Power of Positive Thinking Extends, It Seems, to Aging

By MARY DUENWALD

o happy people live longer? A growing body of evidence suggests they may. Recent studies have correlated long life with optimism, with positive thinking, and with a lack of hostility, anxiety and depression.

One thing that remains unclear, however, is whether happiness can actually cause longevity. Perhaps happy people live longer because they practice healthy behaviors, or for some other unknown reason.

"It is definitely the case that certain people who are psychologically healthier live longer," said Dr. Howard S. Friedman of the University of California at Riverside, a psychologist who has studied personality traits that correlate with longevity. "But the explanations are usually complicated."

The second open question is: What, if anything, can unhappy people do about it?

The most recent study of personality and longevity was conducted among a group of 660 people over 50 in Oxford, Ohio, who, in 1975, had answered questions having to do with, among other things, their attitudes about aging. They had been asked whether they agreed or disagreed with statements like "Things keep getting worse as I get older," "I have as much pep as I did last year," and "I am as happy now as I was when I was younger."

Researchers checked to see which participants were still alive in 1998, and they noted when the others had died. It turned out that those who viewed aging as a positive experience lived, on average, 7.5 years longer than those who took a darker view.

That is an advantage far greater, the researchers point out, than what can be gained from lowering blood pressure or reducing cholesterol, each of which has been found to lengthen life about four years. It also beats exercise, not smoking and maintaining a healthy weight, strategies that add one to three years.

The researchers who conducted the study have been careful not to suggest that views of aging are more important for one's health than exercise, nutrition and not smoking. "I think they are all important in predicting survival," said Dr. Becca Levy, a social psychologist at Yale. But, Dr. Levy said, it is surprising to find that a psychological characteristic could also be such a strong predictor of life span.

In analyzing the data, Dr. Levy and her colleagues took into account race, sex, socioeconomic status, self-reported health, overall morale and loneliness — all factors that might have clouded the picture. But even after statistically controlling for such characteristics, views of aging were highly correlated with long life.

Optimism was linked to longevity in a study reported two years ago by researchers at the Mayo Clinic in Rochester, Minn. Dr. Toshihiko Maruta, a psychiatrist, reviewed psychological tests that had been given to more than 800 people in the early 1960's, and based on the people's responses, he classified 197 of them as pessimistic. He then checked to see how long they lived.

Dr. Maruta found that the pessimists had a risk of death for any given year that was 19 percent greater than average.

Other studies have drawn connections between longevity and the degree of control people feel over their lives and between longevity and mindfulness, defined as an awareness of one's environment and one's reactions to it. Some research has shown that people who are relatively more depressed, hostile or anxious are unlikely to live as long as others.

Dr. Carolyn Aldwin, a professor of human and community development at the University of California at Davis, has reviewed many such studies and examined another group of people who took psychological tests in the 1960's. She found that those who seemed to be relatively stable emotionally had lived longer.

"You're better off if you are less likely to go to extremes emotionally," Dr. Aldwin said, "if you keep on an even keel and don't let yourself get too upset."

How do happy, upbeat, calm people keep themselves alive?

Dr. Levy suspected that the answer might be linked to the positive thinkers' will to live. Previous studies showing, for example, that people of all cultures are more likely to die in the days and weeks after holidays than they are in the days leading up to them, had suggested that will to live could affect survival.

So Dr. Levy and her colleagues checked back to see how the respondents had answered other questions in the original survey. In these, they had been asked to choose from three pairs of adjectives — empty-full, hopeless-hopeful and worthless-worthy — the ones that best described their lives. Those who answered full, hopeful and worthy were deemed to have the greater will to live.

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"Will to live appeared to be a partial mediator," Dr. Levy said, "but it didn't completely explain why the people with positive views lived longer. So there must be other things involved. One likely candidate is how people respond to stress. Older people with a negative view of aging show higher levels of stress."

Dr. Friedman questioned whether something as simple as will to live could explain the difference in longevity. Longevity, he said, is affected by a variety of health behaviors that people practice throughout life. For many years, Dr. Friedman has observed the health and longevity of a group of subjects who were originally recruited in 1921 for the studies of psychology and intelligence conducted by Dr. Lewis Terman of Stanford. Over the decades, these subjects periodically answered extensive psychological questionnaires.

After examining their profiles, and checking to see how long the subjects lived, Dr. Friedman found one general characteristic of childhood personality to be associated with longevity, and that was what he called "conscientiousness."

"It's basically a kind of prudence and care," Dr. Friedman said. Conscientious people are generally competent, truthful and responsible, and they tend to lead stable, productive lives.

"My own studies suggest that certain people engage in a whole host of healthy or unhealthy behaviors and situations — cooperating with medical treatment, wearing seat belts, avoiding drug abuse, staying active, associating with healthier and more stable people, and more," Dr. Friedman said. "Together, these can have a big impact on mortality risk across time."

Cheerfulness, on the other hand, was not related to longevity among the people Dr. Friedman studied. In fact, this trait was linked to shorter-than-average life span, he found.

"If you are sociable and carefree, you may have lower levels of stress hormones and more friends to assist you, which is healthy," he said, "but you may also wind up with excessive drinking, smoking and partying, which is unhealthy over the long term. So we need to see how the psychology is playing out in terms of one's own particular life path."

Optimism itself may not always be a healthy trait. In old age, pessimism may be more protective, according to a study of older people last year by Dr. Derek M. Isaacowitz, a psychologist now at Brandeis University.

When faced with the death of a friend or family member or some other negative life event, Dr. Isaacowitz said, the older pessimists were less likely than the optimists to suffer from depression. Perhaps, Dr. Isaacowitz concluded, the pessimists at this age were better able to accept life's realities.

"It's important that optimism not be footless and unwarranted," said Dr. Martin E. P. Seligman, a psychologist at the University of Pennsylvania who was a co-author of the study.

Cantankerousness, on the other hand, has been found to be a protective characteristic among the elderly. In a study of residents of homes for the elderly conducted in the 1970's, Dr. Morton A. Lieberman, a psychologist now at the University of California at San Francisco, found that those who were ornery and argumentative with the nursing home staff members lived longer than those who were not.

"I'm not sure it was because they got more attention," Dr. Lieberman said, "because the staff found them so difficult. What caused them to live longer, what the biology is, we don't know."

Most experts agree that the connections between personality and life span are not simple.

"It's bad advice to tell people to cheer up and you'll live longer," Dr. Friedman said. "There's very little evidence to show that's true. We should be beyond the point where we think it's just mind over body."

Many psychologists question whether it is even possible for people to change their personalities and thus improve their survival. "Personality is stable," Dr. Maruta of Mayo Clinic said. "There might be fluctuations now and then, but I'm not sure we can really change."

Dr. Seligman said it might be possible at least to train people to adapt a somewhat more optimistic outlook. Each year, at the University of Pennsylvania, he recruits a group of freshmen to receive "optimism training," intended to help them cope with the stress of adjustment to college life. And has found that the students who receive the training suffer fewer illnesses throughout college than those who do not.

Dr. Seligman's books — including "Learned Optimism" (1991), "What You Can Change . . . and What You Can't" (1993) and most recently, "Authentic Happiness" (2002) — teach that it is possible at least to shift one's way of explaining life events toward the positive.

But he is no more inclined than any other experts to say that people can simply cheer up and live longer. "It is entirely possible that some third variable like your genes both makes you happy and gives you longer life," Dr. Seligman said.