Serotonin and Depression

The featured paper is an article on serotonin by Philip Cowen which is provocatively titled ‘Serotonin and depression: Pathophysiological Mechanism or Marketing Myth?’. The article is only a few pages long and as it clearly states that it is an opinion paper there is a more flexible structure than other types of papers (e.g. meta-analyses or research papers). Indeed in the conclusion Cowen introduces an interesting model of how serotonin might play a role in the experience of depression which I will come onto a bit later. Cowen also declares a conflict of interest as having acted as a paid advisor to pharmaceutical companies in the development of antidepressants.

There are some brief references in the first section to critics of the serotonin hypothesis including Healy, Lacasse and Leo although these are not covered in much detail. There is a section looking at the evidence for involvement of 5HT in depression which inludes a table summarising the results of 10 studies. Essentially the studies look at four areas: Platelets and 5HT, CSF 5-HIAA, Prolactin response and brain 5HT binding. There is also some discussion of the promoter region of the 5HT allele as well as a discussion of the effects of Tryptophan depletion on mood, before Cowen moves onto a possible relationship between 5HT and subjective experience in depression.

Cowen proposes a model in which people with depression may be sensitive to changes in 5HT (perhaps even a genetic vulnerability e.g. through the promoter regions) which affects the regions innervated by serotonin predominantly the prefrontal cortex and amygdala. These regions in turn would bias emotional processing and perhaps activate mood related memory circuits. This is a neat model as it ties together some findings from gene studies all the way through to subjective experience via cognitive psychological mechanisms. The model is the highlight of the article for me.  It would be interesting to see a more detailed exposition of the criticisms of the serotonin model, which this article helps with by referencing appropriate papers.



Cowen, P. Serotonin and depression: pathophysiological mechanism or marketing myth? Trends in Pharmacological Sciences. Vol 29. No 9. p433-436.


The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

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