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Why Your Race or Gender May Affect How Much Pain You Feel

A new study from Stanford says that pain is neither gender- nor race-neutral.

Pain isn't gender-neutral.

Researchers have long known that women are far more likely than men to develop chronic-pain disorders such as fibromyalgia, irritable bowel syndrome, rheumatoid arthritis and migraines. According to the National Institutes of Health, 80 to 90 percent of fibromyalgia patients are female. According to the US Department of Health and Human Services, severe headaches and migraines are twice as common in women as in men -- 17 percent vs. 7 percent, respectively. HHS also reports that over 12 million American women suffer from chronic pain, at an annual cost of about $13 billion.

Some might argue that women don't feel more pain, they just feel more comfortable than men do about admitting that they hurt. Studies do show that more women than men report chronic pain. But other studies showing higher female than male pain responses among newborns indicate that this is a physiological rather than sociocultural matter. If so, then the better these differences can be understood, the better all patients can be treated for pain.

"Someday there might be a different pain pill for men than for women," says behavioral neuroscientist Jeffrey Mogil, head of the Pain Genetics Lab at Montreal's McGill University. "I know of some pain drugs that work in male mice and not female mice. Whether those drugs will ever be approved for human use is another question."

Studies such as a large-scale new one out of Stanford that's getting lots of buzz show that women have lower pain thresholds than men. Sure, women endure menstrual periods and childbirth. But women are three to six times likelier than men to have chronic-pain conditions such as migraines and fibromyalgia, women suffer significantly more than men do even when both suffer from the same medical conditions, and women require 30 percent more morphine after surgery than men do.

"The differences are real and surprisingly large," Mogil says. "What can explain those differences? It's the answer to all questions: genes and environmental differences."

As for the latter, "Some people have experienced pain more often than others," says Mogil, and/or grew up with certain beliefs about pain, and/or were exposed to physical or sociopsychological phenomena that affected their sensitivities. Scientists have spent the last 20 years "trying to break it down and see if we can come up with specific genes and specific environmental experiences" that determine who suffers how much and why.

Any male-female disparity points to sex hormones. Researchers are investigating these in earnest, having found that women are more sensitive to pain during some parts of their menstrual cycles than others.

Studies on rodents "suggest that the neural circuitry modulating pain is surprisingly different between the sexes," Mogil says. In other words, men and women might be wired differently for pain.

What gets less attention yet is just as fascinating is the fact that pain isn't race-neutral either.

The fact that studies linking pain and race are less numerous than studies linking pain and gender "is a political-correctness thing, not a science thing," Mogil says. "For many years it wasn't a place people wanted to go, because it would be hard to get funding, and a lot of people wouldn't want to admit that these things might be true."

Many studies conducted over the last few decades show that African Americans demonstrate lower pain thresholds and pain tolerance than people from other ethnic backgrounds. In tests gauging physical and verbal responses to pain, African Americans are consistently shown to be more sensitive.

In one study involving the application of tourniquet-like devices, African American participants were able to tolerate the pain for only about half as long as were Caucasian participants. According to the Centers for Disease Control, African American arthritis patients report significantly more severe pain than arthritis patients of other ethnic backgrounds, and nearly twice as much as Asian-Pacific Islander arthritis patients.

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