The Biological Approach to Treating OCD 

Drug Therapy: Treatment involving drugs. In the case of psychological disorders such drugs usually affect neurotransmitter levels.

SSRIs: A selective serotonin reuptake inhibitor which prevents the reabsorption and breakdown of serotonin in the presynaptic neuron, levels of serotonin are increased in the synapse and so continue to stimulate the postsynaptic neuron which compensates for whatever is wrong with the serotonin system in OCD.

Dosage and Advice: Fluoxetine has a typical daily dose of 20mg although this may be increased. It is available as capsules or liquid and takes 3-4 months of daily use for SSRIs to have much impact on symptoms.

Combining of Treatment: SSRIs are often used alongside CBT to reduce the persons emotional symptoms so they can engage more effectively with the CBT.

Tricyclics: An older type of antidepressant, such as clomipramine. It acts on various systems including the serotonin however it has more severe side-effects than SSRIs so is generally kept in reserve for people who do not respond to SSRIs.

SNRIs: Serotonin noradrenaline reuptake inhibitors are a second line of defence for people who don’t respond to SSRIs. They increase levels of serotonin as well as noradrenaline.

Evidence of Effectiveness: Soomro et al (2009) reviewed 17 studies that compared SSRIs to placebos in the treatment of OCD and all studies showed significantly better outcomes for SSRIs than the placebo conditions. Symptoms typically reduced for around 70% of people and the remaining 30% could be helped by either alternative drugs or combination of drugs and therapy.

Cost-Effective and Non-Disruptive: Drugs are cheap compared to psychological treatments because many thousands of tablets or liquid doses can be manufactured in the time it takes to conduct one session of a psychological therapy. This is beneficial for public health systems like the NHS.

Serious Side Effects: A small minority will get no benefit from SSRIs and experience side effects such as indigestion, blurred vision and loss of sex drive. Although these effects are usually temporary they can be distressing for people and for a minority they are long lasting. More than 1/10 experience erection problems and weight gain and 1/100 become aggressive and experience heart related problems whilst on clomipramine.