Biological Explanations For OCD Flashcards
What is the biological approach to explaining ocd?
The biological approach to explaining OCD assumes that OCD is caused by biochemical and genetic factors.
OCD can be described as polygenic - what does this mean?
One single gene is not responsible for OCD, but many different genes could be responsible for OCD. This can be up o 230 different genes. These are known as candidate genes.
What is the COMT gene?
This gene may have roles in the development of OCD. This gene is responsible for the regulating the production of a neurotransmitter called dopamine, which in high levels, is associated with OCD as high levels of dopamine are responsible for drive and motivation and sometimes aggression. COMT gene increases dopamine levels. The COMT gene is found more commonly in OCD patients than with patients without OCD
What is the SERT gene?
The SERT gene may also have roles in causing OCD as the SERT gene affects the transmission of serotonin, which results in low levels of serotonin. And low levels of serotonin is related to OCD and depression. The SERT gene is found on chromosome 17 as a result of a mutation. This mutation could be the cause of low levels of serotonin. Ozaki found that 6/7 family members with OCD had the SERT gene.
Evaluation of the genetic explanations to OCD?
+Nestadt supports the genetic explanation for OCD. He found that people who are a first degree relative to OCD sufferers are 5x more likely to get this illness. Supporting the idea that OCD is transmitted genetically
+Billet supports that OCD is transmitted genetically. From a meta analysis of 14 twin studies, he found that OCD is twice more likely to be concordat in monozygotic twins than dizygotic non identical twins. Supporting the fact that OCD is transmitted genetically
- A criticism is that the concordance rate for OCD in identical twins is not completely 100%, therefore highlighting that OCD can’t purely be caused by genetic factors.
- Diathesis Stress model would argue that it is a combination of genes and environmental triggers such as stress that cause ocd. Therefore genes alone cannot be the cause of OCD as it would need to combine with other factors in order to develop. This model would weaken the genetic argument
What are dopamine and serotonin?
They are neurotransmitters that affect mood. Extreme levels of either neurotransmitter are associated with the abnormal transmission of mood related information.
Dopamine in OCD?
Dopamine is a neurotransmitter that affects mood and may be a cause of OCD, especially in high levels. High levels of dopamine have been linked to hyperactivity in the basal ganglia of the brain. This causes repetitive motor functions, otherwise known as compulsions. Research on animals has found that drugs that increase dopamine levels induce movements resemble compulsive and repetitive behaviour, similar to a human ocd
Serotonin in OCD?
Serotonin is also a neurotransmitter that affects mood. OCD sufferers tend to have low levels of serotonin and this can also cause depression. Many OCD sufferers are actually depressed Because of low serotonin levels. Serotonin is key in operating the caudate nucleus in the basal ganglia. And low levels of serotonin causes rhe caudate nucleus to malfunction, resulting in obsessions. Caudate nucleus plays a vital role in how the brain learns.
Evaluation of neural explanations
+Anti depressant drugs increase serotonin levels in OCD patients. This leads to a reduction of OCD symptoms. Therefore it is solid evidence that low levels of serotonin is a cause of OCD.
+Dopamine antagonists also cuh
- Disadvantge of the neural explanation is that neurotransmitters such as dopamine and serotonin might not be the cause of OCD, but instead a symptom of OCD. Cause and effect are unclear.
- A problem with the neural explanation is that OCD is Co-morbid with depression. Therefore it isn’t clear weather low levels of serotonin cause OCD or depression or both? The link between low serotonin levels and OCD is not clear and need to be investigated further.
