Background <p>This study examined whether the timing of adverse childhood experiences (ACEs) is associated with differences in intellectual ability in adults with autism spectrum disorder (ASD) without intellectual disability.</p> Methods <p>A total of 161 adults with ASD were categorized into three groups based on ACE onset: no ACEs (Group 0), early childhood ACEs (≤ 10 years; Group 1), and adolescent ACEs (11–18 years; Group 2). Intellectual ability was assessed using the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV).</p> Results <p>Findings revealed that Group 1 outperformed Group 2 on the picture completion and figure weights subtests, suggesting that early ACE exposure may be linked to distinct cognitive profiles in ASD. To account for the higher severity of post-traumatic stress disorder (PTSD) symptoms, including hypervigilance, in Group 1 compared to Group 2, we conducted multivariate analyses of covariance and logistic regression to control for potential confounders such as years of education and PTSD symptom severity, given that hypervigilance may influence cognitive task performance. However, the observed differences remained significant.</p> Conclusion <p>These results suggest a potential association between the timing of ACE exposure and specific cognitive subdomains in adults with ASD. Furthermore, WAIS-IV subtests, particularly picture completion and figure weights, may serve as potential markers for identifying cognitive adaptations associated with early adversity in ASD individuals.</p> Clinical Trial Registration <p>Since this study was not a clinical trial, this section does not apply.</p>