Parental age and autism severity in the Rhode Island Consortium for Autism Research and Treatment (RI-CART) study.

Advanced parental age at offspring birth has been associated with autism spectrum disorder (ASD). The objective of the current study was to investigate associations between parental age at birth and autism severity. The Rhode Island Consortium for Autism Research and Treatment (RI-CART) study represents a community-based sample with a range of autism severity, including participants with and without ASD. This study involved participants (n = 1178) enrolled in RI-CART with available mother and father ages at birth. Primary data points included the age of mother and father at the participant's birth and results from the Autism Diagnostic Observation Schedule - Second Edition (ADOS-2). Mothers were 1.7 years older at the time of birth of the child with ASD, as compared to mothers of offspring without ASD. Fathers of children with ASD were 1.6 years older at the time of birth than fathers of children without ASD. The age of both parents at offspring birth displayed a positive, statistically significant association with overall ASD severity and the severity of restricted/repetitive behaviors. This finding was driven by the association between parental age and the severity of compulsions or rituals. Intelligence and adaptive functioning did not moderate the relationship between parental age and ASD severity. This study extends prior research to show that advanced parental age at birth is associated with the severity as well as the presence of ASD in offspring.