Are Your Hormones Up?

Scientists have long known that changes in a woman's hormone levels during her menstrual cycle can affect her mood. Now a controversial new study, presented last week at a Toronto meeting of the Society for Neuroscience, suggests that a woman's skill at performing some everyday tasks could be influenced by the time of the month.

During the menstrual cycle, the blood level of estrogen, a female sex hormone, rises sharply before ovulation, about midway in the cycle, and then drops again before menstruation occurs. In a study of 200 women, Doreen Kimura, a University of Western Ontario psychology professor, found that when levels of estrogen were high, the women showed greater verbal fluency and used their hands more skillfully than when levels were low. In one test of verbal dexterity, the women were asked to say "A box of mixed biscuits in a biscuit mixer" as fast as possible five times. Their average time was 14 sec. on high-estrogen days, vs. 17 sec. when hormone levels were low. On the other hand, the women's spatial abilities -- picking a shape out of a complex pattern, for example -- were stronger on low-estrogen days.

Kimura's research is intriguing, but scientists will reserve judgment on the results until they are confirmed or refuted by other studies involving greater * numbers of women -- and men. In the meantime, the findings could easily be misused. For one thing, the study could encourage some male-chauvinist bosses in their belief that women workers are unpredictable and unreliable because of their menstrual cycles. Says Molly Yard, president of the National Organization for Women: "I think the study could be used by some people to denigrate women."

Even if Kimura's results are accurate, they may have little practical significance. Skeptical scientists point out that the impact of hormones on performance could be overwhelmed by other factors, from how much sleep a women has had to when she drank her last cup of coffee.