Unipolar depression - monoamine hypothesis - description and evaluation

/monoamine hypothesis

According to this hypothesis, depression is caused by biochemical imbalances in the monoamine groups in the brain, more specifically depletion of certain monoamines is responsible for corresponding symptoms of depression.

Norepinephrine may be related to alertness and energy as well as anxiety, attention and interest in life. Lack of serotonin may be related to anxiety, obsessions and compulsions.  And dopamine is related to attention, motivation, pleasure, and reward, as well as interest in life.

So, for example, levels of norepinephrine may be responsible for abnormally poor concentration and loss in things an individual used to enjoy.

The depletion may be related to a lack of neurotransmitters or some other fault e.g. people with the major depressive disorder may also have fewer monoamine nerve receptors, or possibly less sensitive receptors than people without depression. The effect would be the same as a low level of neurotransmitters.

It cannot be concluded that depression is strictly biological. The diathesis-stress model explains that some mental disorders may have a biological underlying cause but require an environmental trigger to become active.

evaluation

A strength of this explanation is that it is supported by empirical evidence, suggesting that the explanation is valid. For example, Rosenhal et al. found low levels of serotonin in the urine of depressed patients, supporting the idea that depressed people have low levels of serotonin.

Furthermore, a lot of evidence lies in the…