The researchers learned that the drugs were only effective for very severely depressed patients. In people with lower levels of depression, the results of the antidepressants were quite modest or disappeared entirely. For the study, researchers analyzed 47 clinical studies conducted by pharmaceutical companies that were never released.

It included studies submitted to the FDA during the drug approval process, but not published in medical journals. The studies involved four drugs: fluoxetine (Prozac), venlafaxine (Effexor), nefazodone (Serzone), and paroxetine (Seroxat/Paxil).

Approximately 118 million prescriptions are written for these and other antidepressants in the United States each year; that’s one prescription for every 2.5 Americans. In the U.K., an estimated 3.5 million people take antidepressants.

According to Blair T. Johnson, a psychology professor and researcher at the University of Connecticut, "The implications from this research is that antidepressant medications are over-prescribed and people should probably try other options before they consider the medications."

Other studies have had similar findings. In a 2002 Washington State study, investigators looked at 52 studies of antidepressants in the FDA’s database and determined that in 48% of the studies the results were no better than placebo. They also concluded that antidepressants were only more effective that sugar pills with the severest forms of depression.

Another study funded by the National Institute of Mental Health concluded that antidepressants worked very well for about a third of people; those with serious clinical depression, but not as well for others with mild to moderate depression.

In light of these findings, it’s important to remember that this large body of clinical research suggests that antidepressants do work in most cases of severe depression. This type of depression can include feelings of suicidality, making immediate treatment essential. In these cases, an evaluation by a mental health care professional is needed to determine the appropriate course of action. Because antidepressants are effective for severe depression, the incidence of suicide has decreased significantly since the introduction of these drugs. What these studies do suggest is that antidepressants tend to be no more effective than placebo for mild to moderate depression, leading the researchers to suggest that non-drug approaches such as diet, exercise and psychotherapy may be more beneficial.

References
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