Researchers at Northwestern University in Chicago have discovered that patients suffering from chronic back pain lose gray matter in the brain. A study of 26 long- suffering patients found that the loss amounts to about 1.3 cubic centimeters for each year of pain.

The researchers estimate that this loss would correspond to about 10-20 years of aging. The loss is concentrated in the regions of the brain involved in emotional processing and behavioral control and in the thalamus, which relays sensory information to the cortex.

The researchers earlier reported that people with chronic back pain perform poorly in emotional decision-making tasks. It is not entirely clear which is the chicken and which is the egg.

Does the brain matter loss cause back pain or does the chronic back pain result in loss of gray matter? Exploration is ongoing.