Obsessive–compulsive disorder Study Guide

📖 Core Concepts Obsessions – intrusive, unwanted thoughts, images, or urges that cause anxiety, disgust, or distress. Compulsions – repetitive behaviors or mental acts performed to neutralize obsession‑related anxiety; usually > 1 h/day. Ego‑dystonic – patients recognize thoughts/behaviors as inconsistent with their self‑image and distressing. Insight Spectrum – ranges from good (recognizes irrationality) to absent/delusional (holds conviction). Four‑Factor Symptom Dimensions – (1) Symmetry (ordering/counting), (2) Forbidden thoughts (violent, sexual, religious), (3) Cleaning (contamination/washing), (4) Hoarding (distinct, treatment‑resistant). Cortico‑Striato‑Thalamo‑Cortical (CSTC) Loop – hyperactive circuit (orbitofrontal cortex, caudate, ACC) underlying obsessions & compulsions. Epidemiology – lifetime prevalence ≈ 2 %; onset < 25 y (median ≈ 10 y); chronic with waxing‑waning course. --- 📌 Must Remember Diagnostic criteria: obsessions and/or compulsions that are time‑consuming (≥ 1 h/day) and cause clinically significant distress/impairment. Yale‑Brown Obsessive‑Compulsive Scale (Y‑BOCS): ≥ 25 % reduction = meaningful improvement; ≥ 45‑50 % or score < 15 = remission. First‑line treatment: CBT – Exposure & Response Prevention (ERP) for mild‑moderate OCD. SSRIs (fluoxetine, sertraline, fluvoxamine) – dose‑dependent response; ≈ 2× response vs placebo. Combined CBT + SSRI superior for moderate‑severe cases. Treatment‑resistant: clomipramine, atypical antipsychotic augmentation (risperidone/aripiprazole), TMS, deep brain stimulation. Hoarding = poorest response to standard OCD interventions; often requires specialized approach. Comorbidities: depression (40 %), anxiety disorders, tic disorders (≈ 30 %), suicidality (> 50 % have thoughts, 15 % attempts). Genetics: 50 % heritable; twin studies show higher concordance in MZ vs DZ twins. --- 🔄 Key Processes ERP Workflow Identify obsession trigger → design graded exposure hierarchy → conduct exposure while preventing the compulsion → repeat until anxiety habituates. Pharmacologic Titration Start SSRI at low dose → increase gradually (often 2‑3 × antidepressant dose) → monitor for 10‑12 weeks → assess Y‑BOCS reduction ≥ 25 %. Augmentation Decision If SSRI trial (adequate dose + ≥ 12 weeks) → < 25 % Y‑BOCS improvement → add low‑dose atypical antipsychotic. Pediatric Assessment Administer Children’s Yale‑Brown OCD Scale → ≥ 25 % score drop = response; ≥ 45‑50 % or score < 15 = remission. --- 🔍 Key Comparisons OCD vs. OCPD – OCD: ego‑dystonic, distressing obsessions/compulsions; OCPD: ego‑syntonic, perceived as rational perfectionism. Obsessions vs. Overvalued Ideas – Obsessions: recognized as irrational; Overvalued ideas: strongly held, less insight, more treatment‑resistant. SSRIs vs. Clomipramine – SSRIs: better side‑effect profile; Clomipramine: similar efficacy, higher adverse‑event rate. ERP alone vs. ERP + SSRI – Combined therapy yields larger symptom reduction, especially in moderate‑severe OCD. --- ⚠️ Common Misunderstandings “All rituals are OCD.” Only rituals performed to relieve obsession‑related anxiety and that are ego‑dystonic qualify. “OCD patients enjoy their compulsions.” Compulsions are performed to reduce distress, not for pleasure. “Hoarding is just a subtype of OCD.” DSM‑5 classifies hoarding as a separate disorder; it responds poorly to standard OCD treatment. “SSRIs work at antidepressant doses.” OCD often requires higher doses than those used for depression. --- 🧠 Mental Models / Intuition “Alarm‑and‑Shutdown Loop” – Think of the CSTC circuit as a faulty alarm system: the orbitofrontal cortex sounds an alarm (obsession), the striatum triggers a shutdown routine (compulsion). ERP teaches the system that the alarm can be ignored, weakening the loop. “Cost‑Benefit Analysis of Avoidance” – Compulsions provide immediate anxiety relief (high short‑term payoff) but maintain the long‑term “cost” of persistent obsessions. ERP flips the payoff by tolerating short‑term discomfort for long‑term freedom. --- 🚩 Exceptions & Edge Cases Hoarding – may require specialized behavioral interventions (e.g., skills training, motivational interviewing) rather than standard ERP. Poor Insight / Delusional OCD – may need antipsychotic augmentation earlier, as patients may resist exposure. PANDAS/PANS – abrupt onset after streptococcal infection; may respond to immunomodulatory treatment plus standard OCD therapies. Substance‑Induced OCD – rule out methamphetamine, cocaine, atypical antipsychotics as causal; treat underlying substance issue first. --- 📍 When to Use Which Mild‑moderate OCD → start ERP (or CBT) alone. Moderate‑severe OCD or significant functional impairment → ERP + SSRI. Treatment‑resistant after adequate SSRI trial → Clomipramine or antipsychotic augmentation. Severe refractory cases → TMS → Deep Brain Stimulation (last resort). Pediatric patients – prioritize ERP; add SSRI if moderate‑severe or poor response to therapy alone. Hoarding dominant – consider specialized hoarding therapy and behavioral activation, not first‑line ERP alone. --- 👀 Patterns to Recognize Time‑consumption – ≥ 1 h/day of rituals → meets severity threshold. Ego‑dystonic vs. Ego‑syntonic – patient’s distress level clues toward OCD vs. OCPD. Symptom clusters – contamination/washing → cleaning dimension; ordering/counting → symmetry dimension; intrusive taboo thoughts → forbidden thoughts dimension. Comorbidity flag – depressive symptoms + suicidal ideation → higher relapse risk, may need integrated treatment. --- 🗂️ Exam Traps “Hoarding is an OCD subtype.” – Incorrect; hoarding is now a separate diagnosis. “Any repetitive behavior is a compulsion.” – Wrong; must be performed to reduce obsession‑related anxiety and be ego‑dystonic. “SSRIs are ineffective for OCD.” – Misleading; they are first‑line, especially at higher doses. “A 10 % Y‑BOCS reduction is clinically meaningful.” – False; need ≥ 25 % reduction. “OCD can be diagnosed by a blood test.” – Incorrect; diagnosis is clinical, no lab test predicts it. ---