Timing of Prenatal Stressors and Autism D. Q. Beversdorf, S.E. Manning, A. Hillier, S.L. Anderson, R.E. Nordgren, S.E. Walters, Abstract: J Autism Dev Disord. 2005 Aug; 35(4):471-8. Findings There is substantial evidence that while genetic factors contribute to autism, other factors play a role as well. Past research has shown that there are structural differences in the amygdala, hippocampus, and cerebellum of the autistic brain. Abnormal changes in the cerebellum in autism are thought to occur before 30-32 weeks gestation. The purpose of this study was to determine if the mothers of children with autism experienced more stressors before this time period in their pregnancies than mothers of children with Down syndrome or mothers of children without a neurodevelopmental disorder. Information about the incidence and timing of stressors during pregnancy was collected from parent surveys. Incidence of stressors were adjusted for severity by assigning a score for major stressful events (for example: spouse's death - 100, divorce - 73, close family member's death - 63). The authors found that there were more prenatal stressors reported among mothers of children with autism than in the other two groups, with a peak in stressors at 21-32 weeks gestation. They also found that children with autism who experienced prenatal stress at 21-32 weeks were more likely to lack language than other children with autism. Conclusions The peak timeframe for stressors (21 – 32 weeks) corresponds to when abnormal development of the cerebellum is thought to occur. Thus, the authors believe their findings provide possible evidence that prenatal stress related changes in the brain contribute to autism. The authors also propose that autism resulting from prenatal stressors may tend to be more severe since children with autism who experienced prenatal stressors during 21 – 32 weeks are less likely than other autistic children to have language. It is not known whether prenatal stress could be an independent risk factor or whether it might contribute to the development of autism only in at-risk individuals. These are very preliminary results and future studies would be needed to confirm the findings.
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