Obsessive compulsive disorder (OCD) is the most common mental illness after depression. It affects one person in 100, so the average GP with 1,800 patients will have 18 patients with OCD.
There is strong evidence that genetic factors play an important role in the presentation of OCD. Its association with other syndromes, such as Tourette’s and Asperger’s, and with autism, Sydenham’s chorea, trichotillomania and tic disorders, also emphasises an overlap with neurological conditions.
There is an hypothesis that OCD and tics may begin after a streptococcal infection in children. There is also evidence that serotonergic and dopaminergic pathways are involved, and that the corticostriatal-thalamic-cortical circuits in the brain, important in the process of harm assessment, are crucial. Functional imaging data support the association between OCD and activity in the corticostriatal regions.
People with OCD will typically see three to four doctors and spend nine years seeking treatment before a correct diagnosis is made.
OCD is under-diagnosed and under-treated and because patients are so secretive about their symptoms and healthcare providers may be unfamiliar with it, or lack the resources to deliver appropriate treatment.
The severity of OCD ranges from mildly inconvenient to incapacitating, with approximately 20 per cent of patients unable to lead normal lives.
Patients present with obsessions, compulsions or both and one may predominate. Obsessions are unwanted thoughts, images or impulses acknowledged as irrational; fears of contamination or harm to others are also common.
Compulsions are repetitive behaviours or acts that a person is compelled to perform and may repeat until there is a sense of completeness. Washing and checking are common compulsions. They can reduce distress or anxiety in the short term but become involuntary, repetitive and time-consuming.
People with OCD are often ashamed of their symptoms, especially when they contain ideas about harming others or have a sexual element. They also become distressed when discussing or recalling obsessions, which may delay help.
OCD patients generally lead law-abiding, well-ordered lives and initially appear to be ideal patients. However, they are frequently embarrassed by their thoughts and rituals and are reluctant to talk.
They may try to hide their symptoms and be controlling to the point where they take up more time than their GP has available.
Most OCD patients gain enormous benefit from cognitive behavioural therapy (CBT) that includes exposure and response prevention, while others respond better to pharmacotherapy. Some patients need both behavioural therapy and medication. CBT is generally effective and takes between 10-20 hours of treatment carried out by a skilled therapist.
Ultimately, treatment depends on availability; with long NHS waiting lists for psychological therapies, most patients will initially try medication. Many controlled clinical trials have shown that SSRIs such as venlafaxine, fluoxetine, sertraline, paroxetine and fluvoxamine can decrease OCD symptoms.
Clomipramine, a tricyclic antidepressant with noradrenaline and serotonin reuptake inhibitor actions, was the first medication proven to be effective for OCD, in the 1970s. Today, it is still the gold standard.
There is also increasing evidence that co-prescribing atypical antipsychotic agents such as risperidone, olanzapine and quetiapine may bring a positive response. Selection depends on the side-effect profile and how well each drug is tolerated.
The response to these drugs in OCD is different to that observed when they are prescribed for depression. The dosage for OCD can be significantly higher — up to 300mg of venlafaxine or 80mg of fluoxetine daily — and given for six to eight weeks.
Dosages in excess of licensed limits may be required in severe cases of OCD and these should only be given under specialist supervision.
If medication alone is used, it should be given on a long-term basis, otherwise relapse is common. Referral to a psychiatric consultant or unit is indicated for patients who have resistant OCD.
Dr Campbell is consultant psychiatrist at the Priory Hospital, Roehampton
Five questions to help identify an OCD patient
- Do you frequently wash or clean?
- Do you continually check things?
- Are there any thoughts that keep bothering you that you would like to banish but cannot?
- Do your daily activities take a long time to finish?
- Are you concerned about orderliness or symmetry?