A really long time ago, Aristotle said, “Happiness is the meaning and the purpose of life, the whole aim and end of human existence.” We all want happiness in our lives. Millions of us take antidepressants because our doctors tell us they may help. In fact, antidepressants were the most prescribed drug in 2007, and adult use of antidepressants rose nearly 50% between 1995 and 2002 (most recent stats.) These high rates suggest these pills might actually work, right?

Maybe not. Last month PLoS published a meta-analysis on antidepressants that found little difference between SSRIs (includes Prozac, Effexor, Serzone, and Paxil) and placebos except among very severely depressed patients, a response the researchers attribute to reduced placebo response rather than to the drug’s efficacy.

The researchers conclude that there is little reason to prescribe new-generation antidepressant medications to any but the most severely depressed patients unless alternative treatments have been ineffective.

The researchers used both published and unpublished clinical trial data filed with the FDA. This tidbit is important since we learned in January that drug companies weren’t publishing unfavorable studies on antidepressants.

Unfortunately this PLoS study has received very limited U.S. media attention (not to ignore this), but I think the millions of people swallowing these medications would want to know if they’re actually backed by science and doctors should demand no less. This antidepressant-placebo debate has been going on for a while, and if anything, this study shows the need for continued oversight of these relatively new and powerful drugs.

In 2003, drug companies spent $3.2 billion on direct-to-consumer ads for antidepressants; ads which, according to Dr. Matthew Hollon from the University of Washington, Seattle, “provide a minimal amount of health information, describe the benefits in vague, qualitative terms, and rarely offer evidence to support claims.”

Some people found flaws in this meta-study, so feel free to share your opinion here.