People who suffer from chronic pain often feel like the experience dominates their lives, and changes them profoundly.
Now, a group of pain researchers and geneticists have discovered that this feeling isn’t far from scientific truth. Being in chronic pain changes the way your brain functions on a physical level. The good news is that you can also change it back.
Pain researcher Maral Tajerian and her colleague Sebastian Alvarado wanted to find out whether chronic pain was changing the way the brain functions on a genetic level. Alvarado specializes in a burgeoning field called epigenetics, which looks at the way environment and experience affect gene expression, or activity. Was chronic pain epigenetic, an experience that changed brain gene function? They quickly discovered the answer was a resounding yes.
Tajerian and Alvarado’s work centered on mice who suffered a nerve injury that put them in chronic pain. Over a period of months, they discovered that the pain was affecting regions of the mice’s brains that had nothing to do with processing pain. In fact, they found that gene activity had been severely curtailed in the prefrontal cortex, a brain area that serves as the seat of higher reason and decision-making, as well as many emotions, in both rodents and humans.
“We saw chemical changes to the DNA in [the prefrontal cortex],” Alvarado told io9. Specifically, they found a 12 percent downward shift in DNA activity. “That’s really big,” he added. “Normally these changes are associated with cancer.” This lack of activity, Tajerian said, leads to a loss of density in this region of the brain — which ultimately causes cognitive impairment, depression and anxiety.
Taking the “Chronic” Out of Pain
If pain could change brain activity, Tajerian and Alvarado wondered, were there activities that could change it back? The two worked with colleagues at McGill University to design a simple experiment that might answer this question. They created groups of mice who had all suffered injuries that would cause long-term pain. One group was subjected to “impoverishment,” which meant a very small cage where they lived alone. Another group enjoyed “enrichment,” which meant they had a roomy cage with other mouse friends, as well as marbles to play with. Both groups had the same amount of food and care otherwise. (There was also a control that got typical lab mouse treatment.)
After two months, the mice in the enriched environment did not suffer chronic pain any longer. Or rather, their prefrontal cortexes showed normal mouse activity. Meanwhile, the impoverished mice showed the reduction in brain activity, which led to cognitive impairment. Along with colleagues, the two published a paper in PLoS One about the study earlier this year. The paper provides strong evidence that chronic pain is an epigenetic phenomenon, a life experience that actually changes gene expression in the brain.
Translated into human terms, this means that some people experience chronic pain because they have literally rewired their brains to be more sensitive to pain. The more pain they feel, the more anxious and vulnerable they are to feeling further pain.
And that’s actually a good thing.
“This paper gives me hope,” said Tajerian. The brain is a much more plastic organ than scientists realized even a decade ago, and the actions we take today can actually change how our brains function tomorrow. “A different environment will give you a different experience of pain. By changing the environment we could change the pain,” she said. “Having fun and friends is really good for you.”
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