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. Last Updated: 07/27/2016

Report: Genders React Differently to Stress

For more than a half-century, scientific gospel has held that animals, including humans, respond to stress by preparing to do battle or to flee, a physiological syndrome commonly known as "fight or flight."

But in a newly released report, a group of researchers asserts that females often show a very different reaction to stress, one that revolves around nurturing and seeking the support of others rather than aggression or escape.

This "tend and befriend" response, seen both in humans and in animal species, is based in hormonal differences between the sexes, the researchers suggest. And it may help explain why women are less vulnerable than men to stress-related illnesses like hypertension and alcohol and drug abuse.

Moreover, the researchers contend, in a long-ago world, women's more social response to stress may have conferred an evolutionary advantage, promoting survival and reducing the risk to females and their offspring posed by predators, natural disasters and other Pleistocene Epoch threats.

"Fight or flight is basically a response that doesn't involve the hands-on protection of others," said Dr. Shelley Taylor, professor of psychology at the University of California at Los Angeles and lead author of the report, which is to be published in the journal Psychological Review.

"But females needed to protect their young, and affiliating with a social group afforded more protection for females with one or more young children."

Although many links in the researchers' theory still await scientific confirmation, evidence from a variety of research areas supports their basic thesis. And if the link between the differences in physiology and behavior in men and women is confirmed, it may shift the way scientists approach stress research, as well as research in other areas of health.

The theory, said Dr. Bruce McEwen, professor and director of the Laboratory of Neuroendocrinology at Rockefeller University, "still has to reach out and connect to biology."

But he said Taylor's work offered "a new and broader framework" for thinking about responses to stress, and that "it captures something I do not think has ever been captured before in describing gender differences that seem to apply across animal species."

Taylor said her study of "tend and befriend" responses began with an offhand comment by a post-doctoral student, who noted most animal studies of stress were conducted using only male rats.

Doing a little digging, Taylor and her colleagues discovered that the same was true for human studies. In laboratory studies of biological responses to stress conducted before 1995, for example, only 17 percent of subjects were women.

And the notion of a lone warrior locked in combat or surrender mode that emerged from such research did not mesh neatly with evidence from psychological studies, which showed that in stressful situations, women often sought out the company and support of others, or coped by nurturing their children.

A 1989 study, for example, found that mothers returning home after a stressful day at the office were more likely to devote time to their children. Fathers, in contrast, were more likely to withdraw from their families or incite conflict.

For the journal report, Taylor and her colleagues reviewed several hundred studies in a variety of scientific areas, including human and animal research on the body's hormonal response to stress.

In the process, they found that oxytocin, one of a cascade of hormones released in response to stress, appeared to play a central role in females' response.

Studies have linked oxytocin, which is also produced during childbirth and nursing, both with maternal behavior and with social affiliation. And animals and people with high oxytocin levels, researchers have found, are calmer, more relaxed, more social and less anxious.

The effects of oxytocin during stress, Taylor and her colleagues found, appear to vary between males and females. In males, male hormones like testosterone, which studies have shown increases during stress, seem to mitigate the more calming, affiliative impact of oxytocin.

The female hormone estrogen, in contrast, appears to enhance the action of oxytocin. In a study at UCLA, Taylor and her colleagues found that post-menopausal women who were receiving estrogen therapy had more than three times the level of oxytocin as women not receiving hormone replacement therapy.

"This may explain why women are more likely to turn to others, both their children and friends, than men are in response to stress," Taylor said.

She added that females of course also displayed aggression in some circumstances. But studies show they are less likely to be physically aggressive, and more likely to express aggression indirectly. And while the revving up of the sympathetic nervous system that occurs during stress appears intimately tied to high testosterone levels and aggression in men, the same mechanism may not be at work in female aggression.

The researchers' study adds to growing evidence that men and women differ markedly in the way their bodies respond to a number of health-related conditions, and in some cases may help scientists understand more about why this is so. Studies show that the "classic" symptoms of heart attack - pain radiating down the arm - occur more often in men than in women, who may experience shortness of breath instead.

The growing awareness of these differences led the federal government in 1995 to insist that women be included in health-related studies.

Still, not everyone is convinced that the different behaviors men and women show during stress are tied to physiology.

Dr. Alice Eagly, professor of psychology at Northwestern University, said gender differences could be rooted in hormones, but they could also be a result of learning and cultural conditioning.

"I think we have a certain amount of evidence that women are in some sense more affiliative," Eagly said. "But what that's due to becomes the question. Is it biologically hardwired? Or is it because women have more family responsibility and preparation for that in their development? That is the big question for psychologists."