Evidence for Effectiveness of Antidepressants Seems Underwhelming

A new study shows that the results of around a third of drug trials have not been released. Once these are taken into account, the advantage of antidepressants over placebos shrinks significantly. This amounts to seriously misleading the public about the drugs’ effectiveness.

The New York Times is among the many major news outlets covering a forthcoming study in the New England Journal of Medicine which shows that the makers of antidepressants have not released the results of around a third of drug trials. Once these are taken into account, the advantage of antidepressants over placebos shrinks significantly. This amounts to seriously misleading the public about the drugs’ effectiveness.

In published trials, about 60 percent of people taking the drugs report significant relief from depression, compared with roughly 40 percent of those on placebo pills. But when the unpublished trials are taken into account, drugs outperform placebos by a modest margin.

This analysis reviews data from 74 trials involving 12 drugs, between 1987 and 2004, and found that 94% of studies showing a positive result for antidepressants were published, as opposed to 14% of those with less strikingly positive results.

The reasons for this may be myriad; not only the large pharmaceutical companies’ financial interests come into play here but also study authors who may feel that the study is unsatisfactory, or journal editors who may feel that the study is just not conclusive enough to be interesting.

But the ethical issue here is that if information is available, it should be available to the doctors who prescribe medicine and the people who take it, so that neither are left wondering what is wrong with them when the drugs don’t work.

All clinical material on this site is peer reviewed by one or more clinical psychologists or other qualified mental health professionals. This specific article was originally published by on and was last reviewed or updated by Dr Greg Mulhauser, Managing Editor on .

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