Biological explanations of OCD Flashcards
Psychopathology
What are the two types of biological explanations of OCD?
Genetic
Neural
What is the genetic explanation of OCD?
It suggests we may inherit genes that make us vulnerable to developing OCD. Twin studies and concordance rates allows us to see the genetic vulnerability. Nestadt (2010)- meta-analysis of 14 twin studies into OCD and found a concordance rate of 68% for mono-zygotic twins and 31% for dizygotic twins. As the concordance rate was higher for the MZ twins, it indicates that OCD must at least be partly genetic as each twin shared a gene making them vulnerable to this disorder.
What are candidate genes?
Mutated SERT gene- affects levels and regulation of serotonin
However, OCD is believed to be polygenic. Instead, a combination of genetic variations increase the vulnerability of developing OCD. Taylor (2013)- reports over 200 genes may be linked to OCD so it seems unlikely only one candidate gene is responsible.
What is a strength of the genetic explanations of OCD?
Research to support- Ozaki et al (2003)- two unrelated families, found that six of the seven participants with the mutation on the SERT gene had OCD or a related disorder- supports the role of the SERT gene in developing this disorder
What is a limitation of the genetic explanations of OCD?
It ignores the influence of the environment/nurture- would expect the MZ twins to have a 100% concordance rate if it was genes alone- however, no twins’ studies have ever had a 100% concordance rate so OCD isn’t just genetics- an interactionist approach- caused by an interaction between biological and environmental factors- limits the genetic explanation
What are the neural explanations?
Brain structures of biochemicals/neurotransmitters that may influence the development of OCD
Serotonin and basal ganglia
How is serotonin a neural explanations of OCD?
Serotonin is a neurotransmitter which controls our mood. Low levels of serotonin have been found in those with OCD. This means messages about regulating mood are not normally transmitted - so may explain the intense anxiety felt by sufferers with OCD, that may then cause the obsessions
How is the basal ganglia a neural explanation of OCD?
The basal ganglia is a set of brain structures located at the base of the forebrain. One of their functions is related to making decisions surrounding movements that are likely to lead to positive consequences and avoiding unpleasant things. It has been argued that an abnormality in the basal ganglia might lead to OCD. This can explain the compulsions that are done to avoid the unpleasantness of the obsessions
What is the evaluation of the basal ganglia as a neural explanation of OCD?
Evidence to support- Wise and Rapoport (1989)- OCD is common in sufferers of Huntington’s chorea, Parkinson’s and Tourette’s which are all movement disorders and involve abnormalities in the basal ganglia so perhaps it can account for the symptoms of these disorders which has caused them to develop OCD too.
However, not every sufferer of these disorders has OCD which suggests that this cannot be the only explanation
What is the evaluation of serotonin as a neural explanation of OCD?
Evidence to support- OCD is often treated with drugs such as SSRIs which block reuptake sites so that serotonin levels can be increased- this relives symptoms of OCD supporting the idea that OCD and low serotonin are linked
However- cause and effect is hard to determine- is a relationship between serotonin and OCD but cannot say for certain that that’s the cause- could be caused by anger factor and serotonin levels decrease because of the disorder itself
