metabolites. However there was a differential increase in N-acetyl aspartate with aging in premutation FraX individuals compared to controls. Conclusions This is the first 1 H-MRS study to examine premutation FraX individuals. Although we demonstrated no difference in the concentration of any of the metabolites examined between the groups, this may be due to the large age ranges included in the two samples. The differential increase in NAA levels with aging may reflect an abnormal synaptic pruning process.
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Affiliation(s)
- Brian P Hallahan
- Department of Psychiatry, National University of Ireland Galway, Galway, Ireland.
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Meguid NA, Fahim C, Sami R, Nashaat NH, Yoon U, Anwar M, El-Dessouky HM, Shahine EA, Ibrahim AS, Mancini-Marie A, Evans AC. Cognition and lobar morphology in full mutation boys with fragile X syndrome. Brain Cogn 2011; 78:74-84. [PMID: 22070923 DOI: 10.1016/j.bandc.2011.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 09/13/2011] [Accepted: 09/15/2011] [Indexed: 01/05/2023]
Abstract
The aims of the present study are twofold: (1) to examine cortical morphology (CM) associated with alterations in cognition in fragile X syndrome (FXS); (2) to characterize the CM profile of FXS versus FXS with an autism diagnosis (FXS+Aut) as a preliminary attempt to further elucidate the behavioral distinctions between the two sub-groups. We used anatomical magnetic resonance imaging surface-based morphometry in 21 male children (FXS N=11 and age [2.27-13.3] matched controls [C] N=10). We found (1) increased whole hemispheric and lobar cortical volume, cortical thickness and cortical complexity bilaterally, yet insignificant changes in hemispheric surface area and gyrification index in FXS compared to C; (2) linear regression analyses revealed significant negative correlations between CM and cognition; (3) significant CM differences between FXS and FXS+Aut associated with their distinctive behavioral phenotypes. These findings are critical in understanding the neuropathophysiology of one of the most common intellectual deficiency syndromes associated with altered cognition as they provide human in vivo information about genetic control of CM and cognition.
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Affiliation(s)
- Nagwa A Meguid
- Department of Research on Children with Special Needs, Medical Genetics Division, The National Research Centre, Cairo, Egypt
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17
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Gallagher A, Hallahan B. Fragile X-associated disorders: a clinical overview. J Neurol 2011; 259:401-13. [PMID: 21748281 DOI: 10.1007/s00415-011-6161-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 06/24/2011] [Accepted: 06/25/2011] [Indexed: 01/13/2023]
Abstract
Fragile X Syndrome (FraX) is the most common inherited cause of learning disability worldwide. FraX is an X-linked neuro-developmental disorder involving an unstable trinucleotide repeat expansion of cytosine guanine guanine (CGG). Individuals with the full mutation of FraX have >200 GG repeats with premutation carriers having 55-200 GG repeats. A wide spectrum of physical, behavioural, cognitive, psychiatric and medical problems have been associated with both full mutation and premutation carriers of FraX. In this review, we detail the clinical profile and examine the aetiology, epidemiology, neuropathology, neuroimaging findings and possible management strategies for individuals with both the full mutation and premutation of FraX.
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Affiliation(s)
- Anne Gallagher
- Department of Psychiatry, Clinical Science Institute, National University of Ireland Galway, Galway, Ireland
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18
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Abstract
The purpose of this review was to understand the types of memory impairments that are associated with intellectual disability (ID, formerly called mental retardation) and the implications of these impairments for reading development. Specifically, studies on working memory, delayed memory and learning, and semantic/conceptual memory in Down syndrome, Williams syndrome, and fragile X syndrome were examined. A distinct memory profile emerged for each of the 3 etiologies of ID. Memory profiles are discussed in relation to strengths and weaknesses in reading skills in these three etiologies. We suggest that reading instruction be designed to capitalize on relatively stronger memory skills while providing extra support for especially challenging aspects of reading.
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Bussy G, Charrin E, Brun A, Curie A, des Portes V. Implicit procedural learning in fragile X and Down syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2011; 55:521-528. [PMID: 21418366 DOI: 10.1111/j.1365-2788.2011.01410.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND Procedural learning refers to rule-based motor skill learning and storage. It involves the cerebellum, striatum and motor areas of the frontal lobe network. Fragile X syndrome, which has been linked with anatomical abnormalities within the striatum, may result in implicit procedural learning deficit. METHODS To address this issue, a serial reaction time (RT) task including six blocks of trials was performed by 14 individuals with fragile X syndrome, 12 individuals with Down syndrome and 12 mental age-matched control subjects. The first (B1) and fifth (B5) blocks were random whereas the others (B2, B3, B4 and B6) consisted of a repeated 10-step sequence. Results were analysed by Kruskal-Wallis one-way analysis of variance and Wilcoxon signed-rank test. RESULTS For patients with fragile X syndrome, the RT was highly suggestive of preserved implicit learning as a significant difference was observed between blocks B5 and B6 (P = 0.009). However, the difference of RT between B4 and B5 did not reach significance, possibly due to a subgroup of individuals who did not learn. In contrast, in the Down syndrome group, RT decreased significantly between B4 and B5 (W = 2; P = 0.003) but not between the last ordered block (B6) and the last random block (B5), suggesting a weakness in procedural learning which was sensitive to the interfering random block. CONCLUSION implicit learning is variable in genetic syndromes and therefore relatively independent of general intellectual capacities. The results are discussed together with previous reports.
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Affiliation(s)
- G Bussy
- CNRS UMR, Institut des Sciences Cognitives, Bron, France.
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Hallahan BP, Craig MC, Toal F, Daly EM, Moore CJ, Ambikapathy A, Robertson D, Murphy KC, Murphy DG. In vivo brain anatomy of adult males with Fragile X syndrome: An MRI study. Neuroimage 2011; 54:16-24. [DOI: 10.1016/j.neuroimage.2010.08.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 08/04/2010] [Accepted: 08/06/2010] [Indexed: 10/19/2022] Open
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Baker S, Hooper S, Skinner M, Hatton D, Schaaf J, Ornstein P, Bailey D. Working memory subsystems and task complexity in young boys with Fragile X syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2011; 55:19-29. [PMID: 21121991 PMCID: PMC4437210 DOI: 10.1111/j.1365-2788.2010.01343.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
BACKGROUND Working memory problems have been targeted as core deficits in individuals with Fragile X syndrome (FXS); however, there have been few studies that have examined working memory in young boys with FXS, and even fewer studies that have studied the working memory performance of young boys with FXS across different degrees of complexity. The purpose of this study was to investigate the phonological loop and visual-spatial working memory in young boys with FXS, in comparison to mental age-matched typical boys, and to examine the impact of complexity of the working memory tasks on performance. METHODS The performance of young boys (7 to 13-years-old) with FXS (n = 40) was compared with that of mental age and race matched typically developing boys (n = 40) on measures designed to test the phonological loop and the visuospatial sketchpad across low, moderate and high degrees of complexity. Multivariate analyses were used to examine group differences across the specific working memory systems and degrees of complexity. RESULTS Results suggested that boys with FXS showed deficits in phonological loop and visual-spatial working memory tasks when compared with typically developing mental age-matched boys. For the boys with FXS, the phonological loop was significantly lower than the visual-spatial sketchpad; however, there was no significant difference in performance across the low, moderate and high degrees of complexity in the working memory tasks. Reverse tasks from both the phonological loop and visual-spatial sketchpad appeared to be the most challenging for both groups, but particularly for the boys with FXS. CONCLUSIONS These findings implicate a generalised deficit in working memory in young boys with FXS, with a specific disproportionate impairment in the phonological loop. Given the lack of differentiation on the low versus high complexity tasks, simple span tasks may provide an adequate estimate of working memory until greater involvement of the central executive is achieved.
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Affiliation(s)
- S Baker
- Department of Neuropsychology, WakeMed Health and Hospital, Raleigh, North Carolina, USA
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Brouwer J, Willemsen R, Oostra B. The FMR1 gene and fragile X-associated tremor/ataxia syndrome. Am J Med Genet B Neuropsychiatr Genet 2009; 150B:782-98. [PMID: 19105204 PMCID: PMC4320942 DOI: 10.1002/ajmg.b.30910] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The CGG-repeat present in the 5'UTR of the FMR1 gene is unstable upon transmission to the next generation. The repeat is up to 55 CGGs long in the normal population. In fragile X patients, a repeat length exceeding 200 CGGs (full mutation: FM) generally leads to methylation of the repeat and the promoter region, which is accompanied by silencing of the FMR1 gene. The gene product FMRP is involved in regulation of transport and translation of certain mRNA in the dendrite, thereby affecting synaptic plasticity. This is central to learning and memory processes. The absence of FMRP seen in FM is the cause of the mental retardation seen in fragile X patients. The premutation (PM) is defined as 55-200 CGGs. Female PM carriers are at risk of developing primary ovarian insufficiency. Recently it was discovered that elderly PM carriers might develop a progressive neurodegenerative disorder called fragile X-associated tremor/ataxia syndrome. Although arising from the mutations in the same gene, distinct mechanisms lead to fragile X syndrome (absence of FMRP) and FXTAS (toxic RNA gain of function). The pathogenic mechanisms thought to underlie these disorders are discussed, with a specific emphasis on FXTAS. This review gives insight on the implications of all possible repeat length categories seen in fragile X families.
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Affiliation(s)
- J.R. Brouwer
- Department of Clinical Genetics, ErasmusMC, Rotterdam, The Netherlands
| | - R. Willemsen
- Department of Clinical Genetics, ErasmusMC, Rotterdam, The Netherlands
| | - B.A. Oostra
- Department of Clinical Genetics, ErasmusMC, Rotterdam, The Netherlands
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MacLeod LS, Kogan CS, Collin CA, Berry-Kravis E, Messier C, Gandhi R. A comparative study of the performance of individuals with fragile X syndrome and Fmr1 knockout mice on Hebb-Williams mazes. GENES BRAIN AND BEHAVIOR 2009; 9:53-64. [PMID: 19796132 DOI: 10.1111/j.1601-183x.2009.00534.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fragile X syndrome (FXS) is the most prevalent form of heritable mental retardation. It arises from a mutation in the FMR1 gene on the X chromosome that interferes with expression of fragile X mental retardation protein (FMRP) and leads to a wide range of behavioural and cognitive deficits. Previous studies have shown a deficit in basic visual perceptual processing as well as spatial abilities in FXS. How such a deficit may impact spatial navigation remains unknown. The current study extended previous research by evaluating spatial learning and memory using both virtual and physical versions of Hebb-Williams mazes, which allows for testing of humans and animals under comparable conditions. We compared the performance of individuals affected by FXS to typically developing individuals of equivalent mental age as well as the performance of Fmr1 knockout mice to wild-type control mice on the same maze problems. In human participants, performance of the comparison group improved across trials, showing expected significant decreases in both errors and latency. In contrast, the performance of the fragile X group remained at similar levels across trials. Although wild-type control mice made significantly fewer errors than the Fmr1 knockout mice, latencies were not statistically different between the groups. These findings suggest that affected humans and mice show similar spatial learning deficits attributable to the lack of FMRP. The implications of these data are discussed including the notion that Hebb-Williams mazes may represent a useful tool to examine the impact of pharmacological interventions on mitigating or reversing the symptoms associated with FXS.
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Affiliation(s)
- L S MacLeod
- School of Psychology, University of Ottawa, Ottawa, Ontario, Canada
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Whole-brain expression analysis of FMRP in adult monkey and its relationship to cognitive deficits in fragile X syndrome. Brain Res 2009; 1264:76-84. [PMID: 19368811 DOI: 10.1016/j.brainres.2009.01.059] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 01/24/2009] [Accepted: 01/26/2009] [Indexed: 11/20/2022]
Abstract
Fragile X syndrome (FXS) is one of the most prevalent forms of heritable mental retardation and developmental delay in males. The syndrome is caused by the silencing of a single gene (fragile X mental retardation-1; FMR1) and the lack of expression of its protein product (fragile X mental retardation-1 protein; FMRP). Recent work has linked the high expression levels of FMRP in the magnocellular layers of lateral geniculate nucleus (M-LGN) of the visual system to a specific reduction of perceptual function known to be mediated by that neural structure. This finding has given rise to the intriguing notion that FMRP expression level may be used as an index of susceptibility of specific brain regions to the observed perceptual and cognitive deficits in FXS. We undertook a comprehensive expression profiling study of FMRP in the monkey to obtain further insight into the link between FMPR expression and the behavioural impact of its loss in FXS. We report here the first 3D whole-brain map of FMRP expression in the Old-World monkey and show that certain brain structures display high FMRP levels, such as the cerebellum, striatum, and temporal lobe structures. This finding provides support for the notion that FMRP expression loss is linked to behavioural and cognitive impairment associated with these structures. We argue that whole-brain FMRP expression mapping may be used to formulate and test new hypotheses about other forms of impairments in FXS that were not specifically examined in this study.
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Kogan CS, Boutet I, Cornish K, Graham GE, Berry-Kravis E, Drouin A, Milgram NW. A comparative neuropsychological test battery differentiates cognitive signatures of Fragile X and Down syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2009; 53:125-42. [PMID: 19054268 DOI: 10.1111/j.1365-2788.2008.01135.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
BACKGROUND Standardised neuropsychological and cognitive measures present some limitations in their applicability and generalisability to individuals with intellectual disability (ID). Alternative approaches to defining the cognitive signatures of various forms of ID are needed to advance our understanding of the profiles of strengths and weaknesses as well as the affected brain areas. AIM To evaluate the utility and feasibility of six non-verbal comparative neuropsychological (CN) tasks administered in a modified version of the Wisconsin General Test Apparatus (WGTA) to confirm and extend our knowledge of unique cognitive signatures of Fragile X syndrome (FXS) and Down syndrome (DS). METHOD A test battery of CN tasks adapted from the animal literature was administered in a modified WGTA. Tasks were selected that have established or emerging brain-behaviour relationships in the domains of visual-perceptual, visual-spatial, working memory and inhibition. RESULTS Despite the fact that these tasks revealed cognitive signatures for the two ID groups, only some hypotheses were supported. Results suggest that whereas individuals with DS were relatively impaired on visual-perceptual and visual-spatial reversal learning tasks they showed strengths in egocentric spatial learning and object discrimination tasks. Individuals with FXS were relatively impaired on object discrimination learning and reversal tasks, which was attributable to side preferences. In contrast, these same individuals exhibited strengths in egocentric spatial learning and reversal tasks as well as on an object recognition memory task. Both ID groups demonstrated relatively poor performance for a visual-spatial working memory task. CONCLUSION Performance on the modified WGTA tasks differentiated cognitive signatures between two of the most common forms of ID. Results are discussed in the context of the literature on the cognitive and neurobiological features of FXS and DS.
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Affiliation(s)
- C S Kogan
- School of Psychology, University of Ottawa, Ottawa, ON, Canada.
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26
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Elevated glycogen synthase kinase-3 activity in Fragile X mice: key metabolic regulator with evidence for treatment potential. Neuropharmacology 2008; 56:463-72. [PMID: 18952114 DOI: 10.1016/j.neuropharm.2008.09.017] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Revised: 09/20/2008] [Accepted: 09/30/2008] [Indexed: 11/20/2022]
Abstract
Significant advances have been made in understanding the underlying defects of and developing potential treatments for Fragile X syndrome (FXS), the most common heritable mental retardation. It has been shown that neuronal metabotropic glutamate receptor 5 (mGluR5)-mediated signaling is affected in FX animal models, with consequent alterations in activity-dependent protein translation and synaptic spine functionality. We demonstrate here that a central metabolic regulatory enzyme, glycogen synthase kinase-3 (GSK3) is present in a form indicating elevated activity in several regions of the FX mouse brain. Furthermore, we show that selective GSK3 inhibitors, as well as lithium, are able to revert mutant phenotypes of the FX mouse. Lithium, in particular, remained effective with chronic administration, although its effects were reversible even when given from birth. The combination of an mGluR5 antagonist and GSK3 inhibitors was not additive. Instead, it was discovered that mGluR5 signaling and GSK3 activation in the FX mouse are coordinately elevated, with inhibition of mGluR5 leading to inhibition of GSK3. These findings raise the possibility that GSK3 is a fundamental and central component of FXS pathology, with a substantial treatment potential.
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Lanfranchi S, Cornoldi C, Drigo S, Vianello R. Working memory in individuals with fragile X syndrome. Child Neuropsychol 2008; 15:105-19. [PMID: 18608221 DOI: 10.1080/09297040802112564] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The present research tests the hypothesis that fragile X syndrome (FXS) is associated with a deficit in working memory (WM) and the deficit is more pronounced the higher the control requirements of the task. To this purpose, 15 boys with FXS and 15 typically developing children, matched for mental age, assessed with Logical Operation Test, were tested with batteries of 4 verbal and 4 visuospatial WM tasks requiring different levels of control. Children with FXS showed a performance equal to controls, in WM tasks requiring low and medium-low control but significant impairment in correspondence with greater control requirements. Results show that boys with FXS present a WM deficit only when high control is required by the task, supporting the hypothesis that control can be a critical variable distinguishing WM functions and explaining intellectual differences. On the contrary the hypothesis that the FXS is associated with a visuospatial deficit was not supported.
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Affiliation(s)
- Silvia Lanfranchi
- University of Padova, Department of Developmental Psychology, Padova, Italy.
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Lee AD, Leow AD, Lu A, Reiss AL, Hall S, Chiang MC, Toga AW, Thompson PM. 3D pattern of brain abnormalities in Fragile X syndrome visualized using tensor-based morphometry. Neuroimage 2007; 34:924-38. [PMID: 17161622 PMCID: PMC1995408 DOI: 10.1016/j.neuroimage.2006.09.043] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Revised: 08/22/2006] [Accepted: 09/21/2006] [Indexed: 11/17/2022] Open
Abstract
Fragile X syndrome (FraX), a genetic neurodevelopmental disorder, results in impaired cognition with particular deficits in executive function and visuo-spatial skills. Here we report the first detailed 3D maps of the effects of the Fragile X mutation on brain structure, using tensor-based morphometry. TBM visualizes structural brain deficits automatically, without time-consuming specification of regions-of-interest. We compared 36 subjects with FraX (age: 14.66+/-1.58 S.D., 18 females/18 males), and 33 age-matched healthy controls (age: 14.67+/-2.2 S.D., 17 females/16 males), using high-dimensional elastic image registration. All 69 subjects' 3D T1-weighted brain MRIs were spatially deformed to match a high-resolution single-subject average MRI scan in ICBM space, whose geometry was optimized to produce a minimal deformation target. Maps of the local Jacobian determinant (expansion factor) were computed from the deformation fields. Statistical maps showed increased caudate (10% higher; p = 0.001) and lateral ventricle volumes (19% higher; p = 0.003), and trend-level parietal and temporal white matter excesses (10% higher locally; p = 0.04). In affected females, volume abnormalities correlated with reduction in systemically measured levels of the Fragile X mental retardation protein (FMRP; Spearman's r < -0.5 locally). Decreased FMRP correlated with ventricular expansion (p = 0.042; permutation test), and anterior cingulate tissue reductions (p = 0.0026; permutation test) supporting theories that FMRP is required for normal dendritic pruning in fronto-striatal-limbic pathways. No sex differences were found; findings were confirmed using traditional volumetric measures in regions of interest. Deficit patterns were replicated by performing statistics after logarithmic transformation, which may be more appropriate for tensor-valued data. Investigation of how these anomalies emerge over time will accelerate our understanding of FraX and its treatment.
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Affiliation(s)
- Agatha D Lee
- Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, 635 Charles E. Young Drive South, Suite 225E, Los Angeles, CA 90095-7332, USA
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Kabakus N, Aydin M, Akin H, Balci TA, Kurt A, Kekilli E. Fragile X syndrome and cerebral perfusion abnormalities: single-photon emission computed tomographic study. J Child Neurol 2006; 21:1040-6. [PMID: 17156695 DOI: 10.1177/7010.2006.00230] [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] [Indexed: 11/16/2022]
Abstract
Fragile X syndrome is an inherited disorder caused by a defective gene on the X chromosome. It is associated with developmental or behavioral symptoms and various degrees of mental retardation. Morphologic abnormalities and altered perfusion of various brain areas can underlie these functional disturbances. The aim of this study was to investigate the cerebral perfusion state in patients with fragile X syndrome using single-photon emission computed tomography (SPECT). Structural and functional assessment was also performed by magnetic resonance imaging (MRI) and electroencephalography (EEG). Eight boys with cytogenetically confirmed fragile X syndrome (mean age 8.8 +/- 4.4 years, range 5-18 years), were included. All patients had mental retardation, with a mean IQ of 58.9 +/- 8.8 (range 40-68), and additional neurobehavioral symptoms. SPECT revealed cerebral perfusion abnormalities in six patients (75%), most commonly in the frontoparietotemporal area and prominent in the right hemisphere. The SPECT and EEG findings were concordant: hypoperfused areas in SPECT corresponded to regions of persistent slow-wave paroxysms on EEG. On the other hand, cranial MRI was abnormal qualitatively only in two patients (25%) showing cerebellar and vermal hypoplasia and cerebral hemispheric asymmetry. Our results indicate that cerebral perfusion abnormalities, which are correlated with electrophysiologic findings but not necessarily with anatomic abnormalities, can underlie the pathogenesis of the clinical findings observed in fragile X syndrome.
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Affiliation(s)
- Nimet Kabakus
- Department of Pediatric Neurology, Firat University Faculty of Medicine, Elazig, Turkey.
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30
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Hall SS, Debernardis GM, Reiss AL. The acquisition of stimulus equivalence in individuals with fragile X syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2006; 50:643-51. [PMID: 16901291 DOI: 10.1111/j.1365-2788.2006.00814.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
BACKGROUND Few studies have employed stimulus equivalence procedures to teach individuals with intellectual disabilities (IDs) new skills. To date, no studies of stimulus equivalence have been conducted in individuals with fragile X syndrome (FXS), the most common known cause of inherited ID. METHOD Five adolescents with FXS were taught basic math and geography skills by using a computerized stimulus equivalence training programme administered over 2 days in 2-h sessions. RESULTS Four of the five participants learned the math relations, with one participant demonstrating stimulus equivalence at post-test. Three of the five participants learned the geography relations, with all three of these participants demonstrating stimulus equivalence at post-test. CONCLUSIONS These data indicate that computerized stimulus equivalence procedures, conducted in time-limited sessions, may help individuals with FXS learn new skills. Hypotheses concerning the failure of some participants to learn the training relations and to demonstrate stimulus equivalence at post-test are discussed.
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Affiliation(s)
- S S Hall
- Department of Psychiatry & Behavioural Sciences, Stanford University, CA 94365, USA.
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Lightbody AA, Hall SS, Reiss AL. Chronological age, but not FMRP levels, predicts neuropsychological performance in girls with fragile X syndrome. Am J Med Genet B Neuropsychiatr Genet 2006; 141B:468-72. [PMID: 16741913 PMCID: PMC2663575 DOI: 10.1002/ajmg.b.30307] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The effect of FMRP levels and chronological age on executive functioning, visual-spatial abilities ,and verbal fluency tasks were examined in 46 school-age girls with fragile X syndrome (FXS). Results indicated that FMRP levels were not predictive of outcome on the neuropsychological tests but that performance on the executive functioning task tended to worsen with chronological age. This age effect was not observed on the tests of visual-spatial abilities or verbal fluency. These data indicate that relative deficits in executive functioning in girls with FXS become more pronounced with age. In contrast, the relative deficits in spatial and verbal abilities of these girls did not appear to increase with age, suggesting that these abilities may be spared.
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Affiliation(s)
- Amy A Lightbody
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, USA
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Larson J, Jessen RE, Kim D, Fine AKS, du Hoffmann J. Age-dependent and selective impairment of long-term potentiation in the anterior piriform cortex of mice lacking the fragile X mental retardation protein. J Neurosci 2006; 25:9460-9. [PMID: 16221856 PMCID: PMC6725716 DOI: 10.1523/jneurosci.2638-05.2005] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Synaptic function and plasticity were studied in mice lacking the fragile X mental retardation protein (FMRP), a model for the fragile X mental retardation syndrome. Associational connections were studied in slices of anterior piriform (olfactory) cortex, and Schaffer-commissural synapses were studied in slices of hippocampus. Knock-out (KO) mice lacking FMRP were compared with congenic C57BL/6J wild-type (WT) controls. Input-output curves and paired-pulse plasticity were not significantly altered in KO compared with WT mice in either the olfactory cortex or hippocampus. Long-term potentiation (LTP) induced by theta burst stimulation in the anterior piriform cortex was normal in KO mice aged < 6 months but was impaired in KO mice aged > 6 months. The deficit in LTP was significant in mice aged 6-12 months and more pronounced in mice aged 12-18 months. Similar differences between WT and KO mice were seen whether LTP was induced in the presence or absence of a GABAA receptor blocker. Postsynaptic responses to patterned burst stimulation in KO mice showing impaired LTP were not significantly different from those in WT mice, suggesting that the LTP deficit was not caused by alterations in circuit properties. No differences in hippocampal LTP were observed in WT and KO mice at any ages. The results indicate that FMRP deficiency is associated with an age-dependent and region-selective impairment in long-term synaptic plasticity.
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Affiliation(s)
- John Larson
- Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois, Chicago, Illinois 60612, USA.
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Abstract
The fragile X mental retardation 1 gene (FMR1) mutation causes two disorders: fragile X syndrome (FXS) in those with the full mutation and the fragile X-associated tremor/ataxia syndrome (FXTAS) in some older individuals with the premutation. FXS is caused by a deficiency of the FMR1 protein (FMRP) leading to dysregulation of many genes that create a phenotype with ADHD, anxiety, and autism. FXTAS is caused by the elevation of FMR1-mRNA to levels 2 to 8 times normal in the premutation. This causes an RNA gain of function toxicity leading to brain atrophy, white matter disease, neuronal and astrocytic inclusion formation, and subsequent ataxia, intention tremor, peripheral neuropathy, and cognitive decline. The neurobiology and pathophysiology of FXS and FXTAS are described in detail.
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Affiliation(s)
- Randi J Hagerman
- Department of Pediatrics, M.I.N.D. Institute, University of California Davis Health System, Sacramento, California 95817, USA.
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Balci TA, Ciftci I, Kabakus N, Aydin M. Enhanced Perfusion in Eyes and Cerebral Perfusion Defects in a Patient with Fragile X Syndrome. TOHOKU J EXP MED 2006; 210:169-73. [PMID: 17023772 DOI: 10.1620/tjem.210.169] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fragile X syndrome (FXS) is known as the most common form of inherited mental retardation. In our study, brain perfusion single photon emission computed tomography (SPECT) was performed in a 6 year-old boy diagnosed with FXS. Diffuse bilateral uptake of Technetium-99m hexamethyl propylene amine oxime (99mTc-HMPAO) was noted in his orbits, as well as cortical perfusion defects (hypoperfusion in the right parietal and the left temporal lobe). Ophthalmologic examination showed no pathological findings. Magnetic resonance imaging (MRI) revealed no abnormality in the orbital structures, although hypoplasia of cerebellum and vermis was visualized. Since the patient was crying during the injection, the increased blood flow or the increased metabolism of the eyes and/or ocular muscles may be responsible for this orbital finding. Alternatively, the enhanced uptake of HMPAO in the orbits may reflect the pathology associated with FXS, because patients with FXS might have visual-motor abnormalities. To the best of our knowledge, there has been no report documenting such an orbital uptake of HMPAO. Moreover, the visualization of decreased cerebral perfusion, with the normal findings of MRI, indicates that brain SPECT imaging with HMPAO is helpful for detecting brain abnormalities in children with FXS.
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Affiliation(s)
- Tansel Ansal Balci
- Department of Nuclear Medicine, Firat University Medical Faculty, Elazig, Turkey.
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Skinner M, Hooper S, Hatton DD, Roberts J, Mirrett P, Schaaf J, Sullivan K, Wheeler A, Bailey DB. Mapping nonverbal IQ in young boys with fragile X syndrome. Am J Med Genet A 2005; 132A:25-32. [PMID: 15551333 DOI: 10.1002/ajmg.a.30353] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This study examines the developmental changes in nonverbal intellectual functioning evident in males with fragile X syndrome (FXS) measured by the Leiter International Performance Scales-Revised (Leiter-R). The Leiter-R provides both IQ scores and associated growth scores which permit the examination of both age-based IQ scores and overall intellectual growth. Participants were 45 males with full mutation FXS and ranged in age from 4.0 to 13.8 years. Each child was assessed annually using the Leiter-R as part of a larger longitudinal battery for an average of 3.5 assessments per child and a range of 2-6 assessments, representing a total of 156 assessment occasions. Longitudinal analyzes of Leiter scores consisted primarily of hierarchical linear modeling, with the impact of chronological age, maternal education, fragile X mental retardation 1 protein (FMRP), autistic behaviors also being assessed. Findings revealed a significant linear decline in nonverbal IQ scores, with no effects of maternal education, autistic behaviors, or FMRP on mean level or rate of change in IQ scores over time. The decline slowed significantly around 8 years of age, but scores continued to decline into the 12th year of age. In contrast, a significant linear increase was observed in Leiter-R growth scores, which was negatively influenced by autistic behaviors. The rate of increase did not change over time, and neither mean level nor rate of increase was influenced by maternal education or FMRP levels. These findings suggest that declines in IQ are the result of steady, but suboptimal intellectual growth, rather than a true deterioration in overall intellectual functioning.
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Affiliation(s)
- Martie Skinner
- Social Development Research Group, University of Washington, Seattle, Washington 98115, USA.
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Cornish KM, Turk J, Wilding J, Sudhalter V, Munir F, Kooy F, Hagerman R. Annotation: Deconstructing the attention deficit in fragile X syndrome: a developmental neuropsychological approach. J Child Psychol Psychiatry 2004; 45:1042-53. [PMID: 15257661 DOI: 10.1111/j.1469-7610.2004.t01-1-00297.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Fragile X syndrome is one of the world's leading hereditary causes of developmental delay in males. The past decade has witnessed an explosion of research that has begun to unravel the condition at its various levels: from the genetic and brain levels to the cognitive level, and then to the environmental and behavioural levels. Our aim in this review is to attempt to integrate some of the extensive body of knowledge to move the research a step closer to understanding how the dynamics of atypical development can influence the specific cognitive and behavioural end-states frequently observed in children and adolescents with fragile X syndrome. METHODS We conducted a review of the current neuropsychological and neuropsychiatric approaches that have attempted to delineate the pattern of 'spared' and 'impaired' functions associated with the phenotype. RESULTS The profile of findings suggests that fragile X syndrome should not be viewed merely as a catalogue of spared and impaired cognitive functions or modules. Instead, there appears to be a process of almost gradual modularisation whereby cognitive mechanisms become domain specific as a function of development itself (Karmiloff-Smith, 1992). The results of a decade of intense research point towards an early weakness in one or more components of executive control rather than single, static higher-level deficits (e.g., spatial cognition, speech processing). This weakness affects both the development of more complex functions and current performance. CONCLUSIONS The prevailing tendency to interpret developmental disorders in terms of fixed damage to distinct modular functions needs to be reconsidered. We offer this review as an example of an alternative approach, attempting to identify an initial deficit and its consequences for the course of development. Through better definition of the cognitive and behavioural phenotype, in combination with current progress in brain imaging techniques and molecular studies, the next decade should continue to hold exciting promise for fragile X syndrome and other neurodevelopmental disorders.
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Affiliation(s)
- K M Cornish
- Department of Educational Psychology, McGill University, Montréal, Canada.
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Abstract
Evolution of the prefrontal cortex was an essential precursor to civilization. During the past decade, it became increasingly obvious that human prefrontal function is under substantial genetic control. In particular, heritability studies of frontal lobe-related neuropsychological function, electrophysiology and neuroimaging have greatly improved our insight. Moreover, the first genes that are relevant for prefrontal function such as catechol-O-methyltransferase (COMT) are currently discovered. In this review, we summarize the present knowledge on the genetics of human prefrontal function. For historical reasons, we discuss the genetics of prefrontal function within the broader concept of general cognitive ability (intelligence). Special emphasis is also given to methodological concerns that need to be addressed when conducting research on the genetics of prefrontal function in humans.
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Affiliation(s)
- Georg Winterer
- Clinical Brain Disorders Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
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Abstract
Fragile X syndrome (FXS) is a well-recognized cause of mental retardation and developmental delay in males. Alongside the well-documented clinical characteristics of the condition, recent advances in technology and methodology have begun to define FXS at a number of different levels: genetic, brain structure and function, cognition, and behavior. This article suggests that the FXS phenotype is not merely a juxtaposition of spared and impaired functions but rather may be characterized by an inhibitory control deficit that interferes with the individual's ability to modulate output causing perseverative responding across various skill areas. It is further suggested that an inability to modulate arousal may be at least one cause for the inhibitory control deficit that typifies the FXS phenotype. The approach to understanding atypical development outlined here holds exciting promise for future research in FXS and other developmental disorders.
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Affiliation(s)
- Kim Cornish
- Department of Educational Psychology, McGill University, Montreal, Canada.
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Barnea-Goraly N, Eliez S, Hedeus M, Menon V, White CD, Moseley M, Reiss AL. White matter tract alterations in fragile X syndrome: preliminary evidence from diffusion tensor imaging. Am J Med Genet B Neuropsychiatr Genet 2003; 118B:81-8. [PMID: 12627472 DOI: 10.1002/ajmg.b.10035] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Fragile X syndrome, the most common form of hereditary mental retardation, causes disruption in the development of dendrites and synapses, the targets for axonal growth in the central nervous system. This disruption could potentially affect the development, wiring, and targeting of axons. The current study utilized diffusion tensor imaging (DTI) to investigate whether white matter tract integrity and connectivity are altered in fragile X syndrome. Ten females with a diagnosis of fragile X syndrome and ten, age matched, female control subjects underwent diffusion weighted MRI scans. A whole brain analysis of fractional anisotropy (FA) values was performed using statistical parametric mapping (SPM). A follow-up, regions-of-interest analysis also was conducted. Relative to controls, females with fragile X exhibited lower FA values in white matter in fronto-striatal pathways, as well as in parietal sensory-motor tracts. This preliminary study suggests that regionally specific alterations of white matter integrity occur in females with fragile X. Aberrant white matter connectivity in these regions is consistent with the profile of cognitive and behavioral features of fragile X syndrome, and potentially provide additional insight into the detrimental effects of suboptimal levels of FMRP in the developing brain.
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Affiliation(s)
- Naama Barnea-Goraly
- Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Road, Stanford, CA 94305-5719, USA
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Cohen MM. Mental deficiency, alterations in performance, and CNS abnormalities in overgrowth syndromes. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2003; 117C:49-56. [PMID: 12561058 DOI: 10.1002/ajmg.c.10013] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mental deficiency, alterations in performance, and central nervous system (CNS) abnormalities are discussed in the following overgrowth syndromes: Sotos syndrome, Weaver syndrome, Proteus syndrome, neurofibromatosis type 1, fragile X syndrome, syndromes with neonatal hypoglycemia, Simpson-Golabi-Behmel syndrome, hemihyperplasia, Sturge-Weber syndrome, Bannayan-Riley-Ruvalcaba/Cowden syndrome, macrocephaly-autism syndrome, PEHO syndrome, chromosomal syndromes, and other miscellaneous syndromes.
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Qin M, Kang J, Smith CB. Increased rates of cerebral glucose metabolism in a mouse model of fragile X mental retardation. Proc Natl Acad Sci U S A 2002; 99:15758-63. [PMID: 12427968 PMCID: PMC137789 DOI: 10.1073/pnas.242377399] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In humans, failure to express the fragile X mental retardation protein (FMRP) gives rise to fragile X syndrome, the most common form of inherited mental retardation. A fragile X knockout (fmr1 KO) mouse has been described that has some of the characteristics of patients with fragile X syndrome, including immature dendritic spines and subtle behavioral deficits. In our behavioral studies, fmr1 KO mice exhibited hyperactivity and a higher rate of entrance into the center of an open field compared with controls, suggesting decreased levels of anxiety. Our finding of impaired performance of fmr1 KO mice on a passive avoidance task is suggestive of a deficit in learning and memory. In an effort to understand what brain regions are involved in the behavioral abnormalities, we applied the [(14)C]deoxyglucose method for the determination of cerebral metabolic rates for glucose (CMR(glc)). We measured CMR(glc) in 38 regions in adult male fmr1 KO and WT littermates. We found CMR(glc) was higher in all 38 regions in fmr1 KO mice, and in 26 of the regions, differences were statistically significant. Differences in CMR(glc) ranged from 12% to 46%, and the greatest differences occurred in regions of the limbic system and primary sensory and posterior parietal cortical areas. Regions most affected are consistent with behavioral deficiencies and regions in which FMRP expression is highest. Higher CMR(glc) in fragile X mice may be a function of abnormalities found in dendritic spines.
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Affiliation(s)
- Mei Qin
- Unit on Neurobiology, Laboratory of Cerebral Metabolism, National Institute of Mental Health, Bethesda, MD, USA
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Abstract
Spines are neuronal protrusions, each of which receives input typically from one excitatory synapse. They contain neurotransmitter receptors, organelles, and signaling systems essential for synaptic function and plasticity. Numerous brain disorders are associated with abnormal dendritic spines. Spine formation, plasticity, and maintenance depend on synaptic activity and can be modulated by sensory experience. Studies of compartmentalization have shown that spines serve primarily as biochemical, rather than electrical, compartments. In particular, recent work has highlighted that spines are highly specialized compartments for rapid large-amplitude Ca(2+) signals underlying the induction of synaptic plasticity.
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Affiliation(s)
- Esther A Nimchinsky
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
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Hagerman RJ, Miller LJ, McGrath-Clarke J, Riley K, Goldson E, Harris SW, Simon J, Church K, Bonnell J, Ognibene TC, McIntosh DN. Influence of stimulants on electrodermal studies in Fragile X syndrome. Microsc Res Tech 2002; 57:168-73. [PMID: 12112453 DOI: 10.1002/jemt.10067] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Attention Deficit Hyperactivity Disorder (ADHD) is seen in the majority of children with Fragile X Syndrome (FraX). Previous work has documented an enhanced sweat response to stimuli in children with FraX compared to controls utilizing electrodermal response (EDR) measures. The present study assesses the EDRs both on and off stimulants in 19 children with ADHD and FraX compared to 17 age- and IQ-matched control patients with ADHD and developmental delays. Although the baseline EDRs were comparable between FraX patients and controls, the patients with FraX had a significant decrease in EDR amplitude and number of peaks when treated with stimulants compared to controls. This suggests that patients with FraX are more responsive to the enhancement of inhibitory systems that occur with stimulant use for ADHD. The use of a quantifiable measure, such as EDR, is recommended in future studies of treatment efficacy.
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Affiliation(s)
- Randi J Hagerman
- M.I.N.D. Institute, University of California Davis Health System, Sacramento, California 95817, USA.
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Affiliation(s)
- R J Hagerman
- M.I.N.D. Institute and Department of Pediatrics, University of California at Davis Medical Center, Sacramento, California 95817, USA.
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Abstract
Fragile X syndrome is caused by a mutation in the FMR1 gene leading to absence of the fragile X mental retardation protein (FMRP). Reports that patients and adult FMR1 knock-out mice have abnormally long dendritic spines of increased density suggested that the disorder might involve abnormal spine development. Because spine length, density, and motility change dramatically in the first postnatal weeks, we analyzed these properties in mutant mice and littermate controls at 1, 2, and 4 weeks of age. To label neurons, a viral vector carrying the enhanced green fluorescent protein gene was injected into the barrel cortex. Layer V neurons were imaged on a two-photon laser scanning microscope in fixed tissue sections. Analysis of >16,000 spines showed clear developmental patterns. Between 1 and 4 weeks of age, spine density increased 2.5-fold, and mean spine length decreased by 17% in normal animals. Early during cortical synaptogenesis, pyramidal cells in mutant mice had longer spines than controls. At 1 week, spine length was 28% greater in mutants than in controls. At 2 weeks, this difference was 10%, and at 4 weeks only 3%. Similarly, spine density was 33% greater in mutants than in controls at 1 week of age. At 2 or 4 weeks of age, differences were not detectable. The spine abnormality was not detected in neocortical organotypic cultures. The transient nature of the spine abnormality in the intact animal suggests that FMRP might play a role in the normal process of dendritic spine growth in coordination with the experience-dependent development of cortical circuits.
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Abstract
Working memory performance in a group of young Fragile X males with FMR-1 full mutation was compared to a learning disabled comparison group comprising Down's syndrome males and two control groups of mainstream schoolchildren. Performance was assessed on a battery of tasks tapping the three components of working memory-phonological loop, visual-spatial sketch pad, and the central executive. The results indicated that the Fragile X group displayed a general impairment on working memory tasks that cannot be attributed to a single working memory component per se. Instead, the results suggest that Fragile X males have a working memory deficit that may be attributed to how much attentional resource a specific task requires and their overall available executive capacity, irrespective of the working memory subsystem.
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Affiliation(s)
- F Munir
- Section of Developmental Psychiatry, University of Nottingham, Nottingham, NG7 2UH, United Kingdom
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Hjalgrim H, Fisher Hansen B, Brondum-Nielsen K, Nolting D, Kjaer I. Aspects of skeletal development in fragile X syndrome fetuses. AMERICAN JOURNAL OF MEDICAL GENETICS 2000; 95:123-9. [PMID: 11078561 DOI: 10.1002/1096-8628(20001113)95:2<123::aid-ajmg6>3.0.co;2-u] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of the present investigation was to describe the skeletal development in prenatal fragile X syndrome. We studied fetuses (4 males, 2 females), with gestational ages (GA) 12-14 weeks, from 5 unrelated, different, known carrier mothers. Because of trauma to the fetus during abortion, different parts of the 6 fetuses were available for investigation. The vertebral column and the facial skeleton of all the fetuses were examined, the feet and hands of 5 fetuses, and the cranial base of 3 fetuses. The tissue remnants were examined radiographically and histochemically, and the results compared with previously published normal findings. Radiographic findings included normal ossification sequence, except for 1 fetus where there was an abnormal sequence in the first finger; normal morphology of ossification centres; and nasal bones were absent in the 5 fetuses and present in 1 (14 weeks of gestation). The histological study suggests presence of an acid mucopolysaccharide malfunction in the supporting tissue, because the normal cartilage resorption and orthochromatic cartilage reactions do not appear during the initial enchondral ossification. In addition, the apoptosis of ectodermally derived cells (notochord and palatal epithelial layers) appears delayed or abnormal. The sella turcica was malformed in the 2 fetuses investigated for sella turcica morphology.
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Affiliation(s)
- H Hjalgrim
- Department of Medical Genetics, John F. Kennedy Institute, Glostrup, Denmark
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Munir F, Cornish KM, Wilding J. A neuropsychological profile of attention deficits in young males with fragile X syndrome. Neuropsychologia 2000; 38:1261-70. [PMID: 10865102 DOI: 10.1016/s0028-3932(00)00036-1] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Different processes of attention were examined in a group of 25 fragile X boys with FMR-1 full mutation and compared with three control groups: a learning disabled comparison group comprising 25 boys with Down's syndrome, matched to the fragile X boys on verbal mental age; and 50 mainstream school boys (controls) matched to the fragile X boys on verbal mental age. The controls were further divided into those matched on "poor attention" to the fragile X boys and a "good" attention group, as rated by the ACTeRS questionnaire. Four categories of attention tasks were employed: selective attention, divided attention, sustained attention and executive functioning. The main findings of the study indicate that fragile X boys display an attention deficit at higher levels of attention function/executive functioning and that this profile is different from the profile identified in Down's syndrome boys and more extreme than the profile identified in the poor attention control group. These findings are discussed in the context of functional neuroimaging and brain-behaviour correlates in fragile X syndrome.
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Affiliation(s)
- F Munir
- Section of Developmental Psychiatry, Division of Psychiatry, E Floor, South Block, Queens Medical Centre, University of Nottingham, NG7 2UH, Nottingham, UK
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Menon V, Kwon H, Eliez S, Taylor AK, Reiss AL. Functional brain activation during cognition is related to FMR1 gene expression. Brain Res 2000; 877:367-70. [PMID: 10986352 DOI: 10.1016/s0006-8993(00)02617-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Fragile X syndrome, the most common known cause of inherited mental retardation, is caused by alterations of the FMR1 gene encoding the FMRP protein. We investigated the relation between FMRP protein levels and functional brain activation during a working memory task. Our study provides the first evidence for a relation between FMR1 gene expression and neural activity during higher-order cognition. More broadly, our findings provide the first demonstration of how gene-brain-behavior investigations can help to bridge the gap between molecular and systems neuroscience.
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Affiliation(s)
- V Menon
- Department of Psychiatry, 401 Quarry Road, Stanford University School of Medicine, Stanford, CA 94305-5719, USA.
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50
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