Sunday, January 15, 2006

intelligence, elderly

The notion that everyone becomes senile with age is as widespread as it is false. Research on the intellectual abilities of older people does show some evidence of slowing of mental powers over the years (for example in ability to assimilate new information, speed of learning, solving of problems, and retention of short-term memory), yet the question is not how much mental power one loses, but rather how much mental power one retains. On that score the research is quite unequivocal- the overwhelming majority of older people retain the mental ability necessary to get along satisfactorily even in very old age. Of all the body organs, the brain normally deteriorates least, and only about 5 percent of the total population over 65, and about 20 percent of the population over 85, suffer senile dementia.
Actually, the peak of intelligence as measured by IQ tests-most of which stress speed in performance of mental tasks--comes in the teen years. By comparison with their teen years even people in their twenties are not as swift at mental tasks. According to research done by a leading gerontological psychologist, K. Warner Schaie of Pennsylvania State University, there is no uniformly reliable evidence of any notable decline in performance on mental tests until age 74, and even then the decline depends on the specific abilities being measured.
Schaie has conducted more than 30 years of research with hundreds of individuals who fairly well represent the U.S. population. His subjects have been residents of Seattle, Washington, from all walks of life, whose common characteristic was membership in a large health maintenance organization (HMO). He gave mental tests to this group in 1956, and over the years has tested and retested their mental abilities.
Through this research Schaie has identified the factors that promote favorable cognitive aging (ability to understand, to learn, to process information--other types of aging that involve the mind relate to the emotions, the senses, motor skills, etc.). These factors include: freedom from cardiovascular disease and other severe chronic illnesses; a good environment supported by a good education and a comfortable job and income; a complex and mentally stimulating environment; a flexible personality style in midlife; a spouse with a high cognitive status; and maintaining a level of perceptual processing speed (i.e., ability to take in information, understand it, and use it).
Further, Schaie has shown that disuse of the mind may account for much of the decline in mental power in late life; and, training in mental tasks can reverse decline of mental power for many people. In general, the research done by Schaie and others suggests that although mental abilities decline just as physical abilities do, individuals who keep active and use their minds remain mentally keen and competent as long as their health permits.
Schaie, K. Warner. "The Hazards of Cognitive Aging." The Gerontologist. 29:4, 484-493 (August 1989).


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