Sugar pills, antidepressants, and the miracle of the human brain

[drwex]

Chasing other links I stumbled across this:

As a proportion of the drug response, the placebo response was constant across different types of [antidepressant] medication (75%), and the correlation between placebo effect and drug effect was .90. [...] These data raise the possibility that the apparent drug effect (25% of the drug response) is actually an active placebo effect.

In English: it's possible that all reported effects of antidepressant medication are placebo effects. It's quite likely that 75% of reported effects are placebo.

More recently, these authors replicated the work using studies from the FDA database. FDA studies are done as part of drug approval processes. They're generally not published in refereed literature and there have been accusations that they're slanted in favor of the drugs. That is, the studies are done in order to speed drugs through the approval process and may overreport positive effects and underreport negatives. So in theory you'd see a larger effect for ADs if you analyzed these studies. In fact:

Kirsch et al. reported an 18% difference between drug and placebo.

The debate is actually fairly nuanced. There's been some good work recently looking (via MRI) at the neurochemical mechanisms triggered by placebos. There is some evidence that the difference between AD and placebo increases with the severity of depression, though that might be due to differences between active and inert placebos - people with serious depression are often familiar with the side effects of ADs and can recognize when given a sugar pill that doesn't have the expected side effects.

Nobody's claiming that ADs don't work. The claim is that they do work... and sugar pills work, too.

Title: "Listening to Prozac but hearing placebo: A meta-analysis of antidepressant medication."
Authors: Kirsch, Irving; Sapirstein, Guy
Publication: Prevention & Treatment. 1(1), Jun 1998
<http://content.apa.org/journals/pre/1/1/2>

Title: "The emperor's new drugs: An analysis of antidepressant medication data submitted
 to the U.S. Food and Drug Administration."
Authors: Kirsch, I., Moore, T. J., Scoboria, A., & Nicholls, S. S.
Publication: Prevention & Treatment, 5, art. 23
<http://journals.apa.org/prevention/volume5/pre0050023a.html>

Comments

[earthling177.livejournal.com]

Take this with a huge amount of salt if you need to, but I'd just like to add that the results don't affect me one way or another, having never been on anti-depressants in my life, or read the paper(s).

But I wonder what they mean by "placebo".

Why, might you ask?

Because eons ago, when Zantac became OTC, I bought a box. When I opened the box, there was a nice insert explaining what the drug does etc, and among the data was how effective it was complete with a chart. The chart claimed that the drug was (I forget the real number, but it was on the order of) 30% more effective than the placebo, so I was telling Dave how nuts it was that I could just take a sugar pill and it could be just as nice, and I was making up stuff like "wouldn't it be funny if in 30 years we found out that sugar *is* actually a remarkably good medicine?" when I noticed they had a URL (less common back then) so I went to their web site, where they actually explained the whole protocol. Well, darn, wouldn't you know it, it's considered unethical to give placebos to certain classes of patients, like people with heart conditions and, apparently, people with acid reflux. So the protocol is that the "placebo" is a very well known medicine that is known to work and the new medicine is compared to that one, so, no, sugar pills are not just 30% less efficient as an acid-reflux drug, sugar pills are nearly zero effect.

After that, I try to find out about the protocols and what the "placebos" were in studies. It's important. For example, for the continuous-wear (30 days, 29 nights) contact lens studies, the "placebos" are typically Accuvue, which compare poorly to the Night&Day (silicone hydrogel) contacts, of course, given that they can only be worn for 7 days, and very poorly to Menicon Z (which behave better because they are rigid gas-perm contacts).

YMMV.