Despite their continued failure to understand how psychiatric drugs work, doctors continue to tell patients that their troubles are the result of chemical imbalances in their brains. As Frank Ayd pointed out, this explanation helps reassure patients even as it encourages them to take their medicine, and it fits in perfectly with our expectation that doctors will seek out and destroy the chemical villains responsible for all of our suffering, both physical and mental. The theory may not work as science, but it is a devastatingly effective myth. - http://www.newyorker.com/tech/elements/the-psychiatric-drug-crisis