Persistance, Prudence.

Eighty Years Along, a Longevity Study Still Has Ground to Cover
By KATHERINE BOUTON
After reading “The Longevity Project,” I took an unscientific survey of friends and relatives asking them what personality characteristic they thought was most associated with long life. Several said “optimism,” followed by “equanimity,” “happiness,” “a good marriage,” “the ability to handle stress.” One offered, jokingly, “good table manners.”

In fact, “good table manners” is closest to the correct answer. Cheerfulness, optimism, extroversion and sociability may make life more enjoyable, but they won’t necessarily extend it, Howard S. Friedman and Leslie R. Martin found in a study that covered eight decades. The key traits are prudence and persistence. “The findings clearly revealed that the best childhood personality predictor of longevity was conscientiousness,” they write, “the qualities of a prudent, persistent, well-organized person, like a scientist-professor — somewhat obsessive and not at all carefree.”

“Howard, that sounds like you!” Dr. Friedman’s graduate students joked when they saw the statistical findings. On a recent visit to New York, Dr. Friedman and Dr. Martin did both seem statistically inclined to longevity. Conscientiousness abounded. They had persisted in a 20-year study — following up on documentation that had been collected over the previous 60 years by Lewis Terman and his successors — despite scoffing from students: Get a life!

The hotel room (Dr. Martin’s) was meticulously neat, and they had prudently ordered tea and fruit from room service. Both were trim and tanned, measured in their answers, trading off responses like the longtime collaborators they are. Despite a busy schedule they were organized enough for a relaxed talk.

In 1990, Dr. Friedman and Leslie Martin, his graduate student at the time, realized that an invaluable resource for studying well-being and longevity existed right in their own state of California. In 1921, Dr. Terman had chosen 1,528 bright San Francisco 11-year-olds for a long-term study of the social predictors of intellectual leadership. Dr. Terman interviewed the children, their families, their teachers. He studied their play habits, their parents’ marriages and their personalities: were they diligent, extroverted, cheerful? He and his team followed up with the participants every five or 10 years. Dr. Terman died in 1956, but colleagues continued the regular interviews with the original subjects, asking the same questions Dr. Terman had asked.

Dr. Friedman and Dr. Martin pored through Dr. Terman’s records, dredged up death certificates and asked Dr. Terman’s questions of study participants’ survivors. They also conducted a group analysis of other similar studies, and collaborated with experts in many fields.

The secret to a long life has been much studied. The health economist James Smith, at the RAND Corporation, found that the answer was education. Stay in school. This is no doubt true. But his findings don’t necessarily conflict with Dr. Friedman and Dr. Martin’s: what keeps people in school is often conscientiousness.

The New England Centenarian Study, on the other hand, found that the children of centenarians scored in the low range for neuroticism and the high range for extroversion. (For women it also helped to be agreeable.) Both men and women were about average in conscientiousness. Dr. Friedman pointed out that this was a selected group — the researchers could not study the centenarians themselves, except by self-reporting, so they turned to their children. There was also no control group. The Friedman/Martin/Terman study is unique in that it followed a single set of participants from childhood to death.

How do you pose the same questions to participants over an 80-year period? Dr. Friedman deferred to Dr. Martin. One of Dr. Terman’s original questions to parents was “How likely are you to upbraid a workman?” Not very relevant in contemporary life. Employing a complicated linguistic measurement called factor analysis, Dr. Martin said, the researchers were able to come up with the 21st-century equivalent: “How do you deal with co-workers?”

Many assume biology is the critical factor in longevity. If your parents lived to be 85, you probably will, too. Not so, Dr. Friedman said. “Genes constitute about one-third of the factors leading to long life,” he said. “The other two-thirds have to do with lifestyles and chance.” As an example of chance, he cited veterans of World War II. “A disproportionate number of those sent overseas, especially to the Pacific, died at a greater rate after the war than the men who had been deployed at home,” he said. In any given year, men sent overseas were more than one and a half times as likely to die, compared with their peers who had stayed home.

There are three explanations for the dominant role of conscientiousness. The first and most obvious is that conscientious people are more likely to live healthy lifestyles, to not smoke or drink to excess, wear seat belts, follow doctors’ orders and take medication as prescribed. Second, conscientious people tend to find themselves not only in healthier situations but also in healthier relationships: happier marriages, better friendships, healthier work situations.

The third explanation for the link between conscientiousness and longevity is the most intriguing. “We thought it must be something biological,” Dr. Friedman said. “We ruled out every other factor.” He and other researchers found that some people are biologically predisposed to be not only more conscientiousness but also healthier. “Not only do they tend to avoid violent deaths and illnesses linked to smoking and drinking,” they write, “but conscientious individuals are less prone to a whole host of diseases, not just those caused by dangerous habits.” The precise physiological explanation is unknown but seems to have to do with levels of chemicals like serotonin in the brain.

As for optimism, it has its downside. “If you’re cheerful, very optimistic, especially in the face of illness and recovery, if you don’t consider the possibility that you might have setbacks, then those setbacks are harder to deal with,” Dr. Martin said. “If you’re one of those people who think everything’s fine — ‘no need to back up those computer files’ — the stress of failure, because you haven’t been more careful, is harmful. You almost set yourself up for more problems.”

How about exercise? Dr. Martin once ran the Marathon des Sables, a six-day race across the Moroccan desert, carrying her own food, bedding and clothing over 150 miles. But extreme exercise is not a predictable indicator of longevity (though the organization and persistence required to get there probably are). As important as exercise and lifestyle are to health, and thus to longevity, pushing yourself to extremes is not necessarily going to lengthen your life span, particularly if you don’t enjoy it.

Spend your time working at a job you like instead. “There’s a misconception about stress,” Dr. Friedman said. “People think everyone should take it easy.” Rather, he said, “a hard job that is also stressful can be associated with longevity. Challenges, even if stressful, are also a link.” In the end, he said, “if people were involved, working hard, succeeded, were responsible —no matter what field they were in — they were more likely to live longer.” Many people, of course, have to stay in a job they don’t like or don’t do well in. That’s bad stress, and they found those people were more likely to die young.

When it comes to marriage, there are many caveats. Marriage itself, adding together the husband’s and the wife’s happiness, was a good predictor of future health and longevity. But more interestingly, it was the man’s happiness that was the better predictor of health and well-being — for both the husband and the wife. Her own happiness mattered much less to her future well-being. Their mutual compatibility was also a strong factor in predicting their children’s longevity: the single strongest social predictor (as opposed to personality predictor) of early death was parental divorce during childhood.

I asked Dr. Friedman and Dr. Martin what the single strongest social predictor of long life was. Their unhesitating answer: a strong social network. Widows outlive widowers. (Widows also tended to outlive still-married women.) Women tend to have stronger social networks. Interestingly, neurotic widowers tended to outlive their less neurotic peers — they were more likely to take care of their health after their wives were gone.

One of my friends commented after hearing about the importance of conscientiousness, “No wonder women live longer than men.” That’s partly true, Dr. Friedman said, but a great deal of it also has to do with social networks, a social support system, which women are often more likely to have. “Among male/female differences, that’s a big piece,” he said.

The project is far from finished. Dr. Martin also wants to look into other variables affecting health, like sleep patterns. And she is interested in how their findings can begin to have an effect on public policy. Dr. Friedman said he thought the most important as-yet-unanswered question was about work — “retirement kinds of issues,” he said. “We know it’s not good to retire and go to the beach.” But it’s also not good to stay in a stressful boring job. “We need to think about negotiating these transitions in a healthy way,” he added.

“The Longevity Project” is written for the general reader, and it is full of self-assessment questionnaires, structured cleverly so the correct answers are not obvious. The subject matter of the questionnaires is illustrative of some of the other factors that are associated either positively or less positively with longevity: They include sociability (are you the life of the party?), emotional sociability, neuroticism, catastrophic thinking, life satisfaction, marital happiness, job passion and accomplishment, religiosity and social support network.

But the book is also amply footnoted with scholarly citations that others may want to follow up. It’s far more nuanced in its discussion than any short summary could be. When I asked Dr. Friedman how he could prevent people from oversimplifying his findings, he sighed. He said he tells them they have to read the book. I have oversimplified, of course, and I, too, would recommend you read the book. It’s a lot more complex than it sounds.