The biological approach to treating OCD

How is OCD treated biologically?

Drug therapy

What is drug therapy?

Treatment involving drugs that increase the level of serotonin in the brain.

Why is drug therapy used?

Low levels of serotonin are associated with OCD.

Thus, drugs such as SSRIs increase the level of serotonin in the brain

What does SSRI stand for?

Selective serotonin reuptake inhibitor

How do SSRIs work?

• Serotonin is released by presynaptic neurons in the brain and travels across a synapse.

• The neurotransmitter chemically conveys the signal from the presynaptic neuron to the postsynaptic neuron

• And then it is reabsorbed by the presynaptic neuron where it is broken down and reused.

By preventing the reabsorption and breakdown, SSRIs effectively increase levels of serotonin in the synapse and thus continue to stimulate the postsynaptic neuron

What is an example of an SSRI?

A typical daily dose of fluoxetine is 20mg.

Available as capsules or liquid

It takes 3-4 months of daily use for SSRIs to have much impact on symptoms

How are SSRIs combined with other treatments?

SSRIs are often used alongside CBT to treat OCD.

The drugs reduce a person’s emotional symptoms (e.g. anxiety or depression)

This means that people with OCD can engage more effectively with the CBT

What are alternatives to SSRIs?

• When an SSRI is not effective after 3-4 months, the dose can be increased or it can be combined with other drugs.

• People respond differently to different drugs and alternatives work well for some people or not!

• Tricyclics - (older type of antidepressant) such as clomipramine. Acts on the serotonin system and has the same effect as SSRIs. Clomipramine has more severe side effects than SSRIs

• SNRIs (serotonin- noradrenaline - reuptake - inhibitors) - Increase levels of serotonin and noradrenaline

What is a strength of drug therapy?

Good evidence of its effectiveness

Clear evidence to show that SSRIs reduce symptom severity and improve quality of life for people with OCD.

Soomro et al reviewed 17 studies that compared SSRIs to placebos in the treatment of OCD. All 17 studies showed significantly better outcomes for SSRIs than for the placebo conditions. Typically symptoms reduce for around 70% of people taking SSRIs. For the remaining 30%, most can be helped by either alternative or combinations of drugs and therapy.

This means that drugs appear to be helpful for most people with OCD.

What is another strength of drug therapies?

Cost effective and non-disruptive to people’s lives

They 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.

Good value for public health systems like the NHS and represents a good use of limited funds.

SSRIs are non-disruptive to people’s lives compared to psychological therapy which involves time spent attending therapy sessions.

This means that drugs are popular with many people with OCD and their doctors.

What is a limitation of drug therapy?

Drugs can have potentially serious side-effects

Some people experience side-effects such as indigestion, blurred vision and loss of sex drive.

These side effects are usually temporary but can be distressing and for a minority they are long-lasting.

For those taking the tricylic clomipramine, side effects are more common and serious. E.g. more than 1 in 10 people experience erection problems and weight gain, 1 in 100 become aggressive and experience heart-related problems.

This means that some people have a reduced quality of life as a result of taking drugs and may stop taking them altogether, meaning the drugs cease to be effective.

What is another limitation of drug therapies?

Biased evidence

Researchers are sponsored by drug companies and may selectively publish positive outcomes for drugs their sponsors are selling (Goldacre 2013)