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Nerve 'Memories' Hold Clues to Treating Chronic Pain

FILE - OxyContin, an opioid drug. Americans, even though comprising only five percent of the world's population, consume eighty percent of the its supply of pain medication

With the U.S. Congress focusing on an epidemic of opioid abuse in this country, some new research is focusing on chronic pain as one of the reasons people get hooked on pain meds.

As VOA reported Wednesday, an estimated 30,000 people in the United States will die this year as a direct result of opiate abuse.

The United States consumes 80 percent of the world's prescription opiates, and an estimated 100 million Americans live with pain.

The U.S. Congress, in a rare show of bipartisan support, is considering all kinds of initiatives to fight the epidemic and restrict the free flow of painkillers.

Meanwhile, some scientists are focusing on why our natural response to pain can persist long after an injury is fully healed.

Your nerves remember

We've all had our share of scrapes, cuts, bruises, sprained ankles and broken bones. They hurt, then they heal. The pain comes, and then it goes.

Except sometimes it doesn't.

Researchers from King's College London set out to answer a simple question: why does pain sometimes persist even after an injury is fully healed?

"We are ultimately trying to reveal why pain can turn into a chronic condition," said Dr. Franziska Denk, an author of the study. "We already knew that chronic pain patients have nerves that are more active."

In those cases, the nervous system remains highly sensitive in an area of injury, causing pain that doesn't go away for weeks, months, even years.

So the scientists focused on some particular immune cells in mice that previous research has shown play a role in persistent pain. What they found is that when SOME nerves are damaged something called their epigenetics change, and it stays changed.

Think of the epigenetics as the nerves' "memory." In the same way a particularly bad memory can cause emotional pain long after a breakup or the loss of a loved one, epigenetics seem to keep the nerves active long after an injury has passed.

Therapy for your nerves

What the researchers don't know is why some nerves don't remember pain, and why others just can't forget.

After all, nerve cells are replaced just like skin cells and blood cells.

"Cells have housekeeping systems" Denk said, "... the majority of their content are replaced and renewed every few weeks and months. So why do crucial proteins keep being replaced by malfunctioning versions of themselves?"

Understanding that, and finding a way to coax the nerve cells into letting go of their bad memories, could open the door to solving the problem of chronic pain, and the wave of damage, death and addiction that is its hallmark.