The biological approach to OCD suggests it is caused by biological abnormalities such as genetic and neural factors. Genetically, variants of the COMT and SERT genes have been linked to OCD as they affect dopamine and serotonin levels. While these genes may increase risk, they do not solely cause OCD. Research also shows abnormal levels of neurotransmitters like dopamine and serotonin in the brain regions involved in OCD. Brain scan studies further support neural abnormalities in OCD patients and their relatives. The biological approach is useful for mapping genes to detect OCD risk early.

1. Describe and evaluate the biological approach to explaining OCD (12 marks)
The biological approach is also known as the medical model and suggests that abnormality is
caused by abnormal biological approaches. A popular explanation for mental disorders is that
they are inherited, and so this would mean that individuals inherit specific genes from their
parents that are related to the onset of OCD.
The COMT gene regulates the production of dopamine which has been implicated in OCD;
and one form of the COMT gene has been found to be more common in OCD patients than
those without the disorder. This variation produces decreased activity of the COMT gene and
therefore increased levels of dopamine.
The SERT gene affects the transport of serotonin which results in decreased levels of this
neurotransmitter which is associated with OCD and depression.
Although the presence of these genes has been linked to OCD it cannot be said to be the
cause of a mental disorder like OCD. The diathesis-stress model instead suggests that the
inheritance of certain genes only creates a vulnerability for OCD, and that other factors affect
what condition develops. Therefore, some people could possess the COMT or SERT gene
variations but suffer no ill effects.
There are various research studies that support this genetic explanation. Nestadt et al. (2000)
found that people with a first- degree relative with OCD had a 5 times greater risk of having
the illness themselves; whilst Grootheest et al. (2005) found that twin studies did indicate a
genetic component to the transmission of OCD but that heritability of this mental disorder
appeared greater in children than among adults. However, concordance rates were never
100% and so suggests that environmental factors must play a role.
Another explanation is the neural explanation and refers to the perception that OCD results
from abnormally functioning brain mechanisms. Abnormally high levels of the
neurotransmitter dopamine have been associated with OCD, and can lead to over activity in
the basal ganglia. In comparison, low levels of serotonin have also been associated with
OCD. Piggett et al. (1990) support this idea as they state that antidepressant drugs that
increase serotonin activity have been shown to decrease OCD symptoms. Abnormal levels of
serotonin might also cause the OFC and the caudate nuclei to malfunction.
The use of MRI and PET scans support the neural explanation. Menzies et al. (2007) found
reduced grey matter in key areas of the brain in OCD patients and their close relatives
suggesting that anatomical differences are inherited, and that these may lead to OCD.
Therefore, brain scans may be used to detect OCD risk in the future.
The use of the biological approach can be especially useful in the mapping of the human
genome as mother’s fertilised eggs can be screened for certain genes, and then the decision to
abort can be made.