Think young

11 September 2003, 850 words

Max Richards and ANR Robinson are both in their 70s. Yet the physical contrast between our present and past President is quite marked. Richards has an erect carriage, solidity of flesh, and a strong voice. Robinson is frail in appearance, manner, and speech.

One of the reasons for this is undoubtedly genetic. But the latest research suggests that lifestyle may be a more important factor in how long an individual lives and how healthy they are in old age. In the Harvard Study of Adult Development, one of the most thorough studies of aging ever conducted, the longevity of one's forbears was only weakly correlated with healthy aging.

So what are these lifestyle factors? In his book Aging Well (available at RIK) George Vaillant, who is director of the Harvard Study, lists the following: Not smoking or stopping young, not abusing alcohol, the ability to turn stumbling blocks into stepping stones, a stable marriage, some exercise and a healthy weight. Vaillant also lists psychological "protective factors" which, if adopted, help one to live a long and healthy old age. These are the ability to plan, anticipate and hope; a capacity for gratitude and forgiveness; empathy; and the desire to do things with people rather than to them.

But aging remains mysterious in many ways. It is difficult, for example, to separate the genetic from the lifestyle factors. A Mayo Clinic study of 839 patients found that optimists lived 19 percent longer than the expected lifespan; another US study found that happy people were half as likely to die or become disabled. This is not only because happy people have lower blood pressure and stronger immune systems, but they also have healthier lifestyles and seek out more health risk information. But happiness itself has a strong genetic foundation, so it may be their genes that lead happy people to adopt healthy habits and attitudes.

One of the oddest correlations in healthy aging, though, is also one of the strongest: education. Since the 19th-century, researchers have noted a strong link between education, health and longevity. But in the 19th century educated persons were also rich persons, so it was possible that this effect was just due to a better diet and less risk of diseases like tuberculosis.

However, in 1986, the US National Institute of Aging began the Nun Study, which took as its subjects 678 members of the School Sisters of Notre Dame. With factors such as income, smoking, diet, health care and housing controlled for, the researchers still found that education conferred health and longevity benefits. Nuns with a university degree had a better chance of surviving old age and being independent.

The Harvard Study had similar findings. Comparing Harvard graduates and Inner City men in the Study, the researchers found that it was the person's level of education, not their social class or job prestige or even their intelligence, which was strongly correlated with healthy aging. Indeed, education was correlated with a lower risk of death at every age. "Parity of education alone was enough to produce parity in physical health," writes Vaillant.

No one has yet figured out why this should be so. Vaillant suggests that the capacity to take the long view facilitates both prolonged education and self-care; that people seek education because they believe it is possible to control the course of their lives; and that education leads to a better appreciation of causal connections between personal behaviour and consequences.

But there is another possibility. It is incorrect for Vaillant to say that IQ is irrelevant, because IQ is genetically heritable and cannot be compared between different cultural groups (whether defined by race or class). And it is known that people with high IQs exhibit higher left-right body symmetry and that high symmetry is a sign of health. "So the heritability of IQ might not be caused by 'genes for intelligence' at all, but by indirect genes for resistance to toxins or infections," suggests science writer Matt Ridley in his book Genome.

My own view (which on this matter is worth as much &endash; or as little &endash; as the experts') is that, while people with high IQs naturally seek further education, education itself is not necessarily correlated with high intelligence. Richards is a PhD, but he doesn't impress me as being especially smart. So education's aging benefits may well be separate from IQ.

My suspicion is that using one's brain confers health benefits in itself. After all, that five pounds of tissue consumes 20 percent of our body's energy. We also know now that keeping mentally active not only creates new brain connections throughout one's life, but also helps grow new brain cells. So reading a book may actually help keep you healthy and alive. It is also significant that openness to new experiences is highly correlated with healthy aging.

It could be, then, that curiosity is the secret to a long and healthy life. If so, it gives added meaning to a sardonic comment once made by the philosopher Bertrand Russell: "Most men would rather die than think. In fact, they do." Russell himself lived to the ripe old age of 98.