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Some Brains Are Primed for the Placebo Effect

A new study finds similarities among patients whose pain is relieved by sugar pills

Hands of a woman holding prescription medicine.

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Whether or not you experience pain relief from a placebo may be predicted by your brain anatomy and personality traits. That’s the conclusion of a new study by researchers at Northwestern University who gave patients with chronic back pain either pain-relief medication or a sugar pill, without indicating whether or not they were receiving the active drug.

About half of those who received the placebo reported a drastic reduction in pain — as much as 30 percent — which means that the sugar pills were as effective as any drug on the market, says senior study author A. Vania Apkarian, professor of physiology, anesthesiology and physical medicine and rehabilitation at the Northwestern University Feinberg School of Medicine. “The results are exciting because it’s the first real convincing evidence that the placebo response is predictable,” says Apkarian, whose study was published this week in the journal Nature Communications.

The 63 participants (an almost equal number of men and women whose ages averaged about 50) took two pills a day, morning and evening, for two weeks, a process that was repeated twice with a two-week break in-between. They rated their pain throughout the study on a smartphone app. 

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Doctors have long known that placebos can work, especially with pain relief, though the psychological/biological mechanism is not entirely understood. What’s remarkable about this study is its finding that those patients who responded to the sugar pills share distinctive characteristics. Their brains’ cortical sensory areas are larger. (Apkarian and fellow researchers identified this as the “sweet spot” in the brain responsible for the placebo response in a 2016 study.)

They also exhibit certain personality traits, indicated by a written self-assessment/test (called the Multidimensional Assessment of Interoceptive Awareness); some key traits among placebo-receptive participants included being emotionally self-aware, sensitive to painful situations and mindful of their environment.

It’s not practical to scan patients’ brains to determine whether or not a placebo will be effective, Apkarian concedes, but the fact that “personality was a big factor is very encouraging because that’s a very simple thing to check, so that could be of great use down the line.”

Of course, doctors are not likely to start prescribing sugar pills to unsuspecting pain patients outside the bounds of a clinical trial anytime soon. Placebos are “the gold standard” for control groups in research studies, says Mark Bicket, M.D., assistant professor of anesthesiology and critical care at the Johns Hopkins University School of Medicine. “If people want to start getting placebos as part of routine treatment they’d need to discuss that with their doctors. And we’re not quite at that stage where we’ve seen convincing evidence that patients who are aware that they’re being given sugar pills do much better.”  

Bicket adds that the study is nonetheless valuable for “providing initial insight into what defines a group of people who derive benefits from placebo pills…. And knowing more about the placebo response can one day perhaps lead to better treatments.”