Biological explanations and treatments of depression - incomplete left out ECT due to exhaustion

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  • Created on: 19-06-11 21:39

Biological explanations and treatments for depression

There are several reasons why the origins of depression are thought to be biological

·   The symptoms include physical changes such as weight gain/loss, sleep disturbance, and fatigue

·   Depression runs in families

·   Biological therapies such as the use of antidepressant drugs alleviate symptoms of depression

·   Certain drugs involved in treatment of other medical problems can result in symptoms of depression in non-depressed individuals,and brain injuries and other illnesses can lead to depressive symptoms.


Genetic factors

·   One way of looking at genetic factors in depression is twin studies, where one twin has depressive disorder, and look at the likelihood of the other twin having the disorder by looking at concordance rates.

·   Bipolar disorder has a 60% concordance rate between monozygotic twins.

·         Unipolar disorder has a less high concordance rate. McGuffin et al found that on the Maudsley Hospital Twin register, 46 per cent of monozygotic twins had unipolar compared to 20 per cent of dizygotic twins. This can separate nature from nurture however monozygotic twins may have identical upbringing, and dizygotic twins due to being born at the same time also have the same environment compared to other brother and sisters. So this cannot offer a complete explanation, especially as concordance rates are never 100 per cent.

·         Andrew et al found that predisposition to mood disorders are likely to be genetically transmitted, however it is not clear what is genetically transmitted and by what mechanisms.

·         The diasthesis stress model suggests that individuals have a genetic predisposition which is then triggered by environmental stressors. Kendler et al’s Virginia twin study showed that women with a predisposition to depression (with a twin already diagnosed with depression) were more likely to develop depressive symptoms when faced with environmental stressors than those without a genetic predisposition.


Biochemical factors

·         The amine hypothesis suggests that depression is caused by low activity of certain monoamine neurotransmitters, noradrenaline, serotonin and to a lesser extent dopamine

·         These neurotransmitters act like chemical messengers and are known to be particularly active in parts of the brain associated with rewards and punishment.

·         The neurotransmitters regulate the hypothalamus, which is a crucial link between the nervous and endocrine systems, and is involved in sleep appetite and physical movement, which are key areas affected in depressive disorders

·         Drug therapy supports these ideas to some extent as antidepressants Monoamine oxidase inhibitors and tricyclics which increase noradrenaline and 5HT (receptors for serotonin) have been found to be effective in alleviating symptoms of depression

·         Depression is an unwanted side effect of reserpine which is used to treat high blood pressure, and depletes levels of noradrenaline. Prozac, which produces relief from depressive symptoms, increases the availability of serotonin but has negligible effects on noradrenaline.

·         However, the treatment ideology fallacy is a common error, which assumes that just because raising levels of something


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