[acb-hsp] Race, Gender, and Sensitivity to Pain

[peter altschul]

Why Your Race or Gender May Affect How Much Pain You Feel
  Anneli Rufus, Alterationet February 18, 2012
  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.
  "We were doing a study primarily on sex differences and pain 
and of course, lo and behold, when people bring their gender to 
the lab they also bring their ethnic background," says pain 
researcher Roger Fillingim, a behavioral science professor at the 
University of Florida.  His team began investigating race and 
pain as well -- adding new data acquired with new technology 
under a more enlightened mindset to a long-established if 
controversial field.
  It's controversial because scientific studies proving 
physiological differences between people of various ethnic 
backgrounds contradict the thesis that race is just a social 
construct.  Critics might also argue that such research would 
only be conducted for racist purposes, and/or that its results 
might be used in racist contexts.
  Has Fillingim been accused of racism for doing this kind of 
work?
  "We encountered some of that thinking as we were publishing our 
early studies," he recalls, "as if we were somehow trying to 
promulgate the idea that one race is inferior to another.  I can 
understand those sensitivities, but we do a larger injustice if 
we ignore the fact that pain is different in some individuals 
than in others.  If ethnic background is associated with the pain 
experience, then we can use that information to better alleviate 
pain."
  Better late than never, because it has also long been known 
that African Americans are typically underserved by medical 
professionals when it comes to pain treatment.  A University of 
California-Riverside study found that African American patients 
are "considerably less likely" than Caucasians to receive 
painkillers in American hospitals.  This study, whose findings 
have been confirmed by many others also noted that when black 
males are given painkiller prescriptions, they are given smaller 
prescriptions and fewer drugs than any other type of patient.  
The study also found that African American males are less likely 
than any other patients to be advised by medical professionals to 
take over-the-counter pain medications upon leaving hospitals.  
Yet African Americans' higher pain sensitivity has also been 
indicated in test after test.
  One much-cited Harvard-affiliated study published in 1943, 
examined the results of pain inflicted via hot lamps applied to 
participants' foreheads and balloons gradually inflated in their 
throats.  This study found black people to be more sensitive to 
both types of pain than Northern Europeans, while "Jewish and 
other Mediterranean races ...  had both pain-perception and 
pain-reaction values which corresponded closely" with African 
Americans.
  "Ethnic differences in pain tolerance are very much like gender 
differences, although perhaps more politically charged and 
complicated," says Fillingim, whose recent studies confirm lower 
pain thresholds and lower pain tolerance among African Americans.  
"If I talk about sex differences, everybody agrees on who's a man 
and who's a woman.  There are clear biological differences.  When 
you talk about ethnicity, there's no biological smoking gun 
saying that because these people are African American, they 
differ from whites.  There's no estrogen difference.  So what is 
it?" Talk about a world of hurt.
  Because pain is highly subjective and many studies depend on 
self-reported pain levels, it has been suggested that people from 
different ethnic backgrounds don't actually experience different 
pain levels, but rather express pain differently or apply 
different coping styles.
  "Pervasive mistrust of the medical research community has been 
documented among African Americans," one study reads, "and it is 
certainly possible that a less trusting attitude among African 
Americans might have contributed to greater report of pain." Such 
factors might affect gender-related pain studies too: Does 
society pressure men to act tougher than women and refuse to 
admit feeling pain?
  Recent studies have sought -- and found -- ever more evidence 
of physiological rather than sociopsychological sources for pain 
reactions.  In one such study, Filllingim's team gauged the 
muscular reflexes resulting from the painful electrical 
stimulation of a nerve near the ankle.
  "It's not a conscious reflex.  You can't control it 
consciously.  It happens too quickly," Fillingim says.  "And it 
required a less intense stimulation for that reflex to occur in 
African Americans than in whites."
  But why?
  "Half of the differences in pain response are genetically 
determined.  Half are determined by experiential and 
psychological factors," he explains.  "We want to get a better 
picture of what drives increased pain and how pain systems 
function."
  That picture could someday lead to highly customized pain 
treatments rather than one-size-fits-all meds such as morphine 
and ibuprofen.
  "Wouldn't it be best for everyone, and most cost-effective, to 
pick drugs with the best therapeutic profiles for each patient?" 
Fillingim asks.  "Let's say somebody you know had to go in for 
surgery next week.  If they're not treated for pain, it will be 
exquisitely painful.  Say everybody gets the exact same drug.  
But if your acquaintance happens to be a poor metabolizer of that 
drug or has a genetic background that does not respond favorably 
to that drug, they could suffer considerably.  Or say they have a 
great genetic background for that drug, but they also have an 
ethnic background that makes them vomit uncontrollably if they 
get that drug.  Wouldn't it be better to know all this in 
advance?"
  Anneli Rufus is the author of several books, most recently The 
Scavenger's Manifesto (Tarcher Press, 2009).  Read more of 
Anneli's writings on scavenging at scavengingddwordpressddcom.
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