The biological approach to explaining OCD Flashcards
Genetic explanations
The COMT gene
What horomes does this gene regulate
(Tukel et al 2013) found what?
A gene that may contribute to OCD as it involved in the production of catechol-O-methyltransferase, or COMT.
regulates the production of the neurotransmitter dopamine that has been implicated in OCD.
One form of COMT gene has been found to be more common in OCD paitents than people without the disorder.
(Tukel et al 2013) found that this variation produces lower activity of the COMT gene and higher levels of dopamine.
The SERT gene
What horomone does this gene lower?
Ozaki et al 2003
A gene that affects the transport of the seretonin, creating lower levels of this neurotransmitter, these lower levels are implicated in OCD.
Ozaki et al 2003 conducted a study and found that a mutation of this gene in two unrelated families where 6 of the 7 families had OCD.
Diathesis-stress
The idea of a simple link between one gene and a complex disorder like OCD is unlikely. Something as simple as eye colour may have one gene that determines it but the same is not true for complex behaviours.
e.g the sert gene are also implicated in a number of other disorders such as depression and PTSD.
Indicating each indivudal gene only creates a vulnerability for OCD as well as other conditions such as depression. Other factors affect what condition devekios indeed whether any mental illness develop.
Neural Explanations
Abnormal levels of neurotransmitters
Piggot et al (1990)
Dopamine levels are thought to be abnormally high in people with OCD. This is based on animal studies - high does of drugs that enhance levels of dopamine included sterotyped movements resembling the complusive behaviours found in OCD paitents.
- Lower levels of serotonin indicate OCD. Piggot et al (1990) Based on the fact that antidepressant drugs that increase serotonin activity have been show to reduce OCD symptoms.
- Jenicke (1992) found that antidepressants have less effect on serotonin do not reduce OCD symptoms.
Abnormal brain circuits
Several areas in the frontal lobes of the brain are though to be abnormal in people with OCD. The caudate nucleus normally supresses signals from the obitofrontal cortext (OFC)
AO3
The role of genetic factor is supported by family studies of OCD
Nestadt et al (2003)
Weakness.
E: For example, Nestadt et al (2003) found that people with first-degree relative with OCD are more at risk of developing the disorder.
E: However, families typically share the enviroments as we as genes
L: This means that enviromental factors could also play a part in the development of OCD
Tourette’s syndrome and other factors
(Strength)
Pauls and leckham (1986)
PEE
P: This is evidence for the role of genes in OCD comes from studies of people with other disorders
E: Pauls and leckham (1986) studies wih Tourettes syndrom and their familes, and concluded that OCD is one form of expression of the same gene that determines Tourettes. The obsesssive behaviour of OCD and tourettes paitents is also found in children wit autism
EX: This all supports the view that there is not one specific gene or genes unique to OCD, but they merely act as predisposing factor towards Obsessive-type behaviour.
Studies have demonstrated a genetic link to the abnormalities in brain structure and function in paitents with OCD.
Menzies et al (2007)
strength
EEL
E: People with OCD and their very close relatives have reduced grey matter in key brain regions, including the OFC
E: This supports the view that anatomical differences are inherited and these may lead to OCD in certain people
L: Menzies et al (20070 have suggested that brain scans could be used in the future as a way of detecting people’s risk of developing OCD
There is evidence that indicates application to the real world as the mapping of the human genome has led to the hope that specific genes could be linked tO particular mental and physical disorders.
PEEL
E: For example, it might be that where one or other paitent be has the COMT gene, the mother’s fertillsed egg could be screened, thus giving the parents choice of whether to abort those eggs with the gene.
Ex: Gene theraphy may produce a means of turning certain gene’s off so that a disorder therefore illustrating that there is a relationship between a disorder like ocd and genes which may not always be the case.
L: For this we can see that biologial therapies such as gene therapies is there more complex and contriversial than it may at first appear.
What AO3 are you using?
Nestadt et al (2003) Family & twin studies
Pauls and leckham (1986) - Tourette’s syndrome
Menzies et al (2007) - Research to support for genes and OFC
Real-world application - Mapping of human geneome
Concordane rate
A measure of genetic similarity, in a sample of e.g 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 disordr then the concordance rate is 40%
Dopamine
A neurotransmitter in the brain, with effects on motivation and ‘drive’.
