Sex Differences Poorly Understood

From a workshop on sex differences and their implications for translational neuroscience research, sponsored by the Institute of Medicine.

Sex, sex, sex. That’s all they talked about at this day-long workshop in San Francisco, and it was more interesting than you might think. (Or maybe not, depending on what you’re expecting…)

Researchers from basic scientists to clinicians decried how too few studies look at sex — as in the differences between males and females (not sexuality or sex behaviors). The terminology is important, and they clarified up front that the topic of the day was sex, not gender.

Surprisingly, that clarification prompted one of the speakers to change her terminology on the fly. (She had been planning to refer to sex differences as gender differences.) That, as much as anything I heard that day, showed me how far the scientific and medical communities have to go to get the topic of sex differences front and center. In fact, the Institute of Medicine convened the workshop to assess progress since it called for more research on sex differences in its 2001 report, “Exploring the Biological Contributions to Human Health: Does Sex Matter?” (National Academies Press).

Why is this important? Although the impetus for better understanding of sex differences largely has come from proponents of improving the health of women (who long have been under-represented as research subjects), the lack of attention to biological differences between the sexes hurts both men and women.

Just one example: After more than 100 rodent studies showed that dextromethorphan (a common ingredient in cough syrups) potentiated the analgesic effects of morphine, a drug company launched a clinical trial in humans on treating chronic pain with the drug combination. It bombed. The company abandoned the formulation.

But a review of rodent studies in general found that 87% used only male rodents, didn’t specify the rodent sex, or didn’t assess sex differences in the few studies that included female mice or rats. Jeffrey S. Mogil, Ph.D. of McGill University’s Centre for Research on Pain, Montreal and his associates discovered that the potentiating effects of dextromethorphan on morphine work only in male rodents. Because the drug company’s clinical trial of the combination didn’t assess differences in response by sex, it may have abandoned a drug that might have effectively treated chronic pain in men, if not women.

At the workshop, fascinating talks described some of the progress made in studying sex differences in stroke, depression, pain and pain perception, sleep medicine, multiple sclerosis and neuroinflammation, and more. It was clear we’ve only uncovered the tip of the iceberg.

From the start, participants acknowledge an elephant in the room — politics. Ever since 2005, when then-president of Harvard University Lawrence H. Summers drew intense public criticism for what one workshop participant called “unfortunate wording” about sex differences, researchers have felt a chilling effect on public discussion about sex differences. The workshop attendees (many — perhaps even most — of whom were women) see it as just one more obstacle that must be overcome.

Physicians who may wonder what they can do to stay up to speed on consideration of sex differences can take an online course (for Continuing Medical Education credits) created by the National Institutes of Health and the Food and Drug Administration: The Science of Sex and Gender in Human Health.”

— Sherry Boschert (@sherryboschert on Twitter)
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Filed under Cardiovascular Medicine, Endocrinology, Diabetes, and Metabolism, Family Medicine, Health Policy, IMNG, Internal Medicine, Medical Genetics, Neurology and Neurological Surgery, Primary care, Psychiatry, Uncategorized

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