Obsessive-Compulsive Disorder

Definition

Obsessive-Compulsive Disorder (OCD) is a mental health disorder characterized by the presence of obsessions (intrusive, unwanted thoughts, images, or urges) and/or compulsions (repetitive behaviors or mental acts performed to reduce anxiety), leading to significant distress and impairment.

Epidemiology

• Lifetime prevalence around 2–3%
• Onset typically in late childhood, adolescence, or early adulthood
• Slightly more common in males during childhood, but equalizes in adulthood
• Often chronic if untreated
• High comorbidity with anxiety disorders, depression, and tic disorders

Etiology

• Genetic predisposition: familial clustering and higher risk in first-degree relatives
• Neurobiological factors: dysfunction in cortico-striato-thalamo-cortical circuits
• Neurotransmitter abnormalities: serotonin dysregulation
• Environmental stressors and trauma may trigger onset or exacerbate symptoms
• PANDAS: post-streptococcal autoimmune contribution in some pediatric cases
• Psychosocial and cognitive factors influencing thought patterns and compulsions

Pathophysiology

• Hyperactivity in orbitofrontal cortex, anterior cingulate cortex, and caudate nucleus
• Impaired inhibitory control over intrusive thoughts
• Serotonergic dysregulation affecting anxiety modulation
• Altered functional connectivity in brain circuits regulating habit formation
• Genetic and environmental interactions influencing symptom severity
• Heightened error detection and cognitive rigidity
• Reinforcement loop between obsessions and compulsions maintains symptoms