Scientists, for the first time, have been able to predict how much pain people are feeling just by looking at their brain scans.
The study, led by the University of Colorado, Boulder identified a distinct neurologic signature for physical pain in the brain.
The findings may help measure pain in those who are unable to communicate and even tell whether a medication to relieve pain was working.
"Right now, there's no clinically acceptable way to measure pain and other emotions other than to ask a person how they feel," said lead researcher Tor Wager, associate professor of psychology and neuroscience at CU-Boulder.
The study used computer data-mining techniques to comb through images of 114 brains that were taken when the subjects were exposed to multiple levels of heat, ranging from benignly warm to painfully hot.
With the help of the computer, the scientists identified a distinct neurologic signature for the pain.
"We found a pattern across multiple systems in the brain that is diagnostic of how much pain people feel in response to painful heat," Wager said in a statement.
Scientists could predict how much pain a person was being caused by the applied heat, with between 90 and 100 per cent accuracy. They found that the signature was specific to physical pain.
Researchers also tested to see if the neurologic signature could detect when an analgesic was used to dull the pain. The results showed that the signature registered a decrease in pain in subjects given a painkiller.
"The pattern we have found is not a measure of chronic pain, but we think it may be an 'ingredient' of chronic pain under some circumstances," Wager said.
"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.
The study was published in the New England Journal of Medicine.
