Clinical trials in all areas of medicine turn up some degree of "placebo effect" -- the phenomenon of people who are given a sham treatment, instead of the real thing, getting better anyway. Placebo responses are particularly common in certain disorders, depression being one.
In the new study, researchers re-analyzed findings from a 2002 clinical trial that compared the antidepressant sertraline (Zoloft), the herbal depression treatment St. John's wort and a placebo.
The original study, which included 340 people with moderate depression, had found that neither treatment was any more effective than the placebo when taken for up to six months.
But the current study looked at the data in a different way: It asked whether patients who thought they were getting the real treatment were more likely to improve than those who thought they were on the placebo.
All of the trial patients had been "blinded" as to whether they were receiving the antidepressant, the herb or the placebo. But at the eight-week mark of the study, they were asked to guess which treatment they were taking.
And it turns out that people who thought they were using the antidepressant or St. John's wort were more likely to improve than those who thought they'd been assigned to the placebo group.
via www.msnbc.msn.com