Chronic pain is a poorly understood condition in which the nervous system consistently fires out pain signals for a long period of time, sometimes without an actual injury to trigger it. Compared to acute pain, chronic pain typically lasts for six months or more, and it turns out that it might change our bodies on a genetic level.

A new study out of McGill University is one of the first to find that chronic pain may change the DNA in our immune systems and brain — proving the condition may have more far-reaching effects than previously believed.

“We found that chronic pain changes the way DNA is marked not only in the brain but also in T cells, a type of white blood cell essential for immunity,” said Moshe Szyf, a professor in the Faculty of Medicine at McGill, in the press release. “Our findings highlight the devastating impact of chronic pain on other important parts of the body such as the immune system.”

For the study, the researchers analyzed DNA in the brain and white blood cells of rats, using a chemical known as a methyl group to map out the DNA and allow them to see how the genes function. They found that a large number of genes in the brain and immune system had been completely changed, suggesting that other parts of the body may also be altered by persistent chronic pain.

Researchers are currently working to better understand chronic pain, as it’s difficult to treat and can lead to lifelong disability for some sufferers. According to an NIH study released last year, some 25.3 million American adults have experienced chronic pain every day for the past three months. That’s a large chunk of the population who suffer from back pain, arthritis, or headaches, and often turn to painkillers to ease the burden — especially veterans. Because opioid addiction is a huge problem in the U.S., a more sustainable treatment for — and a better understanding of — chronic pain will need to be investigated. Aside from opioids, many chronic pain sufferers turn to alternative medicine and even yoga to help treat their condition.

More research will be needed, but Szyf and his team are hoping that the study can jumpstart new avenues of treatment for specific genes marked by chronic pain.

“We were surprised by the sheer number of genes that were marked by the chronic pain — hundreds to thousands of different genes were changed,” Szyf said. “We can now consider the implications that chronic pain might have on other systems in the body that we don’t normally associate with pain."

Source: Massart R, Dymov S, Millecamps M, Suderman M, Gregoire S, Koenigs K. Overlapping signatures of chronic pain in the DNA methylation landscape of prefrontal cortex and peripheral T cells. Scientific Reports, 2016.