Description

• An anxiety disorder characterized by pathologic obsessions (recurrent intrusive thoughts, ideas, or images) and compulsions (repetitive, ritualistic behaviors or mental acts) causing significant distress
• Not to be confused with obsessive-compulsive personality disorder

Epidemiology

Incidence

• Predominant age: mean age of onset is 19.5 years (1).
  • Three subtypes: child/adolescent-onset (<18 years), adult-onset (18 to 39 years) and late-onset (≥40 years)
  • Child/adolescent-onset in 50% of cases (usually by age 18 years) (2)
  • Diagnosis rarely made at >50 years of age
• Predominant gender: females > males
  • Childhood-onset obsessive-compulsive disorder (OCD) (age <10 years) is more prevalent in males, more likely to be heritable and associated with co-morbid tic disorder.
  • Adolescent-onset OCD is more prevalent in females, although OCD can be precipitated in the peripartum or postpartum period as well.

Pediatric Considerations
Insidious onset; consider brain insult in acute presentation of childhood OCD.

Geriatric Considerations
Consider neurologic disorders in new-onset OCD.

Prevalence

• 2.3% lifetime in adults
• 1–2.3% prevalence in children/adolescents (3)

Etiology and Pathophysiology

Exact pathophysiology/etiology unknown. Potential role of:

• Cognitive-affective dysfunction
• Dysregulation of serotonergic, catecholaminergic, and glutamatergic pathways
• Dysfunction of cortico-striatal-thalamo-cortical (CSTC) circuit, involving the orbitofrontal cortex (OFC) and anterior cingulate cortex (ACC)
• Brain injury (physical trauma, stroke, etc.)
• Autoimmune insult to basal ganglia, as seen in Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcus (PANDAS); controversial

Genetics

• Polygenic disorder, with variants in serotonergic, catecholaminergic, and glutamatergic genes
• Positive family history: prevalence rates of 7–15% in first-degree relatives of children/adolescents with OCD
• Greater concordance in monozygotic twins

Risk Factors

Combination of biologic and environmental factors:

• Family history of OCD
• Advanced paternal and maternal age
• Coexisting psychiatric disorders, most commonly anxiety disorders and schizophrenia
• Low serotonin levels (Antipsychotics with greater anti-serotoninergic mechanism, such as clozapine and olanzapine, have been associated with onset of OCD.)
• Brain insult (i.e., encephalitis, pediatric streptococcal infection, or head injury)
• Perinatal insults (birth complications)
• History of childhood traumatic events, including social isolation and physical abuse

General Prevention

• Early diagnosis and treatment can decrease patient’s distress and impairment.

Commonly Associated Conditions

• Major depressive disorder
• Panic disorder/phobia/social phobia
• Tourette syndrome/tic syndromes
• Substance abuse/eating disorder/body dysmorphic disorder