Who Says Stress Is Bad For You?

These chronic effects may disappear when the stressor does. In medical students studying for exams, the medial prefrontal cortex shrinks during cram sessions but grows back after a month off. The bad news is that after a stressful event, we don't always get a month off. Even when we do, we may spend it worrying ("Sure, the test is over, but how did I do?"), and that's just as biochemically bad as the original stressor. This is why stress is linked to depression and Alzheimer's; neurons weakened by years of exposure to stress hormones are more susceptible to killers. It also suggests that those of us with constant stress in our lives should be reduced to depressed, forgetful wrecks. But most of us aren't. Why?

Step away from the lab, and you'll find the beginnings of an answer. In the 1970s and '80s, Salvatore Maddi, a psychologist at the University of California, Irvine, followed 430 employees at Illinois Bell during a companywide crisis. While most of the workers suffered as their company fell apart—performing poorly on the job, getting divorced and developing high rates of heart attacks, obesity and strokes— a third of them fared well. They stayed healthy, kept their jobs or found others quickly. It would be easy to assume these were the workers who'd grown up in peaceful, privileged circumstances. It would also be wrong. Many of those who did best as adults had had fairly tough childhoods. They had suffered no abuse or trauma but "maybe had fathers in the military and moved around a lot, or had parents who were alcoholics," says Maddi. "There was a lot of stress in their early lives, but their parents had convinced them that they were the hope of the family—that they would make everyone proud of them—and they had accepted that role. That led to their being very hardy people." Childhood stress, then, had been good for them—it had given them something to transcend.

More recently, Robert Sapolsky of Stanford University has studied a similar phenomenon in alpha males. He's seen plenty of "totally insane son of a bitch" types who respond to stress by lashing out, but he's also interested in another type that gets less press: the nice guy who finishes first. These alphas don't often get into fights; when they do, they pick battles they know they can win. They're just as dominant as their angry counterparts, and they're subject to the same stressors—power struggles, unsuccessful sexual overtures, the occasional need to slap down a subordinate—but their hormone levels never get out of whack for long, and they probably don't suffer much stress-induced brain dysfunction.Sapolsky likes to joke that they've all been relaxing in hot tubs in Big Sur, transforming themselves into "minimalist Zen masters." This is a joke because they've clearly come by their attitudes unconsciously: Sapolsky studies wild baboons.

Sapolsky's and Maddi's work points to a flaw with much of the neurobiological research: so far, it has done a poor job of accounting for differences in how individuals process stress. Researchers haven't identified the point at which the effects of stress tip over from positive to negative, and they know little about why that point differs from person to person. (This is why they don't like to tell people that a little stress can be good, says Rabin—because "we don't know how to judge for each individual what a 'little' stress is.") The research thus tends to paint stress as a universal phenomenon, even though we all experience it differently. "If there are rats or mice or cultured neurons in a dish that seem superresilient to stress, far too many lab scientists view this as a pain in the ass, something that just throws off patterns," says Sapolsky. "It's only people who are tuned into animal behavior or humans and the real world who are interested in how amazing the outliers are." Explaining these outliers' healthy attitudes, says Sapolsky, is now "the field's biggest challenge."

As Maddi's work makes clear, a lot of the explanation stems from early experiences. This may be true of Sapolsky's baboons as well. Sapolsky suspects that part of what makes an animal a dominant Zen master instead of an angry alpha lies in what sort of childhood he had. If an adult baboon picks up on conflict around him but keeps his cool, "quelling the anxiety and exercising impulse control," that may be behavior his mom modeled for him years earlier. The key? Factors such as how many steps the baby baboon could take away from his mother before she pulled him back—i.e., how much she allowed him to learn for himself, even if that meant a few bumps and bruises along the way. "I think the males who had mothers who were less anxious, who allowed them to be more exploratory in the absence of agitated maternal worry, are more likely to be the Zen ones who are calm enough to resist provocation," he says. A little properly handled stress, then, may be necessary to turn children into well-adjusted adults.

Part of the explanation will also be found in genes. Scientists have already identified one that helps control how the brain processes serotonin; some variants seem to protect people from depression, depending on whether they've suffered through previous traumas. This gene may not mediate everyday stress, but others are bound to be fingered eventually, and "once people have found scores of genes," says Sapolsky, "I'm willing to bet the farm that that's going to begin to explain who gets depressed after disastrous unrequited love and who just feels lousy for two weeks."