Measuring Pain

How much pain do you feel, on a scale of one to 10? We’ve all been asked this question at one time or another, but what do our answers really mean? Is a rating of four the same for an arthritis sufferer and a cancer patient? How about for a child?

Finding an objective way for doctors to measure pain has been an elusive goal until now. Researchers at the University of Colorado at Boulder have found a unique neurologic signature in patients’ brain scans that allows them to predict how much pain a person is feeling with 90 to 100 percent accuracy.

"Right now, there's no clinically acceptable way to measure pain and other emotions other than to ask a person how they feel," Tor Wager, lead study author and associate professor of psychology and neuroscience at CU-Boulder, said in a press release.

Wager’s study was funded by the National Institute on Drug Abuse, the National Institute of Mental Health, and the National Science Foundation, and appears in the latest issue of the New England Journal of Medicine.

Feeling the Heat but Not the Heartbreak

Researchers used computer analysis to look for patterns in the brain scans of 114 patients who were exposed to heat ranging from pleasantly warm to painfully hot.

They were surprised to find a pattern emerge that was the same across all the study subjects. Researchers had assumed the pain signature would be different for each individual, but since it’s fairly universal, they were able to accurately predict how much heat pain a subject was feeling even with no previous brain scans of that person to use as a reference.

The scientists were also intrigued by a 2011 study published in Proceedings of the National Academy of Sciences (PNAS), which Wager co-authored. That study found that the brain activity of people who’ve just been through a break-up and are shown a picture of their ex is similar to activity in the brains of subjects in physical pain.

Wager’s team examined the brain scans from the PNAS study, but did not find their neurologic pain marker. This result indicates that, though it may hurt just as much, heartbreak doesn’t manifest in the same way as, say, a broken arm.

Creating a Universal Pain Test

Scientists haven’t created a Pain-o-Meter—yet—but Wager’s work could provide the basis for not only a pain test, but also a way to measure other “subjective” mental states, such as anger, anxiety, and depression.

"I think there are many ways to extend this study, and we're looking to test the patterns that we've developed for predicting pain across different conditions," Wager said. "Is the predictive signature different if you experience pressure pain or mechanical pain, or pain on different parts of the body?”

More than 100 million American adults experience chronic pain, and it is among the leading causes of disability in the U.S. Though the pain signature Wager identified does not measure chronic pain, he’s hopeful that researchers can use his technique to create a test for that as well.

“Understanding the different contributions of different systems to chronic pain and other forms of suffering is an important step towards understanding and alleviating human suffering," Wager said.

Learn More: