Post-traumatic stress disorder, or P-T-S-D… and the anxiety that comes with it… can occur in people who have been exposed to a traumatic event. It usually develops after exposure to violent personal assaults, natural or human-caused disasters or military combat. And just as the persistent frightening thoughts and memories that accompany an ordeal seldom fade, research is now finding that reaction to outside stimuli like acute pain is actually dulled by the disorder as well.

Research published in the Archives of General Psychiatry finds that patients with post-traumatic stress disorder show reduced pain sensitivity.

Doctors designed a novel study to look at the tie between the brain and pain processing in patients who had P-T-S-D. Twelve male veterans with P-T-S-D and twelve male veterans who didn’t have the disorder were matched for age and period of deployment.

Researchers attached a probe to the hand of each research subject and, while subjecting them to fixed and variable bursts of heat on a small spot on the hand, conducted functional M-R-I imaging of the pain centers in the brain. The patients also verbally rated the pain they experienced.

The result? The M-R-Is showed less activity in pain centers of the brains of P-T-S-D sufferers, and they reported experiencing less pain than subjects who did not suffer from P-T-S-D.

Researchers concluded that pain processing is actually altered in patients who have post-traumatic stress disorder, leaving them not only emotionally numb, but more numb to pain as well.