Obsessive–Compulsive Disorder (OCD) and Autism Spectrum Disorder (ASD): Clinical Fingerprints of the Comorbidity

Background: Obsessive–compulsive disorder (OCD) frequently co-occurs with autism spectrum disorder (ASD), but the prevalence and clinical correlates of this comorbidity remain incompletely understood. Methods: We examined a clinical sample of 603 patients with a primary diagnosis of OCD, of whom 149 (24.7%) presented with comorbid ASD. Sociodemographic variables, clinical characteristics, comorbidities, and obsessive–compulsive symptom dimensions were compared between patients with and without ASD. Results: Patients with OCD + ASD reported an earlier onset of both obsessive–compulsive symptoms and full-blown disorder. While overall symptom severity (Y-BOCS, HAM-D, and HAM-A) was comparable, OCD + ASD patients were characterized by a higher exposure to stressful and traumatic life events, including severe trauma (e.g., death of a close family member, sexual abuse, physical violence, serious illness, and bullying). Severe traumatic events, in particular, were independently associated with ASD comorbidity in our OCD cohort (exploratory model). Comorbidities were also distinct: onychophagia (66.4% vs. 0.4%) and trichotillomania (8.7% vs. 0%) were markedly more prevalent in the OCD + ASD group. Phenomenologically, OCD + ASD patients more often exhibited religious and somatic obsessions, as well as repetition compulsions. Specifically, somatic obsessions were independently associated with ASD in our regression analysis. Conclusions: OCD with comorbid ASD represents a clinically distinct subgroup, characterized by greater vulnerability to trauma, earlier onset, unique symptom profiles, and specific comorbidities. Recognition of these features, and in particular a history of severe traumatic experiences and the presence of somatic obsessions, may support earlier consideration of ASD comorbidity during OCD assessment and may inform personalized treatment planning.