En español l Scientists have long known that stress complicates a host of health problems. Now they are discovering that chronic stress — a mainstay of modern life — doesn't merely exacerbate disease, it actually can cause it.
"We are just beginning to understand the ways that stress influences a wide range of diseases of aging, including heart disease, metabolic syndrome, type 2 diabetes and certain types of disability, even early death," says Sheldon Cohen, a professor of psychology at Carnegie Mellon University in Pittsburgh who has been at the forefront of stress research for 30 years.
Everyone experiences stress, of course, but it's particularly prevalent among adults over 50. In a recent Harvard University-Robert Wood Johnson Foundation-NPR poll, about a quarter of 2,500 participants said they'd experienced "a great deal" of stress in the last month. Another poll, conducted in August by AARP, found 37 percent of adults over 50 experienced a major stressful life event in the past year, such as the death of a family member, chronic illness or a job loss.
Certainly, many people who are stressed end up eating, drinking and smoking more, and sleeping and exercising less — tendencies that have obvious negative consequences for our health. But scientists are discovering a much more nuanced picture, says Bruce McEwen, a neuroscientist at Rockefeller University in New York and the author of The End of Stress as We Know It.
The human body reacts to stress by first pumping adrenaline and then cortisol into the bloodstream to focus the mind and body for immediate action — a response that has ensured our survival over the millennia. The adrenaline rush from the initial stress response can occasionally pose health risks, according to Cohen, but the more significant hazard is the subsequent release of cortisol. Generally considered a bad stress hormone, cortisol does serve many important functions — one of which is turning off inflammation. But when chronic stress exposes the body to a relentless stream of cortisol, as happens when stress is constant, cells become desensitized to the hormone, "causing inflammation to go wild," Cohen says. Long-term chronic inflammation damages blood vessels and brain cells, leads to insulin resistance (a precursor to diabetes) and promotes painful joint diseases.
Here are eight other conditions that may be caused by stress.
1. The common cold
In one groundbreaking 2012 study, Cohen and his colleagues interviewed 276 healthy adults about stressful events in their lives and then exposed them to a cold virus. Those experiencing chronic stress were cortisol resistant — and were more likely to get sick. "The immune system's ability to regulate inflammation predicts who will develop a cold, but more importantly it provides an explanation of how stress can promote disease," Cohen says. "When under continuous stress, cells of the immune system are unable to respond properly, and consequently produce levels of inflammation that lead to disease."
2. Weight gain
We've long known that stress hormones stimulate a preference for foods that are full of sugar, starch and fat — that's why we're more likely to reach for a candy bar to get through a stressful day at the office. But new research shows that the link between stress and weight gain is far more complex than simply poor food choices. In a study published in July in Biological Psychiatry, women who had one or more stressful events during the previous 24 hours burned 104 fewer calories in the seven hours following a fast-food meal than women who ate a similar meal but were stress-free. Although 104 calories may sound negligible, that can add up to 11 extra pounds a year. In addition to triggering these apparent changes in metabolism, the stress response produces a rise in insulin levels and a fall in fat oxidation, a dual process that promotes fat storage, says stress researcher Janice Kiecolt-Glaser, professor of psychiatry at Ohio State University College of Medicine in Columbus and the study's lead author. Other research has revealed a correlation between excess cortisol and abdominal fat.
3. Slower healing
Excess cortisol slows wound healing and lowers vaccines' effectiveness in older people who are caring for sick family members, new research shows. In another of Kiecolt-Glaser's studies, older women caring for relatives with dementia took about 10 days longer to heal from a biopsy wound than a noncaregiver control group. And, she says, "the longer the stress goes on, the longer the immune response is disrupted." Significantly, the caregivers in the study who had a strong network of friends and family healed faster than those who lacked such support.
4. Sleep dysfunction
Older adults already experience a natural decrease in their amount of deep sleep and an increase in nighttime wakefulness, says sleep researcher Martica Hall, professor of psychiatry at the University of Pittsburgh Medical Center. Stress may aggravate these sleep deficits, making it especially hard for older people to get back to sleep when they wake up at night. Because sleep deprivation impairs memory and emotional control, people with troubled sleep may then find it harder to handle the stress in their lives. In other words, "cortisol levels may contribute to nighttime wakefulness and then our brains respond by reminding us of our problems," Hall says.
5. Heart disease
Scientists have known for years that there's a connection between long-term stress and heart attacks, but until recently the reasons were imperfectly understood. A study in the June issue of Nature Medicine sheds light on the phenomenon. Matthias Nahrendorf, a researcher at Harvard Medical School, discovered that blood samples taken from medical residents enduring high levels of stress contained a surplus of disease-fighting white blood cells. Previous research had suggested that cortisol actually changes the texture of white blood cells, encouraging the cells to attach themselves to blood vessel walls. The result is plaque, a key marker of heart disease. Nahrendorf's team confirmed this hypothesis when they found that a surplus of white blood cells caused hardening of the arteries in stressed but otherwise healthy mice.
Over the past decade, researchers have reevaluated stress's role in depression and brain health, says Huda Akil, professor of neuroscience at the University of Michigan. While it is often triggered by a stress-inducing episode, depression eventually "takes on a life of its own," she says. Stress throws several brain neurotransmitter systems — such as serotonin, dopamine and norepinephrine — out of balance, negatively affecting mood, appetite, sleep and libido. Some severely depressed people have permanently elevated cortisol levels, which can eventually alter the hippocampus and permanently damage brain cells. "Depression truly is an illness that changes the brain," Akil says.
7. Ulcers and other stomach problems
For 50 years, scientists attributed stomach ulcers to stress. Then in 1983, Australian researchers Robin Warren and Barry Marshall discovered that ulcers are actually caused by the bacteria H. pylori. So were the godfathers of stress research wrong? It turns out that around 15 percent of stomach ulcers occur in people not infected with the bacteria and only about 10 percent of infected people get ulcers, according to Robert Sapolsky, a stress researcher at Stanford University and author of Why Zebras Don't Get Ulcers. One theory holds that the effect of chronic stress on the immune system allows the H. pylori bacteria to thrive. Another is that exposure to stress can change the balance of bacteria in the gut, giving harmful ones the upper hand. "The bacteria are able to grow because the immune system is not functioning properly," neuroscientist Bruce McEwen says. "So ulcers ultimately do come down to a stress impairment." Scientists remain divided about this conclusion, but agree that stress can be a critical factor in irritable bowel syndrome, indigestion, heartburn, ulcerative colitis and Crohn's disease, which is characterized by chronic inflammation.
8. Back, neck and shoulder pain
Millions of Americans spend their days hunched over computer screens and mobile phones, so it's no surprise that neck, shoulder and back pain are among the most common — and costly — health complaints. The combination of physical inactivity and mental strain does not in itself create the disk tears, spinal stenosis and scoliosis that plague people as they age, but once the pain kicks in, stress can intensify both its severity and its duration. Musculoskeletal pain seems particularly sensitive to workplace stress. Researchers aren't sure why people with stressful jobs have more back, neck and shoulder pain, but have theorized that stress-induced inflammation prevents the full healing that would make the pain recede.
Jay Thompson, 54
Proof it works: Princeton University researchers have shown physical activity actually reorganizes the brain, teaching it stress resilience.
In many ways, Thompson was a heart attack waiting to happen. A sedentary smoker, he loved fast food and was 70 pounds overweight. But it was stress that likely triggered his massive 2012 “widow maker” cardiac event. “I had just started a new job, and because my youngest child was about to start college, we needed to keep our residence here in Phoenix while I relocated to Seattle,” he says. “My stress levels were off the charts.” Five days in the ICU, two titanium stents and the look on his family’s faces convinced Thompson that everything had to change. “I vowed to stop sweating the small stuff,” he says. He also dropped 70 pounds and started exercising. “When I am out walking, running or biking, it’s much easier to just let go of what’s bothering me.”
Val Ferrero, 65
Rx: Social support systems
Proof it works: The New York University Spouse Caregiver Intervention study has found that those who join support groups are significantly less stressed than those who don’t.
Like many of those caring for a spouse with dementia, Ferrero, who lives near San Luis Obispo, Calif., thought she was coping just fine. “My husband, Lee, was diagnosed with early onset Alzheimer’s disease in 2008, and the stress is very sneaky. You think you’re fine. Then something changes, and it throws everything off.” Worn down, she got a run-of-the-mill cold last year, which turned into pneumonia. She began seeing a counselor a few years ago, who urged her to attend support groups at the Alzheimer’s Association. “I made close friends who know exactly what I am going through. Whether through phone calls, email, support groups or coffee dates, they are a lifeline.”
Tommie Mae Bender, 80
Rx: Community gardening
Proof it works: Dutch studies have shown that spending just 30 minutes gardening is enough to significantly zap stress, as measured by both cortisol levels and mood.
Bender concedes she’s had plenty of stress in her life, from years spent living on a minimal income to losing her husband in 2009. But the death of her daughter last March to complications from multiple sclerosis made Bender’s chronic hypertension more acute. So she turned to the activity that provides her the most comfort: gardening. These days, she works two days a week with local gardening projects, raising food (including turnips and beans) to sell at farmers markets. And while she loves socializing with the other gardeners, it’s getting her hands in the soil and working with plants that offers the most healing: “It’s very calming to me.”
Adam Bernstein, 50
Rx: Mindfulness meditation
Proof it works: New research from Carnegie Mellon University in Pittsburgh has shown that just 25 minutes of mindfulness meditation for three consecutive days is enough to make you more resilient under stress.
Bernstein, a musician, has been meditating regularly for 20 years, he says, but a recent divorce turned his world upside down. “You’re completely uprooted, and everything — family, friends, finances, where you live — it’s all up in the air. Everything changed. It was difficult.” Although Bernstein, who lives in Brooklyn, had long practiced more formal Zen Buddhist meditation, he decided to embrace simple, mindful breathing whenever — and wherever — he felt anxiety overwhelm him. “Pushing the pain away, it was more helpful to just breathe, and go deeper into it. Within a minute, I’d start to feel relief, and realize this emotional distress isn’t permanent. When you stop resisting the feeling, you feel much better. It does pass.”
Smartphones, laptops, tablets—have all our digital devices ratcheted up our stress? Absolutely, says neuroscientist Bruce McEwen of Rockefeller University in New York. “It’s hard to take a break. Many of us can no longer turn the stress response off. It alters our lifestyle.”
In Overworked and Overwhelmed, Scott Eblin writes that the 2008 financial crisis combined with skyrocketing use of smartphones has sharply increased American stress levels in the last five years. “The average smartphone-enabled professional is connected to work 72 hours a week,” Eblin says. Consider that 70 percent of professionals check their smartphones within an hour of waking up, and half check them constantly while on vacation, a Harvard Business School study found.
So how do we dial down stress, but still handle daily demands?
- Set boundaries: If your boss or colleagues call at night, make it clear that you are spending time with family and will respond first thing in the morning, Eblin recommends.
- Learn to say no: Don’t mindlessly say yes to every request. If saying no isn’t an option, a qualified “yes, if” can work.
- Set a daily no-email time. Regular email users are distracted nearly 37 times an hour, according to research from the University of California, Irvine. Establish a distraction-free time.
- Schedule what matters most first: Time with family and friends, exercise, vacations, volunteering and hobbies should go on the calendar first, says Eblin.
- Establish a cellphone-free area. Make it a place for conversation, reading and relaxing, suggests yoga therapist Carol Krucoff of Duke Integrative Medicine in Durham, N.C., in her book, Yoga Sparks: 108 Easy Practices for Stress Relief in a Minute or Less.
- Turn off the TV when you are finished watching a show. Avoid screen time before bed — it can contribute to sleep problems, Krucoff says.
- Limit news to no more than 30 minutes a day.
- Go off-line for a set time during which you don’t use or respond to electronics. If you’re a real addict, start with a minute and build up to an hour or more, Krucoff suggests.
Elizabeth Agnvall, features editor health, with AARP Media, reduces stress through exercise — and occasional wine with friends.