Obsessive-Compulsive Disorder (OCD): Age of Onset and Its Implications for Disorder Definition. A Literature Review

Abstract Introduction Obsessive-compulsive disorder (OCD) is a common mental disorder that causes substantial impairment in daily functioning. OCD is known to affect individuals of all ages; however, whether juvenile and adult presentations represent the same disease or distinct entities with similar phenotypic expressions remains under discussion. This review aims to analyze the literature on this topic. Methods A literature review was conducted using the PubMed and Cochrane Library databases with the search terms “obsessive-compulsive disorder,” “age of onset,” “etiology,” “phenotype,” and “subtype.” A total of 26 records were identified, of which 13 were excluded, resulting in a final selection of 12 studies for inclusion in this review. Results and Discussion Our review suggests that early-onset OCD is characterized by a male predominance, a higher familial OCD burden, specific comorbidities such as tics, Tourette syndrome, and schizotypy, as well as associated genetic variants. In contrast, late-onset OCD appears to exhibit no significant gender differences or specific genetic associations. Understanding OCD may require reconsidering its classification, with early-onset OCD potentially belonging to the neurodevelopmental spectrum and late-onset OCD being more closely related to anxiety disorders. Therefore, the age at onset of obsessive-compulsive (OC) symptoms may help clinicians identify specific subgroups with implications for the disease course, treatment, and prognosis. Conclusion Available evidence suggests that OCD is clinically and genetically heterogeneous, with a complex interplay of neurobiological and environmental factors influencing its phenotypic expression. To determine whether early- and late-onset OCD represent distinct disorders, further research is needed to clarify their relationship in terms of etiology, phenotype, OC symptomatology, and prognosis.