NEW YORK (Reuters Health) - If you’ve ever thought that you literally feel other people’s pain, you may be right. A brain-imaging study suggests that some people have true physical reactions to others’ injuries.

Using an imaging technique called functional MRI, UK researchers found evidence that people who say they feel vicarious pain do, in fact, have heightened activity in pain-sensing brain regions upon witnessing another person being hurt.

The findings, published in the journal Pain, could have implications for understanding, and possibly treating, cases of unexplained “functional” pain.

“Patients with functional pain experience pain in the absence of an obvious disease or injury to explain their pain,” explained Dr. Stuart W. G. Derbyshire of the University of Birmingham, one of the researchers on the new study.

“Consequently,” he told Reuters Health in an email, “there is considerable effort to uncover other ways in which the pain might be generated.”

Derbyshire said he now wants to study whether the brains of patients with functional pain respond to images of injury in the same way that the current study participants’ did.

For the study, Derbyshire and colleague Jody Osborn first had 108 college students view several images of painful situations -- including athletes suffering sports injuries and patients receiving an injection. Close to one-third of the students said that, for at least one image, they not only had an emotional reaction, but also fleetingly felt pain in the same site as the injury in the image.

Derbyshire and Osborn then took functional MRI scans of 10 of these “responders,” along with 10 “non-responders” who reported no pain while viewing the images.

Functional MRI charts changes in brain blood flow, allowing researchers to see which brain areas become more active in response to a particular stimulus. Here, the researchers scanned participants’ brains as they viewed either images of people in pain, images that were emotional but not painful, or neutral images.

The investigators found that while viewing the painful images, both responders and non-responders showed activity in the emotional centers of the brain. But responders showed greater activity in pain-related brain regions compared with non-responders, and as compared with their own brain responses to the emotional images.

“We think this confirms that at least some people have an actual physical reaction when observing others being injured or expressing pain,” Derbyshire said.

He noted that the responders also tended to say that they avoided horror movies and disturbing images on the news “so as to avoid being in pain” -- which, the researcher said, is more than just an empathetic response.

As far as the potential practical implications of the findings, Derbyshire said it would be a “reach” to think that such brain mechanisms might be behind all functional pain. But, he added, “they might explain some of it.”

SOURCE: Pain, online December 11, 2009.