Obese people may be more sensitive to pain
than people who aren't overweight, a new study suggests.
Researchers gauged reaction to pain among 62 older adults
who had osteoarthritis of the knee, a disease that affects
more than 20 million people in the United States. The
study participants -- one-third of whom were obese --
were given a mild electrical shock on the left ankle that
caused sensations of tingling and mild pain in the lower
leg. This was done before and after the participants took
a 45-minute, coping-skills session that included progressive
muscle-relaxation exercises.
The researchers wanted to see if coping-skills training
would help people with osteoarthritis to better cope with
the pain caused by the disease.
But the scientists were especially interested in determining
how the obese group responded to pain. A small number
of studies have looked at pain sensitivity among obese
people, but they have produced conflicting results.
The researchers found that obese individuals had a greater
physical response to the electrical stimulation than non-obese
people. They based their findings by measuring the reflex
of the lower leg muscles; this indicated that the obese
individuals had a lower tolerance for pain, even though
they said that they felt no more pain than non-obese people.
The findings are to be presented Saturday at the American
Psychosomatic Society annual meeting, in Denver.
"For subjective indicators of pain, obese people
indicated similar levels of pain to non-obese people,"
said study author Charles Emery, a professor of psychology
at Ohio State University. "But when we looked at
objective indicators, we found that the obese group had
a lower threshold for pain."
Emery believes that obese people may have more experience
with pain because of their weight. "They may be used
to some degree of pain," he said.
But obese people appear to experience greater pain than
non-obese people, Emery added. "It is important to
look at both objective indicators of pain, as well as
subjective indicators," he said. "We need to
keep in mind that the subjective rating may not be reflective
of physiological processes that are going on."
One expert found the study results compatible with what
is known about how people experience pain.
"These results do not surprise me at all,"
said Dr. Doris K. Cope, director of the Pain Medicine
Division at the University of Pittsburgh.
Pain is not only a physiological stimulus-response, but
the psychological interpretation of that stimulus providing
a total experience of pain, Cope said. "Psychological
studies of the obese demonstrate personality differences
between obese and non-obese subjects, so it would not
surprise me if these patients also experience pain differently
as well," she said.
