Biological approach to treating OCD

What is the main aim of drug therapy for OCD?

To restore chemical imbalances in the brain, especially low serotonin, and reduce anxiety, obsessions, and compulsions.

What assumption is drug therapy for OCD based on?

That OCD is mainly caused by biological factors like chemical imbalances in the brain.

What are SSRIs and how do they work?

SSRIs (e.g., Prozac) increase serotonin in the synapse by blocking reabsorption into the presynaptic neuron, improving mood and reducing obsessions.

What are tricyclics and SNRIs used for?

If SSRIs fail, tricyclics (e.g., clomipramine) or SNRIs are used, but they have stronger side effects.

How do benzodiazepines (BZs) work for OCD?

BZs (e.g., Valium) enhance GABA, which slows down neuron activity, reducing anxiety from obsessions.

What is psychosurgery in severe OCD?

Surgery that changes brain circuits (e.g., orbitofrontal cortex) to stop compulsive behaviours.

Extra: Deep brain stimulation uses electrodes to alter brain activity for OCD.

Evidence supporting drug treatment?

• Greist (1995): 4 drugs more effective than placebo; Clomipramine best.

• Soomro (2008): SSRIs work better than placebo in 17 trials.

• Deep brain stimulation also shows promise.

Strength: scientific evidence

Drug effectiveness is shown in controlled trials and meta-analyses, giving strong support.

Strength: cost-effectiveness

Drugs are cheaper than CBT, making them preferred by health services.

Strength: ease of use

Drugs don’t require motivation, suitable for patients who cannot engage in therapy.

Weakness: side effects

SSRIs can cause indigestion, sexual problems, hallucinations; BZs can be addictive and affect memory.

Weakness: treat symptoms, not cause

Drugs reduce symptoms but don’t fix the underlying cause. Simpson (2004): 45% relapse after stopping drugs vs 12% for CBT.

Weakness: publication bias

Positive drug trials are more likely published, possibly overestimating effectiveness.

Why might drugs be preferred for some patients?

They are fast, easy to take, non-disruptive, and effective for patients lacking motivation.