Torture Alters the Way the Brain Perceives Pain, Study Suggests

Torture permanently alters the way a person's body perceives pain, a new study led by Tel Aviv University researchers found.

The scientists looked at 104 combat veterans from the 1973 Yom Kippur War, 60 of whom were taken prisoner. As part of the study, all underwent a series of psychological pain tests, such as applying a heating device to one arm, submerging the other in a hot water bath and pressing a nylon fiber into a middle finger. Each was also given a questionnaire.

Those who had been prisoners of war exhibited diminished pain inhibition, or the degree to which the body eases one pain in response to the other. They also showed heightened pain excitation, or the degree to which repeated exposure to the same sensation increases the resulting pain.

Whether these differences were the result of years of chronic pain or of the original torture is not clear, the researchers note, though a statistical analysis of test data suggested torture has a direct effect on one's ability to regulate pain. Overall, it was clear that the ex-POWs had worse pain regulation than those who suffered from chronic pain but were not taken prisoner and tortured.

"The human body's pain system can either inhibit or excite pain. It's two sides of the same coin," co-author Ruth Defrin of the Department of Physical Therapy said in a statement. "Usually, when it does more of one, it does less of the other. But in Israeli ex-POWs, torture appears to have caused dysfunction in both directions. Our findings emphasize that tissue damage can have long-term systemic effects and needs to be treated immediately."

Non-physical torture may also contribute to to the ex-POWs' chronic pain, according to the study. Among other things, the former prisoners were not allowed to use the toilet, threatened and told misinformation about loved ones. Most were moved to a group cell later in their imprisonment, replacing their isolation with intense crowding.

"We think psychological torture also affects the physiological pain system," Defrin said. "We still have to fully analyze the data, but preliminary analysis suggests there is a connection."