CHICAGO, Sept. 15 (Xinhua) -- Researchers at Northwestern University (NU) Medicine now can reliably predict what chronic pain patients will respond to a sugar placebo pill based on the patients' brain anatomy and psychological characteristics.

This means someday doctors may prescribe sugar pills for certain chronic pain patients based on their brain anatomy and psychology, and the pills will reduce their pain as effectively as any powerful drug on the market.

NU researchers randomized about 60 chronic back pain patients into two arms of the study. In one arm, subjects didn't know if they got the drug or the placebo. Researchers didn't study the people who got the real drug. The other study arm included people who came to the clinic but didn't get a placebo or drug. They were the control group.

The individuals whose pain decreased as a result of the sugar pill had a similar brain anatomy and psychological traits. The right side of their emotional brain was larger than the left, and they had a larger cortical sensory area than people who were not responsive to the placebo. The chronic pain placebo responders also were emotionally self-aware, sensitive to painful situations and mindful of their environment.

"Clinicians who are treating chronic pain patients should seriously consider that some will get as good a response to a sugar pill as any other drug," said senior study author A. Vania Apkarian, professor of physiology at NU Feinberg School of Medicine. "This opens up a whole new field."

The researchers said there are three potential benefits of the findings: prescribing non-active drugs rather than active drugs; eliminating the placebo effect from drug trials; reducing health care costs.

The study was published on Sept. 12 in Nature Communications.