Debunking the power of the placebo effect.

Health and medicine explained.
Oct. 23 2007 5:32 PM

Pill Popping

Debunking the power of the placebo effect.

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There's no question that placebos have psychological effects. The question is whether those effects really trigger healing on their own. For too long, medical science has accepted the magical thinking that patients' beliefs could activate dying neurons, heal knee cartilage, prevent air bubbles from traveling through the heart to cause migraines, lower bad cholesterol, and even cure cancer and AIDS. Like Beecher's original paper, a good deal of research about placebos is flawed. For example, a recent publicized Science study of brain scans purporting to show a placebo effect in Parkinson's disease included no objective measure of patients' symptoms and had no long-term follow-up.

Meanwhile, in a stunning 2001 article in the New England Journal of Medicine, two Danish physicians debunked the mighty placebo effect. Although most clinical trials include only active treatment and placebo groups, the researchers systematically collected all the studies in the medical literature (130 at the time) that also included a critical third group: patients who received neither active nor placebo treatment—just passive observation. The patients in placebo groups did report slightly less pain than the no-treatment groups; the analogy of a parent kissing a skinned knee comes to mind. But on almost every other objective measure of illness, the placebo-treated patients improved the same amount as the ones who got nothing at all. In other words, just believing you were getting treatment—the power of positive thinking—didn't really fix anything. It just made the patients hurt a little less.

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The Danish authors sensibly pointed out that, like the Dow Jones industrial average, diseases' symptoms fluctuate up and down over time without clear explanations. For example, on 9/11, when Doeschner was stranded on the 34th floor of the World Trade Center when the jets hit, he had improved enough to run down the stairs and save himself despite his Parkinson's disease. Months afterward, his symptoms worsened without cause. It's these variations over time in clinical trials that get chalked up to the placebo effect. But according to the Danish review, these upswings and downturns are just the random course of illness, not the manifestations of a patient's psychic mojo.

If the belief in active treatment does little good, why not disclose to patients in clinical trials what treatment group they are in and spare them from sham surgeries and the empty ritual of taking a placebo pill? That's not likely. The decades-old belief in strong placebo effects has become a quasireligious idée fixe. Arthur Kleinman, the Harvard anthropologist who chaired an NIH forum on placebos in 2000, says the Danish study hasn't altered his faith that positive thinking can heal. Kaptchuk, for his part, suggests that a persistent belief in placebos is a misguided protest against cultural and personal insensitivity in modern medicine. It's also conceivable that some researchers fully understand the powerless nature of placebos—but realize patients are more likely to stay put in the no-treatment groups of clinical trials if they're convinced they're getting active medication.

For many people, the belief that one's mental state can heal is a comforting fantasy. But there's a dark side to wish-thinking that goes beyond pointless groin incisions, sugar pills, or drills to the cranium. If the only obstacle to perfect health is one's state of mind, then why not exhort the unfulfilled and the infirm to imagine their way to happiness and health, rather than work toward it or seek proven treatment? The door to quackery and exploitation yawns open close by.

Darshak Sanghavi, a pediatric cardiologist, is a fellow of the Brookings Institution and Slate’s health care columnist. Follow him on Twitter.