Biological Approach to Treating OCD

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Drug Therapy

Antidepressants: SSRIs

Most commonly used drug for OCD are antidepressants

Low levels of neurotransmitter serotonin are associated with depression as well as OCD

So drugs are used to increase levels

Low levels of serotonin are implicated in "worry circuit", so increasing levels of serotonin may therefore normalise this circuit

Antidepressants are used to reduce anxiety associated with OCD

SSRIs - selective serotonin re-uptake inhibitors --> regulate mood and anxiety by increasing levels of serotonin

SSRIs:

Serotonin is released into synapse from one nerve (neuron) --> targets receptor cells on receiving neuron at receptor sites

Afterwards, is re-absorbed by initial neuron sending message

SSRIs inhibit this re-absorption in order to increase levels of serotonin at the synapse, and increase simulation to receiving neuron

Antidepressants: Tricyclics

Tricyclics are primarily used in treatment of OCD rather than depression

They block transporter mechanism that re-absorbs serotonin and nor-adrenaline into pre-synaptic cell after it has fired

More of these neurotransmitters are left in synapse, prolonging their activity and easing transmission of next impulse

Advantage of targeting more than one neurotransmitter

Greater side effects so are used as second-line treatment where SSRIs aren't effective

Anti-Anxiety Drugs

BZs are commonly used to reduce anxiety

Slow down activity of neurotransmitter GABA (gamma-aminobutyric acid) --> when released has general quietening effect on many of neurons in brain

Reacts with special sites (GABA receptors) on outside of receiving neurons

When GABA locks onto these receptors, it opens channel that increases flow of chloride ions into neuron

Chloride ions make it harder for stimulation by neurotransmitters, thus slowing down activity and making person feel more relaxed

Other Drugs

Research has found that D-Cycloserine has effect on reducing anxiety and thus may be an effective treatment for OCD, particularly when used in conjunction with psychotherapy

Antibiotic used in treatment of tuberculosis

Appears to enhance transmission of GABA and thus reduce anxiety (Kushner et al 2007)

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Evaluation

Effectiveness

Considerable evidence for effectiveness of drug treatments

Typically a randomised control trial is used to compare effectiveness of drug versus placebo

Soomro et al (2008) reviewed 17 studies of use of SSRIs with OCD patients

Found them to be more effective than placebos in reducing symptoms of OCD up to three months after treatment

One issue is that most studies are only short term, and therefore little-long term data exists (Koran et al 2007)

Drug Therapies are preferred to other treatments

Requires little effort from user and little input in terms of time, considerably less than required for therapies such as CBT

Also cheaper because they require less monitoring and are cheap compared to psychological treatments --> may still benefit from talking with a doctor during consultations

Side Effects

All drugs have side effects, some more severe than others --> for example, nausea, headaches and insomnia are common side effects of SSRIs (Soomro et al 2008)

These may not seem bad but often are enough to make a patient prefer not to take the drug

Tricyclic antidepressants tend to have more side effects than SSRIs

Tricyclics are only used in cases where SSRIs aren't effective

Possible side effects of BZs include aggression and long-term impairment of memory

Also problems with addiction, so recommendation is that use should be limited to maximum of four weeks (Ashton, 1997)

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Further Evaluation

Not a lasting cure

Koran et al (2007) in comprehensive review of treatments for OCD, suggested that although drug therapy may be more commonly used, psychotherapies such as CBT should be tried first

Drug therapy may require less effort and also may be relatively effective in short term but it doesn't provide lasting cure, as indicated by relapse rates (Maina et al 2001)

Publication Bias

Turner et al (2008) claim that there's evidence of publication bias towards studies that show positive outcome of antidepressant treatment, thus exaggerating benefits of antidepressant drugs

Authors found that, not only were positive results more likely to be published, but studies that weren't positive were often published in a way that conveyed a positive outcome

Drug companies have strong interest in continuing success of psychotherapeutic drugs and much of research is funded by these companies

Turner et al consider that such selective publications can lead doctors to make inappropriate treatment decisions