Chronic Stress: The Hidden Health Risks

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By Meryl Davids Landau, for U.S. News

According to a recent American Psychological Association poll, nearly a quarter of Americans confessed to currently feeling under "extreme stress." Respondents especially blamed money, work, and the economy—a feeling 50-year-old Sue Wasserman knows all too well. In February, the public relations manager left Atlanta after her job was eliminated by a corporate restructuring and took a new post in Asheville, N.C. When that proved a bad fit, she struck out on her own as a freelance writer and publicist. Though Wasserman is thrilled some days to be living near the Blue Ridge Mountains, the uncertainty of her income overwhelms her. "There's a sense of foreboding—of 'What did I just do?' " she says.

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Short periods of tension can actually be beneficial to people, sharpening thinking and heightening physical response in situations where performance counts, such as business meetings or athletic competitions. But experts are clear that when individuals are routinely under assault—over money, health woes, a daily freeway commute, whatever—a biological system that was designed to occasionally fight or flee a predator gets markedly out of balance. "The body's delicate feedback system starts to malfunction," says David Spiegel, director of the Center on Stress and Health at Stanford University.

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Stress has been found to play a role in so many diseases of modern life—from asthma, depression, and migraine flares to heart attacks, cancer, and diabetes—that it likely accounts for more than half of the country's healthcare-related expenses, says George Chrousos, a distinguished visiting scientist at the National Institutes of Health. In March, Chrousos spearheaded a conference on "The Profound Impact of Stress" in Washington, D.C., to educate policymakers and the public.

For decades, researchers have worked to unlock the scientific puzzle of how stress pervades and influences so many organ systems. In recent years, with an improved knowledge of biology and advanced laboratory techniques, they have produced a picture that identifies many more complex, and longer-lasting, effects than were previously understood.

One of the more disconcerting findings is that children (and perhaps even unborn babies) exposed to extreme emotional stressors may face a lifetime of consequences. "Children are extremely vulnerable to stress, because of their rapidly developing brain and their lack of prior experience with it," Chrousos says. In early March, Duke University scientists reported that twins ages 5 to 10 who had been targets of frequent bullying or physical assault or who watched their mothers become victims of domestic violence showed signs of premature aging in their cells, a risk factor for many diseases in adulthood.

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Even more disturbing research reported in summer 2011 by German scientists and researchers at the University of California found that fetuses can be affected by their mother's emotional stress. Young adults whose mothers experienced a major event while pregnant with them, such as the loss of their home or the death of a relative, also had significant premature cell aging. Still, moms-to-be should not be too concerned, cautions Roberto Romero, chief of the Perinatology Research Branch of the National Institute of Child Health and Human Development, who was not involved with the research. For one thing, more studies are needed to confirm the findings. Moreover, these moms experienced highly traumatic events. "There's no evidence of a deleterious effect when pregnant women face the regular modern-life stressors of having 200 E-mails in their inbox," he says.

A chemical cascade. How does stress cause so much physical harm? In adults, at least, experts know that one route is its direct effect on the cardiovascular system. Lab studies confirm that blood pressure and heart rates rise in response to a stressor. Incidents of heart attacks also increase. After the big central California earthquake of 1983, heart attacks killed more people than the quake itself, says Noel Bairey Merz, director of the Cedars-Sinai Barbra Streisand Women's Heart Center in Los Angeles, who notes that victims likely already had some level of heart disease. Another mechanism: the poor habits people readily adopt during periods of prolonged tension. "People who are under stress are more likely to gain weight and to smoke, and are less likely to sleep well or exercise," which can lead to cardiovascular and other diseases, Bairey Merz says.

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Researchers also blame stress's ability to impede the delicate dance of chemicals that keep the body functioning smoothly. Recent studies especially implicate chemicals involved in fat storage, the immune system, and the longevity of cells themselves. Among the most important findings for long-term health:

• Telomerase. Perhaps the most intriguing discovery focuses on this enzyme, which is so important to cell health that the researchers who discovered it were awarded the Nobel Prize in 2009. Likened to plastic shoelace tips, telomeres are caps on the ends of chromosomes that shorten each time a cell divides; when they become very small, the cell dies. An enzyme called telomerase adds some length back to the telomeres. Levels of telomerase seem to be enhanced by stress reduction techniques like yoga and meditation, while high levels of stress have been linked to premature telomere contraction. (This was the measure of cell aging used in the studies of stress in childhood and in utero.) In a landmark 2004 study by Elissa Epel and colleagues at the University of California–San Francisco, for example, women who felt the most stressed while caring for a chronically ill child had telomere lengths indicating their cells were 10 years older than those of the least stressed mothers. Shorter lengths predict a variety of the diseases of aging, from arthritis and diabetes to neurodegenerative diseases like dementia, says Epel, an associate professor of psychiatry.

•Cortisol. Scientists continue to uncover the myriad ways this key stress hormone damages the body. Chronically high levels are now known to trigger insulin resistance, a precursor to diabetes. Spiegel, who regularly works with cancer patients, says cortisol is thought to be involved in that disease as well by interfering with expression of tumor suppressor genes. "By inhibiting suppression of certain cancer-related genes, there is some evidence that abnormal cortisol can increase the rate of cancer progression," he says. Excess cortisol also affects the heart, and at least one study links it to premature death. When Dutch researchers followed more than 800 people 65 and older for six years, they found that those with the highest cortisol levels at the start of the study were five times as likely to die of cardiovascular disease in the subsequent years as those with the lowest levels, they reported in 2010. This was true even in people with no signs of heart trouble when the study began.

•Neuropeptide Y (NPY). A decade ago, UCSF researcher Epel made headlines when her lab discovered that chronic stress causes people to pack on dangerous deep belly or "visceral" fat, the kind linked to cardiovascular and other diseases. Since then, other researchers have identified NPY, a neurotransmitter in the brain and body that regulates energy use, as the prime culprit. Under stress, NPY sends messages to the abdomen to both store fat there and recruit other cells to transform themselves into fat. This makes sense from an evolutionary standpoint, Epel says, because substances in belly fat are more easily converted to the energy needed to outrun a predator than those in the fat stored around the thighs and buttocks. This effect often combines with the desire to seek out the dense calories of comfort food when unnerved, another adaptive stress response (this one to famine). It also at least partly explains society's expanding waistlines, Epel says.

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• Inflammatory molecules. Bouts of stress also trigger proteins like cytokines that activate an inflammatory response in the body. "We think that happens to protect the body from injury that might occur while it is fighting or fleeing," explains Philip Gold, a senior investigator at the National Institute of Mental Health, who codirected the Washington conference. Short-term inflammation is actually a good thing, since it prevents infection and, by increasing blood flow and releasing numerous compounds, starts the healing process. But over a prolonged period, too much inflammation is believed to play a role in promoting a host of medical conditions, including heart disease.

What you can do. Psychologists use the term "resilience" to describe how quickly people tend to recover from emotional setbacks, whether getting cut off in traffic or losing a job. The more resilient you are, the more you can limit the impact of stress on your health. Genetics play only a small role, says Richard Davidson, founder and chair of the Center for Investigating Healthy Minds at the University of Wisconsin–Madison. In fact, research spanning decades at Davidson's and other labs confirms that anyone can become more resilient with practice.

To help his own patients, Stanford's Spiegel coined an acronym, FACE. In short: Face or acknowledge stressors rather than running away from them; Alter perceptions to view these challenges in a more positive way, such as through cognitive therapy, hypnosis, or mindfulness training; Cope actively, by proactively heading off future stressors when possible; and Express your emotions rather than holding them in. "People under stress often view emotion as the enemy, but expressing it appropriately is important," Spiegel says. For example, you don't want to tell your boss he's a jerk, but you can say, "I felt negated when you said that at the meeting. " Or sound off instead to your partner, a friend, support group, or therapist.

Finally, help your body function at its optimum level: Eat regular, balanced meals; aim for the recommended daily seven to nine hours of sleep for adults; and, especially, exercise 30 minutes each day. Even gentle walking is sufficient to boost mood and lower stress, according to the NIMH. More vigorous exercise may provide additional protection. A 2010 study by Epel's lab found that those all-important telomeres were longer in highly stressed postmenopausal women who met the exercise goals outlined by the Centers for Disease Control and Prevention, which includes at least 150 minutes of brisk walking each week, plus two days of strength training. Sue Wasserman keeps her anxiety in check with daily treks along local hiking trails. "I may get stressed about an incoming check being late," she says, but as she starts moving, her worries and tension seem to ebb away.

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