Millions of Americans take SSRI antidepressants to balance their emotions. Profits are high, and pharmaceutical companies have every reason to emphasize positive studies and bury negative results. Unfortunately, these biased corporations are the ones responsible for performing a significant number of drug trials. In January, we reported on a meta-study in the New England Journal of Medicine that demonstrated a clear bias towards not publishing unfavorable studies. It was troubling news, but it did not show to what extent the results were being twisted. An article published this month in the Public Library of Science attempts to gauge the distortion caused by selectively publishing results.
Irving Kirsch’s team of researchers analyzed every clinical trial that they could get their hands on for fluoxetine, venlafaxine, nefazodone, and paroxetine, four of the most commonly prescribed SSRIs (sold as Prozac, Effexor, Serzone, and Paxil, respectively). Though some were well hidden, a combination of Freedom of Information filings and detective work yielded 47 trials. With the never-published studies included, new information emerged: average SSRI effects were not significantly larger than placebo effects for most patient populations. Taken in the context of the larger debate surrounding SSRIs, this appears a damaging blow, but it’s important that no one discontinue medication that has helped them based on this one study. Consultation with the prescribing physician is always the best strategy. For those thinking of starting SSRIs for the first time, this new information may lead to extra consideration for alternatives to drugs, like therapy and exercise.
The placebo effect is notoriously large for antidepressants, which is why it is often difficult to determine whether a recovery was due to an intended chemical reaction or a dose of positive thinking and attention. One positive note from Kirsh’s report was that SSRIs do seem to have a benefit for the most severe cases of depression. The team found that patients with extreme symptoms typically benefit from SSRIs above what a placebo could do.
Recent studies have already shown that genetic differences can theoretically predict antidepressant reactions, so the population that really could benefit may some day be precisely targeted with success. While this latest meta-study is disheartening, it may spur a reinvigoration of the antidepressant field. Journalists and consumer groups are demanding that every study result be reported to the FDA from start to finish, whether the numbers look good or not. In this way, even set-backs will eventually contribute to the inevitable march of scientific progress.
People currently taking SSRIs should not abruptly discontinue their medication regimen. Rash decisions based on one study are never advisable, and discontinuing some SSRIs can trigger withdrawal symptoms. Stay informed and speak with your doctor about what options are best for you.
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