Overview
Obsessive-compulsive disorder (OCD) is a mental health condition characterised by intrusive, unwanted thoughts (obsessions) and repetitive behaviours or mental acts (compulsions) that a person feels driven to perform in response. OCD is not about being tidy or organised — it is a distressing, time-consuming condition that can severely impair daily functioning.
How common is it?
OCD affects approximately 1 to 2% of adults and 1 to 2% of children in the UK. It affects men and women roughly equally. Average delay between onset and effective treatment is 11 years, due to underdiagnosis and misdiagnosis.
Causes and risk factors
OCD results from abnormal activity in frontal-striatal brain circuits, combined with genetic predisposition and psychological vulnerability.
Common risk factors
- Genetic factors (higher concordance in identical twins)
- Abnormal serotonin and glutamate neurotransmission
- Dysregulation of fronto-striato-thalamo-cortical circuits
- Psychological: perfectionism, inflated sense of responsibility, thought-action fusion
- Life stress and traumatic events
- Paediatric OCD: PANDAS (paediatric autoimmune neuropsychiatric disorders associated with Streptococcal infections) — controversial but recognised subgroup
Symptoms
- Obsessions: persistent, intrusive thoughts, images, or urges causing marked anxiety (common themes: contamination, harm, symmetry, forbidden sexual or religious thoughts)
- Compulsions: repetitive behaviours (handwashing, checking, ordering, counting) or mental acts (praying, repeating phrases) performed to reduce distress from obsessions
- Recognition that obsessions and compulsions are excessive (usually)
- At least 1 hour per day spent on OCD symptoms, causing significant distress or impairment
- Avoidance of situations that trigger obsessions
When to see a doctor
Seek help when OCD symptoms are taking more than an hour per day, causing distress, or interfering with work, relationships, or social life. OCD responds well to treatment — delay increases its grip.
Diagnosis
Clinical assessment using Y-BOCS (Yale-Brown Obsessive Compulsive Scale). Distinguish from normal intrusive thoughts (which all people experience), GAD, health anxiety, autism spectrum disorder, and psychosis.
Treatments
Cognitive behavioural therapy with ERP (exposure and response prevention)
ERP is the evidence-based psychological treatment for OCD. The patient gradually confronts feared situations or thoughts (exposure) without performing the compulsion (response prevention), allowing anxiety to habituate naturally. Highly effective: 60 to 80% response rate. First-line treatment.
SSRI antidepressants
SSRIs at high doses (fluoxetine 60mg, sertraline 200mg, fluvoxamine) are effective for OCD. Effect takes 8 to 12 weeks to assess fully. Clomipramine (a tricyclic) is an alternative. Used alone or combined with ERP.
Augmentation strategies
For treatment-resistant OCD: augmentation with low-dose risperidone, aripiprazole, or quetiapine added to SSRI. Ketamine infusions, deep brain stimulation, and transcranial magnetic stimulation are emerging options for severe refractory cases.
Self-care and lifestyle
- Do not accommodate or enable OCD by rearranging life to avoid triggers
- Family members: avoid assisting compulsions (reassurance seeking is a compulsion)
- Regular exercise reduces OCD symptom severity
- Mindfulness helps observers distance from intrusive thoughts without engaging
Prevention
OCD cannot be reliably prevented. Early intervention when symptoms first appear prevents entrenchment of compulsive habits.