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 were significantly younger at assessment and reported an earlier onset of both obsessive–compulsive symptoms and full-blown disorder. A family history of affective disorders was more frequent in this subgroup. While overall symptom severity (Y-BOCS, HAM-D, HAM-A) was comparable, OCD+ASD patients reported higher exposure to stressful and traumatic life events, including severe trauma. Severe traumatic events, in particular, were found to be a predictor of ASD in our OCD cohort. 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, as were Cluster B personality disorders (18.1% vs. 11.4%). Phenomenologically, OCD+ASD patients more often exhibited religious and somatic obsessions, as well as checking and repetition compulsions. 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 severe traumatic experiences, is crucial for early detection of ASD in individuals with OCD, personalized treatment planning and improved outcomes.