14th February 2025

Obsessive-compulsive disorder (OCD)

Obsessive-compulsive disorder is a common, chronic condition characterised by obsessions and compulsions.

An obsession is an unwanted, unpleasant and intrusive thought, mental image or impulse which the patient recognises as abnormal. Obsessions lead to a compulsion, which is a stereotyped behaviour that neutralises the obsession and provides relief.

Epidemiology and aetiology of OCD

OCD affects up to 3% of the population. Men and women are equally affected. It affects younger people more commonly, with an average age of 20 years at diagnosis.

Risk factors include family history, comorbid depressive or anxiety disorders, alcohol or substance misuse, and certain personality traits, e.g. avoidant, dependent, or histrionic. OCD is also associated with schizophrenia, Sydenham’s chorea, and Tourette’s syndrome.

Presentation and diagnosis of OCD

Obsessions and compulsions must be time consuming (taking more than an hour per day) or result in significant distress or functional impairment.

Common obsessions include contamination, symmetry, safety and sexual or violent thoughts. Common compulsions include checking (e.g. doors), cleaning, counting, and hoarding.

Management of OCD

If functional impairment is mild, first-line treatment is low-intensity psychological treatments such as CBT. If not suitable or ineffective, an SSRI and/or intensive CBT should be offered. Clomipramine (a TCA) is an alternative to SSRIs, although not commonly used.

Other antidepressants such as TCAs (except clomipramine), SNRIs or MAOIs should not be used unless there is a comorbid anxiety or depressive disorder.

References

• Semple D, Smyth R. Oxford handbook of psychiatry. Oxford; New York: Oxford University Press; 2019
• World Health Organization. ICD-11 for Mortality and Morbidity Statistics [Internet]. icd.who.int. World Health Organization; 2019 [cited 2022 Feb 23]. Available from: https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/1707067746
• Sawchuck C, Veitengruber J. Panic disorders – Symptoms, diagnosis and treatment [Internet]. BMJ Best Practice; 2021 [cited 2022 Feb 23]. Available from: https://bestpractice.bmj.com/topics/en-gb/121
• The National Institute for Health and Care Excellence. Generalised anxiety disorder and panic disorder in adults [Internet]. NICE, 2019. [cited 2022 Feb 23] Available from: https://www.nice.org.uk/guidance/cg113
• Gale C. Generalised anxiety disorder [Internet]. BMJ Best Practice; 2021. [cited 2022 Feb 23] Available from: https://bestpractice.bmj.com/topics/en-gb/120
• Seibell P. Obsessive-compulsive disorder [Internet]. BMJ Best Practice; 2021 [cited 2022 Feb 24]. Available from: https://bestpractice.bmj.com/topics/en-gb/362
• The National Institute for Health and Care Excellence. Obsessive-compulsive disorder and body dysmorphic disorder [Internet]. NICE; 2005. [cited 2022 Feb 23] Available from: https://www.nice.org.uk/guidance/cg31