Risk factors, prevalence and impact of comorbid autism in pediatric epilepsy: A population-based study

Abstract

Objective: To determine the prevalence and risk factors for the development of autism in a population-based, retrospective cohort of children with new-onset epilepsy. Methods: Children with epilepsy, newly-diagnosed between 1980 and 2009, while resident in Olmsted County, MN, were identified through the Rochester Epidemiology Project database. Those followed beyond two years of age were included for study. Charts were reviewed to determine if subjects had been diagnosed with autism spectrum disorder (ASD), and also to collect seizure variables. Results: 459 children were identified (53% male). Mean age at seizure onset was 6.9 years (SD 5.0) and at follow-up was 17.2 years (SD 8.7). ASD was diagnosed in 34 (7.4%) cases, and preceded seizure onset in 15 children. Of those children for whom ASD was diagnosed after seizure onset, 58% had preceding established developmental delay. The most robust factor correlating with comorbid ASD was intellectual disability at seizure onset, with ASD being diagnosed in 4/295 (1.4%) of intellectually normal children, 19/101 (18.8%) with mild delay and 9/59 (15.3%) with moderate to severe delay (p<0.001). Other significant correlates were abnormal neurological examination (p<0.001), male sex (p=0.013), abnormal EEG background (p=0.023) and lack of a genetic etiology (p=0.012). Children with earlier onset of epilepsy did not have significantly higher rates of ASD. Comorbid ASD did not impact on epilepsy outcome, with similar rates of both seizure freedom at final follow-up (65% in those with ASD versus 69% in those without ASD, p=0.61) and medical intractability or need for epilepsy surgery (29% with ASD versus 18% without ASD, p=0.12). Conclusion: Comorbid ASD affects approximately 7.4% of children with epilepsy and coexisting intellectual disability is the most significant correlate. However, ASD does not appear to adversely impact epilepsy prognosis, as the majority of children still achieve seizure freedom long-term.