Biological approach to explaining phobias Flashcards
What are the two biological explanations for OCD?
-genetic
-neural
What did Lewis find about genes and vulnerability for OCD?
-genes involved in vulnerability to OCD
-observed OCD patients
-37% had parents with OCD and 21%had siblings with OCD
-suggest OCD runs in the family
- what is passed on is genetic vulnerability for OCD
What does the diathesis stress model say?
-certain genes leave some people more likely to develop a mental disorder but it is not certain
-environmental stressor necessary to trigger conditions e.g. bereavement
what are candidate genes?
-genes identified by researchers which create a vulnerability for OCD
-SERT gene which affects the transport of serotonin creating lower levels
-COMT regulates the production of the neurotransmitter
dopamine that has been implicated in OCD.
OCD is polygenic
OCD is not caused by one single gene but by a combination of genetic variations =increase vulnerability
What did Taylor analyse & find?
-analysed findings from previous studies and found evidence that up to 230 different genes may be involved in OCD
Different types of OCD
-One group of genes may cause OCD in one person while another group of genes may cause disorder in another person =aetiologically heterogeneous
Evidence also suggests that different types of OCD may be a result of…
particular genetic variations e.g. hoarding disorder and religious obsession
The role of serotonin
-regulates mood
-if the neurotransmitter serotonin is low then normal transmission of mood-relevant information does not take place & a person may experience low moods
What is the neural explanation?
Explanation that focuses on the nervous system and structures in the brain
decision making systems
-hoarding disorder = associated with abnormal functioning of the lateral frontal lobes (associated with logical thinking)
-left parahippocampal gyrus (associated with processing unpleasant emotions) functions abnormally in OCD
What support is there for the genetic explanation?
-Nestadt et al reviewed twin studies & found that 68% of MZ twins shared OCD as opposed to 31% of DZ twins
Counterpoint - concordance not 100%, other factors
-Marini & Stebnicki found that a person with a family diagnosed with OCD is 4x more likely to develop compared to someone without
What is a limitation of the genetic explanation for OCD?
-there are also environmental risk factors
-OCD is not entirely genetic in origins»
environmental factors may also trigger or increase risk of developing OCD
-Cromer found that over half of the OCD clients in their sample had experienced a traumatic event in their past & OCD more severe in those with one or more traumas
What research support is there for the neural explanation?
-Antidepressants that work purely on serotonin are effective in reducing OCD symptoms
-Soomro et al found that 70% of his patients symptoms were reduced when taking SSRI’s
-suggest serotonin plays role & biological process implicated in OCD
What is a limitation of the neural explanation?
-serotonin-OCD link many not be unique to OCD
-many people with OCD also experience clinical depression =co-morbidity
-depression possibly caused by disruption to action of serotonin
-serotonin may not be relevant- activity may be disrupted because those with OCD are depressed as well
