In fact, drug trials show that antidepressants are barely distinguishable from a placebo (dummy pill) when it comes to treating depression. There are other explanations for antidepressantsвЂ™ effects. SSRIs temporarily increase the availability of serotonin in the brain, but this does not necessarily imply that depression is caused by the opposite of this effect. Until now, however, there has been no comprehensive review of the research on serotonin and depression that could enable firm conclusions either way.ДЄt first sight, the fact that SSRI-type antidepressants act on the serotonin system appears to support the serotonin theory of depression. In the period of this marketing push, antidepressant use climbed dramatically, and they are now prescribed to one in six of the adult population in England, for example.ДЇor a long time, certain academics, including some leading psychiatrists, have suggested that there is no satisfactory evidence to support the idea that depression is a result of abnormally low or inactive serotonin. And many started taking antidepressants because they believed they had something wrong with their brain that required an antidepressant to put right.

The idea was also endorsed by official institutions such as the American Psychiatric Association, which still tells the public that вЂњdifferences in certain chemicals in the brain may contribute to symptoms of depressionвЂќ.Д¬ountless doctors have repeated the message all over the world, in their private surgeries and in the media.

You can listen to more articles from The Conversation, narrated by Noa, here.ДЄlthough first proposed in the 1960s, the serotonin theory of depression started to be widely promoted by the pharmaceutical industry in the 1990s in association with its efforts to market a new range of antidepressants, known as selective serotonin-reuptake inhibitors or SSRIs. However, our latest research review shows that the evidence does not support it. For three decades, people have been deluged with information suggesting that depression is caused by a вЂњchemical imbalanceвЂќ in the brain вЂ“ namely an imbalance of a brain chemical called serotonin.

Serotonin transporter