For chronic pain sufferers, the daily frustrations of a condition that can impair their mobility, prevent them from working, and draw scorn from others often leads to other psychiatric conditions. Depression, anxiety disorders, and sleep disturbances are common among patients with chronic pain. In addition to the external stress of coping with a painful and debilitating condition, new research indicates that chronic pain may also alter the brain's neural circuitry, potentially increasing an individual's vulnerability to other psychiatric conditions.
Using fMRI scans, researchers from Northwestern University's Feinberg School of Medicine examined neural activity of 30 subjects at baseline and while performing a simple task. Half of the subjects suffered from chronic back pain. Task accuracy did not differ among the subjects, but patterns in brain activity did. As part of what has been termed the brain's "default mode network," some areas of the brain become active when the brain is idle, taking over for other areas that have deactivated. While being scanned, the subjects were asked to track the height of a moving image on a computer screen. In the healthy control subjects, brain regions that compose the default mode network deactivated in response to this task, while other areas of the brain became active. In chronic pain sufferers, however, one part of the default mode network did not deactivate. The researchers surmise that the constant perception of pain could cause disruptions in the default mode network, and these disruptions can have harmful consequences for the brain. Heightened activity in areas that should be deactivated may lead to changes in neural connections or cause neurons to die.
This overly active region of the brain, the medial prefrontal cortex, is involved in emotions, and this is the first study to find that chronic pain may affect the brain's ability to process information not related to pain. The researchers suggest that changes in the how the default mode network functions could have lasting consequences and play a role in the cognitive and behavioral symptoms associated with chronic pain. As head researcher Dante Chialvo explained in a press release, the brain changes associated with chronic pain "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."
It's important for physicians to recognize that the stress and frustration of chronic pain put patients at risk for depression, anxiety, and other psychiatric disorders. This study indicates the importance of also considering the potential for biological changes brought about by chronic pain. The researchers theorize that these changes increase over time, and they believe that early treatment addressing the behavioral and cognitive symptoms of chronic pain as well as pain management may be beneficial. Depression, anxiety, and other conditions often accompany chronic pain, and researchers should continue studying the potential relationships between these disorders.
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