L12-Biological Explanations of OCD Flashcards
Biological Approach
The biological approach to explaining OCD assumes that OCD is caused by genetic and biochemical factors.
Genetic Explanation(1)
Some researchers suggest that OCD is an inherited condition and so a vulnerability to developing the condition is passed on across generations.
Genetic Explanation(2)—Polygenic
OCD is considered to be polygenic which means that one single gene is not responsible for the disorder. Instead as many as 230 genes might be responsible for causing OCD-these are known as candidate genes.
Genetic Explanation(3)—Aetiological Heterogeneity
This suggests that different combinations of genes may cause the disorder in different people. Different combinations of genes may also account for different types of OCD.
Genetic Explanation(4)—COMT Gene
The COMT gene may have a role in causing OCD. This gene regulates the production of a neurotransmitter called dopamine. One variation of the COMT gene results in higher levels of dopamine. This variation has been found to be more common in OCD patients than in people who don’t have the disorder.
Genetic Explanation(5)—SERT Gene
A second gene which has been implicated in OCD is the SERT gene. This gene affects the transportation of serotonin, causing lower levels of serotonin. Low levels of serotonin have been linked to OCD.
Genetic Explanation Evaluation(1)
+ Nestadt et al(2010) supports the genetic explanation for OCD. They found that the concordance rates for OCD between monozygotic twins(68%) was significantly higher than between dizygotic twins(32%)
Genetic Explanation Evaluation(2)
+ Animal studies have found that there is a genetic basis for repetitive ritualistic behaviour in animals. For example, Ahmari(2016) found a common gene in mice who display ritualistic behaviour.
Genetic Explanation Evaluation(3)
-Around half of all cases of OCD tend to follow trauma, undermining the genetic explanation of OCD. This explanation also can’t account for cases of OCD in families where there is no previous history of OCD.
Neural Explanations(1)
Dopamine and serotonin are neurotransmitters that affect mood. Abnormal levels of these neurotransmitters are associated with abnormal transmission of mood-related information.
Neural Explanations(2)—Dopamine
OCD sufferers have high levels of dopamine. High dopamine levels have been linked to over hyperactivity in the basal ganglia area in the brain. This causes repetitive motor functions(compulsions).
Neural Explanations(3)—Serotonin
Serotonin plays a key role in operating the caudate nucleus in the basal ganglia of the brain, and it seems that low levels of serotonin cause the caudate nucleus to malfunction. In particular, low levels of serotonin result in obsessions.
Neural Explanations Evaluation(1)
+ Antidepressant drugs increase serotonin levels in OCD patients, and this has lead to a reduction in OCD symptoms. Therefore there is good evidence to suggest that low levels of serotonin could be a cause for OCD.
Neural Explanations Evaluation(2)
- A disadvantage of the neural explanations of OCD is that neurotransmitters such as dopamine and serotonin might not necessarily cause OCD. Instead low levels of serotonin and high levels of dopamine might be a symptom of OCD.
