Psychopathology - Biological Approach to explaining OCD Flashcards
What is the Biological explanation
it views abnormal behavior and mental disorders as being similar to physical illnesses caused by abnormal biological processes in the body.
what are the two biological explanations of OCD
- genetic explanations
- Neural explanations
what does the genetic explanation suggest
The individuals inherit specific genes from their parents which are implicated in the development of OCD
What are candidate genes
they are certain genes which create vulnerability for OCD . two genes linked to OCD are SERT and COMT
SERT GENE
the sert gene helps transport and regulate the use of serotonin in braain. the mutated sert gene can affect the transportation and regulation of serotonin, leading to an increase in the reuptake of serotonin into the neuron that decreases the level of serotonin in the synapse. lower levels of serotonin cause low moods and anxiety which may explain the anxious obsessional thoughts in OCD suffers.
COMT gene
The gene breaks down dopamine in the synapse. Dopamine influences compulsive behaviors. Mutated variation of the COMT gene lowers the production of the enzyme and as a result increases the dopamine in the synapse. High levels of dopamine have been linked to the compulsive behaviors in OCD.
What does the diathesis model suggest?
the presence of the SERT and COMT gene does not mean you will develop OCD but does make some people more vulnerable to developing OCD, some environmental stress is necessary to trigger the condition.
OCD is polygenic
OCD is not caused by one single gene but the result of many defective genes. each defective genes increases the risk of developing OCD. Taylor found evidence that up to 230 genes may be involved in OCD.
OCD is aetiologically hetergenous
this means that a certain group of defective genes may cause OCD in one person but a different group of defective genes may cause the disorder in another person.
Neural Explanation
focusess on neurotransmitter activity and structures of the brain as the possible cause of OCD.
neurotransmitters - OCD
Lower levels of serotonin (neurotransmitter which regulates our mood)
higher levels of dopamine (neurotransmitter which influences compulsive behaviors)
Orbitofrontal cortex
notices something wrong and sends impulses to the thoughts/actions. heightened activity in the ofc may lead to OCD.
parahippocampal gyrus
The left part is associated with processing + regulating unpleasant emotions.
Abnormal functioning of this part of the brain may indicate OCD
stength of genetic explnations
evidence. A strength of the genetic explanation for OCD is that there is strong evidence from research studies. Lewis (1936) examined patients with OCD and found that 37% of the patients had parents with the disorder and 21% had siblings who also suffered from OCD. Further support comes from Nestasdt et al. (2010) who reviewed previous twin studies
examining OCD. They found that 68% of identical twins and 31% of non-identical twins experience
OCD. These two studies strongly suggest a genetic component to OCD: the closer the genetic
similarity to someone suffering from OCD, the higher the risk of the other person developing the
disorder as a result of their genetic makeup. As a result, these findings enhance the validity of a
genetic explanation (and therefore the biological approach) for OCD.
weakness of genetic explnations
A criticism of the evidence provided by twin studies to support that OCD is genetic is that the evidence is unclear. For example, although there is a higher concordance rate for OCD in identical (monozygotic or MZ) twins, compared to non-identical twins, the
concordance rate for identical twins is less than 100%. If OCD was due to genetic inheritance, then
we should see 100% of both MZ twins develop the disorder. This was not the case, which means that
environmental factors must also play a role in OCD. One reason may be that twins very often share
the same social environment, so the similarities in abnormal behaviour may be due to environments
they share, rather than genetic factors, or it could be both. This suggests that the evidence is
inconclusive on the cause of OCD.
Neural Explanation strength
A strength of neural explanations for OCD is that it is supported by
drug therapy. For example, some antidepressants drugs such as SSRI (Selective Serotonin Reuptake
Inhibitors), stop nerve cells that have just released serotonin from absorbing it back into the cell.
This therefore increases the levels of this neurotransmitter in the brain and thus helps reduce the
symptoms of OCD. Approximately 50% of people show an improvement after taking SSRI, proving
that the neurotransmitters do play a part in OCD. However, what about the other 50% of people
who don’t improve after taking SSRI? This finding reduces support for the abnormal levels of
neurotransmitters being the sole cause of the disorder, suggesting that there are psychological and
environmental influences in the development of OCD.
However, it could be argued that the success of antidepressant drugs as a treatment does not
necessarily mean the biochemicals are the cause of OCD in the first place. This is known as the
‘treatment fallacy’. For instance, using headaches as an example, aspirin works well as a treatment,
but this doesn’t mean the headache was due to an absence of aspirin.
strengths of neural explnations - brain scans
There is also research evidence that supports abnormal neurotransmitter levels as an
explanation for OCD. For example, brain scans of patients that suffer from OCD show heightened
activity in the orbitofrontal cortex. This happens if the scans are taken while their OCD is active, such
as someone with a germ obsession holding a dirty cloth. This suggests that obsessional thinking
might be caused by damage to the brain circuits.
weakness of neural explnation
Biological explanations do not distinguish cause-and-effect factors. A limitation of the
biological approach to OCD is that it cannot distinguish cause-and-effect factors. We cannot be sure
that low levels of serotonin and activity of the orbitofrontal cortex cause OCD or that OCD leads
to low levels of serotonin activity. All that’s known is that low serotonin and OCD are related. This
means the biological explanation for OCD is weakened because a causative relationship cannot be
determined. This may point to other factors, such as psychological and environmental factors.
weakness of neural explnations
A further limitation of the genetic/neural explanations for OCD is that they are
reductionist. This is because because they reduce the explanation of a complex disorder to a genetic/
biochemical level and do not consider other potential environmental factors that may trigger or
increase the risk of developing OCD, as suggested by the diathesis-stress model. To support this view,
Cromer et al. (2007) found that over half the OCD patients they studied had suffered a traumatic
event in their past, and that OCD was more severe in those with more than one trauma. This suggests
that OCD cannot be entirely genetic or biochemical in origin and we must account for psychological
and environmental factors or provide a better explanation for OCD. As a result, the validity of the
biological explanations for OCD is reduced.
