New Research Suggests Infections Can Contribute to Autism and Intellectual Disability
A team of Swedish researchers set out to explore the associations between early childhood infections and later diagnoses of autism spectrum disorder (ASD) and intellectual disability (ID), in an attempt to understand whether any observed associations varied by their co-occurrence, age at infection, or age at first diagnosis. The study’s design involved surveilling 556,732 individuals born between 1987-2010, residing in Stockholm County, from birth to their 18th birthday or December 31, 2016. Medical records of these individuals were examined for any infection, defined by ICD-codes, and later ASD or ID diagnoses. Sensitivity analyses were conducted to exclude congenital causes of ASD/ID and documented risk for infections were also performed. Results showed that infections requiring specialized care between ages 1 and <6 were associated with the risk of being diagnosed with “ASD without ID” before age 12. Infections before age 12 were linked with “ASD with ID” diagnosed throughout childhood. Comparable observations were found for “ID without ASD” with even larger point estimates, especially for infections experienced in the first few years of childhood. The study’s authors noted larger risks for all outcomes associated with central nervous system infections (CNS) than for non-CNS infections, particularly for those diagnoses that included ID. The research team also suggested that the association between infections during periods of rapid growth and plasticity of the brain and later diagnosis of ASD/ID could be explained by components of the immune system interfering with the normal trajectories of brain development. It should be noted that this study looked at infections that occured post birth.
