Biological Approach To Explaining OCD Flashcards
What is a gene
Short section of DNA that codes for a specific characteristic
What is genetics
The study of genes, heredity and genetic variation in living organisms
Limitation of twin studies
The greater similarity found in MZ twins may not be due to their identical genetics but more to do with their environment as they are more likely to have a similar environment that DZ twins
What have family studies and Nestadt Et al found
Family studies have shown relatives of OCD sufferers have a greater tendency to suffer from OCD
-Nestadt Et al found first degree relatives (parents/siblings/children) of OCD patients have an 12% chance of developing OCD while first degree relatives of control patients without OCD had a 3% of developing it, MZ 68% and DZ 31%
Why is OCD a polygenic condition
Up to 230 genes may be involved
How does a mutated SERT gene lead to OCD
Leads to the re absorption of too much serotonin meaning lower levels of this neurotransmitter meaning serotonin has less of an effect and low serotonin levels which links to anxiety
How does a mutated COMT gene lead to OCD
-decreases re absorption of dopamine therefore dopamine not controlled and there is too much in synaptic cleft which can lead to the development of OCD as linked with compulsive behaviour
Expand on strength that genetic explanation of OCD has objective research support
-for example Nestadt Et al conducted a meta-analysis of twin studies and found concordance rates for OCD to be 68% for MZ twins but only 31% for DZ twins
-suggests that OCD has a genetic basis which increases the validity of the genetic explanation
H: twin studies do not consider factors other than genetics such as environment and the concordance rates for MZ twins is not 100% suggesting other factors must be at play
Expand on limitation that the genetic explanation of OCD does not consider environmental factors
Many people with OCD have experienced trauma in their life and may have developed OCD because of this eg an obsession with being clean could be a response to feeling dirty because of abuse
-suggests the genetic explanation is limited as it cannot be applied to all cases of OCD
H: diathesis-stress model may be more appropriate which takes into account genetic vulnerability but suggests this only has effect if an environmental stressor triggers the OCD
Research evidence for dopamine and serotonin link to OCD
-Szechtman Et al found high dose of drugs that enhance dopamine induce movements resembling compulsive behaviours found in OCD patients (animal studies)
-Piggott found antidepressants that increase serotonin activity (SSRIs) have been seen to reduce OCD symptoms
Outline the worry circuit
Impulses arising in the OFC (in pre-frontal cortex) and are passed to caudate nuclei which acts as a filter screening out irrelevant/unimportant impulses, the most powerful ones are passed onto the thalamus, then the individual is driven to think about them and take action
How is worry circuit different in those with OCD
-serotonin deficiency initiates faulty signals from OFC and caudate nucleus filters out less information
Expand on strength that neural explanation has research support for the role of serotonin in OCD
-for example Soomro Et al found that SSRIs were significantly better than placebos in reducing symptoms in 17 different clinical trials
-this suggests that serotonin does play a role in OCD, also SSRIs proven to work therefore patients can be treated and better manage their symptoms, benefits economy
Expand on strength that there is empirical evidence supporting the neural explanation of OCD
-research by Menzies Et al revealed consistent abnormalities in multiple areas of the prefrontal cortex in fMRI scans of OCD patients
-this suggests that the prefrontal cortex plays a role in the development of OCD which is backed by evidence from objective brain scanning techniques
Expand on limitation that the neural explanation does not consider the influence of environmental factors in the development of OCD
-we do not know for example whether abnormalities in brain function cause OCD or whether OCD is caused by an environmental factor which then causes the change in neural mechanisms
-this suggests we cannot draw a cause and effect relationship between abnormal brain function and the development of OCD which challenges the validity of the explanation
