A study indicates that chronic pain affects overall brain function, which may explain many of the common cognitive and behavioral problems seen in such patients.
MRI studies at Northwestern University, in Chicago, Illinois, found that individuals with chronic back pain (CBP) also had changes in the functional connectivity of their cortical regions _ areas of the brain that are unrelated to pain _ compared with healthy control subjects in the study.
“This is the first clue we have that conditions such as depression, anxiety, sleep disturbances, and decision-making difficulties, which affect the quality of life of chronic pain patients as much as the pain itself, may be directly related to altered brain function as a result of chronic pain,” states principal investigator Dante Chialvo, Neurology & Neurosurgery.
According to Dr. Chialvo, at rest, the healthy brain is in a state of cooperative equilibrium, so that when one region is active, the others are less active or deactivated. These resting areas, known as the default mode network (DMN), usually “shut off” when a person pays attention or undertakes a task.
However, the regions of the DMN in chronic pain patients never “quiet down.”
“Our paper shows pain not only hurts patients, but the unrelenting perception of pain also harms the brain. Using technology such as MRI, we can objectively quantify this effect,” said Dr. Chialvo.
The MRI studies showed that although CBP subjects could complete a given task as well as healthy controls, it was at the expense “of using their brain differently from the pain-free group.”
Furthermore, the study suggests that over time, chronic pain may lead to permanent reorganization of the brain. “We observed that the effect on the cortical regions was greater among individuals who had had chronic pain for a longer period of time.”
If these findings are confirmed, he added, this may indicate a need for early, aggressive treatment of pain to mitigate discomfort and/or prevent associated conditions such as depression, sleep disturbances, and cognitive impairment.
Dr. Chialvo’s next research steps will include investigating potential functional differences in cortical regions of the brains of men and women.
“It is well-known that chronic pain affects 3 times as many women as men, but no one has a clue why this is. We are going to look at resting-state levels initially in healthy females and males and ultimately in individuals with chronic pain to determine whether the default network is different between the sexes,” he said.
The National Institutes of Health supported the study.
J Neurosci. 2008;28:1398-1403.