Behavioral and synaptic circuit analysis in models of neuropsychiatric disorders: Dissecting the in vivo role of the postsynaptic density proteins nArgBP2 and Shank3 using genetic engineered mice

Dissertation presented to obtain the Ph.D degree in Biology

A 600 kb deletion syndrome at 16p11.2 leads to energy imbalance and neuropsychiatric disorders.

BACKGROUND: The recurrent ~600 kb 16p11.2 BP4-BP5 deletion is among the most frequent known genetic aetiologies of autism spectrum disorder (ASD) and related neurodevelopmental disorders. OBJECTIVE: To define the medical, neuropsychological, and behavioural phenotypes in carriers of this deletion. METHODS: We collected clinical data on 285 deletion carriers and performed detailed evaluations on 72 carriers and 68 intrafamilial non-carrier controls. RESULTS: When compared to intrafamilial controls, full scale intelligence quotient (FSIQ) is two standard deviations lower in carriers, and there is no difference between carriers referred for neurodevelopmental disorders and carriers identified through cascade family testing. Verbal IQ (mean 74) is lower than non-verbal IQ (mean 83) and a majority of carriers require speech therapy. Over 80% of individuals exhibit psychiatric disorders including ASD, which is present in 15% of the paediatric carriers. Increase in head circumference (HC) during infancy is similar to the HC and brain growth patterns observed in idiopathic ASD. Obesity, a major comorbidity present in 50% of the carriers by the age of 7 years, does not correlate with FSIQ or any behavioural trait. Seizures are present in 24% of carriers and occur independently of other symptoms. Malformations are infrequently found, confirming only a few of the previously reported associations. CONCLUSIONS: The 16p11.2 deletion impacts in a quantitative and independent manner FSIQ, behaviour and body mass index, possibly through direct influences on neural circuitry. Although non-specific, these features are clinically significant and reproducible. Lastly, this study demonstrates the necessity of studying large patient cohorts ascertained through multiple methods to characterise the clinical consequences of rare variants involved in common diseases.

A controlled clinical trial on the effects of exercise on neuropsychiatric disorders and instrumental activities in women with Alzheimer's disease

OBJETIVO: Analisar os efeitos de seis meses de intervenção de um programa de atividade física sobre os distúrbios neuropsiquiátricos e o desempenho nas atividades instrumentais da vida diária de idosos com Doença de Alzheimer (DA). MÉTODOS: Foram recrutados 20 pacientes nos estágios entre leve e moderado da DA. Segundo o escore clínico de demência (CDR), foram distribuídos em dois grupos: o grupo treinamento (GT), composto por dez mulheres que participaram de um program de exercícios físicos por um período de seis meses, e o grupo controle (GC), composto por dez outras participantes que não realizaram nenhum tipo de intervenção motora estruturada durante o mesmo período. Todas as participantes foram avaliadas por meio do Miniexame do Estado Mental, para obtenção da caracterização cognitiva; Inventário Neuropsiquiátrico, para identificação dos distúrbios neuropsiquiátricos mais prevalentes e Questionário de Atividades Instrumentais de Pfeffer, para verificação do grau de comprometimento funcional. RESULTADOS: Os participantes do GC mostraram uma deterioração tanto no desempenho das atividades instrumentais quanto na intensificação dos distúrbios neuropsiquiátricos, quando comparados os momentos pré e pós-intervenção. CONCLUSÃO: O GT demonstrou uma atenuação da intensificação dos distúrbios neuropsiquiátricos e do desempenho funcional em relação ao grupo sedentário.

Social Cognition and Neural Substrates of Face Perception: Implications for Neurodevelopmental and Neuropsychiatric Disorders

BACKGROUND: Social cognition is an important aspect of social behavior in humans. Social cognitive deficits are associated with neurodevelopmental and neuropsychiatric disorders. In this study we examine the neural substrates of social cognition and face processing in a group of healthy young adults to examine the neural substrates of social cognition. METHODS: Fifty-seven undergraduates completed a battery of social cognition tasks and were assessed with electroencephalography (EEG) during a face-perception task. A subset (N=22) were administered a face-perception task during functional magnetic resonance imaging. RESULTS: Variance in the N170 EEG was predicted by social attribution performance and by a quantitative measure of empathy. Neurally, face processing was more bilateral in females than in males. Variance in fMRI voxel count in the face-sensitive fusiform gyrus was predicted by quantitative measures of social behavior, including the Social Responsiveness Scale (SRS) and the Empathizing Quotient. CONCLUSIONS: When measured as a quantitative trait, social behaviors in typical and pathological populations share common neural pathways. The results highlight the importance of viewing neurodevelopmental and neuropsychiatric disorders as spectrum phenomena that may be informed by studies of the normal distribution of relevant traits in the general population. Copyright 2014 Elsevier B.V. All rights reserved.

A 600 kb deletion syndrome at 16p11.2 leads to energy imbalance and neuropsychiatric disorders

BACKGROUND: The recurrent ~600 kb 16p11.2 BP4-BP5 deletion is among the most frequent known genetic aetiologies of autism spectrum disorder (ASD) and related neurodevelopmental disorders. OBJECTIVE: To define the medical, neuropsychological, and behavioural phenotypes in carriers of this deletion. METHODS: We collected clinical data on 285 deletion carriers and performed detailed evaluations on 72 carriers and 68 intrafamilial non-carrier controls. RESULTS: When compared to intrafamilial controls, full scale intelligence quotient (FSIQ) is two standard deviations lower in carriers, and there is no difference between carriers referred for neurodevelopmental disorders and carriers identified through cascade family testing. Verbal IQ (mean 74) is lower than non-verbal IQ (mean 83) and a majority of carriers require speech therapy. Over 80% of individuals exhibit psychiatric disorders including ASD, which is present in 15% of the paediatric carriers. Increase in head circumference (HC) during infancy is similar to the HC and brain growth patterns observed in idiopathic ASD. Obesity, a major comorbidity present in 50% of the carriers by the age of 7 years, does not correlate with FSIQ or any behavioural trait. Seizures are present in 24% of carriers and occur independently of other symptoms. Malformations are infrequently found, confirming only a few of the previously reported associations. CONCLUSIONS: The 16p11.2 deletion impacts in a quantitative and independent manner FSIQ, behaviour and body mass index, possibly through direct influences on neural circuitry. Although non-specific, these features are clinically significant and reproducible. Lastly, this study demonstrates the necessity of studying large patient cohorts ascertained through multiple methods to characterise the clinical consequences of rare variants involved in common diseases.

ADHD and fetal alcohol spectrum disorders (FASD).

This multi-author book will discuss the history and clinical presentation of Foetal Alcohol Spectrum Disorders(FASD) i.e Fetal Alcohol Syndrome (FAS) and Alcohol Related Neurodevelopmental Disorder (ARND). These developmental neuropsychiatric disorders result from prenatal exposure to alcohol during any gestational period of pregnancy. The book will particularly address the co-occurring presence of ADHD in patients with FASD. ADHD is the most frequent neuropsychiatric presentation of FASD throughout the lifespan and it is particularly difficult to manage because the underlying pathophysiology is related to prenatal neurotoxic brain injury. Although prenatal alcohol exposure , and the resulting FASD, is recognised as the commonest preventable cause of intellectual disability, many clinicians and educators are not aware that 75 to 80% of the patients with FASD have I.Q.s over 70. Thus, the neuropsychiatric presentation of FASD can often be unrecognised or misunderstood. FASD are the true clinical ' masqueraders' and ADHD is their most likely disguise! The authors are all experienced professionals from a wide range of disciplines working throughout the USA and Canada. They have been involved in the diagnosis, research and management of FASD for many years and this book will bring their collective knowledge regarding management from infancy to adulthood to an inter-professional audienceThis resource was contributed by The National Documentation Centre on Drug Use.

Copy number variation characteristics in subpopulations of patients with autism spectrum disorders.

Autism spectrum disorders (ASDs) are a heterogeneous group of disorders with a complex genetic etiology. We used high-resolution whole genome array-based comparative genomic hybridization (array-CGH) to screen 223 ASD patients for gene dose alterations associated with susceptibility for autism. Clinically significant copy number variations (CNVs) were identified in 18 individuals (8%), of which 9 cases (4%) had de novo aberrations. In addition, 20 individuals (9%) were shown to have CNVs of unclear clinical relevance. Among these, 13 cases carried rare but inherited CNVs that may increase the risk for developing ASDs, while parental samples were unavailable in the remaining seven cases. Classification of all patients into different phenotypic and inheritance pattern groups indicated the presence of different CNV patterns in different patient groups. Clinically relevant CNVs were more common in syndromic cases compared to non-syndromic cases. Rare inherited CNVs were present in a higher proportion of ASD cases having first- or second-degree relatives with an ASD-related neuropsychiatric phenotype in comparison with cases without reported heredity (P = 0.0096). We conclude that rare CNVs, encompassing potential candidate regions for ASDs, increase the susceptibility for the development of ASDs and related neuropsychiatric disorders giving us further insight into the complex genetics underlying ASDs.

The 16p11.2 rearrangments genetic paradigms for obesity and neurodevelopmental disorders.

Recent discoveries of recurrent and reciprocal Copy Number Variants (CNVs) using genome- wide studies have led to a new understanding of the etiology of neuropsychiatric disorders. CNVs represent loss (deletion) or gain (duplication) of genomic material. This thesis work is focused on CNVs at the 16p11.2 BP4-BP5 locus, which are among the most frequent etiologies of neurodevelopmental disorders and have been associated with Autism Spectrum Disorders (ASD), schizophrenia, cognitive impairment, alterations of brain size as well as obesity and underweight. Because deletion and duplication of the 16p11.2 locus occur frequently and recurrently (with the same breakpoints), CNVs at this locus represent a powerful paradigm to understand how a genomic region may modulate cognitive and behavioral traits as well as the relationship and shared mechanisms between distinct psychiatric diagnoses such as ASD and schizophrenia. The present dissertation includes three studies: 1) The first project aims at identifying structural brain-imaging endophenotypes in 16p11.2 CNVs carriers at risk for ASD and schizophrenia. The results show that gene dosage at the 16p11.2 locus modulates global brain volumes and neural circuitry, including the reward system, language and social cognition circuits. 2) The second investigates the neuropsychological profile in 16p11.2 deletion and duplication carriers. While deletion carriers show specific deficits in language and inhibition, the profile of duplication carriers is devoid of specific weaknesses and presents enhanced performance in a verbal memory task. 3) The third study on food-related behaviors in 16p11.2 deletion and duplication carriers shows that alterations of the reponse to satiety are present in CNV carriers before the onset of obesity, pointing toward a potential mechanism driving the Body Mass Index increase in deletion carriers. Dysfunctions in the reward system and dopaminergic circuitries could represent a common mechanism playing a role in the phenotype and could be investigated in future studies. Our data strongly suggest that complex cognitive traits correlate to gene dosage in humans. Larger studies including expression data would allow elucidating the contribution of specific genes to these different gene dosage effects. In conclusion, a systematic and careful investigation of cognitive, behavioral and intermediate phenotypes using a gene dosage paradigm has allowed us to advance our understanding of the 16p11.2 BP4-BP5 locus and its effects on neurodevelopment. -- La récente découverte de variations du nombre de copies (CNVs pour 'copy number variants') dans le génome humain a amélioré nos connaissances sur l'étiologie des troubles neuropsychiatriques. Un CNV représente une perte (délétion) ou un gain (duplication) de matériel génétique sur un segment chromosomique. Ce travail de thèse est focalisé sur les CNVs réciproques (délétion et duplication) dans la région 16p11.2 BP4-BP5. Ces CNVs sont une cause fréquente de troubles neurodéveloppementaux et ont été associés à des phénotypes « en miroir » tels que obésité/sous-poids ou macro/microcéphalie mais aussi aux troubles du spectre autistique (TSA), à la schizophrénie et au retard de développement/déficience intellectuelle. La fréquence et la récurrence de la délétion et de la duplication aux mêmes points de cassure font de ces CNVs un paradigme unique pour étudier la relation entre dosage génique et les traits cognitifs et comportementaux, ainsi que les mécanismes partagés par des troubles psychiatriques apparemment distincts tels que les TSA et la schizophrénie. Ce travail de thèse comporte trois études distinctes : 1) l'étude en neuroimagerie structurelle identifie les endophénotypes chez les porteurs de la délétion ou de la duplication. Les résultats montrent une influence du dosage génique sur le volume cérébral total et certaines structures dans les systèmes de récompense, du langage et de la cognition sociale. 2) L'étude des profils neuropsychologiques chez les porteurs de la délétion ou de la duplication montre que la délétion est associée à des troubles spécifiques du langage et de l'inhibition alors que les porteurs de la duplication ne montrent pas de faiblesse spécifique mais des performances mnésiques verbales supérieures à leur niveau cognitif global. 3) L'étude sur les comportements alimentaires met en évidence une altération de la réponse à la satiété qui est présente avant l'apparition de l'obésité. Un dysfonctionnement dans le système de récompense et les circuits dopaminergiques pourrait représenter un mécanisme commun aux différents phénotypes observés chez ces individus porteurs de CNVs au locus 16p11.2. En conclusion, l'utilisation du dosage génique comme outil d'investigation des phénotypes cliniques et endophénotypes nous a permis de mieux comprendre le rôle de la région 16p11.2 BP4-BP5 dans le neurodéveloppement.

Genetics of homocysteine metabolism and associated disorders

Homocysteine is a sulfur-containing amino acid derived from the metabolism of methionine, an essential amino acid, and is metabolized by one of two pathways: remethylation or transsulfuration. Abnormalities of these pathways lead to hyperhomocysteinemia. Hyperhomocysteinemia is observed in approximately 5% of the general population and is associated with an increased risk for many disorders, including vascular and neurodegenerative diseases, autoimmune disorders, birth defects, diabetes, renal disease, osteoporosis, neuropsychiatric disorders, and cancer. We review here the correlation between homocysteine metabolism and the disorders described above with genetic variants on genes coding for enzymes of homocysteine metabolism relevant to clinical practice, especially common variants of the MTHFR gene, 677C>T and 1298A>C. We also discuss the management of hyperhomocysteinemia with folic acid supplementation and fortification of folic acid and the impact of a decrease in the prevalence of congenital anomalies and a decline in the incidence of stroke mortality.

Intelligence functions disorders in patients with complex partial epilepsy

Objective: To compare the performance of patients with complex partial epilepsy with the normal controls in the subtests of an instrument used to assess intelligence function. Method: Fifty epileptic patients, whose ages ranged from 19 to 49 years and 20 normal controls without any neuropsychiatric disorders. The Wechsler-Bellevue adult intelligence test was applied in groups, epileptic patients and control subjects. This test is composed of several subtests that assess specific cognitive functions. A statistical analysis was performed using non-parametric tests. Results: All the Wechsler-Bellevue subtests revealed that the intelligence functions of the patients were significantly inferior to that of the controls (p<0.05). This performance was supported by the patient's complaints in relation to their cognitive performance. Conclusion: Patients with complex partial epilepsy presented poorer results in the intelligence test when compared with individuals without neuropsychiatric disorders.

Increased CNS levels of apolipoprotein D in schizophrenic and bipolar subjects: Implications for the pathophysiology of psychiatric disorders

Chronic administration of the atypical antipsychotic drug, clozapine, to rodents has been shown to increase the concentration of apolipoprotein D (apoD) in several area of the brain, suggesting that apoD could be involved in the therapeutic effects of antipsychotic drugs and/or the pathology of psychotic illnesses. Here, we measured a significant decrease in the concentration of apoD in serum samples from schizophrenic patients. In contrast, apoD levels were significantly increased (92–287%) in dorsolateral prefrontal cortex (Brodmann's area 9) of schizophrenic and bipolar subjects. Elevated levels of apoD expression were also observed in the caudate of schizophrenic and bipolar subjects (68–89%). No differences in apoD immunoreactivity were detected in occipital cortex (Brodmann's area 18) in either group, or in the hippocampus, substantia nigra, or cerebellum of the schizophrenic group. The low serum concentrations of apoD observed in these patients supports recent hypotheses involving systemic insufficiencies in lipid metabolism/signaling in schizophrenia. Elevation of apoD expression selectively within central nervous system regions implicated in the pathology of these neuropsychiatric disorders suggests a focal compensatory response that neuroleptic drug regimens may augment.

Developing multidimensional metrics for evaluating paediatric neurodevelopmental disorders

Healthy brain functioning depends on efficient communication of information between brain regions, forming complex networks. By quantifying synchronisation between brain regions, a functionally connected brain network can be articulated. In neurodevelopmental disorders, where diagnosis is based on measures of behaviour and tasks, a measure of the underlying biological mechanisms holds promise as a potential clinical tool. Graph theory provides a tool for investigating the neural correlates of neuropsychiatric disorders, where there is disruption of efficient communication within and between brain networks. This research aimed to use recent conceptualisation of graph theory, along with measures of behaviour and cognitive functioning, to increase understanding of the neurobiological risk factors of atypical development. Using magnetoencephalography to investigate frequency-specific temporal dynamics at rest, the research aimed to identify potential biological markers derived from sensor-level whole-brain functional connectivity. Whilst graph theory has proved valuable for insight into network efficiency, its application is hampered by two limitations. First, its measures have hardly been validated in MEG studies, and second, graph measures have been shown to depend on methodological assumptions that restrict direct network comparisons. The first experimental study (Chapter 3) addressed the first limitation by examining the reproducibility of graph-based functional connectivity and network parameters in healthy adult volunteers. Subsequent chapters addressed the second limitation through adapted minimum spanning tree (a network analysis approach that allows for unbiased group comparisons) along with graph network tools that had been shown in Chapter 3 to be highly reproducible. Network topologies were modelled in healthy development (Chapter 4), and atypical neurodevelopment (Chapters 5 and 6). The results provided support to the proposition that measures of network organisation, derived from sensor-space MEG data, offer insights helping to unravel the biological basis of typical brain maturation and neurodevelopmental conditions, with the possibility of future clinical utility.

Tourette's syndrome and associated disorders: a systematic review

To compile data on Tourette's syndrome (TS), tics and associated disorders. METHODS: A systematic review of the literature was conducted using the 5S levels of organization of healthcare research evidence (systems, summaries, synopses, syntheses, studies), based on the model described by Haynes. The search keywords were Tourette, tics and comorbidity, which were cross-referenced. Studies provided by publishers and articles being processed on July 31, 2013, were also included. RESULTS: Of all studies retrieved during the search, 64 were selected because they analyzed the epidemiology, clinical features and etiopathogenesis of TS and its comorbidities. TS is classified as a hyperkinetic movement disorder, and at least 90% of the patients have neuropsychiatric comorbidities, of which attention deficit hyperactivity and obsessive-compulsive disorders are the most common. The syndrome is clinically heterogeneous and has been associated with a dysfunction of cortico-striatal-thalamic-cortical circuits involving various neurotransmitters. Although its genetic etiology has been widely studied, other factors may be important to understand this syndrome and its associated disorders. CONCLUSIONS: TS is a neurodevelopmental disorder that results from the impact of stress factors on a vulnerable biological substrate during the critical periods of neurodevelopment. The study of TS and its comorbidities may contribute, at different levels, to the understanding of several neuropsychiatric disorders of clinical and therapeutic relevance.

Tourette's syndrome and associated disorders: a systematic review

To compile data on Tourette's syndrome (TS), tics and associated disorders. METHODS: A systematic review of the literature was conducted using the 5S levels of organization of healthcare research evidence (systems, summaries, synopses, syntheses, studies), based on the model described by Haynes. The search keywords were Tourette, tics and comorbidity, which were cross-referenced. Studies provided by publishers and articles being processed on July 31, 2013, were also included. RESULTS: Of all studies retrieved during the search, 64 were selected because they analyzed the epidemiology, clinical features and etiopathogenesis of TS and its comorbidities. TS is classified as a hyperkinetic movement disorder, and at least 90% of the patients have neuropsychiatric comorbidities, of which attention deficit hyperactivity and obsessive-compulsive disorders are the most common. The syndrome is clinically heterogeneous and has been associated with a dysfunction of cortico-striatal-thalamic-cortical circuits involving various neurotransmitters. Although its genetic etiology has been widely studied, other factors may be important to understand this syndrome and its associated disorders. CONCLUSIONS: TS is a neurodevelopmental disorder that results from the impact of stress factors on a vulnerable biological substrate during the critical periods of neurodevelopment. The study of TS and its comorbidities may contribute, at different levels, to the understanding of several neuropsychiatric disorders of clinical and therapeutic relevance.