Brain’s Natural Pain Killers Increase When in Chronic Pain

Just under a third of our population, or more than 100 million Americans, suffer from chronic pain. Chronic pain is pain that lasts for more than six months and, as the statistics imply, is an enormous burden in America and worldwide.

In fact, in the UK chronic pain afflicts approximately 46 percent of the population comprising 20 percent of consultations in general practice.

Now, a new study from the University of Manchester has shown for the first time that the numbers of opiate receptors in the brain increases to combat severe pain in arthritis sufferers.

The study originated when researchers observed that some people seem to cope better than others with pain. As such, investigators evaluated how these coping mechanisms work in hopes of discovering a new approach to treat this distressing symptom.

It has been known for a long time that we have receptors in our brains that respond to natural painkilling opiates such as endorphins, but the researchers in Manchester have now shown that these receptors increase in number to help cope with long-term, severe pain.

By applying heat to the skin using a laser stimulator, Dr. Christopher Brown and his colleagues showed that the more opiate receptors there are in the brain, the higher the ability to withstand the pain.

The study used Positron Emission Tomography (PET) imaging on 17 patients with arthritis and nine healthy controls to show the spread of the opioid receptors. Investigators found that individuals with arthritis and chronic pain had more opiate receptors sites in their brains than did the healthy control subjects.

Researchers believe the findings suggest the increase in opiate receptors in the brain is an adaptive response to chronic pain, allowing people to deal with it more easily.

Dr Brown said, “As far as we are aware, this is the first time that these changes have been associated with increased resilience to pain and shown to be adaptive.

“Although the mechanisms of these adaptive changes are unknown, if we can understand how we can enhance them, we may find ways of naturally increasing resilience to pain without the side effects associated with many pain killing drugs.”

Professor Anthony Jones, the director of the Manchester Pain Consortium comments, “This is very exciting because it changes the way we think about chronic pain.

“There is generally a rather negative and fatalistic view of chronic pain. This study shows that although the group as a whole are more physiologically vulnerable, the whole pain system is very flexible and that individuals can adaptively upregulate their resilience to pain.

“It may be that some simple interventions can further enhance this natural process, and designing smart molecules or simple non-drug interventions to do a similar thing is potentially attractive.”

Val Derbyshire, a patient with arthritis said, “As a patient who suffers chronic pain from osteoarthritis, I am extremely interested in this research. I feel I have developed coping mechanisms to deal with my pain over the years, yet still have to take opioid medication to relieve my symptoms.

“The fact that this medication has to be increased from time to time concerns me greatly, due to the addictive nature of these drugs. The notion of enhancing the natural opiates in the brain, such as endorphins, as a response to pain, seems to me to be infinitely preferable to long term medication with opiate drugs.

“Anything that can reduce reliance on strong medication must be worth pursuing.”

The study is found in the journal Pain.

Source: University of Manchester/EurekAlert
Abstract of brain photo by shutterstock.