Chronic Pain Linked to Depression and Sleep Problems

Researchers find that chronic pain can disrupt brain function and lead to a host of mental health issues from depression and disturbed sleep to indecisiveness and confusion.

Professor Dante Chialvo and colleagues at Northwestern University's Feinberg School of Medicine in Chicago conducted a study looking at the effects chronic pain has on the way the brain functions. The results are published in the Feb. 6 issue of The Journal of Neuroscience.

The researchers used functional MRI scans to monitor brain activity in people with chronic low back pain while they followed a moving bar on a computer screen with their eyes. They then repeated the test with a control group of people with no pain.

In the participants without any pain the brain appeared to be in a state of balance. The different regions of the brain worked as a team, when one region was active, the others showed reduced activity until it was their turn. In the participants suffering from chronic pain the picture was much different. The MRI scans revealed that a part of the brain in the frontal cortex, which is mainly associated with emotion, was constantly active.

This chronic activation of the cortex has potential long-term consequences for the health and functioning of the brain in pain sufferers. Neurons in this part of the brain could wear out and alter their connections with each other.

"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," Prof. Chialvo said.

He explained that "If you are a chronic pain patient, you have pain 24 hours a day, seven days a week, every minute of your life. 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."

Since it seems to be a region of the brain associated with emotional responses that is most affected, chronic pain patients may have an increased likelihood of being affected by problems such as depression and sleep disorders.

Prof. Chialvo said that the chronic activation in the cortex "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," he said.

Prof. Chialvo and colleagues concluded that the findings show, along with finding new ways to treat pain, it's also important to develop methods to evaluate and prevent disruption of brain function caused by chronic pain.

Although the study used patients with chronic low back pain, the results are likely to be representative of patients who suffer from any kind of chronic pain, such as that experienced by fibromyalgia patients throughout their bodies.

Source: Northwestern University, press release, Feb 5, 2008