Chronic Pain Shrinks the Brain

A Northwestern University study shows chronic back pain shrinks the brain by as much as 11 percent, which is equivalent to the degeneration of 10 to 20 years of aging.

Although chronic pain greatly diminishes quality of life and increases anxiety and depression for 10 percent of Americans, it was previously assumed that the brain reverts backs to its normal state after chronic pain stops. This was the first study to examine brain changes due to chronic pain.

Using magnetic resonance imaging (MRI) data and automated analysis techniques, researchers compared the brain /images of 26 participants with chronic back pain to those of normal participants. The participants with chronic back pain had unrelenting pain for more than one year.

The study shows the reduction in brain density is related to pain duration, pain-related characteristics, and is more severe in the neuropathic type of pain, which is caused by sciatic nerve damage.

Researchers hypothesize that some of the decrease in brain density reflects only tissue shrinkage, which could be reversed with proper treatment. They say it may also be attributed to more irreversible processes like neurodegeneration.

Given that, by definition, chronic pain is a state of continuous persistent perception with associated negative affect and stress, one mechanistic explanation for the decreased gray matter [the part of the brain that processes information and memory] is overuse atrophy [degeneration] caused by excitotoxic and inflammatory mechanisms.

They continue on to say that as the loss in brain elements progresses, it may dictate the properties of the pain state to the point that it becomes more irreversible and less responsive to therapy.