Originally Posted by MoAlpha

Yeah, I have thoughts. This is an authoritative and exhaustive review showing that the simplistic hypothesis that low serotonin levels are responsible for depression is nonsense. Most experts already understood this, since it's thinking from the 1970s when shrinks saw the brain as a sort of soup that just needed the right neurotransmitter seasoning. It is still possible that serotonin transmission is involved in depression in some subtle way that researchers don't understand. Psychiatrists are becoming more like neurologists (accused as seeing the brain as a computer, rather than a soup) and focusing on function in individual brain networks. This is yielding rapid advances in areas like deep brain stimulation for OCD and depression, and identifying individual populations of malfunctioning cells. I think it's likely that serotonin may be rediscovered, but at a much more complex and localized level.

A conclusion of the paper is that drugs (SSRIs) advertised as increasing serotonin probably don't work the way they are advertised as working, i.e., by inhibiting the reuptake of serotonin by nerve cells. This is not, however, to say they don't WORK at all, which is what many people have inferred from their non-reading of the paper or accused the authors of saying.