OK. There are a lot of little problems with this study, most of which are not worth getting into in great detail, at least yet. (Although, for the record, I'd like to point out that "not quite statistically significant" is like "not quite pregnant". It's either significant, or it's not.)
For those who wish to play along at home, the paper itself can be found here:
http://www.frontiersin.org/Evolutionary ... 00117/fullInstead of getting into major nit-picking (and, believe me, there are quite a few nits to pick with this paper), I'm just going to look at two things: the listing of costs and benefits, and the method used to assess effectiveness of anti-depressants.
If you look at their Table 2, you'll find a list of effects of anti-depressants. The list is rather heavily stacked toward showing costs and minimizing benefits. For example, under the "Mood" heading, each class of SSRI has a separate listing for relapse after discontinuation. "Reduce Depressive Symptoms" has a single line for all classes of drug (and is identified as neither a pro nor a con, an issue I'll get to momentarily). If you look at the section for "Gastrointestinal Effects", you'll note that each possible side effect has its own line, with each listed as a con. If you look back up to "Mood", you'll note that "Reduce Depressive Symptoms" is a single entry, and absolutely no attempt is made to look at the range of symptoms.
The assessment of the effectiveness of anti-depressants is even more problematic, particularly since it's the basis for their rather strongly worded conclusion:
Quote:
We have reviewed a great deal of evidence of the effects of antidepressants on serotonergic processes throughout the body. Some of the effects are widely known, but they have been largely ignored in debates about the utility of antidepressants. Indeed, it is widely believed that antidepressant medications are both safe and effective; however, this belief was formed in the absence of adequate scientific verification. The weight of current evidence suggests that, in general, antidepressants are neither safe nor effective; they appear to do more harm than good.
Their basis for this statement is a study that did a comprehensive meta-analysis of all of the data received by the FDA, published or unpublished. That study found that anti-depressants provided, on average, only a 1.8 point improvement in depressive symptoms when measured on a particular scale, when compared with the effectiveness of placebos. The threshold used to determine clinical significance is a three-point improvement. Therefore, they conclude that anti-depressants do not provide a clinically significant improvement compared with placebo.
What they don't mention is just how much improvement placebos generate. The placebo effect on depression is enormous. Placebos are quite effective in anti-depressant treatment. Every study used in the analysis demonstrated at least a three point improvement with placebo use, and many demonstrated 9-10 point improvements. The 1-2 point performacne improvement over placebo is not an improvement from baseline; it's a further improvement beyond the clinically significant effect that placebos have. And, although not "clinically significant", the 1-2 point improvement over placebo is very clearly statistically significant. Basically, placebos typically generate a 7-8 point improvement, and antidepressants a 9-10 point difference.
It's also noteworthy that the relative effectiveness of the antidepressants compared with placebo reaches clinical significance in the most depressed patients. The authors of the study take pains to point out that this is not because the antidepressants are producing more improvement in these groups, but because the placebo is less effective. I'm not sure why that's supposed to be a bad thing, but the authors seem to be attempting to portray it as such.
Antidepressants and placebos both show clinically significant improvements in mood. And placebos cannot ethically be prescribed - and even if they could, they would almost by definition lose effectiveness if it were to become widely known that they are being prescribed. Add to that the modest increase in effectiveness of medication over placebo, and prescription of antidepressants looks much more reasonable.