From the essay:

Serotonin and Depression: A Disconnect between the Advertisements and the Scientific Literature

Lacasse JR, Leo J (2005) Serotonin and Depression: A Disconnect between the Advertisements and the Scientific Literature. PLoS Med 2(12): e392. doi:10.1371/journal.pmed.0020392

"However, in addition to what these authors say about serotonin, it is also important to look at what is not said in the scientific literature. To our knowledge, there is not a single peer-reviewed article that can be accurately cited to directly support claims of serotonin deficiency in any mental disorder, while there are many articles that present counterevidence. Furthermore, the Diagnostic and Statistical Manual of Mental Disorders (DSM), which is published by the American Psychiatric Association and contains the definitions of all psychiatric diagnoses, does not list serotonin as a cause of any mental disorder. The American Psychiatric Press Textbook of Clinical Psychiatry addresses serotonin deficiency as an unconfirmed hypothesis, stating, “Additional experience has not confirmed the monoamine depletion hypothesis.”(emphasis mine)

"In the US, the FDA monitors and regulates DTCA. The FDA requires that advertisements “cannot be false or misleading” and “must present information that is not inconsistent with the product label."

Table 1. Selected Quotations Regarding Serotonin and Antidepressants

doi:10.1371/journal.pmed.0020392.t001

Table 2. Selected Consumer Advertisements from SSRIs from Print, Television, and the World Wide Web

doi:10.1371/journal.pmed.0020392.t002

The advertisements below state the drug advertised increases the brain's serotonin levels--"correcting a chemical imbalance." The chemical imbalance explanation for depression is not even a theory, it is a hypothesis that researchers have spent decades unsuccessfully trying to validate!

OBVIOUSLY MISLEADING