Following a review paper on the relationship between serotonin and depression1, the lead author Professor Joanna Moncrieff, a Psychiatry Professor at UCL (London) notes2: “It is always difficult to prove a negative, but I think we can safely say that after a vast amount of research conducted over several decades, there is no convincing evidence that depression is caused by serotonin abnormalities, particularly by lower levels or reduced activity of serotonin.”
The popularity of framing depression around ‘chemical imbalance’ coincided with a huge increase in the prescribing of antidepressants. It is incorrect and unhelpful to tell patients that they are suffering from low serotonin levels in their brain as an explanation for depression.
This does not mean that SSRIs do not work, more that we don’t have a good understanding of their mechanism of action.