SAN DIEGO, Aug. 20 (UPI) -- People who have quick tempers are likely to be more pain sensitive, while their easygoing neighbors find physical aches less painful, new research presented Tuesday at the 10th World Congress on Pain suggests.
People who suppress their anger also are more likely to feel pain, said the study's author, Stephen P. Bruehl, assistant professor of anesthesiology at Vanderbilt University in Nashville, Tenn.
Individuals with short fuses tend to produce very low levels of brain chemicals called endogenous opioids, also known as the body's natural pain-killers, "so they are feeling more pain and more constant pain," Bruehl said in an interview with United Press International. People who suppress anger, however, "actually have adequate levels of endogenous opioids, but they are still are more pain-sensitive," said Bruehl.
At least in the case of "raging bulls," personal anger management can boost production of endogenous opioids, explained Bruehl, who discovered this link between anger and pain by studying 43 chronic low back pain patients.
The patients completed psychological tests to assess anger management as well as more detailed studies that identified them as either "anger-out" (raging) types or "anger-in" (suppressed anger) types. The subjects also completed anger diaries to describe how they handled various situations and the frequency of their anger.
In two separate sessions, the patients were injected with either an opioid receptor blocker or a simple saline solution. After the injections the subjects were subjected to painful stimuli. When the opioid was blocked the "the anger-out people did not have an increase in acute pain, which indicates that endogenous opioid production is impaired, so blocking the receptor has no effect," Bruehl said.
Other subjects experienced increased pain when the receptor was blocked. Bruehl noted anger-in people also reported in anger diaries they experienced more pain, "but the increased pain among these people is not related to endogenous opioid production, so there must be a different mechanism," he said.
Asked what personality type is associated with decreased pain sensitivity, Breuhl made a peace sign and said it would be the "go with the flow" people.
Bruehl's theory is interesting, neurologist Fleming Bach, of Aarhus University in Aarhus, Denmark, told UPI, but it is far from convincing. For one thing, Bach said, one cannot measure levels of endogenous opioids simply by recording the response to an opioid blocker.
"We would need to test the spinal fluid to determine the true level," he said, adding other researchers have demonstrated it requires very "significant pain to provoke a response in endogenous opioids." Therefore Bruehl's study will "require confirmation," Bach said.
Bruehl's study was funded by the National Institute of Neurological Disorders and Stroke.