Abstract

Background: Autism spectrum disorder (ASD) and epilepsy are prevalent neurodevelopmental conditions with early onset, lifelong impact, and high health-care burden. Their frequent co-occurrence is supported by shared neurobiological mechanisms, including disrupted synaptogenesis, cortical malformations, and excitatory–inhibitory imbalance, as well as overlapping genetic syndromes such as tuberous sclerosis, Rett, and Fragile X. Despite multiple reviews, estimates of co-occurrence remain inconsistent due to heterogeneity in study design, populations, and diagnostic methods.Objective: To synthesize existing evidence on the correlation between ASD and epilepsy through a systematic narrative review, and to identify moderators influencing prevalence estimates.Methods: Following PRISMA 2020 guidelines, we searched PubMed, EMBASE, PsycINFO, Scopus, Web of Science, and Cochrane Library through March 2025. Eligible studies included observational cohorts, cross-sectional, and case-control designs reporting prevalence or correlation between ASD and epilepsy. Given the methodological inconsistency of pooling primary studies with existing meta-analyses, we conducted a narrative synthesis of published systematic reviews and meta-analyses. Random-effects models from these prior syntheses generated pooled prevalence and correlation coefficients (r), with heterogeneity assessed using Q and I² statistics. Data extraction focused on subgroup analyses examining age, sex, intellectual disability, and sampling frame. Risk of bias in the included reviews was appraised using adapted Newcastle–Ottawa and JBI tools. Results: We synthesized evidence from 4 key systematic reviews and meta-analyses, which themselves encompassed 66 primary studies. Reported pooled prevalence of epilepsy in ASD was 10.0% (95% CI 6–14), higher in adults (19%) than children (7%), and substantially elevated in those with intellectual disability (≈21.5% vs 8%). Reported pooled prevalence of ASD in epilepsy cohorts was 6.3% (range 0.6–41.9%). The reported pooled correlation coefficient indicated a robust association, though heterogeneity was high (I² >70%). Evidence of publication bias was reported. Conclusion: ASD and epilepsy co-occur at rates far above chance, shaped by age, sex, and intellectual disability. Findings support routine bidirectional screening and integrated clinical management, while highlighting the need for standardized diagnostic approaches and longitudinal studies to clarify causal mechanisms.

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