Biological explanation of depression can be explained by neurotransmitter dysfunction. Neurotransmitters such as noradrenalin and serotonin have been shown to be linked with depression.
Bunney at al (1965) found that there was low levels of noradrenaline function in the brain of depressed individuals. Also, post mortem studies found increased noradrenaline receptors in the brains of depressed suicide victims. When there is low noradrenaline, more receptors are present to pick up as much of the neurotransmitter as possible. This suggests that the neurotransmitter noradrenaline is linked to depression. This is a good explanation because it is supported by lots of studies, such as Lenard 2000 who found that drugs that lower noradrenaline bring about depressive states, while those that increase the neurotransmitter levels show antidepressant effects. Another study, which also supports this explanation is Kraft et al (2005) who studied 96 depressed patients who were given a drug that increased serotonin levels. He found a more positive mood in those who were treated with the drug rather than those who were treated with a placebo. This strengthens the idea that serotonin levels are linked with depression.
Another neurotransmitter which has been found to be linked with depression is serotonin. McNeal and Cimbloic (1990) found low levels of synaptic serotonin by-product were found in depressed, especially suicidal patients. This suggests that there are low levels of serotonin in the brain. Also, the introduction of Prozac (and other antidepressants and block serotonin re-uptake confirms the association between serotonin and depression. This confirms the link between serotonin and depression. This is a good explanation as it has supporting research. For example, Ruhe et al (2007) found that drugs that reduce serotonin levels in the brain produced depressive symptoms, suggesting that low levels of