Updates and trends in the treatment of major depressive disorder.

Mental illness accounts for 7.4% of the total disease burden worldwide-more than HIV/AIDS, tuberculosis, or diabetes-making it the leading cause of years lost to disability. Depressive disorders make up 40.5% of that disability, the most of all mental illnesses. Despite the devastating global effects of depression, a report on approval trends by the US Food and Drug Administration (FDA) found that new molecular entities (NMEs) approved for targeting psychiatric illness peaked in the 1960s and have been declining since.