biological approach to explaining and treating ocd Flashcards
what are candidate genes?
genes which create a vulnerability for ocd
what is the COMT gene?
● regulates neurotransmitter dopamine
● one variation of COMT gene results in higher levels of dopamine
● variation is more common in patients with ocd
what is the SERT gene?
● linked to serotonin
● affects the transport of this transmitter
● issues cause lower levels of serotonin to be active in the brain - associated with ocd (and depression)
what does polygenic mean?
● idea that ocd is not caused by 1 single gene but several are involved
● research has found evidence that up to 230 genes may be involved in ocd
● ocd is polygenic
what does aetiologically heterogenous mean?
one group of genes may cause ocd in one person but a different group of genes may cause the disorder in another person
genetic explanation of ocd evaluation
● strengths:
p: supporting evidence from twin studies - suggesting strong biological genetic link for ocd
e: researchers reviewed twin studies - found that 68% identical twins (MZ) shared ocd as opposed to 31% of non-identical twins (DZ)
research found - person with a family member with ocd is around 4 times as likely to develop disorder as someone without a family member with ocd
c: people who are genetically similar are more likely to share ocd - supporting a role for genetic vulnerability
● limitations:
p: they do not show a concordance rate of 100% - suggesting there must be environmental risk factors
e: research found - one sample of over half of people with ocd experienced a traumatic event
ocd severity positively correlated with number of traumas
c: matters as genetic vulnerability only provides a partial explanation for ocd
what is the role of serotonin?
● if a person has low levels of serotonin, then normal transmission of mood-related information does not take place and a person may experience low moods (and other mental processes may be affected)
● at least some cases of ocd may be explained by a reduction in functioning of the serotonin system in the brain
what are the frontal lobes and what are they responsible for?
frontal lobes are the front part of brain that are responsible for decision making and thinking
why is ocd (particularly hoarding disorder) associated with abnormal functioning in the frontal lobes?
ocd leads to impaired thinking (in the form of obsessions) and impaired decision making (in the form of compulsions)
what is the left parahippocampal gyrus associated with?
processing unpleasant emotions
why might ocd be associated with abnormal functioning in the left parahippocampal gyrus?
links to the emotional element of ocd - anxiety and guilt
neural explanation of ocd evaluation
● strengths:
p: useful in developing treatments
e: pet scans - identified low levels of serotonin in ocd patients brains - drugs that increase serotonin levels have been found to reduce ocd symptoms
c: matters as the fact these drugs have high effectiveness suggests that biological factors such as low serotonin are likely to be involved in ocd
counter: drugs do not reduce ocd symptoms in all patients - low serotonin may not link to every individual- meaning neural explanation of ocd cannot explain ocd for everyone - traumatic life events could play a role
● limitations:
p: cause and effect cannot be established
e: biological model suggests that ocd is explained by brain dysfunction causing the ocd
just a correlation which does not necessarily indicate a causal relationship - ocd might cause abnormal brain function
c: means theres a lack of strong evidence for a neural basis to ocd
