Frontier: Chronic pain harms the brain
News from the frontier

by Faith Hickman Brynie

March, 2008

Chronic pain carries with it a load of other miseries: depression, anxiety, sleep disturbances, even difficulty making decisions. Reporting in the Feb. 6 Journal of Neuroscience, a team of Northwestern University scientists explains why.

A healthy, pain-free brain maintains a state of equilibrium, explains lead researcher Dante Chialvo, an associate research professor of physiology at Northwestern University’s Feinberg School of Medicine. When some regions are active, others quiet down.

But in people who feel chronic pain, many brain regions fail to deactivate. A front region of the cortex “never shuts up,” Chialvo says. The sustained activity can damage neurons and disrupt their connections.

Chialvo’s team used functional magnetic resonance imaging (fMRI) to scan the brains of 30 adult volunteers, half with chronic low-back pain and the other half pain-free.

The subjects used a modified joystick to rate the height of a bar continuously moving across a computer screen. The subjects with chronic pain performed as well as the painfree subjects did, but their brains operated differently.

In the pain-free group, activation of some parts of the cortex while performing the task corresponded with deactivation of other parts—a state Chialvo calls a “cooperative equilibrium.” But in the chronic-pain group, some parts of the brain did not quiet down as they did in the pain-free subjects, which may cause the neuron damage described above.    

The resultant changes in the brain’s wiring may make it harder for people in chronic pain “to make a decision or be in a good mood to get up in the morning,” Chialvo says. “It could be that pain produces depression and other abnormalities because it disturbs the balance of the brain as a whole.”