The biological approach to explaining OCD Flashcards
what are the two explanations of OCD?
genetic explanation
neural explanation
What is involved in vulnerability to OCD?
Genes are involved in individual vulnerability - Lewis (1936), found that of his OCD patients 37% have parents with OCD and 21% had siblings with OCD. OCD runs in the family, genetic vulnerability passed down.
According to diathesis-stress model certain genes leave people more likely to develop a mental disorder but an environmental stressor is needed to trigger the condition
What are candidate genes?
Genes which create vulnerability for OCD. some of these genes are involved in regulating development of serotonin system. e.g. 5HT1-D beta is implicated in transport of serotonin across synapses
What is OCD regarding genes, and what support is there?
OCD is polygenic, caused by combination of genetic variations that increase vulnerability. Taylor (2013) found up to 230 different genes may be involved in OCD, associated with action of dopamine and serotonin.
What is OCD in different people?
Aetiologically heterogenous- origins of OCD vary from one person to another
What is the role of serotonin?
Serotonin is believed to help regulate mood.
If a person has low levels of serotonin then normal transmission of mood-relevant info doesn’t take place and a person experiences low moods. at least some cases of OCD can be explained by reduced functioning of serotonin system in the brain
What can be impaired in OCD?
Decision- making can be impaired. OCD may be associated with abnormal functioning of lateral of frontal lobes of brain. Frontal lobes are responsible for decision making and logical thinking. Evidence suggests the left parahippocampal gyrus, associated with processing unpleasant emotions, functions abnormally.
evaluation of genetic explanation (brief)
strength - research support, Nestadt et al
weakness - also environmental risk factors
strength of genetic explanation
one strength of the genetic explanation is that there is a strong evidence base. there is research support for the fact that some people are vulnerable to OCD as a result of their genetic makeup. Nestadt et al reviewed twin studies and found that 68% of MZ twins shared OCD as opposed to 31% of DZ twins. Research has also found that a person with a family member diagnosed with OCD is around 4x as likely to develop it as someone without. these research studies suggest that there must be some genetic influence on the development of OCD.
weakness of genetic explanation
One limitation of the genetic explanation is that there are also environmental risk factors. OCD doesn’t appear to be entirely genetic in origin and environmental risk factors can also trigger or increase the risk of developing OCD. Cromer et al found that over half the OCD clients in their sample had experienced a traumatic event in their past. OCD was also more severe in those with one or more traumas. this means that genetic vulnerability only provides a partial explanation for OCD.
evaluation of neural explanation (brief)
strength - research support, antidepressants + serotonin
weakness - serotonin-OCD link may not be unique to OCD
strength of neural explanation
a strength of the neural explanation is that there is supporting evidence. Antidepressants that work purely on serotonin are effective in reducing OCD symptoms, suggesting that serotonin may be involved in OCD. OCD symptoms also form part of conditions that are known to be biological in origin, such as Parkinson’s disease. If a biological disorder produces OCD symptoms, we may assume the biological processes underlie OCD. Therefore this suggests that biological factors may also be responsible for OCD.
weakness of neural explanation
a limitation of the neural model is that the serotonin-OCD link may not be unique to OCD. Many people with OCD also experience clinical depression, which is co-morbidity. This depression probably involves disruption to the action of serotonin. It could simply be that serotonin activity is disrupted in many people with OCD because they are depressed as well. This means that serotonin may not be relevant to OCD symptoms.
