WASHINGTON - Scientists may objectively measure anxiety, depression, anger or other emotional states by using brain scans, findings published in Wednesday's New England Journal of Medicine showed.

"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 author Tor Wager from the University of Colorado Boulder.

Wager's team 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 researchers identified a distinct neurologic signature for the pain and found that the signature was transferable across different people, allowing them to predict how much pain a person was feeling, with between 90 and 100 percent accuracy.

They were also surprised to find that the signature was specific to physical pain.

Finally, they 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 results of the study do not yet allow physicians to quantify physical pain, but they lay the foundation for future work that could produce the first objective tests of pain by doctors and hospitals.

To that end, Wager and his colleagues are already testing how the neurologic signature holds up when applied to different types of pain.

"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?"

"We're also looking towards using these same techniques to develop measures for chronic pain," 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 added.