The Biological Approach To Explaining OCD – (Genetic And Neural Explanations)

March 5, 2021 - Paper 1 Introductory Topics in Psychology | Psychopathology

The Biological Approach to Explaining OCD (Genetic and Neural Explanations)


Recap the general principles of the Biological Approach before learning specifically about how it can be used to explain the onset of OCD

Descrption, AO1:


The Genetic Explanation:

A popular explanation for mental disorders is that they are inherited. This would mean that individuals inherited specific genes from their parents that are related to the onset of OCD.

(1) The COMT Gene:


This gene may be involved in the onset of OCD. It is called the COMT gene because it involves the production of catechol-O-methyltransferase. In turn, COMT regulates the production of the neurotransmitter dopamine that has been implicated in OCD. All genes come in different forms (alleles) and one form of the COMT gene has been found to be more common in OCD patients than with people without the disorder. It has been found (according to Tukel et al, 2013) that this form of the COMT gene produces lower activity of the gene and higher levels of dopamine.

(2) The SERT Gene:

Also called 5-HTT, the SERT gene is thought to affect the transport of serotonin creating lower levels of the neurotransmitter. These changed levels of serotonin are also implicated in OCD.

(3) The Diathesis-Stress Model:


Genotype & phenotype: Although evidence suggests that OCD can have a genetic biological cause, it can also be seen that biology, specifically genetics, are not the sole reason why an individual can develop OCD. It makes sense to suggest that an individual may have a genetic vulnerability to develop OCD (i.e. they have the SERT or the COMPT gene) however, this gene alone does not cause the OCD, the interaction with our environmental triggers (e.g. stress, our up bringing) and the gene  combined causes the OCD.
The Neural Explanation:

(1) Abnormal Levels of Neurotransmitters serotonin and dopamine

High Dopamine levels are thought to be associated with OCD. Szechtman, 1998 conducted animal studies and found that high doses of drugs that enhanced levels of dopamine induced stereotyped movements that resembled the compulsive behaviours witnessed in OCD patients.

Low Serotonin levels are associated with OCD. Pigott, 1990 found that anti-depressant drugs (which increase serotonin activity) have been shown to reduce the symptoms of OCD. 


(2)Increased activity in the Obofrontal Cortex:

A feature that is often witnessed on PET scans of OCD sufferers, The Obofrontal Cortex (associated with higher level thought and conversion of sensory information into thoughts.) This brain area is thought to help initiate activity upon receiving impulses to act and then stop the activity when the impulses lessen. A non-sufferer may have an impulse to wash dirt from their hands; once this is done, the impulse to perform the activity stops as does the behaviour. It may be that those with OCD have difficulty switching off or ignoring impulses so that they turn into obsessions resulting in compulsive behaviour.

Evaluation, AO3 of Biological Explanations of OCD:



(1) POINT: A strength of the Biological explanation of OCD is that there is evidence to support that the disorder has a genetic basis.EXAMPLE: Billett et al (1998) using a meta-analysis of 14 twin studies of OCD found that, on average, identical (MZ) twins were more than twice as likely to develop OCD if their co-twin had the disorder, the chances of developing OCD was lower for the co-twin of a non-identical (DZ) pair. EVALUATION: This is positive because the research suggests that genetics does play a part in the development of OCD.


(1) POINT: The biological explanations of OCD can be criticised for being deterministic: EVIDENCE: For example, the biological explanation states that if an individual has the presence of COMT or SERT gene, or a lower level of serotonin in the brain than they are pre-programmed to develop OCD EVALUATION: This is a weakness because this theory of OCD ignores individual free will and the fact that an individual’s free choice can also have an influence on their behaviour.

(2) POINT: The biological explanations of OCD can be criticised for being reductionist.EVIDENCE: For example, the biological explanation suggests that OCD is caused by the presence of the SERT or COMT gene or by a lower level of serotonin in the brain, it states that OCD is a product of just an individual’s nature. EVALUATION: This is a problem because the biological approach to explaining OCD can be seen to be too simplistic as it ignores the role of other factors such as our childhood experiences, everyday stressors and the role of learning in the development of abnormality.


Click here to learn about the biological treatments of OCD.

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