Researchers Found a Biomarker for Chronic Pain in the Brain

The new discovery offers clues to understanding the neuroscience behind chronic pain.

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A distraught senior Asian woman feeling unwell, suffering from neck and shoulder pain, massaging ach...
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Chronic pain is a double-whammy condition. It’s not only poorly understood, but its incredibly common. A study out last month found that between 2019 and 2020, the incidence of chronic pain in adults surpassed that of diabetes, depression, and high blood pressure. And even though every organism experiences pain, there’s still much we don’t know.

A new discovery, however, offers clues to understanding the neuroscience behind chronic pain. Published on May 22 in the journal Nature Neuroscience, a study funded by two branches of the National Institutes of Health details the first observed pain-related biomarkers from within the brain. Of the four study participants, three experienced chronic pain caused by stroke and one by amputation, resulting in phantom limb pain.

To better understand what was going on in the brains of these four chronic pain patients, the study’s authors at the University of California, San Francisco, surgically implanted electrodes in each participant’s brain that tracked activity in their anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC). For three to six months, the researchers tracked chronic pain in these patients in two ways. Several times a day, they asked the participants to describe the pain verbally. At the same time, the researchers took recordings of the two brain regions to see what their brains looked like. They took these instantaneous recordings using a remote control.

"What we saw is each patient's biomarker was actually like a unique fingerprint," first author Prasad Shirvalkar, a professor of anesthesia and neurological surgery at UCSF, stated in a press conference on May 18, according to Live Science. Some patients’ pain, Science News reports, fluctuated on a three-day cycle and corresponded with activity in the OFC.

Why is this so important? The ACC processes emotions and regulates emotional responses, while the OFC, which is also involved in emotional processing, analyzes the consequences of complex situations. The ACC has been more rigorously studied in relation to chronic pain, but the UCSF team hypothesized, based on available research, that both regions offer brain waves that could serve as objective metrics for chronic pain.

This finding won’t become the new benchmark in decoding a patient’s pain experience but as a starting point to employ pain-relieving therapy. This technology is a sophisticated step up from the 0 through 10 pain scale used today.

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