biological approach to explaining OCD

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the biological approach to explaining OCD considers genetic and neural explanations

genetic explanations suggest that OCD is inherited. neural explanations suggest that abnormal levels of neurotransmitters are implicated. OCD is a polygenic condition, meaning multiple genes are implicated.

Taylor 2003 suggests that as many as 230 genes may be involved and different genetic variations contribute to different types of OCD e.g hoarding and obsessions with a religion. A teen that has been linked to OCD is the COMT which regulates dopamine and is more common in patients with OCD than patients without OCD.

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lower levels of serotonin are also associated with OCD. evidence for this comes from research examining antidepressants (SSRIs)

piggott et al 1990 found that drugs which increase the level of serotonin in the synaptic gap are effective in creating patients with OCD, suggesting that serotonin is a contributory factor.

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genetic predisposition to develop OCD because of specific alleles of the COMT or SERT genes inherited form their parents

one allele of the COMT gene common in OCD patients s linked to higher levels of dopamine, a motivating neurotransmitter, which may cause compulsive behaviour

Mutation in the SERT gene can result in lower levels of serotonin, linked to anxiety. Serotonin is removed from the synaptic cleft before the signal is transmitted

However, not everyone who inherits these genes will get OCD. Instead these genes create a diathesis to OCD which can then develop as a result of other stressors

AO3 - research support

• Lewis examined patients with OCD and found that 37% of the paitents with OCD had parents with the disorder and 21% had siblings who suffered

• Nestadt et al. took this further and proposes - people with a first degree relative with OCD had a five times greater risk of developing OCD compared to the general population. 

• A meta analysis of 14 twins found monozygotic twins were twice as likely to develop OCD if their twin had it than dizygotic twins. 

• This supports the genetic explanation of OCD as it shows people that share the same genes as someone with OCD are more likely to develop OCD. 

• However the concordance is never 100%,supporting the idea that other environmental factors must also have an effect. therefore diathesis stress model may be a better explanation whereby a genetic vulnerability is inherited and triggered by a stressor in the envrionment

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FURTHERMORE……

• Complex behaviours are not coded for by a single gene.

• Not everyone that has these alleles of the COMT or SERT genes will developed OCD

• Therefore it is suggested these genes create a diathesis (vulnerability) to OCD.

• Other factors called stressors affect if, and to what extent, the person develops OCD.

AO3 - strength - research from family studies

Lewis 1936 examined paitents with OCD and found that 37% of the patients with OCD had parents with the disorder and 21% had siblings who suffered.

Nested et al 2000 took this point further and proposes that individuals who have a first degree relative with OCD are upto 5 times more likely to develop the disorder in their lifetime compared to members of the general population without this genetic link.

research from family studies like this provides support for a genetic explanation of OCD, although it does not rule out other environmental factors playing a role.

this explanation for OCD reduces a complex human behaviour to a single gene or brain chemical and so is considered biologically reductionist. For example, the biological explanation does not consider the role of cognition or learning in the development or maintenance of OCD and is therefore criticised by behavioural and cognitive psychologists for its overly simplistic view

AO3 - alternative explanations for the development of OCD

For example, the two process model proposed by behaviourists suggest that learning could play a crucial role in the disorder

initial learning of the anxiety inducing stimulus could occur through classical conditioning for example if germs are paired with anxiety (becoming ill) or potentially watching a parent react in a certain way to a stimulus, this may be associated with the anxiety and instead learn from their parent.

compulsive behaviour (e.g continuous hand washing) is then maintained through operant conditioning and negative reinforcement, as the compulsive behaviour reduces the anxiety associated with the anxiety inducing stimulus which serves to reinforce the condition

support for this alternative explantion is found in the success of behavioural treatments for OCD where symptoms of patients are improved for 60-90% ofd adults