Premigration social adversity: a factor of vulnerability for Autism Spectrum Disorder

Background: Several studies suggest significant relationships between migration and Autism Spectrum Disorder (ASD) but there are discrepant results. Given that no study included a pathological control group, the specificity of the results in ASD can be questioned. Aims: To compare the migration experience (premigration, migratory trip, postmigration) in ASD and non-ASD pathological control groups, and study relationships between migration and autism severity.Method: Parents’ and grandparents’ migrant status was compared in 30 prepubertal ASD boys and 30 prepubertal non-ASD boys with language disorders, using a questionnaire including Human Development Indices (IDH/IDHI) of native countries. Autism severity was assessed using the Child Autism Rating Scale, Autism Diagnostic Observation Schedule and Autism Diagnostic Interview-Revised scales. Results: The parents’ and grandparents’ migrant status frequency did not differ between ASD and control groups and was not associated with autism severity. The HDI/IHDI values of native countries were significantly lower for parents and grandparents of ASD children compared to controls, especially for paternal grandparents. Furthermore, HDI/IDHI levels from the paternal line (father and especially paternal grandparents) were significantly negatively correlated with autism severity, particularly for social interaction impairments.Conclusions: In this study, parents’ and/or grandparents’ migrant status did not discriminate ASD and pathological control groups and did not contribute either to autism severity. However, the HDI/IHDI results suggest that social adversity-related stress experienced in native countries, especially by paternal grandparents, is potentially a traumatic experience which may play a role in ASD development. A “premigration theory” of autism is then proposed.