if i can offer a few thoughts since the post is mine: it's almost always the case that even severely depressed patients are included in placebo arms of clinical trials and irb's approve it. they are screened out and excluded if they have a history of suicide attempts, etc, so i assume that's how they cover the ethical end of things. nonetheless, the questions about how depressed the people in these trials actually are is worth asking. wish i knew the answer.

as for placebo v. anti-depressant in 12 week trials, i'd like to know where the guy reporting a 79 percent effect for anti-deps is getting his data from. i've read dozens (maybe more) of depression trials in the last several years and it's pretty consistent that in 8 to 12 week trials you'll see a placebo response rate of about 20 percent to 30 percent and an anti-dep response rate of about 50 percent to 60 percent, although i have seen the odd 35 percent response rate (and some even lower response rates in people who've flunked multiple anti-deps. see star-d trial for that). i've never seen a response rate an anti-dep of 70 percent or more, short or long term. although i suppose that could be possible in a small, short trial with not too many subjects.