genetic and hormonal explanations of mood disorders

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  • Created on: 18-06-12 12:00

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Genetic and hormonal explanations for depression
Family history and twin studies suggest that mood disorders have a genetic basis ­ you are
twice as likely to develop a mood disorder if a relative has it than if no relative has it
In twin studies if there is a 100% concordance rate then mood disorders have a genetic basis
McKinnon et al., (1997) found that Monozygotic twins have a much higher rate for bipolar
depression than Dizygotic twins and other relatives this suggests a genetic basis.
In twin studies the concordance rate for identical twins is not 100% suggesting the
environment also has a role
Higher rates for identical pairs than non-identical pairs would also be predicted by
environmentalists as identical pairs usually have a more shared environment than
non-identical pairs
No single gene for mood disorders has been identified although several have been linked
with bipolar disorder
Wilhelm et al. suggested that an abnormal serotonin transporter gene could play a key role
Present view is that mood disorders may result from multi-gene and not single gene action
Adoption studies may be more useful in determining the cause for mood disorders but the
sample is too small for this to be signification
McGuffin et al. (1996) studied the contribution of genes and shared family environment in
unipolar depression. Concordance rated found that unipolar depression has a substantial
genetic component
Hormones can have an influence on thought processes and behaviour
An increase in the levels of certain hormones can cause a physiological response
Cortisol is a hormone which responds to stress during fight or flight situations
People with unipolar depression have high levels of cortisol. Feeling depressed is a reaction
to stressful situations where the person is unable to cope
People with depression maintain the high level of cortisol after the stressful event is over.
This means that they are depressed without an obvious extended course.
Some evidence suggests mood disorders are caused, or at least triggered, by social factors.
Reducing such a complex disorder down to the level of genes and chemicals may be an

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Research suggests that women who have depression due to the menstrual cycle have a
history of depression not related to the menstrual cycle, suggesting that hormone such as
oestrogen do not have an influence on depression…read more


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