Boris Chaumette

French Institute of Health and Medical Research | Inserm · Institute of Psychiatry and Neurosciences of Paris

The onset of psychosis is the consequence of complex interactions between genetic vulnerability to psychosis and response to environmental and/or maturational changes. Epigenetics is hypothesized to mediate the interplay between genes and environment leading to the onset of psychosis. We believe we performed the first longitudinal prospective study...

The biological processes associated with the onset of schizophrenia remain largely unknown. Current hypotheses favor gene × environment interactions as supported by our recent report about DNA methylation changes during the onset of psychosis. Here, we conducted the first longitudinal transcriptomic analysis of blood samples from 31 at-risk individ...

Psychosis is a progressive mental disorder which normally occurs during adolescence in at-risk subjects following a dynamic process termed “psychotic transition”. These at-risk subjects are clinically identifiable but biological data are still insufficient in explaining the onset of psychosis. Throughout this thesis, we aim to identify biological f...

Clear diagnostic definition is required for clinical practice in psychiatry. Nowadays, the categorical approaches as defined in Diagnostic and Statistical Manual of mental disorders (DSM) are insufficient to explain the variety of clinical presentations and the overlap between psychiatric diseases. The dimensional approaches hypothesized a continuu...

Bipolar disorder (BD) is a multifactorial psychiatric illness affecting about 1% of the world population. The first line treatment, lithium (Li), is effective in only a subset of patients and its mechanism of action remains largely elusive. In the present study, we used iPSC-derived neurons from BD patients responsive (LR) or not (LNR) to lithium a...

Genetic research has identified a large number of genetic variants, both rare and common, underlying neurodevelopmental disorders (NDD) and major psychiatric disorders. Currently, these findings are being translated into clinical practice. However, there is a lack of knowledge and guidelines for psychiatric genetic testing (PsychGT) and genetic cou...

Background and hypothesis: The emergence of psychosis in ultra-high-risk subjects (UHR) is influenced by gene-environment interactions that rely on epigenetic mechanisms such as microRNAs. However, whether they can be relevant pathophysiological biomarkers of psychosis' onset remains unknown. Study design: We present a longitudinal study of micr...

Compared to disorders of similar heritability and contribution of common variants, few genome-wide significant loci have been implicated in autism spectrum disorder (ASD). This undermines the use of polygenic risk scores (PRSs) to investigate the common genetic architecture of ASD. Deconstructing PRS-ASD into its related traits via "developmental d...

Background: EEG microstates translate the resting-state temporal dynamics of neuronal networks throughout the brain and could constitute markers of psychiatric disorders. We tested the hypothesis of an increased imbalance between a predominant self referential mode (microstate C) and a decreased attentional mode (microstate D) in psychosis spectrum...

Alterations in membrane lipids are reported in schizophrenia. However, no conclusion can be drawn regarding the extended and predictive value of these alterations in persons at ultra-high risk of psychosis (UHR). Recent studies suggested that sterols’ impact on psychiatric disorders was underestimated. Here, we simultaneously explored sterols, fatt...

Depression is one of the leading causes of morbidity worldwide and increases the risk of suicide. Students are known as a population at risk for depression. This study aimed to evaluate the prevalence of 12 months major depressive episode (MDE) and suicidal thoughts in French students and investigate associated factors. A questionnaire was sent by...

[This corrects the article DOI: 10.3389/fnins.2023.1126970.].

We report two series of individuals with DDX3X variations, one (48 individuals) from physicians and one (44 individuals) from caregivers. These two series include several symptoms in common, with fairly similar distribution, which suggests that caregivers’ data are close to physicians’ data. For example, both series identified early childhood sympt...

Down syndrome (DS) is one of the most frequent genetic disorders and represents the first cause of intellectual disability of genetic origin. While the majority of patients with DS follow a harmonious evolution, an unusual neurodevelopmental regression may occur, distinct from that described in the context of autism spectrum disorders, called down...

Introduction: Prader-Willi Syndrome (PWS) is a rare genetic condition, which affects one in 25,000 births and results in various phenotypes. It leads to a wide range of metabolic and endocrine disorders including growth delay, hypogonadism, narcolepsy, lack of satiety and compulsive eating, associated with mild to moderate cognitive impairment. Pr...

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IntroductionFolates, the main actors in one-carbon (C1) metabolism, are involved in synthesising monoamines and maintaining genomic stability. Previous studies support the association between C1 metabolism and schizophrenia. The main purpose of this study was to assess the prevalence of plasma folate, and/or vitamin B12 deficiencies and hyperhomocy...

On June 2022, the 2nd Webinar "Neurodevelopmental Disorders (NDD) without boundaries took place at the Imagine Institute in Paris and was broadcasted live and in replay. The aim of this webinar is to address NDD in a dimensional rather than in a categorical approach. Several speakers were invited to present their researches on the subject. Classifi...

Background: Contactin-5 (CNTN5) is a candidate risk gene for autism spectrum disorder (ASD). Previous attempts to associate CNTN5 CNVs with ASD-susceptibility were limited by insufficient statistical power. Here, we aim to clarify the putative association between CNTN5 CNVs and ASD-risk using large-scale case-control analyses. Method: A CNTN5 CNV...

Treatment and prevention strategies for schizophrenia require knowledge about the mechanisms involved in the psychotic transition. Increasing evidence suggests a redox imbalance in schizophrenia patients. This narrative review presents an overview of the scientific literature regarding blood oxidative stress markers’ evolution in the early stages o...

Over the past decades, researchers and psychiatrists in the field of psychosis have moved from a conception of a chronic presentation to a more dynamic paradigm. Accordingly, schizophrenia is now conceptualized as a progressive illness that typically emerges during late adolescence and follows different stages: early vulnerability, ultra-high risk...

Introduction Health student’s mental health is considered a public health issue that dramatically increased with COVID 19’s pandemic. However, very few studies assessed the prevalence of mental health in medical, pharmacist, and dental students. Objectives Our goal was to assess mental health in health students from the same university one year af...

Pharmacological treatments used for psychiatric disorders, such as clozapine, demonstrate large interindividual variability in terms of possible adverse effects and therapeutic benefit. This variability can be explained by multiple factors, including pharmacogenetic factors. Clozapine efficacy can be impacted by CYP polymorphisms. A growing body of...

Background The mental health of health students is considered a public health issue which increased dramatically with the COVID 19’s pandemic. Few studies have assessed the prevalence of depression in medical, pharmacy, and dental students. Our goal was to assess mental health in health students from the same university and identify the associated...

Brain anomalies are frequently found in early psychoses. Although they may remain undetected for many years, their interpretation is critical for differential diagnosis. In secondary psychoses, their identification may allow specific management. They may also shed light on various pathophysiological aspects of primary psychoses. Here we reviewed ca...

Psychosis frequently occurs during adolescence and young adulthood, possibly as a result of gene-environment interactions, mediated by epigenetic mechanisms such as DNA methylation. Methylation patterns can be leveraged to predict epigenetic age in order to identify anomalies in aging trajectories that may be associated with the emergence of psycho...

Schizophrenia has a heritability of 60–80%1, much of which is attributable to common risk alleles. Here, in a two-stage genome-wide association study of up to 76,755 individuals with schizophrenia and 243,649 control individuals, we report common variant associations at 287 distinct genomic loci. Associations were concentrated in genes that are exp...

Schizophrenia has a heritability of 60–80%1, much of which is attributable to common risk alleles. Here, in a two-stage genome-wide association study of up to 76,755 individuals with schizophrenia and 243,649 control individuals, we report common variant associations at 287 distinct genomic loci. Associations were concentrated in genes that are exp...

Cognitive impairment is a core feature of schizophrenia which precedes the onset of full psychotic symptoms, even in the ultra-high-risk stage (UHR). Polygenic risk scores (PRS) can be computed for many psychiatric disorders and phenotyping traits, including scores for resilience. We explored the correlations between several PRS and neurocognition...

Background Suicide is a leading cause of death worldwide, and non-fatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genom...

Schizophrenia typically emerges during adolescence, with progression from an ultra-high risk state (UHR) to the first episode of psychosis (FEP) followed by a chronic phase. The detailed pathophysiology of schizophrenia and the factors leading to progression across these stages remain relatively unknown. The current treatment relies on antipsychoti...

Background Contactin-5 (CNTN5) is a candidate risk gene for autism spectrum disorder (ASD), yet previous attempts to associate copy-number variants (CNVs) encompassing CNTN5 with ASD-susceptibility were limited by insufficient statistical power. Here, we aim to clarify the putative association between CNTN5 CNVs and ASD-risk using large samples. Me...

Despite its drastic efficacy in resistant psychiatric disorders, clozapine remains rarely used in youth due to its side effects. Clozapine plasma level is determined through its metabolism involving several isoforms of cytochromes 450 (CYP450) family. Isoform CYP1A2 appears as a limiting enzyme involved in the metabolism of clozapine, while isoform...

Background Bipolar disorder is characterized by cyclical alternation between mania and depression, often comorbid with psychosis and suicide. Compared with other medications, the mood stabilizer lithium is the most effective treatment for the prevention of manic and depressive episodes. However, the pathophysiology of bipolar disorder and lithium’s...

The understanding of the genetic architecture of psychiatric disorders has made significant advances in the last decade and some scientific findings can now be translated into clinical practice. The rise of genetic testing and the awareness of patients and their families motivate psychiatrists to examine this approach. The COST Action EnGagE (CA171...

Background Despite its drastic efficacy in resistant psychiatric disorders, clozapine remains rarely used in youth due to its side effects. Clozapine plasma level is determined through its metabolism involving several isoforms of cytochromes 450 (CYP450) family. Isoform CYP1A2 appears as a limiting enzyme involved in the metabolism of clozapine whi...

Background COMT had been considered a promising candidate gene in pharmacogenetics studies in ADHD; yet the findings from these studies have been inconsistent. Part of these inconsistencies could be related to epigenetic mechanisms (including DNA methylation). Here we investigated the role of genetic variants of the COMT gene on the methylation lev...

Introduction: Bipolar disorder (BD) is a chronic, disabling disease characterised by alternate mood episodes, switching through depressive and manic/hypomanic phases. Mood stabilizers, in particular lithium salts, constitute the cornerstone of the treatment in the acute phase as well as for the prevention of recurrences. The pathophysiology of BD...

Suicide is a leading cause of death worldwide and non-fatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both are known to have a substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. We conducted a genome-wide...

Objectives: The number of DNA methylome and RNA transcriptome studies is growing, but investigators have to consider the cell type composition of tissues used. In blood samples, the data reflect the picture of a mixture of different cells. Specialized algorithms can address the cell-type heterogeneity issue. We tested if these corrections are corr...

The implementation of pharmacogenomic (PGx) testing in psychiatry remains modest, in part due to divergent perceptions of the quality and completeness of the evidence base and diverse perspectives on the clinical utility of PGx testing among psychiatrists and other healthcare providers. Recognizing the current lack of consensus within the field, th...

This Research Topic highlights the key role of neuroendocrinological and immune-inflammatory factors in the development, maintenance, and outcome of psychotic disorders. The papers in the issue summarized here clearly show that body and mind are one, and that a holistic approach is vital for the effective clinical management of patients with psycho...

Bipolar disorder (BD) is characterized by cyclical alternations between mania and depression, often comorbid with psychosis, and suicide. The mood stabilizer lithium, compared to other medications, is the most efficient treatment for prevention of manic and depressive episodes. The pathophysiology of BD, and lithium’s mode of action, are yet to be...

La moitié des maladies psychiatriques se manifeste avant l’âge de 14 ans, et les trois quarts avant 24 ans, suggérant que l’enfance, l’adolescence, et le début de l’âge adulte sont des fenêtres de grande fragilité aux troubles mentaux. La schizophrénie survient ainsi à l’adolescence tardive chez des individus à risque, repérables cliniquement, et d...

Objectives Few studies have investigated pharmacologic treatment for pediatric post-traumatic stress disorder (PTSD). Prazosin, an alpha-1 adrenergic receptor antagonist, has been studied and demonstrated to be efficacious in an adult population for PTSD related sleep disturbances; however, in the pediatric population, data is limited to case repor...

Introduction: The emergence of psychosis in at-risk individuals results from interactions between genetic vulnerability and environmental factors, possibly involving dysregulation of the hypothalamic-pituitary-adrenal axis. Hypercorticism was indeed described in schizophrenia and ultra-high-risk states, but its association with clinical outcome ha...

Schizophrenia is an illness characterized by positive symptoms, negative symptoms, and cognitive impairments. Cognitive impairments occur before the onset of psychosis and could reflect glutamatergic dysregulation. Thus, identifying associations between genetic variations in genes coding for glutamatergic receptors and cognitive impairment in schiz...

The seven human 14-3-3 proteins are encoded by the YWHA-gene family. They are expressed in the brain where they play multiple roles including the modulation of synaptic plasticity and neuronal development. Previous studies have provided arguments for their involvement in schizophrenia, but their role during disease onset is unknown. We explored the...

Résumé Les patients souffrant de trouble psychiatrique ont une espérance de vie réduite. Cette diminution est d’environ 15 ans dans la schizophrénie. De nombreux facteurs étiologiques ont été proposés : conséquences des symptômes psychiatriques, mauvaise alimentation, absence d’activité physique, tabagisme, effets secondaires du traitement antipsyc...

Childhood-onset schizophrenia (COS) is a rare and severe form of schizophrenia defined as onset before age of 13. Here we report on two unrelated cases diagnosed with both COS and alternating hemiplegia of childhood (AHC), and for whom two distinct pathogenic de novo variants were identified in the ATP1A3 gene. ATP1A3 encodes the α-subunit of a neu...

Résumé Les lipides membranaires jouent un rôle important dans le fonctionnement cérébral et peuvent désormais être étudiés de manière précise. Cette revue vise à familiariser le lecteur avec les lipides membranaires et les conséquences de leurs anomalies dans les troubles du spectre schizophrénique. Nous nous intéresserons aux données concernant le...

Objectives : The number of DNA methylome and RNA transcriptome studies is growing, but investigators have to consider the cell type composition of tissues used. In blood samples, the data reflect the picture of a mixture of different cells. Specialized algorithms can address the cell-type heterogeneity issue. We tested if these corrections are corr...

Objectives : The number of DNA methylome and RNA transcriptome studies is growing, but investigators have to consider the cell type composition of tissues used. In blood samples, the data reflect the picture of a mixture of different cells. Specialized algorithms can address the cell-type heterogeneity issue. We tested if these corrections are corr...

Objectives: DNA methylome and RNA transcriptome studies are growing, but investigators have to consider the cell type composition of tissues used. In blood samples, for instance, data reflect the picture of a mixture of cells. Specialized algorithms address the cell-type heterogeneity issue. We tested if the estimation of cell-type composition in t...

La santé psychique des étudiants est un problème de santé publique qui semble sous-considéré, en partie en raison de l’hétérogénéité des résultats obtenus dans les différentes enquêtes. Cette hétérogénéité a différentes causes : imprécision dans les termes utilisés ; confusion dans les périodes de temps étudiées ; variabilité des questionnaires uti...