In depression, the placebo also rises

Placebos–medical treatments that contain no active ingredients–have triggered an outbreak of controversy (SN: 2/03/01, p. 74: Medicinal Mimicry). Some researchers regard placebos as surprisingly powerful, at least when given to people who believe in their effectiveness. Other scientists say that studies have yet to confirm the value of placebos in treating any illness.

A new study, published in the May American Journal of Psychiatry, offers ammunition to the pro-placebo crowd. In a small group of depressed patients, those whose condition improved after taking placebo pills for 6 weeks displayed many of the same brain changes observed in people who benefited from an antidepressant drug, report psychiatrist Helen Mayberg of the University of Toronto and her coworkers.

The researchers studied 17 men, all hospitalized for major depression, who received either Prozac or a placebo for 6 weeks. Despair, sleep difficulties, and other symptoms of depression substantially diminished in four of seven men who took the placebo and in 4 of 10 others who received the antidepressant.

Before and after treatment, positron emission tomography measured glucose uptake throughout the brain of each volunteer. This technique provides an indirect sign of activity in a given area. Patients who responded to either treatment showed increased activity in several of the same parts of the cortex, the brain’s outer layer. All these patients also exhibited activity declines in a handful of regions below the cortex.

As compared with men who improved on the placebo, those who profited from Prozac displayed slightly larger areas of boosted activity and unique metabolism hikes in a few other structures, including the brain stem and the hippocampus. Neural stirrings in those lower-brain realms may contribute to the longer-lasting effects of antidepressants compared with placebos, the researchers theorize.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.