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The biological approach to explaining OCD (Evaluation (Family and twin…
The biological approach to explaining OCD
key terms
concordance rate - a measure of genetic similarity. In a sample of, for example, 100 twin pairs, one twin of each pair has a phobic disorder. The number of times their other twin also shows the illness determines the concordance rate, so if 40 have phobic disorder, then the concordance rate is 40%
dopamine - one of the key neurotransmitter in the brain, with effects on motivation and 'drive'.
gene - a part of chromosome of an organism that carries information in the form of DNA.
neurotransmitter - chemical substances that play an important part in the workings of the nervous system by transmitting nerve impulses across a synapse.
Genetic explanations
The COMT gene
Contribute to OCD
COMT regulates the production of the neurotransmitter dopamine that has been implicated in OCD
The SERT gene
affects the transport of serotonin, creating lower levels of this neurotransmitter
Lower levels of are also implicated in OCD
Diathesis-gene
The link between one gene and a complex disorder like OCD is unliekly
That each individual gene only creates a vulnerability for OCD as well as other conditions, such as depression.
Neural explanations
Abnormal levels of neurotransmitters
dopamine levels are high with people with OCD
lower levels serotonin is low with that have OCD
Abnormal brain circuits
frontal lobes are supposed to be abnormal
The caudate nucleus normally suppresses signal from the orbitofrontal cortex. The OFC sends signals to the thamulus about things that are worrying, such as a potential germ hazard.
Serotonin and dopamine are linked to these regions of the frontal lobes. Corner (1998) reports that serotonin plays a key role in the operation of the OFC and the caudate nuclei, and it would therefore appear that abnormal levels of serotonin might cause these areas to malfunction.
Dopamine is also linked to this system, as it is the main neurotransmitter of the basal ganglia. High levels of dopamine lead to over activity of this region
Evaluation
Family and twin studies
Tourette's syndrome and other disorders
Research support for genes and OFC
Real-world application
Alternative explanations