Age And Intellect: When Does One Affect The Other?

``In my soul, I know my qualifications for the presidency-wisdom, wit, historical perspective, toughness-are better at 68 than they were at 48,``

George McGovern wrote a few days ago.

The question of interest here is not McGovern (voters presumably spoke decisively on that matter in 1972). It`s the issue he raises about age.

How old is too old to be considered presidential material? At what age do bright, achieving people begin to lose their mental acuity? Can 80-year-olds function well on the Supreme Court, 70-year-olds on college faculties, 75-year-olds as physicians?

The issue is heating up as the American population grays, the need for older workers increases, age discrimination is largely banned and new tightening rules against mandatory retirement are ready to kick in soon.

What researchers trying to answer aging questions have found is a mixed bag of data that is generally upbeat and encouraging about the mental abilities of the aging people who are described as ``intellectually able.``

Most smart people, essentially, continue to be smart well into their 70s or even longer.

But as the years accumulate, intellectual functioning does show greater variations than existed earlier, researchers have learned. That could make new problems for employers-and voters.

The findings are based on studies of several groups of aging, intellectually able people, some of which were reported at the meeting of the American Association for the Advancement of Science last week in Washington. Among the people studied were 1,102 physicians ranging in age from 28 to 92, a group of retired Harvard faculty members and men who were identified as

``gifted`` by Lewis Terman when they were children in 1921 and have been tracked ever since in the ongoing Terman Study.

The Terman Study long ago showed conclusively that gifted children are more likely to grow up to be more physically and mentally healthy, more successful and longer-lived than average. Periodic re-visitings of Terman men throughout the decade of their 70s find little change in their intellect.

These men now generally use a slightly smaller vocabulary, ``but they do not appear to think less,`` the AAAS was told by Dr. Gordon D. Strauss, University of California at Los Angeles.

``For individuals of high intelligence, not only does the brain work better, but it lasts longer, especially if it is occupied,`` said Dr. Strauss. He said it is researchers` impression the men with a more limited lifestyle during their 70s show more of a decrease in working vocabulary and

intellectual functioning than those who remain more mentally active.

There`s also evidence that throughout their 70s, intellectually able people are capable of continued mental development, according to Dr. Strauss. Many of the same conclusions are turning up in the Harvard studies of retired faculty and of physicians with a wide range of ages.

Some components of mental ability develop relatively late in life and improve with successful aging, the studies indicate. It is possible-perhaps even usual-for intellectually able people to maintain their abilities and health at a level comparable to much younger individuals, researchers said.

``There are, in fact, individuals over the age of 75 who maintain their cognitive skills at a level overlapping with the average performance of individuals under 35,`` reported Sandra Weintraub, Beth Israel Hospital, Boston, on the physician studies.

But these researchers also found increasing variability among people as they age. In general, those under 35 did score better on a wide range of test measurements than all age groups over 55. Even so, those who are aging the most successfully show little diminution of most abilities, even over age 75. Suggests Weintraub, ``there are some components of mental skill that develop late in life and improve with age,`` such as the ``complex mental function we call `wisdom.` ``

Physical health did not seem closely related to successful mental aging. The intellectually able who scored best on assessment tests had roughly the same frequency of illness and used medication about as much as did those who tested lowest.

One intent of the Harvard research is to develop tests that can help measure the increasing variation among intellectually able people as they age. There`s no doubt that the incidence of Alzheimer`s disease and other disorders that affect the brain and the ability to do high level work does rise with age.

On Jan. 1, 1994, amendments to the Age Discrimination in Employment Act of 1967 go into effect, eliminating mandatory retirement for all workers except police officers, firefighters and college faculty members who have tenure. The new law requires further studies of these groups and the impact of setting a fixed retirement age for them.

So far, research into how intellectually able people age is generally good news, despite how much more must be learned about preventing Alzheimer`s disease and other disorders linked to advancing years. But questions about which presidential candidates, judges, physicians, professors, employees and others can still do competent work will have to be answered individual by individual. Even with good tests, such decisions will be politically tricky, legally hazardous and, sometimes, personally cruel.