Overview
Obsessive-Compulsive Disorder (OCD)
1. Clinical Overview
Summary
Obsessive-Compulsive Disorder (OCD) is a chronic mental health condition characterised by Obsessions (Recurrent, Intrusive, Unwanted thoughts, Images, or Urges that cause marked Anxiety or Distress) and Compulsions (Repetitive Behaviours or Mental Acts that the person feels driven to perform in response to an obsession or according to rigid rules, aimed at reducing distress or preventing a dreaded event). OCD affects approximately 1-2% of the population and typically begins in late adolescence or early adulthood. The condition causes significant functional impairment in social, Occupational, and Personal domains. OCD is often associated with insight (Patients recognise the thoughts/Behaviours are excessive or unreasonable), though insight varies. First-line treatment consists of Cognitive Behavioural Therapy (CBT) with Exposure and Response Prevention (ERP) and/or SSRIs (Often at higher doses than for depression). OCD is chronic but treatable, and early intervention improves outcomes. [1,2,3]
Clinical Pearls
"Ego-Dystonic": OCD thoughts are experienced as unwanted and distressing (Unlike delusions). Patients often recognise the irrationality but cannot stop.
"Obsessions Cause Anxiety, Compulsions Reduce It (Temporarily)": The compulsion provides temporary relief, reinforcing the cycle.
"ERP is the Gold Standard": Exposure and Response Prevention – Facing the obsession without performing the compulsion.
"High-Dose SSRIs, Long Trial": OCD often requires higher SSRI doses (e.g., Fluoxetine 60mg) and longer trials (12 weeks) than depression.
2. Epidemiology
Demographics
| Factor | Notes |
|---|---|
| Prevalence | ~1-2% lifetime. |
| Age of Onset | Bimodal: Peak ~10 years (Childhood-onset, More males) and ~21 years (Adult-onset, Equal sex). |
| Sex | Equal overall (Males predominate in childhood-onset). |
| Course | Chronic. Waxing and waning. Rarely spontaneously remits. |
Risk Factors
| Risk Factor | Notes |
|---|---|
| Genetic | First-degree relatives have 4-5x risk. Concordance higher in monozygotic twins. |
| Neurobiological | Cortico-Striatal-Thalamo-Cortical (CSTC) circuit dysregulation. |
| Childhood Trauma | Adverse childhood experiences. |
| PANDAS/PANS | Paediatric autoimmune neuropsychiatric disorders associated with Streptococcal infections. Abrupt OCD onset in children. |
| Comorbidities | Depression, Anxiety, Tic disorders. |
3. Pathophysiology
Neurobiological Model
| Structure | Role in OCD |
|---|---|
| Orbitofrontal Cortex (OFC) | Hyperactive. Error detection, "Something is wrong" feeling. |
| Anterior Cingulate Cortex (ACC) | Hyperactive. Conflict monitoring. |
| Caudate Nucleus | Impaired gating. Fails to filter intrusive thoughts. |
| Thalamus | Overactive loop. |
| CSTC Circuit | Dysregulation leads to intrusive thoughts and repetitive behaviours. |
Neurotransmitters
| Neurotransmitter | Role |
|---|---|
| Serotonin | Core role. SSRIs effective. |
| Dopamine | May contribute. Augmentation with antipsychotics sometimes helpful. |
| Glutamate | Emerging target. Glutamate hyperactivity in CSTC. |
Cognitive Model
- Inflated Responsibility: Belief that one has power to cause or prevent harm.
- Overestimation of Threat: Exaggerated perception of danger.
- Thought-Action Fusion: Belief that having a thought is equivalent to acting on it.
- Intolerance of Uncertainty: Need for certainty drives checking.
- Perfectionism: Need for things to be "Just right".
4. Clinical Presentation
Obsessions (Intrusive Thoughts/Images/Urges)
| Theme | Examples |
|---|---|
| Contamination | Fear of dirt, Germs, Disease, Bodily fluids. |
| Harm / Aggression | Fear of harming self or others, Violent images, Fear of causing accidents. |
| Symmetry / "Just Right" | Need for things to be symmetrical, Ordered, Or feel "Just right". |
| Forbidden Thoughts | Sexual, Religious, Blasphemous, Aggressive, Paedophilic intrusive thoughts. Ego-dystonic. |
| Doubt | Fear of having left the door unlocked, Stove on, Made a mistake. |
Compulsions (Repetitive Behaviours/Mental Acts)
| Type | Examples |
|---|---|
| Washing / Cleaning | Excessive handwashing, Showering, Cleaning. |
| Checking | Repeatedly checking locks, Switches, Appliances. |
| Ordering / Arranging | Arranging items symmetrically, In a particular order. |
| Counting | Counting rituals. |
| Repeating | Repeating actions a set number of times. |
| Mental Compulsions | Praying, Reviewing, Neutralising thoughts, Mental counting. |
| Reassurance Seeking | Repeatedly asking others for reassurance. |
| Avoidance | Avoiding triggers. |
Diagnostic Criteria (DSM-5/ICD-11)
| Criteria |
|---|
| Presence of Obsessions and/or Compulsions. |
| Time-consuming (>1 hour/day) or cause clinically significant distress or functional impairment. |
| Not attributable to substance or another medical condition. |
| Not better explained by another mental disorder (e.g., Generalised anxiety, Body dysmorphic disorder, Hoarding). |
Insight Specifiers (DSM-5)
| Specifier | Description |
|---|---|
| Good Insight | Recognises OCD beliefs are definitely or probably not true. |
| Fair Insight | Thinks beliefs are probably true. |
| Poor/Absent Insight | Completely convinced beliefs are true (Near-delusional). |
5. Differential Diagnosis
| Condition | Key Differentiating Features |
|---|---|
| OCD | Ego-dystonic obsessions + Compulsions. Distressing. Time-consuming. |
| Generalised Anxiety Disorder (GAD) | Worries about real-life concerns (Not intrusive thoughts). No compulsions. |
| Specific Phobia | Fear limited to specific object/Situation. No obsessions or compulsions. |
| Body Dysmorphic Disorder (BDD) | Preoccupation with perceived flaws in appearance. |
| Hoarding Disorder | Difficulty discarding. May or may not have obsessions/Compulsions. |
| Tic Disorders / Tourette's | Tics are semi-voluntary movements/Vocalisations. Often comorbid with OCD. |
| Obsessive-Compulsive Personality Disorder (OCPD) | Ego-syntonic perfectionism, Orderliness, Control. Not intrusive thoughts. |
| Psychotic Disorders | Delusions are ego-syntonic and not resisted. Different thought content. |
6. Assessment
History
| Component | Notes |
|---|---|
| Obsessions | Nature, Content, Frequency, Distress. |
| Compulsions | Type, Frequency, Time spent, Relation to obsessions. |
| Insight | Does patient recognise irrationality? |
| Functional Impact | Work, School, Relationships, Daily activities. |
| Time Spent | >1 hour/day supports diagnosis. |
| Avoidance | What triggers are avoided? |
| Comorbidities | Depression, Anxiety, Tics, BDD. |
| Risk Assessment | Suicidality, Self-harm. |
Scales
| Scale | Notes |
|---|---|
| Y-BOCS (Yale-Brown Obsessive Compulsive Scale) | Gold standard. Severity rating. Time, Interference, Distress, Resistance, Control. |
| OCI-R (Obsessive-Compulsive Inventory-Revised) | Self-report. Screening. |
7. Management
Management Algorithm
SUSPECTED OCD
(Obsessions + Compulsions causing distress/Impairment)
↓
ASSESSMENT
- Clinical interview (Obsessions, Compulsions, Insight)
- Y-BOCS severity
- Screen for comorbidities (Depression, Anxiety)
- Risk assessment
↓
SEVERITY
┌────────────────┴────────────────┐
MILD (Y-BOCS less than 16) MODERATE-SEVERE (Y-BOCS ≥16)
↓ ↓
**LOW-INTENSITY CBT** **HIGH-INTENSITY CBT with ERP**
(Self-help, Guided self-help) + Consider **SSRI**
↓
PSYCHOLOGICAL THERAPY (FIRST-LINE)
┌──────────────────────────────────────────────────────────┐
│ **CBT with ERP (Exposure and Response Prevention)** │
│ - Gold standard psychological treatment │
│ - Typically 10-20 sessions │
│ - Exposure: Gradual exposure to feared obsession/Trigger│
│ - Response Prevention: Resist performing compulsion │
│ - Habituation: Anxiety reduces naturally over time │
└──────────────────────────────────────────────────────────┘
↓
PHARMACOTHERAPY (SSRI)
┌──────────────────────────────────────────────────────────┐
│ **SSRI (First-Line)** │
│ - Fluoxetine, Sertraline, Paroxetine, Fluvoxamine, │
│ Citalopram, Escitalopram │
│ - Start at standard dose, Increase to HIGH DOSE │
│ (e.g., Fluoxetine 60-80mg, Sertraline 200mg) │
│ - Allow **12 weeks at maximum tolerated dose** before │
│ concluding non-response │
│ - Continue for at least 12 months after response │
│ │
│ **Second-Line (If SSRI Fails)** │
│ - Clomipramine (Tricyclic – More effective but more │
│ side effects) │
│ - Augmentation with low-dose antipsychotic (Risperidone,│
│ Aripiprazole) if partial response │
└──────────────────────────────────────────────────────────┘
↓
TREATMENT-RESISTANT OCD
- Re-evaluate diagnosis
- Higher-intensity ERP
- Clomipramine trial
- Antipsychotic augmentation
- Consider inpatient/Intensive outpatient programmes
- Neurosurgical options (DBS – Deep Brain Stimulation):
Last resort for severe refractory cases
ERP Key Principles
| Principle | Notes |
|---|---|
| Exposure | Gradual, Systematic exposure to feared stimuli/Obsession. Start with less anxiety-provoking, Progress to more challenging. |
| Response Prevention | Refrain from performing compulsion. Sit with the anxiety. |
| Habituation | Anxiety naturally decreases over time without the compulsion. |
| Corrective Learning | Patient learns that feared outcome does not occur. |
Medication Summary
| Medication | Notes |
|---|---|
| SSRIs | First-line. High doses. Long trial (12 weeks). |
| Clomipramine | Tricyclic. Possibly most effective but more side effects (Anticholinergic, Cardiac). Second-line. |
| Antipsychotic Augmentation | Risperidone, Aripiprazole. For partial responders. |
8. Complications and Comorbidities
| Comorbidity / Complication | Notes |
|---|---|
| Major Depression | ~60% lifetime. Common comorbidity. Screen and treat. |
| Other Anxiety Disorders | GAD, Social anxiety, Panic. |
| Tic Disorders | Especially in childhood-onset OCD. |
| Body Dysmorphic Disorder | Related condition. |
| Hoarding Disorder | May coexist. |
| Suicidality | Elevated risk, Especially with comorbid depression. Always assess. |
| Impaired Quality of Life | Social isolation, Occupational dysfunction, Relationship problems. |
9. Prognosis and Outcomes
| Factor | Notes |
|---|---|
| Chronic Course | OCD is typically lifelong. Symptom fluctuation. |
| Response to Treatment | ~50-60% achieve significant symptom reduction with ERP +/- SSRI. |
| Early Intervention | Better outcomes. |
| Predictors of Poorer Outcome | Poor insight, Comorbidities, Hoarding symptoms, Delayed treatment. |
10. Evidence and Guidelines
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| OCD | NICE CG31 | CBT with ERP first-line. SSRI (High dose, Long trial). Combined treatment for moderate-severe. |
| OCD | APA | ERP first-line. SSRIs. Clomipramine. Augmentation. |
11. Patient and Layperson Explanation
What is OCD?
OCD (Obsessive-Compulsive Disorder) is a mental health condition where you have:
- Obsessions: Unwanted, Distressing thoughts, Images, Or urges that keep coming back.
- Compulsions: Repetitive behaviours or mental acts you feel you must do to reduce the anxiety.
These thoughts and behaviours take up a lot of time and can interfere with your life.
Examples
- Worrying about germs → Washing hands repeatedly.
- Fear of leaving the door unlocked → Checking the lock over and over.
- Needing things to be "Just right" → Arranging items until it feels correct.
Is it just being tidy or worried?
OCD is more than being organised or a bit of a worrier. The thoughts in OCD are distressing and unwanted. The person usually knows they are excessive but cannot stop.
How is it treated?
- Therapy (ERP): A type of therapy where you gradually face your fears without doing the compulsion. This is very effective.
- Medication (SSRIs): Antidepressant tablets can help reduce the intensity of the obsessions and compulsions.
Most people with OCD can get significantly better with treatment.
12. References
Primary Sources
- National Institute for Health and Care Excellence. Obsessive-compulsive disorder and body dysmorphic disorder (CG31). 2005 (Updated 2020).
- Stein DJ, et al. Obsessive-compulsive disorder. Nat Rev Dis Primers. 2019;5(1):52. PMID: 31371720.
- Abramowitz JS, et al. Obsessive-compulsive disorder. Lancet. 2009;374(9688):491-499. PMID: 19665647.
13. Examination Focus
Common Exam Questions
- Core Features: "What are the two core features of OCD?"
- Answer: Obsessions (Intrusive, Unwanted, Distressing thoughts/Images/Urges) and Compulsions (Repetitive behaviours/Mental acts performed to reduce anxiety).
- First-Line Psychological Treatment: "What is the gold-standard psychological therapy for OCD?"
- Answer: CBT with Exposure and Response Prevention (ERP).
- Pharmacotherapy: "What class of medication is first-line for OCD?"
- Answer: SSRIs (At higher doses than for depression, With a longer trial of at least 12 weeks).
- OCD vs OCPD: "How does OCD differ from OCPD?"
- Answer: OCD: Ego-dystonic (Distressing, Unwanted obsessions, Compulsions). OCPD: Ego-syntonic (Personality trait of perfectionism, Orderliness, Control – Not intrusive thoughts).
Viva Points
- Ego-Dystonic: OCD thoughts are unwanted and resisted.
- High-Dose SSRI, Long Trial: 12 weeks at maximum tolerated dose.
- Y-BOCS: Gold-standard severity scale.
- PANDAS: Consider in sudden-onset childhood OCD following streptococcal infection.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.