Index of Intelligence Adjusted Adult Years

Life expectancy at birth has long been viewed as a useful index. The increase in life expectancy worldwide experienced over the last century is clearly a good thing. The World Health Organization some years ago added another health indicator, disability adjusted life years (DALYs). It recognized that a healthy year is better than a year in which a person is sick, and a year in which someone is in command of all functions is better than one in which that person is disabled in some function as a result of some earlier disease.

I wonder if an index of intelligence adjusted adult years might also be useful.

Intelligence is not fixed at birth. We believe that poor nutrition and frequent illness in infancy can interfere with the full development of the brain. Indeed, it seems that a child's brain needs stimulation to develop; kids whose parents talk to them a lot generally turn out to have better language skills than kids whose parents don't.

The Flynn Effect has also been observed. IQ tests, well designed, have results with frequencies that display the well known bell shaped curve (normal distribution). The average IQ is 100, and known portions of test populations fall above and below given values of IQ. The tests are periodically revised and scores are standardized accordingly. IQ tests are perhaps most useful when used for young people, and can predict something about their likely success in schooling. It has been observed that young people on average score higher on earlier tests than they do on the current IQ test. This is the Flynn Effect, a general creeping up of IQ scores in this limited sense. Still, the Flynn effect suggests that each generation is likely to score higher on average on the same IQ tests than would the previous generation. Somehow, IQ's seem to be increasing.

We also know that older people, especially those afflicted by some form of dementia, show a decrease in mental abilities.

What if the IQ distribution were measured for age cohorts of adults, weighted by the size of the population in those age cohorts, to develop an adult distribution of IQ scores. Could that be tracked? measure changes in the IQ of the population?

Of course, as implied in the previous paragraphs, different public policies could influence population IQ in different ways. Medical intervention to prevent dementia or to slow the progression of dementia would affect intellectual abilities in older people; early childhood care could help assure full brain development in children. Indeed, interventions encouraging parents to talk to their preschoolers seem to be useful in developing language skills in their children. I suspect that schooling is needed to fully develop intelligence for people with potential for high IQ scores.

Perhaps it would be useful to have an indicator that would track the evolution of the intelligence of the population, and that would encourage interventions to increase adult intelligence.