Obsessive-Compulsive Disorder (OCD): A Comprehensive Review

Abstract

Obsessive-compulsive disorder (OCD) represents a chronic neuropsychiatric condition characterized by recurrent intrusive thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) that significantly impair daily functioning and quality of life. Despite substantial advances in understanding its neurobiological underpinnings and therapeutic interventions, OCD remains frequently underdiagnosed, undertreated, and associated with considerable individual and societal burden. This comprehensive review synthesizes current evidence regarding OCD epidemiology, pathophysiology, diagnostic challenges, comorbidity patterns, and evidence-based treatment approaches, with particular emphasis on treatment-resistant populations and emerging therapeutic modalities. A systematic literature search was conducted across PubMed/ MEDLINE, PsycINFO, Scopus, and Google Scholar databases, focusing on peer- reviewed articles published between 2015 and 2025. Search terms included combinations of MeSH headings and keywords related to OCD diagnosis, neurobiology, comorbidities, and treatment interventions. OCD affects approximately 2.3% of the global population across the lifespan, with onset typically occurring in childhood, adolescence, or early adulthood. The disorder demonstrates substantial heritability (approximately 50%) and involves dysregulation within cortico-striatal-thalamic-cortical circuits, with contributions from serotonergic, dopaminergic, and glutamatergic neurotransmitter systems. Comorbidity rates exceed 50% for major depressive disorder and anxiety disorders, while bipolar disorder, schizophrenia spectrum disorders, and attention-deficit/hyperactivity disorder demonstrate prevalence rates of 10-25% in OCD populations. First-line treatments comprising selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavioral therapy with exposure and response prevention (ERP) achieve response rates of 50-70%; however, approximately 30% of patients exhibit treatment resistance, necessitating augmentation strategies, neuromodulation approaches, or neurosurgical interventions. Despite significant therapeutic advances, the substantial proportion of treatment-resistant patients and the complex comorbidity landscape underscore the necessity for continued research into novel treatment targets, personalized medicine approaches, and improved diagnostic methodologies. The integration of neurobiological findings with clinical phenotyping represents a promising avenue for advancing OCD care.