Obsessive-Compulsive Disorder
Summary
Obsessive-Compulsive Disorder (OCD) is a chronic anxiety disorder characterised by obsessions (intrusive, unwanted thoughts causing anxiety) and compulsions (repetitive behaviours or mental acts performed to reduce anxiety). It affects 1-2% of the population and typically begins in adolescence or early adulthood. OCD causes significant distress and functional impairment. First-line treatment is Cognitive Behavioural Therapy with Exposure and Response Prevention (CBT with ERP). SSRIs at higher doses than used for depression are effective, often in combination with CBT. Treatment-resistant cases may require clomipramine or augmentation strategies.
Key Facts
- Definition: Obsessions (intrusive thoughts) + compulsions (repetitive behaviours) causing distress and impairment
- Prevalence: 1-2% lifetime
- Age of Onset: Typically teens to early 20s; bimodal peak (childhood, early adulthood)
- First-Line Treatment: CBT with ERP
- First-Line Medication: SSRI (high dose, e.g., fluoxetine 60-80mg)
- Duration: Often chronic, waxing and waning course
Clinical Pearls
"ERP is the Gold Standard": Exposure and Response Prevention — confronting feared triggers without performing compulsions — is the most effective therapy.
"Higher Doses, Longer Trials": SSRIs for OCD require higher doses than depression (e.g., fluoxetine 60-80mg) and longer trials (10-12 weeks).
"Ask About Insight": Patients vary from good insight ("I know this is irrational") to poor/absent insight ("I truly believe this is necessary").
Why This Matters Clinically
OCD is often hidden and underdiagnosed due to shame. It causes profound disability — ranked by WHO as one of the top 10 most disabling conditions. Early, effective treatment can prevent decades of suffering.
Prevalence
| Measure | Value |
|---|---|
| Lifetime Prevalence | 1-2% |
| 12-month Prevalence | 0.5-1% |
| Male:Female | 1:1 (equal) |
Demographics
| Factor | Details |
|---|---|
| Age of Onset | Bimodal: ~10 years (childhood-onset, more males) and ~20 years (adult-onset) |
| Delay to Treatment | Often 7-10 years from onset |
Risk Factors
| Factor | Details |
|---|---|
| Genetics | 45-65% heritability; higher in childhood-onset |
| Neurological | Streptococcal infection (PANDAS in children) |
| Psychological | Perfectionism, inflated responsibility |
| Life Events | Stress, transitions |
Neurobiological Model
- Dysfunction in cortico-striato-thalamo-cortical (CSTC) circuits
- Orbitofrontal cortex hyperactivity (error detection)
- Caudate nucleus dysfunction (filtering, habit formation)
- Anterior cingulate cortex (conflict monitoring)
Neurotransmitters
- Serotonin system abnormalities (basis for SSRI efficacy)
- Glutamate, dopamine also implicated
Psychological Models
- Inflated Responsibility: Feeling excessively responsible for preventing harm
- Thought-Action Fusion: Thinking something = doing it
- Intolerance of Uncertainty: Need for certainty, difficulty tolerating doubt
Obsessions
Compulsions
Red Flags
[!CAUTION] Red Flags:
- Suicide risk (especially with severe OCD + depression)
- Severe functional impairment
- Co-morbid severe depression
- Poor insight (may be mislabeled as psychosis)
- Skin damage from excessive washing
Assessment
- Detailed history of obsessions and compulsions
- Time spent on symptoms
- Functional impact
- Insight assessment
- Y-BOCS score
Mental State Examination
| Domain | Findings |
|---|---|
| Appearance | May show effects (dry hands from washing) |
| Behaviour | May perform rituals during assessment |
| Mood | Often anxious, depressed |
| Thought Content | Obsessional themes |
| Insight | Variable (good to absent) |
| Test | Purpose |
|---|---|
| Y-BOCS | Severity assessment |
| PHQ-9 | Depression screen |
| GAD-7 | Anxiety screen |
| Bloods (if medication) | Baseline for SSRIs/clomipramine |
| ECG | If using clomipramine |
Stepped Care (NICE CG31)
| Severity | Treatment |
|---|---|
| Mild | Low-intensity CBT, guided self-help |
| Moderate | CBT with ERP or SSRI |
| Severe | CBT with ERP + SSRI; specialist referral |
| Treatment-Resistant | Clomipramine, augmentation, intensive ERP |
Key Medications
| Drug | Dose | Notes |
|---|---|---|
| Fluoxetine | 60-80mg | SSRI first-line |
| Sertraline | 150-200mg | SSRI alternative |
| Clomipramine | 150-250mg | Second-line; more side effects |
| Complication | Notes |
|---|---|
| Depression | 60-70% lifetime comorbidity |
| Anxiety Disorders | Common |
| Suicide | Risk increased, especially with depression |
| Relationship/Occupational | Impairment common |
| Physical | Skin damage (washing), isolation |
Course
| Pattern | Notes |
|---|---|
| Chronic | Most cases; waxing and waning |
| Episodic | Some have discrete episodes |
| Remission | Rare without treatment |
Response to Treatment
- CBT with ERP: 60-80% respond
- SSRI: 40-60% respond
- Combination often best for severe cases
Key Guidelines
- NICE CG31: OCD and BDD (2005)
Evidence Strength
| Intervention | Level | Notes |
|---|---|---|
| CBT with ERP | 1a | Gold standard |
| SSRIs (high dose) | 1a | First-line medication |
| Clomipramine | 1a | Effective but more side effects |
What is OCD?
OCD is a condition where you have unwanted, distressing thoughts (obsessions) that make you feel you must do certain things (compulsions) to reduce the anxiety. It's not about being tidy — it's a real mental health condition that causes a lot of distress.
What are the symptoms?
Obsessions (intrusive thoughts):
- Fear of germs or contamination
- Fear of causing harm
- Unwanted sexual or violent thoughts
- Need for things to be "just right"
Compulsions (repetitive behaviours):
- Excessive washing or cleaning
- Checking things repeatedly
- Counting, ordering, arranging
- Mental rituals
How is it treated?
- CBT with ERP: The most effective treatment. You learn to face your fears without doing compulsions, and the anxiety naturally reduces.
- Medication: SSRIs (like fluoxetine) at higher doses can help, often combined with therapy.
What to expect
- Treatment takes time but is very effective
- You may need to continue medication for 12+ months
- Many people recover significantly
Primary Guidelines
- National Institute for Health and Care Excellence. Obsessive-compulsive disorder and body dysmorphic disorder: treatment (CG31). 2005. nice.org.uk/guidance/cg31
Key Studies
- Foa EB, Liebowitz MR, Kozak MJ, et al. Randomized, placebo-controlled trial of exposure and ritual prevention, clomipramine, and their combination in the treatment of OCD. Am J Psychiatry. 2005;162(1):151-161. PMID: 15625214
Further Resources
- OCD Action: ocdaction.org.uk
- OCD-UK: ocduk.org
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. If you are struggling with OCD, please seek professional help.