Evidence for the Biological Approach

Q: Evidence for Genetic Factors - Billet et al (1998)

**Billet et al (1998)** conducted a meta-analysis of twin studies to investigate the concordance rates of OCD in MZ and DZ twins.

Q: Advantages of Drug Therapy: Soomro et al (2008)

**Soomro et al (2008)** investigated the effectiveness of SSRIs in the treatment of OCD.

Q: Evidence for/Against Neurological Factors

**Max et al's (1995)** study on the neurology of OCD provides evidence for neurological factors. Aylward et al's (1996) study on the abnormality of the caudate nucleus in OCD patients provides evidence against neurological factors.

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Evidence for Genetic Factors - Billet et al (1998)

Billet et al (1998) conducted a meta-analysis of twin studies to investigate the concordance rates of OCD in MZ and DZ twins.

Results and conclusion

Results
- MZ twins were twice as likely to develop OCD if their twin had the disorder than was the case for DZ twins.
Conclusion
- This suggests that there may be a genetic explanation of OCD - however, concordance rates are never 100%. Shared environment and behaviourism might be better explanations for OCD.

Evidence against genetic factors

Although there is evidence that some genes may predispose people towards obsessive and compulsive behaviours, it is too simplistic to say that there is a gene for OCD.
It is much more likely that OCD is a learnt behaviour that can be explained by the two-process model e.g. originally learnt via classical conditioning and maintained by reinforcement by operant conditioning.
OCD could even be learnt via social learning theory with family role models being imitated.

Advantages of Drug Therapy: Soomro et al (2008)

Soomro et al (2008) investigated the effectiveness of SSRIs in the treatment of OCD.

Procedure, results & conclusion

Procedure
- Soomro et al (2008) reviewed 17 studies on the use of SSRIs with OCD patients.
Results
- He found them to be more effective than placebos in reducing the symptoms of OCD up to 3 months after treatment i.e. the short term.
Conclusion
- SSRIs are an effective treatment for OCD at least in the short term.

Evaluation of Soomro et al (2008)

Strengths
- Practical applications.
- Large sample.
Limitations
- No data on long term benefits.
- Treats the symptoms not the cause.
- Side effects of SSRIs.

Evidence against biochemical factors

Koran et al (2007) did a review of studies and found that although drug treatments were most commonly used, psychotherapies like CBT should be used first to provide long term help.
Drug therapy requires little time and effort but it’s not a lasting cure, as indicated by the fact that patients relapse within a few weeks if medication is stopped.

Evidence for/Against Neurological Factors

Max et al's (1995) study on the neurology of OCD provides evidence for neurological factors. Aylward et al's (1996) study on the abnormality of the caudate nucleus in OCD patients provides evidence against neurological factors.

For: Max et al (1995)

Max et al (1995) studied the neurology of OCD. They conducted a case study of a young adolescent who developed OCD and impulsive aggression after a traumatic brain injury.

Results & conclusion

Results
- Damage to the frontal and temporal lobe was discovered.
Conclusion
- The frontal and temporal lobes are implicated in the development of OCD.

Evaluation of Max et al (1995)

Strengths
- Scientific evidence.
- Practical applications.
Limitations
- Small sample, cannot generalise.
- Individual differences.

Against: Aylward et al (1996)

Research aim
- Aylward et al (1996) investigated structural or functional abnormality of the caudate nucleus in patients with obsessive-compulsive disorder (OCD).
Procedure
- 24 patients with adult onset OCD and 21 matched controls had MRI scans.
Results
- No structural or functional differences in the caudate nucleus were found.
Conclusion
- No evidence was discovered of abnormality in the caudate nucleus as an explanation for OCD.