Prevalence of autism in children with epilepsy: A population-based study

To compare the prevalence of autism spectrum disorder (ASD) in children with and without epilepsy using clinical diagnoses and chart review with research-defined criteria and to examine sex ratios, age at ASD onset, and intellectual disability between groups.

The Olmsted County birth cohort included 30 490 individuals, of whom 257 (0.84%) had epilepsy diagnosed before 19 years of age. The cohort was previously screened for ASD using three case definitions: research-inclusive (ASD-R_I), research-narrow (ASD-R_N), and clinically diagnosed ASD (ASD-C). For those with ASD-R_I, we assessed sex, intellectual disability (IQ < 70), and age at ASD onset. Means and proportions are reported when available.

ASD prevalence was significantly higher in participants with epilepsy across all definitions: ASD-R_I 21.4% versus 3.2%; ASD-R_N 14.0% versus 1.6%; and ASD-C 7.9% versus 0.7%. Children with both epilepsy and ASD-R_I were more often female (38.2% vs 25.8%), had higher rates of intellectual disability (56.5% vs 15.4%), and met the ASD-R_I criteria at a younger age (mean 7 years 5 months vs 8 years 8 months).

Co-occurring ASD and epilepsy are frequently associated with intellectual disability, earlier age at ASD diagnosis, and reduced male predominance.