Can Chronic Pain Change How the Brain Perceives Pain?
by Lisa DiFalco
Chronic pain is an issue for many patients. Approximately 1.5 billion people globally experience chronic pain. While recent injuries may result in problems with chronic pain, fibromyalgia and other conditions may increase pain sensitivity for reasons as yet unknown to medical practitioners. Patients suffering from chronic pain may seek to manage symptoms with prescription drugs and conventional and alternative therapies. What is less understood is how the brain responds to chronic pain and how it may be altered.
Previous studies have looked at nociception, but a new study is the first to look at what happens in the brain once sensory signals have arrived. The study, Chronic pain induces generalized enhancement of aversion, reveals that the brain may amplify its reaction to new injuries. Led by NYU Langone researchers, findings from this study were presented to the American Pain Society during their annual meeting.
This initial study provides findings that not only may impact those with chronic pain, but also patients with depression, anxiety or migraines. Research reveals that chronic pain can increase aversion to other forms of stimuli that may not be painful in and of themselves. Learn more about chronic pain and the new study underscoring the influence of chronic pain on the brain.
What Is Chronic Pain?
Chronic pain can be debilitating without intervention. While recent studies are interesting, it will be some time until they impact available treatments for those experiencing chronic pain. Patients should be informed of their options and what type of pain can be defined as chronic pain. According to the American Chronic Pain Association, chronic or persistent pain is defined as:
“Ongoing or recurrent pain, lasting beyond the usual course of acute illness or injury healing, more than three to six months, and which adversely affects the individual’s well-being.”
Chronic pain may be classified as nociceptive, or as a result of an ongoing tissue injury, neuropathic or due to damage to the spinal cord, brain or peripheral nerves, or a mixture of the two combined with undesirable psychosocial effects.
It is not only adults and the elderly that suffer from chronic pain as cases are also found in pediatric populations. Twenty to 40 percent of adolescents and children are believed to be impacted by chronic pain. Children and adolescents most often experience abdominal pain, headaches and musculoskeletal pain.
What Are Chronic Pain Treatments?
There is a range of available options for those suffering from chronic pain. Active interventions are endorsed as patients are involved in learning more about their condition and what they can do to reduce discomfort and increase function. Active therapy is often recommended. Exercise programs may benefit individuals with chronic pain and applicable programs may include a combination of:
- Cardiovascular conditioning exercises;
- Strength training exercises;
- Range-of-motion exercises; and
Aquatic exercises may proceed land-based exercises for certain individuals with comorbidities or that have issues participating in a low-level land program. A health care professional who has experience with chronic pain treatment can create a graded and comfortable exercise program that takes into account the needs and discomfort of a patient. This is only one of the non-invasive treatment options to look into. Patients may also want to explore more invasive interventions, surgery, pain medications including opioids, and alternative therapies, including acupuncture, chiropractic and massage therapy.
Chronic Pain and the Perception of Pain
A recent study published in eLife shows evidence to support the ability of chronic pain to distort the intensity of how pain is perceived elsewhere as it relates to a specific brain region. The study bolsters the theory that chronic pain has the ability to rewire important circuits in the anterior cingulate cortex (ACC), increasing “aversion.” In such a case, more attention is paid toward and a stronger alarm is given to incoming pain signals from areas other than the source of chronic pain. This study came about after unusual observations with patients. Jing Wang, MD, PhD, vice chair for Clinical and Translational Research Department of Anesthesiology, Perioperative Care and Pain Medicine at NYU Langone, said:
“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. Our study results argue that chronic pain causes distortion in how the ACC calculates pain intensity with system-wide consequences.”
This is the first study to demonstrate that chronic pain in a single location can result in an increased reaction to pain-causing stimuli. The stimuli may come from other locations throughout the body. In the study done by NYU Langone Medical Center researchers, it was found that rats with chronic pain in a single limb showed increased aversion response when it came to acute pain stimuli in another limb. Researchers found:
- Chronic pain significantly increased ACC activity;
- Increasing AAC activity also altered the response to low-intensity pain stimuli in the brain; and
- Reducing ACC nerve cell signaling decreased the aversive behavioral response and brought it back to normal.
Chronic pain can alter not only pain processing but also increase responses to other stimuli, such as light in patients that experience migraines, which may be aversive although not painful. There is a suggestion that chronic depression and anxiety may also increase the attention and perception of incoming pain stimuli. Wang and colleagues are working on additional research exploring the relationship between ACC activity and chronic pain. Clinical tests are set to begin in 2018.
Why Is Research into Chronic Pain of Interest?
Healthcare professionals, behavior analysts, case workers and patients want to learn more about underlying mechanisms involved in the perception of pain and how to reduce the severity of pain symptoms and improve function. At this time, additional research on the topic is needed to support the findings surrounding the influence of chronic pain on the brain.