With training and the use of high-tech imaging equipment, subjects were able to influence their pain by controlling activity in one of the pain centers of the brain through the use of mental exercises and by visualizing their own brain activity in real time.
Compare it to exercising your muscles in a top-of-the-line weight room. After repeated practice, you get better at it.
The scientists are hopeful the new technique may have potential for future use as long-term treatment for chronic pain patients - possibly even without all the high-tech equipment. They caution that significantly more work is needed before it can be thought of as a clinical treatment.
"We believe these subjects and patients really learned to control their brain and, through that, their pain," said Sean Mackey, MD, PhD, assistant professor of anesthesia and co-author of the study to be published in the Dec. 12 online issue of the Proceedings of the National Academy of Sciences.
The study posed two questions: "Can healthy subjects and patients with chronic pain learn to control activity in specific regions of their brain? And, in doing so, does this lead to an improved control of their pain?" The answer to both was a resounding "Yes." A second, larger study is under way to test the potential for long-term use in future therapy.
"Pain has a huge impact on individual patients, their families and society," said Mackey, who is also associate director of Stanford's pain management division. A recent national survey showed that more than half of all Americans suffer from chronic pain. "I got incredibly jazzed by the results [of the imaging study]," Mackey added. "We could change people's lives. However, significantly more science and testing must be done before this can be considered a treatment for chronic pain."
Using new technology called real-time functional magnetic resonance imaging, or rtfMRI, scientists placed subjects inside an MRI scanner where they were able to watch their brain activity on a moment-by-moment basis. The subjects were then shown "live" action images of their rostral anterior cingulate cortex, an area of the brain responsible for processing pain.
Subjects were given various mental strategies to try to change their brain activity. "As an example, we asked them to think about changing the meaning of the pain," Mackey said.
"Instead of thinking of it as a terrible experience, to think of it as something relatively pleasant. Then the patients were turned loose. Over time, subjects showed an increased ability to change their brain and by doing so to modulate their pain."
How did they do it exactly? "We really don't know, but then we really don't know how anyone controls their brain to perform an action," Mackey said.
Laura Tibbitt, 31, one of the subjects in the study who suffers from chronic back pain caused by a horseback riding accident seven years ago, said she used different thoughts to decrease the pain while watching her "brain on pain."
"I'd think of little people on my back digging out the pain, or I'd think of snowflakes," she said. "The goal was to exercise your brain, to retrain your brain. Sometimes I felt like I had made a change in my brain. The pain was never completely gone, but it was better."
Mackey said extensive controls were used in the study to make sure the results reflected a direct correlation between brain imaging and pain control.
"One of the questions that always comes up is, 'Did we just design the world's most expensive placebo?' " Mackey said. Researchers used multiple control groups to ensure against this: The first remained outside the MRI machine; the second received no imaging feedback; the third was shown different areas of the brain that don't process pain, and members of the fourth group were shown someone else's brain activity.
None of these control subjects showed an ability to control pain levels.
"Real-time functional neuroimaging is a wonderful tool for investigating the neurosystems in the brain responsible for the perception and processing of pain," Mackey said. "It allows us to do that in ways that we've never been able to before."
The study, which included 36 healthy subjects and eight subjects with chronic pain, was co-sponsored by researcher Christopher deCharms and his Bay Area company, Omneuron Inc. It was co-funded by the National Institutes of Health and Stanford University. Mackey and his Stanford collaborators have no financial ties to the company. Other Stanford researchers involved in the study include Fumiko Maeda, MD, PhD, research associate; Gary Glover, PhD, professor of radiology, and John Pauly, PhD, associate professor of electrical engineering. Former Stanford collaborators include David Ludlow, Deepak Soneji and John Gabrieli.
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