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Clinical psychology - Unipolar depression biological and non-biological…
Clinical psychology - Unipolar depression biological and non-biological explanation
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Biological explanation
Receptor sensitivity hypothesis
:
Depression is caused by changes in the sensitivity of postsynaptic receptors .
The normal response of receptors to a depletion of neurotransmitters is upregulation.
neurons compensate for the reduction in neurotransmitter stimulation by increasing the sensitivity of receptors and - over the longer term - producing more of them.
in depression, serotonin and noradrenaline postsynaptic receptors become even more sensitive (super sensitivity) to reduced stimulation than normal
BDNF hypothesis
:
Levels of BDNF in the hippocampus and prefrontal cortex are abnormally low in people with depression.
There is a close relationship between BDNF levels and symptom severity - the lower the level, the more severe the symptoms.
The BDNF hypothesis has allowed researchers to link depression with stress > the gene for BDNF may be 'switched off' under stress, which leaves the neurons fed by BDNF vulnerable to shrinkage or cell death, this leads to depression.
Monoamine depletion hypothesis
:
Depression is caused by abnormally low levels of the monoamine neurotransmitters serotonin, noradrenaline and dopamine.
^^ known for regulating the functions of the brain limbic system.
The level of serotonin normally controls the level of noradrenaline that causes depression. But an abnormally low level of serotonin permits noradrenaline to decrease as well - the outcome is depression. So low serotonin is a necessary condition for depression but not sufficient on its own
Non - biological explanation
Beck's cognitive explanation of depression
:
faulty or irrational thinking is a symptom of depression but it may also be the root cause of depression.
According to Beck, faulty cognition stem from childhood via criticism and rejection by parents and teachers.
Beck argued that depressed people make three major types of cognitive error, forming what he called the negative cognitive triad.
1)
The self
- the depressed person believes they are worthless.
2)
The future
- The individual views the future in unavoidably negative ways.
3)
The world
- A depressed person perceives the world around them as hopeless.
Ellis' ABC theory
:
Ellis proposed another cognitive explanation for depression. He described how irrational thoughts can cause depression in his ABC theory.
A -
Activating event
= depression occurs when negative external events activate irrational thoughts and beliefs.
B -
Beliefs
= it is the person's belief about the event that causes depression not the event itself.
'
C -
Consequence
s = irrational beliefs have emotional and behavioral consequences.
Evaluation for biological
:check: A strength is that it has application to treatment. This is because BDNF offers yet another route involving a different type of biological treatment. This is a strength of biochemical explanation because treatments base don them may improve quality of life and reduce distress.
:red_cross: A weakness is that the monoamine hypothesis cannot explain the common experience of therapeutic delay. When ppl take antidepressants, it would take as long as 4-6 weeks before they see any improvements in their symptoms. This is a weakness because it is hard to explain when levels of serotonin and noradrenaline increase immediately and are at normal levels after about one week.
:check: A strength is there are two main sources of evidence for BDNF in depression. Some studies have found a negative correlation between blood serum levels of BDNF and the severity of depressive symptoms. This isa strength as it shows a clear association between BDNF level and depressive symptoms.
:red_cross: Researchers assumed that if a biochemical treatment improved the symptoms of depression then this implies that depression must have a biochemical cause. This is not neccessarily true- the treatment is biological but the cause is psychological, a treatment aetiology fallacy.
Balanced conclusion
= The original monoamine depletion hypothesis was overly simplistic but has proven resilient, reappearing over the years in more refined forms. However, there are dangers in inferring the role of neurotransmitters form the effects of antidepressants.
Evaluation for non-biological
:check: A strength is that the theories have led to effective therapies for depression. There is evidence to support Elli's view that challenging the irrational beliefs of depressed people can improve their symptoms. This is a strength because this suggests that cognitive techniques are part of successful treatments for depression.
:check: A strength is a body of research evidence to support Beck's theory. A researcher found that women with the most negative beliefs were more likely to become depressed than women who had positive self-beliefs. This is a strength because these cognitions occurred before the onset of depression, so this supports Beck's view that negative beliefs cause the disorder.
:red_cross: One weakness is that neither Beck's not Ellis' theories can explain all aspects of depression. Depression is a complex disorder with many symptoms and features. Not all of the symptoms are experienced by everyone. This is a weakness as it is hard to see how the negative cognitive triad and dysfunctional beliefs can account for the variety of experiences of depression.
:red_cross: One weakness is that Beck's theory lacks predictive validity. It has been criticized for not explaining depression. It does not identify risk factors for depression and can't predict who is likely to become depressed. This is a weakness because this suggest that Beck's theory may be a better explanation of how depressive episodes are triggered and maintained over time rather than how depression is caused in the first place.
Balanced conclusion
= Beck's and Ellis' theories address the psychological reality of depression- the faulty cognitions that lead us to feel and behave in certain ways. However, there is considerable debate over whether negative cognitions are a cause or consequence of depression.