This has resulted in widespread prescribing of 5HT re-uptake inhibitors that work by stopping the body breaking down serotonin thus increasing levels of the neurotransmitter within the brain. The upshot being that in both the UK and the US about one in six adults are prescribed antidepressants having been told by doctors that they will fix the underlying chemical imbalance responsible for their condition. These drugs come with side effects and with problems concerning long term use and difficulties in withdrawal.
The latest review of the evidence for the role of serotonin in depression is here:
https://www.nature.com/articles/s41380-022-01661-0
a review looking at 17 studies including over 160,000 subjects. The conclusion being
The main areas of serotonin research provide no consistent evidence of there being an association between serotonin and depression, and no support for the hypothesis that depression is caused by lowered serotonin activity or concentrations. Some evidence was consistent with the possibility that long-term antidepressant use reduces serotonin concentration.
To be clear this review does not argue that antidepressants do not work, merely that the mode of action is not that which was previously thought.
While antidepressants do work, it is now clear that they do not do so in the way that clinicians have been led to believe. This may have led to significant over treatment with these drugs in the past in a similar way that led to drugs such as Valium being over prescribed decades previously.
This paper from over a decade ago gives an alternative view of how these drugs might work:
https://www.bmj.com/content/338/bmj.b1963
Drugs for psychiatric problems are prescribed on the assumption that they mostly act against neurochemical substrates of disorders or symptoms. In this article we question that assumption, proposing that drugs’ action be viewed rather as producing altered, drug induced states, a view we have called the drug centred model of action.
Evidence shows that the effect of external events is also likely to be significant so that the number of stressful external events will have a significant impact on how likely an individual is to suffer from depression.
This recent article covers the topic in more detail
https://theconversation.com/chemical-im ... ons-188921
Note that bipolar depression is a separate condition and it is not referred to in any of these articles.
I hope this is of interest to some.
John