[Aggregation of social deficits and psychiatric disorders in parents of children with autism: toward a temperamental link?]

Abstract

Background: Autism is a group of neurodevelopmental disorders with heterogeneous phenotypic expression. Twin and family-based studies have demonstrated the importance of genetic factors in the etiology of these disorders. The pioneering work of Folstein and Rutter (1977), showing concordance - 82 % in non affected monozygotic twins and 10 % in non affected dizygotic twins - for cognitive deficits (mostly affecting language), has directed work towards family-based studies aiming at demonstrating the existence of a "broad autism phenotype" (BAP), corresponding to the extension of the "autistic" phenotype in the relatives of affected children (Bailey et al., 1998). This notion of a broad phenotype makes it possible to take into account abnormalities in one or more of the three domains of the syndrome: communication, socialization and restrained and obsessive interest in a succession of subjects, with qualitatively similar but quantitatively smaller difficulties observed in the relatives.

Literature findings: We review here previous studies investigating the broad phenotype in the relatives of children with autism. We focus specifically on the hypothesis of a link between the aggregation of social deficits and of psychopathological problems, such problems being more frequently observed in these families than in families with other types of handicap (Abbeduto et al., 2004). Although the difficulties observed in these families may be partly explained by the stress of having to raise a heavily disabled child, genetic susceptibility factors may play a role in the occurrence of these problems in the families of autistic children. Constantino and Todd (2003) support the hypothesis that a single factor is transmitted in families - social reciprocity - and may be responsible for the overall dysfunction in the various domains of the syndrome in affected individuals. However, this susceptibility factor may be linked to other deficits observed in certain psychiatric disorders (e.g., attention deficit in ADHD), consistent with the hypothesis that there is a link between the broad phenotype and psychopathological problems.

Conclusion: This paper reviews this issue in the two domains of study described and presents a hypothesis to account for the possible link between the presence of the broad phenotype - or more specifically, of social deficits - and the more frequent occurrence of psychological problems in the families of autistic individuals. The notion of temperament (Garon et al., 2009) is proposed and considered to present essential characteristics that might account for this relationship: indeed, temperament is associated with notions of IQ, psychopathology and social function and could potentially be used as a predictive variable in affected individuals. Finally, the link between temperament and psychopathology in the relatives of affected individuals may be reflected in the presence of cognitive peculiarities more specifically linked to socioemotional dysfunction (Losh and Piven, 2007).