biological approach to explaining OCD Flashcards
genetic explanations
genetic vulnerability
genes are involved in individual vulnerability to OCD
Lewis- 37% of his OCD patients had parents w/ OCD, 21% siblings
suggests families pass on genetic vulnerability to OCD through generations
diathesis-stress model- certain genes leave some people more likely to suffer a mental disorder but it is not certain
some environmental stress is necessary to trigger the condition
genetic explanations
candidate genes
researchers have identified candidate genes that create vulnerability for OCD
some involved in regulating development of serotonin system
e.g. 5HT1-D beta implicated in efficiency of transport of serotonin across synapses
genetic explanations
OCD is polygenic
not caused by one single gene- several involved
Taylor- analysed findings of studies, found evidence that up to 230 genes may be involved in OCD
include those associated with the actions of dopamine and serotonin (both neurotransmitters that have a role in regulating mood)
genetic explanations
diff types of OCD
OCD is aetiologically heterogeneous- the origin of OCD has diff causes
one group of may cause OCD in one person but a diff group may cause it in another person
diff types of OCD may be the result of particular genetic variations
(e.g. hoarding disorder or religious obsession)
neural explanations
the role of serotonin
neurotransmitter serotonin helps regulate mood
neurotransmitters responsible for relaying info from one neuron to another
low serotonin levels- normal transmission of mood-relevant info doesn’t take place- mood and other mental process affected
some cases of OCD may be explained by reduced functioning of the serotonin system
neural explanations
decision-making systems
some cases seem associated with impaired decision-making (e.g. hoarding disorder)
abnormal functioning of the lateral frontal lobes of the brain may cause this (frontal lobes responsible for logical thinking and making decisions)
some evidence shows that left parahippocampal gyrus functions abnormally in OCD (processes unpleasant emotions)
genetic
strength- good supporting evidence
Nestadt et. al- reviewed twin studies
68% identical twins shared OCD, 31% non-identical
strength- strongly suggests a genetic influence on OCD, accurate
genetic
limitation- too many candidate genes
psychologists less successful at identifying all genes involved
appears that several genes involved and each variation only increased OCD’s risk by a fraction
limitation- genetic expl of OCD unlikely to ever be very useful, provides little predictive value
issue- environmental risk factors
environmental factors can trigger or increase risk of developing OCD
Cromer- over half OCD patients in sample had traumatic event in past, OCD more severe with more than one trauma
issue- suggests OCD cannot be entirely genetic in origin in all cases, may be more productive to focus on environmental causes that we can make a diff to
neural
strength- supporting evidence
some antidepressants work solely on increasing levels of serotonin
effective in reducing symptoms
OCD symptoms form part of a number of other conditions that are biological in origin, e.g. Parkinson’s Disease
strength- supports serotonin system involvement in OCD, biological process that cause symptoms in conditions like Parkinson’s may also be responsible for OCD, accurate
neural
weakness- we should not assume the neural mechanisms actually cause OCD
evidence shows that various neurotransmitters and brain structures function abnormally in OCD patients
doesn’t confirm that the abnormal functioning causes the OCD
could be a result of it rather than its cause
weakness- cannot reliably claim that these are the cause of OCD, reduces accuracy
neural
problem- serotonin-OCD link may be co-morbidity with depresion
OCD has high co-morbidity w/ depression
depression often involves disruption to serotonin system
disrupted serotonin system may not be a basis of OCD- just disrupted because they are depressed as well
problem- undermines validity of expl, suggests inaccurate
