Chronic Pain Can Damage Brain

People who suffer chronic pain have constant brain activity in areas of the brain that would normally be at rest, according to a new study at Northwestern University’s Feinberg School of Medicine. 

The study suggests chronic pain changes the way information is processed in the brain, and the findings could explain why those who experience long-term pain frequently suffer other symptoms such as anxiety, depression, sleep disorders, and difficulty making decisions.

During the study, researchers used functional magnetic resonance imaging (fMRI) to scan the brains of 15 people with chronic low back pain and 15 pain-free volunteers while both groups were tracking a moving bar on a computer screen.  Although the pain sufferers performed the task well, when researchers measured areas of the brain activated, differences emerged.

In the healthy brains all regions existed in a state of equilibrium — when one region was active, the others quieted down.  But in those with chronic pain, a front region of the cortex mostly associated with emotion “never shuts up,” said Dante Chialvo, the study’s lead author and associate research professor of physiology at the Feinberg School. The region was stuck on full throttle, wearing out neurons and altering their connections to each other.

“The areas that are affected fail to deactivate when they should,” Chialvo said.

“Where we were surprised is the difference in how much brain they used to do the task compared with the healthy group. It was 50 times larger,” Chialvo told Reuters.

This is the first demonstration of brain disturbances in chronic pain patients not directly related to the sensation of pain.   

When certain parts of the cortex were activated in the pain-free group, some others were deactivated, maintaining a cooperative equilibrium between the regions. This equilibrium is known as the resting state network of the brain. In the chronic pain group, however, one of the nodes of this network did not quiet down as it did in the pain-free subjects.  Instead, a front region of the cortex mostly associated with emotion is constantly active, disrupting the normal equilibrium.

The researchers said disruptions in this default network could explain why pain patients have problems with attention, sleep disturbances and even depression.

This constant firing of neurons in these regions of the brain could cause permanent damage, Chialvo said. “We know when neurons fire too much they may change their connections with other neurons or even die because they can’t sustain high activity for so long,” he explained.  

‘If you are a chronic pain patient, you have pain 24 hours a day, seven days a week, every minute of your life,” Chialvo said. “That permanent perception of pain in your brain makes these areas in your brain continuously active. This continuous dysfunction in the equilibrium of the brain can change the wiring forever and could hurt the brain.”

Chialvo hypothesized the subsequent changes in wiring  “may make it harder for you to make a decision or be in a good mood to get up in the morning. It could be that pain produces depression and the other reported abnormalities because it disturbs the balance of the brain as a whole.”  

“These findings suggest that the brain of a chronic pain patient is not simply a healthy brain processing pain information but rather it is altered by the persistent pain in a manner reminiscent of other neurological conditions associated with cognitive impairments,” the researchers wrote in their report.

Chialvo said the study’s findings show it is essential to research new approaches to treat patients not just to control their pain but also to evaluate and prevent the dysfunction that may be generated in the brain by the chronic pain.

The study was supported by the National Institute of Neurological Disorders and Stroke, and is published in the Feb. 6 issue of The Journal of Neuroscience.

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Video: View evidence of brain disturbance in a chronic pain patient

Audio: Dante Chialvo, associate research professor of physiology at Northwestern University’s Feinberg School of Medicine, discusses the study’s possible implications on clinical treatments

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