Cognition Sociale et caractéristiques Psychotiques : Approche génétique et phénomique

Schizophrenia and mood disorders represent two severe and frequent disease with heterogeneous phenotype sharing some clinical symptoms (possible presence of psychotic symptoms in mood disorders, systematic in schizophrenia) and neurocognitive impairments including social cognition. These disorders result from an interaction of several minor effect genes with various early or late environmental factors, with psychosocial or biological origin.

The association of these pathologies with dysfunctions of major neurotransmission systems has been the subject of numerous studies, but the results have often been contradictory for methodological, clinical (phenotypic heterogeneity) and finally genetic reasons. The definition of the phenotype is an essential issue in research on the genetics of mental disorders. The risk of phenotypic misclassification of subjects during genetic studies confirms the need for a better delimitation of homogeneous patient sub-populations. The development by the National Institute of Mental Health (NIMH) of clinical research criteria is essential to bring sufficient power to modern research in genetics, but also in imaging, neuroscience or behavioral sciences of mental disorders.

The aim of our work is to study a restricted phenotype of schizophrenia and mood disorders: the assessment of social cognitions. Deficits in social cognition constitute one of the subconstructs described by the NIMH and lead to functional and clinical maladjustment hindering psychosocial rehabilitation. Indeed, oxytocin is reported to be a mediator of the regulation of social cognition (including empathy and theory of mind) and emotional behaviors (Meyer-Lindenberg, 2011).

The current project involves the analysis of several social cognition tasks that measure social perception, facial recognition of affect and empathy. The objective of this work is to highlight an association between performance on the 4 social cognition paradigms and polymorphisms of the OXT and OXTR genes and in a population of subjects suffering from schizophrenia or mood disorder with or without psychotic symptoms.

The main hypothesis of this study is that these genes have an impact on social cognition in each of the populations recruited (patients with schizophrenia or patients with a mood disorder). The secondary hypothesis is to show that this impact of the genotype is more marked in patients with psychotic symptoms (suffering from mood disorders or schizophrenia) compared to patients suffering from mood disorders without psychotic symptoms (interaction mechanism).