What to make of the new meta-study purporting to show that SSRIs don't work? Ezra Klein summarizes the conundrum:

To get a sense for the dangers of taking large medical studies at face value, check out this comment thread over at Kevin's place. Kevin wrote up a new study that apparently proves Prozac and other antidepressants in the SSRI family are worthless. It's an interesting result, but a bit hard to believe for anyone who's ever seen a friend cycle through antidepressants till they land on the right pill and dosage and suddenly turn back into themselves. Many of Kevin's commenters, who've seen the same thing, begin instantly complicating the research, and by the end, it seems fairly certain that the research could be technically true but its result utterly misleading. It's worth reading through just to get a sense of how skeptically to treat this stuff.

On the one hand, the placebo effect is real. But like Ezra, I've watched people who'd been depressed for years cycle through medication until they hit the jackpot--maybe they just happened to spontaneously remit when the meds kicked in, but it seems to happen an awful lot. I've also seen anti-depressants stop working, which seems odd if they're not doing anything.

My theory is that depression is overdiagnosed--if you don't actually have a chemical deficiency, antidepressants aren't going to make you feel better. It's also a large basket diagnosis into which we throw a lot of conditions that probably have different underlying causes. The Times suggests that we may soon be able to pick out, genetically, the people who will benefit from antidepressants, similar to the way that we now target drugs to the genetic markers on certain tumors. Moreover, the meta-study seems to have covered a period of 4-8 weeks, when the effect can take months to kick in. Severe depression is sufficiently debilitating that it's probably worth trying, even if the effect isn't huge.

It also says something that none of the people pooh-poohing the effect are afflicted with depression. But I'm not sure what it says, exactly. Maybe depressed people are just deluded by the placebo effect--people with mental illnesses are perhaps not very good judges of alterations in their mental status. On the other hand, who would be better?

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