Are antidepressant ads so ingenious that they've convinced the public of the drugs' efficacy—even those who aren't taking the medications?
Studies comparing placebos to medications often find that the people given fakes get better, too. It's a widespread, if little understood, clinical phenomenon and, oddly, the ranks of placebo responders seem to be growing, perhaps because of our heightened expectations for drugs.
When B. Timothy Walsh, a Columbia University psychiatrist, reviewed 75 trials of antidepressants conducted between 1981 and 2000, he found that, on average, 30 percent of people given placebos improved. This response rate increased about 7 percent per decade; the response rate to real drugs also went up, but not as sharply.
Placebo response to antidepressants is particularly high in young people. A clinical trial for Zoloft found improvements in 59 percent of children given a placebo, compared with 69 percent of the kids taking the drug.
Jon-Kar Zubieta, a University of Michigan researcher, explains that because young people have had fewer bouts with depression, the disorder may not have etched itself as deeply onto their brains. "Placebos may work by activating the circuits in your brain that relate to mood and affective states," says Zubieta. "Someone who is severely depressed and has had the illness longer won't respond as well, because those circuits are more disrupted." The placebo effect could also stem from the attention and support built into clinical trials; younger patients may respond especially strongly to that extra adult interest.