"It is unknown exactly how many patients taking antidepressants have milder cases of depression. But one survey cited by the researchers found that 71% of all patients seeking treatment for depression fall in the milder category, where placebos are likely to do as well.
Drugs are hardly better than a placebo for the mildly depressed, researchers find.
Mildly depressed Americans have spent billions of dollars over the past few decades hoping to relieve their blues by taking designer antidepressants. They might have done just as well by taking a placebo.
That's the surprising implication of a new study by psychologists at the University of Pennsylvania, Vanderbilt University, the University of New Mexico and the University of Colorado. Many industry-sponsored studies have excluded patients with mild depression, even though these patients often end up in doctors' offices looking for help. The new study, published in the Journal of the American Medical Association (JAMA), culled the results from six antidepressant trials that did include mild and moderate cases, totaling 718 people overall.
It found that antidepressants drugs were virtually no better than a placebo for people with mild or moderate depression. Only in people with very severe depression did the antidepressant effect become substantially greater than that produced by a dummy pill.
It is unknown exactly how many patients taking antidepressants have milder cases of depression. But one survey cited by the researchers found that 71% of all patients seeking treatment for depression fall in the milder category, where placebos are likely to do as well.
"The evidence we now have suggests there is very little benefit [from antidepressants] for people with less than very severe depression," says study co-leader Robert DeRubeis, a psychologist at the University of Pennsylvania. He says doctors may want to consider alternative treatments, including exercise, cognitive therapy and self-help books, before using drugs to treat milder cases.
The Penn-led study only looked at two drugs, Paxil from GlaxoSmithKline ( GSK – news – people ) and a well-known older drug called imipramine. But it follows on the heels of a larger 2008 study from University of Hull psychologist Irving Kirsch that compared 35 trials of four different antidepressant medications, including Prozac from Eli Lilly ( LLY – news – people ), Effexor from Pfizer ( PFE – news – people ) and Paxil. This study, published in PLoS Medicine, also found "virtually no difference" between drugs and placebos for the moderately depressed, and only a relatively small difference even in the very severely depressed.
"It seems to be the same pattern no matter which antidepressant you look at," says Kirsch. "Most of the benefits patients get from antidepressants may be the placebo effect."