Chapter 71: Obsessive-Compulsive and Related Disorders

Obsessive-compulsive and related disorders represent a category of psychiatric conditions characterized by the presence of repetitive thoughts, behaviors, or both that cause significant distress and functional impairment. Obsessive-compulsive disorder involves intrusive, unwanted thoughts or urges called obsessions paired with repetitive behaviors or mental acts known as compulsions that individuals perform to manage anxiety. The condition typically begins in childhood or early adulthood and follows a chronic course with periods of worsening and improvement. Underlying mechanisms involve serotonin dysregulation, genetic factors including variants in the glutamate transporter gene, and heightened activity in brain regions such as the orbitofrontal cortex and caudate nuclei. Patients frequently experience obsessions centered on contamination fears, doubt about completed actions, or distressing intrusive thoughts, and engage in compulsions like excessive cleaning, repeated checking behaviors, or arranging items in specific patterns. Primary care providers often encounter these patients when they present with depression or anxiety, as shame frequently delays help-seeking. Diagnosis relies on clinical questioning and severity assessment using standardized instruments such as the Yale-Brown Obsessive-Compulsive Scale. First-line treatment combines selective serotonin reuptake inhibitors at higher doses than those used for depression with cognitive behavioral therapy incorporating exposure and response prevention techniques. Body dysmorphic disorder involves preoccupation with perceived physical flaws that others cannot observe, accompanied by repetitive behaviors such as mirror checking or compulsive skin manipulation. Hoarding disorder is characterized by persistent difficulty discarding possessions regardless of actual value, resulting in hazardous living environments and functional decline. Both conditions show poor treatment response to standard exposure-based approaches and require specialized therapeutic modifications. Additional related disorders include trichotillomania and skin-picking behaviors, which share the repetitive behavior component. Primary care providers serve essential roles in initial identification, establishing therapeutic relationships that accommodate patient shame and stigma, monitoring suicide risk particularly in body dysmorphic disorder where rates are elevated, and coordinating referrals to mental health specialists for complex or treatment-resistant presentations.