Obsessive Compulsive Disorder

Lifetime prevalence ~2–2.5%; mean age of onset around 20; affects men and women equally. Mild obsessional/compulsive behaviour in response to stress is normal — OCD is diagnosed when it causes marked distress or significantly interferes with the person’s life, and symptoms frequently start to affect people living or working with the patient too.

• Obsessions are recurrent, persistent, intrusive ideas, thoughts, impulses, or images. They are ego-dystonic — the patient recognises them as unwanted and usually tries to resist them.
• Compulsions are repetitive, purposeful behaviours performed in response to an obsession, to prevent a feared (but not realistically connected) outcome — e.g. excessive hand-washing to prevent contamination. Most patients recognise the behaviour as unreasonable even while feeling compelled to do it.

Management

Optimal management combines psychological and pharmacological treatment:

• CBT for the obsessions, with an exposure and response prevention (ExRP) component for the compulsions — exposure to the anxiety-triggering cue, paired with preventing the compulsive ritual that would normally relieve it.
• Many patients can’t engage meaningfully with psychological therapy until medication has brought some initial symptom relief.

Pharmacotherapy — SSRIs or clomipramine:

• SSRIs are used at the higher end of the dosing range (higher than for depression), and response can take 6–12 weeks.
• Clomipramine is an alternative, uniquely effective in some patients, though less well tolerated. Target dose 150 mg at night, titrated from 25–75 mg; the dose may be increased to a maximum of 300 mg if response is inadequate.
• Continue therapy for 6–12 months once stable, then taper slowly rather than stopping abruptly.
• Doses of SSRIs/SNRIs needed for OCD are often higher than for other anxiety disorders or depression. Citalopram’s maximum recommended dose is comparatively lower than other SSRIs because of its QT-prolongation risk, which becomes more relevant at OCD-level dosing.

Related “OCD-spectrum” disorders

Body dysmorphic disorder — excessive preoccupation with perceived physical flaws causing significant distress and repetitive checking/reassurance-seeking behaviours; insight ranges from good to delusional. Evidence is limited, so treatment is extrapolated from OCD: combined psychosocial (CBT with ExRP) and pharmacological (SSRI, often at OCD-level higher doses) treatment, ideally via an OCD-spectrum specialist.

Hoarding disorder — anxiety about discarding possessions (regardless of monetary value), leading to substantial clutter/accumulation; insight varies. Poor prognosis, poorly responsive to therapy — psychosocial treatment (CBT with ExRP) by a clinician experienced in hoarding is first-line. Small trials suggest benefit from venlafaxine, atomoxetine, or modified-release methylphenidate, but these aren’t yet used in routine practice.