6.1.4 Obsessive compulsive disorder

Definitions and classification

• Obsessions are recurrent, unwanted thoughts, images or urges.

• Compulsions are repetitive behaviours or mental acts that the person performs to reduce distress or prevent a feared outcome. Mental rituals can disable as much as visible ones.

• Symptoms must take time, commonly more than an hour a day, or cause significant distress or impairment.

• ICD-11 (the International Classification of Diseases, 11th revision) groups obsessive-compulsive disorder (OCD) with body dysmorphic disorder, hypochondriasis, olfactory reference disorder, hoarding disorder, trichotillomania and excoriation disorder.

• Insight is usually preserved: most adults recognise their obsessions and compulsions as excessive or unreasonable. Poor insight does not by itself make the illness psychotic.

Obsessive-compulsive personality disorder is enduring perfectionism, order and control that the person experiences as appropriate, not intrusive obsessions with anxiety-driven rituals. The two can coexist.

Epidemiology

• Lifetime prevalence in community surveys (the National Comorbidity Survey Replication and the Epidemiologic Catchment Area study) is about 2% (1.5 to 2.5%), roughly 1 in 50 adults.

• Adult men and women are affected in roughly equal numbers, unlike the female excess in other anxiety disorders and eating disorders.

• One source gives a modest female excess of about 1.5 to 1 in adult community samples, with near-equal ratios in clinic samples.

• Childhood-onset cases show a male excess; tic disorders are also skewed to males.

• Onset is usually in childhood, adolescence or early adulthood. Late onset calls for a search for secondary causes.

• Heritability is about 40 to 50%, with no single major gene.

• Depression, tic disorders and body dysmorphic disorder commonly coexist, and shame can delay help for years.

Aetiology

• Cortico-striato-thalamo-cortical loop: functional imaging in untreated OCD shows increased metabolism in the orbitofrontal cortex, anterior cingulate and caudate. These changes can shift with treatment and are not diagnostic.

• Behavioural model: compulsions are maintained by negative reinforcement. A ritual that ends obsessional distress removes an aversive state, so it becomes more frequent and blocks corrective learning.

• Salkovskis's cognitive model holds that intrusive thoughts are common, and an inflated sense of responsibility turns them into evidence of danger or moral failure.

• Thought-action fusion (Rachman) is the belief that thinking about harm makes it more likely, or is morally equal to acting.

Tap to enlarge

Symptom dimensions

• Symmetry and ordering carries the strongest familial loading, starts in childhood and is closely tied to tics. The urge for things to feel "just right" resembles the premonitory urge before a tic.

• Contamination with washing responds well to exposure and response prevention (ERP), because the feared objects are concrete.

• Sexual and religious obsessions respond poorly to selective serotonin reuptake inhibitors (SSRIs) and cognitive behavioural therapy (CBT), because covert neutralising is hard to block.

• Hoarding also responds poorly to SSRIs and CBT; it carries poor insight and a distinct imaging profile.

• Harm obsessions are not intent. Judge risk from context, behaviour and separate risk factors, not from content alone.

Hoarding disorder

• Hoarding disorder is a distinct obsessive-compulsive related disorder: persistent difficulty discarding possessions that are wanted and valued, with distress at parting from them.

• Clutter stops living areas being used.

• There is no obsessional driver, and acquiring is secondary to the difficulty discarding.

Differential diagnosis

Assessment

• The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) rates time, interference, distress, resistance and control for obsessions and for compulsions.

• Treatment response in trials is a fall of at least 35% in the Y-BOCS total from baseline, which is distinct from partial response and remission.

• Family accommodation, such as reassuring, joining rituals or rearranging life around triggers, is meant to help but maintains symptoms. Agree changes with relatives without blaming them.

• Ask directly about mental rituals, avoidance, harm from rituals (skin injury, poor intake, self-neglect), depression and suicide.

Psychological treatment

• ERP within CBT is the first-line psychological treatment for adult OCD according to the National Institute for Health and Care Excellence (NICE), and has the best evidence. The person faces the feared cue, working up a hierarchy, while the ritual is blocked.

• Systematic desensitisation differs: it pairs graded exposure with relaxation and lets the neutralising ritual continue.

• Cognitive work targets responsibility, threat and thought-action fusion.

Drug treatment

• An SSRI is the first-line drug for adult OCD. Fluoxetine, fluvoxamine, paroxetine and sertraline are established choices; citalopram is off-label.

• SSRIs are preferred to clomipramine, which works but is less well tolerated (anticholinergic effects) and more toxic to the heart and in overdose, and to venlafaxine.

• An adequate trial uses the higher OCD dose range for 12 weeks before switching or augmenting. A depression-level dose for under 12 weeks is not adequate.

• Antipsychotics are for augmentation only.

After a full trial of an SSRI with CBT including ERP has failed, NICE escalates in this order:

1. Switch to a different SSRI or to clomipramine, a potent serotonin reuptake inhibitor.

2. Add an antipsychotic, commonly low-dose aripiprazole or risperidone, to an SSRI or clomipramine, or combine clomipramine with citalopram.

3. Refer to a multidisciplinary team with specific OCD expertise after full trials of an SSRI alone, an SSRI with CBT, and clomipramine alone.

• Clomipramine covers both conditions when OCD and depression coexist and have not responded to CBT and SSRIs, and comes before antipsychotic augmentation.

• Antidepressant combinations need electrocardiogram, interaction and adverse effect monitoring.

• These late steps belong to the OCD pathway, not to those for generalised anxiety, panic, post-traumatic stress or social anxiety disorders.

• NICE restricts deep brain stimulation for OCD to research, and ablative surgery is exceptional.

• Continue an effective SSRI for at least 12 months, then taper gradually.

Course and prognosis

OCD often fluctuates with stress and may become chronic.

Judge recovery by hours regained and return to work, study or relationships, not by a lower score alone.

Body dysmorphic disorder

• Body dysmorphic disorder (BDD) is preoccupation with a perceived flaw in appearance that others find slight or unnoticeable, held with some insight and driving checking, camouflage and avoidance.

• BDD is not a fear of illness, a wish to remove a body part, a fixed delusion or a fear of social performance.

• NICE recommends CBT incorporating ERP as the first-line psychological treatment for BDD with mild functional impairment.

• An SSRI is the evidence-based first drug, with randomised trial support that antipsychotics (including pimozide augmentation), benzodiazepines and cosmetic surgery lack.

• NICE names fluoxetine as the preferred first drug in adults with BDD, whereas for OCD it allows a choice among several SSRIs.

• Continue a helpful SSRI for at least 12 months in adults with BDD, not the 6 months familiar from depression and from paediatric OCD and BDD advice.

• When BDD has not responded to two adequate SSRI trials plus CBT, the Maudsley guidance suggests adding buspirone to the current SSRI.