The Obsessive–Compulsive Spectrum: A Systematic Review

Background The concept of the obsessive–compulsive spectrum (OCS) has expanded over the last three decades, encompassing disorders characterized by intrusive thoughts, repetitive behaviors, and difficulties in impulse control. Objective To systematically review the literature describing the phenomenology, neurobiology, comorbidity patterns, and treatment implications of OCS conditions. Methods A systematic search of PubMed, Scopus, and Web of Science (1990–2024) identified studies on obsessive–compulsive disorder (OCD), related disorders (trichotillomania, excoriation disorder, body dysmorphic disorder, hoarding disorder), and compulsive behavioral addictions (e.g., gambling, internet gaming). Results Findings indicate partially shared neurobiological circuits—particularly cortico-striatal-thalamo-cortical (CSTC) loops—alongside genetic overlap and frequent clinical comorbidity. Treatment response across the spectrum varies, with SSRIs and CBT effective for OCD and BDD, while behavioral addictions respond better to CBT and opioid antagonists. Conclusion The obsessive–compulsive spectrum framework provides a dimensional approach to mental disorders, though boundaries between impulsive and compulsive behaviors remain debated.