Mildly negative social encounters — the kind often experienced in day-to-day living — can induce stress analgesia and reduce a person's sensitivity to physical pain, according to a new study published in the November issue of Pain.

It is well known that strongly negative social interactions produce stress analgesia in both animals and humans. However, this is one of the first studies to show that encounters that are just slightly negative can also induce this response, Terry Borsook, a PhD candidate at the University of Toronto, Ontario, Canada, told Medscape Medical News.

This is one more study in a growing body of studies showing that our social experiences are so important to us and so important to our lives and our health that they can in fact impact our pain responses.

"This is one more study in a growing body of studies showing that our social experiences are so important to us and so important to our lives and our health that they can in fact impact our pain responses," he said.

The discovery has important implications for physicians and their relationships with their patients, he noted.

"Even something as simple as the doctor's demeanor when he or she comes into the examining room can affect how their patient experiences pain," Borsook said.

Doctors who are aloof, distracted, who don't make eye contact, or who are generally unresponsive to patients may provoke an analgesic response that may cause the patient to report less pain, with insufficient pain control a possible result.

"Doctors who are aloof, distracted, who don't make eye contact, or who are generally unresponsive to patients may provoke an analgesic response that may cause the patient to report less pain, with insufficient pain control a possible result."

No Effect of Positive Interactions

The study included 45 healthy first-year psychology students, who ranged in age from 18 to 30 years. The participants were told that the university was testing different ways of helping new students get acquainted with other students and that they would be working in pairs so that they could practice the different methods on each other.

The "partner" was a trained actor who was instructed to act in a very warm, engaging manner or to be very aloof throughout the exchange.

All participants rated the intensity and unpleasantness of painful stimuli before and after engaging in the structured interaction.

The study found that participants who had the positive social exchange had no change in their pain sensitivity, but those who had the mildly negative exchange showed a significant reduction in pain sensitivity from what it was at baseline.

Pain intensity was rated on a scale from 0 (none) to 10 (worst imaginable). In the negative encounter group, the mean pain intensity score went from 5.9 at baseline to 4.64 after the encounter (mean change, −1.26; P = .006).

In the positive encounter group, the mean pain intensity score was 5.02 at baseline and 5.29 after the encounter (mean change in the pain intensity scale, 0.27; P= .51).

Surprising Result

Borsook admitted that the lack of change in the positive group was a surprise.

"The positive social exchange was very positive. Our confederate was a professional actress, and she was extremely gregarious by nature, so believe me, they had a very positive exchange, and yet there was no change at all.

"We weren't so surprised by the finding in the negative group because we were expecting to get a stress analgesia effect, based on all the literature that shows that when people are socially stressed, you get this stress analgesia effect. But we were surprised to find that the positive experience produced no effect at all."

If such a mildly negative social encounter can provoke these potent physiologic responses, it suggests that people may very well be experiencing more chronic or frequent occurrences of stress responses than has been heretofore recognized, Forsook said.

"Many people may be exposed to chronic fight-or-flight responses, which can have many negative implications for health. This would be particularly true for people who are sensitive to social exclusion, like people who feel lonely or fear rejection."

Generalizable Results?

Medscape Medical News asked Kathi Heffner, PhD, from the Rochester Center for Mind-Body Research at the University of Rochester School of Medicine and Dentistry in New York, for her take on the study.

"This study adds to the efforts by scientists to explain how poor social relationships and social isolation impact physical health," she said.

"We can all think of those mundane and brief but unsatisfying interactions we have had with strangers, like the indifferent customer service representative. These findings suggest that even ordinary but mildly off-putting social exchanges may be stressful enough to reduce pain."

She noted that, because the study was done in college students, the findings may not be applicable to other age groups who may be less stressed by a stranger's disinterest.

"As the authors note, the findings may not apply to people who have, for a long period of time, lacked social connections. Other studies suggest that poor social connections and social isolation can affect the way people respond to stress.

"So for people who are socially disconnected for long periods of time, negative social exchanges may or may not affect pain in the way it affected these study participants," she said.

Dr. Heffner believes that for the study findings to have clinical relevance for physicians, it will be important to determine whether the findings apply to actual clinical situations and to patients with chronic pain. If so, "healthcare providers should be aware that the way they interact with their patients may impact patients' reports of pain."

Mr. Borsook and Dr. Heffner have disclosed no relevant financial relationships.

Pain. 2010;151:372-377. Abstract

Fran Lowry • Medscape Medical News © 2010 WebMD, LLC