Biological - Monoamine
Monoamines include serotonin, noradrenaline and dopamine – it is believed that an imbalance of the monoamines results in depression. Low levels of serotonin affect levels of the other monoamines – this means erratic brain patterns can develop. As serotonin regulates noradrenalin, lower levels of this result in a lack of energy and alertness. Low levels of dopamine affects the dopamine pleasure pathway, affect attention, motivation and feelings of pleasure and reward
Evaluation
The biological explanation has difficulty in establishing cause and effect –low levels of monoamine are said to be the cause of depression, however it could be depression alters monoamine levels.
There are a range of symptoms for depression but patients do not show all of these – this can be supported by the different monoamines
Drugs do not have an immediate effect and take time to work, this would suggest another cause
There are some drugs however such as opipramol that do not act on monoamines, this suggests that the monoamines are not the cause
Experiments where the monoamines are reduced do not produce depressive symptoms
MRI scans show differences in brain structure including a smaller hippocampus between people with depression and those without. Drug treatment that increases serotonin levels increases mass in the hippocampal area. This still links serotonin as the cause but the focus is on structure rather than deficiency
Monoamines include serotonin, noradrenaline and dopamine – it is believed that an imbalance of the monoamines results in depression. Low levels of serotonin affect levels of the other monoamines – this means erratic brain patterns can develop. As serotonin regulates noradrenalin, lower levels of this result in a lack of energy and alertness. Low levels of dopamine affects the dopamine pleasure pathway, affect attention, motivation and feelings of pleasure and reward
Evaluation
The biological explanation has difficulty in establishing cause and effect –low levels of monoamine are said to be the cause of depression, however it could be depression alters monoamine levels.
There are a range of symptoms for depression but patients do not show all of these – this can be supported by the different monoamines
Drugs do not have an immediate effect and take time to work, this would suggest another cause
There are some drugs however such as opipramol that do not act on monoamines, this suggests that the monoamines are not the cause
Experiments where the monoamines are reduced do not produce depressive symptoms
MRI scans show differences in brain structure including a smaller hippocampus between people with depression and those without. Drug treatment that increases serotonin levels increases mass in the hippocampal area. This still links serotonin as the cause but the focus is on structure rather than deficiency