Hassett is studying patients with OA who have had their knee or hip replaced. “About 20 percent continue to have chronic pain. The pain has likely become centralized – they no longer need to have outside input from inflammation or injury. The pain is driven by dysfunction in the central nervous system,” Hassett says.

Fibromyalgia pain, once thought to be in the ligaments and soft tissues, is now believed to be directed by the CNS as well.

According to a 2010 review in the journal Pain, brain changes that result from chronic pain appear to be specific to each type of chronic pain. The brain changes in someone with chronic back pain, for instance, might look different from changes that originated from OA. And pain “looks” different in each brain, depending on how it is perceived. In other words, understanding pain’s imprint on the brain isn’t easy, and is far from complete.

As for whether chronic pain and resulting brain changes can be reversed, no one knows for sure – but small studies suggest it’s possible. A 2010 study in Arthritis & Rheumatism of 16 patients with hip pain found that gray matter in the thalamus, part of the brain involved in sensory perception, decreased during chronic pain. Nine months after hip replacement, the gray matter had normalized.

“The presumption was that the ongoing input from the damaged joint led to reversible changes in the thalamus that contributed to chronic pain,” says Dr. Hochman. “The researchers’ impression was that the abnormalities in pain processing normalized after the removal of the damaged joint and the chronic input into the CNS. But there may be a subset of people in which changes are irreversible.”

Make Pain A Priority

Despite the sobering data about widespread chronic pain, the good news is that, as scientists embrace chronic pain as its own disease, they can begin to explore treatments addressing the CNS instead of – or in addition to – treating whatever condition jump-started your pain. But they can’t treat what they don’t know, so here are ways to help doctors help you.

Don’t Tough It Out. Experts define “chronic pain” as pain that has lasted three months or longer, or pain that persists beyond the expected healing time of an injury. Take steps to stop pain before it becomes chronic.

Immediate, short-term pain is much easier to treat, says Dr. Borenstein. “Patients say, ‘I don’t want medications,’ but I try to convince them to take enough so that the nervous system does not get pain signals,” he says.