AAPM 2009: Negative Emotions About Pain Raise Interleukin-6 Levels

Allison Gandey

February 05, 2009

February 5, 2009 (Honolulu, Hawaii) — Patients who focus on their pain, feel helpless when experiencing it, and are generally pessimistic about outcomes have increased interleukin-6 levels, a new study shows. It is reportedly the first work to demonstrate this link and was presented here at the American Academy of Pain Medicine 25th Annual Meeting.

“Catastrophizing about pain is one of the most potent psychological variables to emerge in the literature in recent years,” Robert Edwards, PhD, from Brigham and Women’s Hospital, in Boston, Massachusetts, said during his presentation.

Pain-related catastrophizing consists of negative cognitive and emotional processes, including the magnification of pain-related symptoms and rumination about pain.

Dr. Edwards reported that at least a dozen other prospective studies have shown that catastrophizing has a negative long-term impact on outcomes. While previous studies have looked at physiological responses to pain, this is reportedly the first to have considered negative emotions as a modifier.

Dr. Edwards, who was at Johns Hopkins at the time of the study, looked at 42 healthy volunteers. Each subject was surveyed and plotted on a pain-catastrophizing scale.

The researchers drew blood to determine baseline Interleukin-6 and cortisol levels. They then administered a series of painful stimuli. These included the immersion of a hand in ice water, the application of heat pain, and pressure stimulation. None of the tests were tissue damaging, but all resulted in moderate to severe ratings of pain.

Increasing Proinflammatory Responses

At 15-minute, 30-minute, and 1-hour intervals during the experiment, researchers took blood again to measure the proinflammatory cytokine interleukin-6 and the stress hormone cortisol.

Dr. Edwards reported that participants who were higher catastrophizers had higher levels of interleukin-6 at 15 minutes (P < .05), 30 minutes (P < .01), and 1 hour (P < .01). The interleukin-6 levels in high-catastrophizing volunteers were roughly double that of the low catastrophizers. Cortisol was elevated, but it was not related to catastrophizing.

“In some people, rumination, feelings of helplessness, and pessimism can trigger inflammatory response that may increase their pain sensitivity,” Dr. Edwards told reporters. “More work needs to be done, but we hope to use these data to create a way to counsel high catastrophizers before procedures to assist them in coping with the pain in a more adaptive way.”

Asked by Medscape Neurology & Neurosurgery to comment on the work, Daniel Wik, MD, from the Midwest Pain Clinics, in Omaha, Nebraska said, “We know that people respond to pain differently, and some people will continue to have clinical difficulties no matter what you do. I personally don’t see a huge amount of difference when I look at the scatter plot, and I think there’s some amount of subjectivity to this as well.”

Dr. Wik says he does not plan to start measuring interleukin-6 levels in clinic at this point, but he considers the work worthy of additional exploration. “It is very interesting and was well presented.”

“It’s an interesting finding,” Fang Xie, PhD, a meeting attendee and statistician with Cephalon, said during an interview. “I don’t know to what extent interleukin-6 is a promoter of pain, but it’s certainly an interesting question.”

Dr. Edwards reports he has no relevant financial relationships to disclose.

American Academy of Pain Medicine 25th Annual Meeting. Presented January 31, 2009.

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