Objectives: To investigate the relationship between parental migration status and risk of autism spectrum disorders (ASD), taking into consideration the importance of region of origin, timing of migration and possible discrepancies in associations between autism subtypes.
Methods: The Stockholm Youth Cohort is a record-linkage study comprising all individuals aged 0-17 years, ever resident in Stockholm County in 2001-2007 (N=589,114). Cases (N=4,952) were identified using a multisource approach, involving registers covering all pathways to ASD diagnosis and care, and categorized according to presence of co-morbid intellectual disability. Extensive and prospectively recorded information on parental migration status and other potential risk factors were retrieved from national and regional health and administrative registers.
Results: Children of migrant parents were at increased risk of ASD with comorbid intellectual disability (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.3-1.7); this risk was highest when parents migrated from regions of low human development, and peaked when migration occurred around pregnancy (OR 2.3, 95% CI 1.7-3.0). A decreased risk of ASD without intellectual disability was observed in children of migrant parents, regardless of area of origin or timing of migration. Parental age, income or obstetric complications did not fully explain any of these associations.
Conclusions: Environmental factors associated with migration may contribute to the development of autism presenting with comorbid intellectual disability, especially when acting during fetal life. ASD presenting with and without intellectual disability may have partly different etiologies, and should be studied separately.
See more of: Epidemiology
See more of: Prevalence, Risk factors & Intervention