In a provocative new study, scientists have reported they were able to “see” pain on brain scans. And, for the first time, they were able to measure the pain's intensity and tell whether a drug was relieving it.
Although the research is in early stages, it opens the door to a host of possibilities:
» Scans might someday be used to tell when pain is hurting a baby, or someone with dementia or someone paralyzed and unable to talk.
» The scans could help lead to new, less-addictive pain medicines.
» They might even help verify disability claims.
“Many people suffer from chronic pain, and they're not always believed. We see this as a way to confirm or corroborate pain if there is a doubt,” said Tor Wager, a neuroscientist at the University of Colorado, Boulder.
He led the research, which was published in the New England Journal of Medicine. So far it has measured pain felt only through the skin — specifically, heat applied to an arm.
More study must be done to apply the brain scans to more common kinds of pain, such as headaches, bad backs and pain from disease.
Independent experts said the research showed a way to measure objectively what is now one of life's most frustratingly subjective experiences.
Pain is the top reason people see a doctor, and there's no way to quantify how bad it is. A doctor can go only by what the patient says or how he or she winces.
Although many studies have found brain areas that light up a scan when pain is present, the new research is the first to combine these signals, to identify a signature or pattern that can be used to measure pain.
“This is very exciting work. They made a huge breakthrough in thinking about brain patterns,” said Dr. David Shurtleff of the National Institute on Drug Abuse, which helped sponsor the research. “We need a brain-based signature for pain. Self-report doesn't cut it. It's not reliable. It's not accurate.”
The research involved four experiments at Columbia University. In all, 114 healthy volunteers were paid $50 to $200 to allow a heating element to be placed against a forearm — at various temperatures but not severe enough to cause burns or lasting damage. Some of the experiments required them to endure it for 10 to 20 seconds.
“It's like holding a hot cup of coffee that you really want to put down but can't quite yet,” Wager said.
While this was going on, functional magnetic resonance imaging scans, which don't require radiation as X-rays do, recorded changes in brain activity. Computers then generated patterns, or signatures, from the readings.
“It's really what seems to be a true measure of the experience that the patient's having,” and it puts a number to pain severity, which could then guide care, said Dr. Costantino Iadecola, director of the Brain and Mind Research Institute at Weill Cornell Medical College. Iadecola had no role in the new studies.
Researchers took their work a step further: It involved 40 people who had recently lost a serious love relationship and were feeling intensely rejected. Besides the heat-on-the-arm tests, each underwent scans while being shown a picture of his or her former partner and then a picture of a good friend.
Researchers found that the brain signatures for emotional pain were different from the ones for physical pain.
“That's very provocative,” an indication of the scans' accuracy, said Dr. Allan Ropper, a neurologist at Brigham and Women's and Harvard University.
In yet another experiment, researchers gave 21 participants two infusions of a morphine-like painkiller while they were being scanned and given the heat tests. The first time, they knew they were getting the drug. The second time, they were told they were getting placebos but in fact got the drug again.
Brain signatures showed their pain was being relieved both times, in proportion to how much drug was in their systems.
“This is beginning to open a new wedge into brain science,” Ropper said. “There may be completely novel ways of treating pain by focusing on these areas of the brain rather than on conventional medications, which block pain impulses from getting into the spinal cord and brain.”
Shurtleff, of the drug abuse agency, said he hoped the research would lead to newer drugs.
“We want medications that can reduce this signature” but that don't have a risk of addiction, he said.
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