Nav: Home

Chronic pain amplifies the brain's reaction to new injuries

May 19, 2017

Chronic pain in any one body part may distort the intensity with which a key brain region perceives pain everywhere else.

This is the finding of a study in rats, which was led by researchers at NYU Langone Medical Center, published in the journal eLife, and presented at the annual meeting of the American Pain Society May 19.

Designed by evolution to help us avoid injury and be more likely to survive, our brains are wired to generate alarm when we are injured, and fear when we again encounter the same injury source.

The new study supports the theory that chronic pain rewires circuits in a brain region called the anterior cingulate cortex (ACC) to increase "aversion," the amount of attention paid to, and alarm felt about, any given pain signal, say the study authors. Most previous studies have focused on nociception, the intensity of incoming sensory signals from say a burnt finger, instead of what the brain does with such signals once they arrive.

"We pursued this study because of what we saw in the clinic, where patients with chronic pain, say in the lower back, report much higher than normal pain after surgery in the knee or abdomen," says Jing Wang, MD, PhD, vice chair for Clinical and Translational Research Department of Anesthesiology, Perioperative Care and Pain Medicine at NYU Langone. "Our study results argue that chronic pain causes distortion in how the ACC calculates pain intensity with system-wide consequences."

As many as 1.5 billion people worldwide suffer from chronic pain, some from fibromyalgia and several other syndromes where patients are more sensitive to pain throughout the body for reasons unknown.

More Pain Everywhere

Past research had shown that a body part that is the source of chronic pain triggers greater than normal signaling activity in ACC nerve cells when that same area is injured again. The new study is the first to show that chronic pain in one locale causes a greater reaction to pain-causing stimuli throughout the body. Specifically, researchers found that chronic pain in one limb in rats increased the aversive response to acute pain stimuli in the opposite limb.

To understand these mechanisms behind this, Wang and colleagues stitched into a certain spot in the DNA of nerve cells in rats the code for a light-sensitive protein. At the same time, the team implanted electrodes in the AAC to measure nerve cell activity. With these elements in place, the team was able to shine light on the ACC, which reacted with the light-sensitive protein to adjust the activity of nerve cells there as rats encountered painful stimuli, judged their intensity, and learned to avoid them.

The researchers found that chronic pain dramatically increases ACC activity, and that artificially increasing AAC activity made the brain region's response to low intensity pain stimuli larger than normal, such that it "bothered" the rat much more than it should. By the same token, turning down ACC nerve cell signaling returned the aversive behavioral response, which had been amplified by chronic pain, back to normal.

Beyond pain processing, the study results imply that chronic pain can magnify responses to stimuli that are aversive but not painful, like the responses to light that worsen migraines. Furthermore, the ACC is known to be involved in emotional processes and connected to many brain regions. That, combined with the current study results, suggests that chronic anxiety and depression may also amplify the attention and alarm attached to pain stimuli that would otherwise be too small to bother us, researchers say.

In zeroing in on the ACC, the research team has also provided a rational target for technologies like deep brain stimulation and transcranial magnetic stimulation, which deliver electric currents to reverse nerve cell signaling patterns that cause disease, says Wang. He and his colleagues are already working on related protocols designed to dial back the increased ACC activity linked to chronic pain, with clinical testing expected to begin in 2018.
-end-
Along with Wang, the NYU Langone study authors were Qiaosheng Zhang, Toby Manders, Ai Phuong Tong, Runtao Yang, Arpan Garg, Erik Martinez, Haocheng Zhou, Jahrane Dale, Abhinav Goyal, Louise Urien, Guang Yang, and Zhe Chen, most of whom are in the Department of Anesthesiology, Perioperative Care and Pain Medicine or the Department of Neuroscience and Physiology, or both. This work was supported by National Institute of General Medical Sciences grants GM102691 and GM115384, National Institute of Neurological Disorders and Stroke grant NS100065, and National Science Foundation grant IIS-1307645, as well as by the Anesthesia Research Fund of New York University Department of Anesthesiology.

NYU Langone Medical Center / New York University School of Medicine

Related Chronic Pain Articles:

Molecular link between chronic pain and depression revealed
Researchers at Hokkaido University have identified the brain mechanism linking chronic pain and depression in rats.
How chikungunya virus may cause chronic joint pain
A new method for permanently marking cells infected with chikungunya virus could reveal how the virus continues to cause joint pain for months to years after the initial infection, according to a study published Aug.
Gastroesophageal reflux associated with chronic pain in temporomandibular joint
Gastroesophageal reflux (GERD) is associated with chronic, painful temporomandibular disorder -- pain in the temporomandibular joint -- and anxiety and poor sleep contribute to this association, according to a study in CMAJ.
One step closer to chronic pain relief
While effective drugs against chronic pain are not just around the corner, researchers from Aarhus University, Denmark, have succeeded in identifying a protein as a future potential target for medicinal drugs.
Gut bacteria associated with chronic pain for first time
In a paper published today in the journal Pain, a Montreal-based research team has shown, for the first time, that there are alterations in the bacteria in the gastrointestinal tracts of people with fibromyalgia.
Nearly 5.4 million cancer survivors suffer chronic pain
A new report finds about one in three cancer survivors (34.6%) reported having chronic pain, representing nearly 5.4 million cancer survivors in the United States.
New opioid speeds up recovery without increasing pain sensitivity or risk of chronic pain
A new type of non-addictive opioid developed by researchers at Tulane University and the Southeast Louisiana Veterans Health Care System accelerates recovery time from pain compared to morphine without increasing pain sensitivity, according to a new study published in the Journal of Neuroinflammation.
New target for chronic pain relief confirmed by scientists
A research group at Hiroshima University observed a potential new target for chronic pain treatment.
Menopause symptoms nearly double the risk of chronic pain
In addition to the other health conditions affected by estrogen, it has also been shown to affect pain sensitivity.
Research finds opioids may help chronic pain, a little
In a study published today by the Journal of the American Medical Association (JAMA), McMaster University researchers reviewed 96 clinical trials with more than 26,000 participants and found opioids provide only small improvements in pain, physical functioning and sleep quality compared to a placebo.
More Chronic Pain News and Chronic Pain Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.