Illuminating post on Neuroskeptic:

Some Quotes:

Why is it that modern trials of antidepressant drugs increasingly show no benefit of the drugs over placebo?.....

They suggest that maybe it's the patients fault: Participation that is induced by cash payments may lead subjects to exaggerate their symptoms [i.e. in order to get included into the trial]... Another contributing factor to high placebo response rates may be the extent to which the volunteers in antidepressant trials are really generalizable to patients in clinical practice.

Since the initial antidepressant trials in the 1960s, participants have gone from being patients who were recruited primarily from inpatient psychiatric populations to outpatient volunteers who are often recruited by advertisements. At times, these symptomatic volunteers have participated in other trials. When we contact potential participants to schedule screening, they often ask to be reminded which trial we are screening for or mistake our research trial for a different protocol in which they recently participated.

A few years ago I was running a study recruiting people who'd recovered from psychiatric illness. The main source of volunteers was online adverts..... We recruited about 20 people. No fewer than 3 turned out to have enrolled in other studies and lied about it. After I realized this I Googled the offender's names and two of them turned up in the court pages of the local newspaper pleading guilty to various petty crimes.

In my view, the authors miss out on the real problem with recruiting depressed people through adverts:  depressed people don't tend to respond to adverts, because depressed people don't do anything. That's why they call it depression.

So while you wouldn't go looking for aquaphobic people in a swimming pool, I'm not sure we should be looking for depressed people through adverts.

Could similar mechanisms hold true for other drugs?