A new brain-imaging study confirms that some people are much more sensitive to pain than others and should help doctors in calibrating patients' descriptions of their pain.
"One of the most difficult aspects of treating pain has been having confidence in the accuracy of patients' self-reports of pain," said Robert Coghill, an assistant professor of neurobiology and anatomy at Wake Forest University Baptist Medical Center. He led the study published online Monday by the Proceedings of the National Academy of Sciences.
"Now, we have objective evidence that confirm individual differences in pain are, in fact, real."
In their study, Coghill and colleagues used magnetic resonance imaging to assess brain function. They found that the brain regions important in registering pain lit up in those participants who said a heat stimulus was intensely painful. But those who said that the same stimulus was only mildly painful had minimal activation of those areas.
During the study, 17 healthy volunteers (eight women and nine men) had a computer-controlled heat stimulator placed on their leg. While their brains were scanned, the device heated a small patch of skin to 120 degrees Fahrenheit, which most people find painful.
Those who reported higher levels of pain showed increased activity in the primary somatosensory cortex, which tells the brain where a painful stimulus is located in the body and how intense it is, and in the anterior cingulate cortex, which is involved in processing the unpleasant feelings evoked by pain.