THURSDAY, January 5, 2012 (Health.com) — For years, many experts have maintained that the subtle changes in memory and mental function that occur naturally as we get older rarely begin before age 60.
That may be optimistic: A new study, published today in the British Medical Journal, suggests that age-related cognitive changes—which may in some cases herald Alzheimer’s disease and other types of dementia—are under way as early as our mid-to-late 40s.
Researchers in Europe tracked the mental function of more than 7,000 British civil servants for a decade, and they found that even the youngest participants, who were between the ages of 45 and 49 at the outset, generally displayed slight yet measurable declines in short-term memory, mental reasoning, and verbal facility over the course of the study.
The declines were too small to be noticeable in everyday life and were detected only through a battery of tests the researchers gave the participants every three to four years. But the findings may have implications for the prevention of dementia, and underscore the importance of caring for our bodies and minds early in life, the researchers say.
“We, and others, have shown healthy lifestyles and good cardiovascular health to be important for cognitive outcomes,” says lead author Archana Singh-Manoux, Ph.D., research director at the French National Institute of Health and Medical Research (INSERM), in Paris. “The fact that cognition declines early implies that midlife levels of these factors—health behaviors and cardiovascular risk factors and disease—might be important for cognitive outcomes later in life.”
Indeed, years of research suggest that heart-healthy habits are also good for the brain. Although the results haven’t always been consistent, previous studies have shown that obesity, unhealthy cholesterol levels, and a lack of exercise in midlife are all linked with an increased risk of dementia later on.
Brain-imaging studies, meanwhile, have found that abnormalities associated with cognitive decline, Alzheimer’s, and other dementias can occur years—even decades—before any outward problems arise.
Researchers haven’t conclusively proven that cognitive decline in middle age predicts Alzheimer’s or other dementias, but on balance the evidence suggests that small changes in midlife mental function can become magnified later in life, says Francine Grodstein, Sc.D., an epidemiologist and associate professor of medicine at Brigham and Women’s Hospital, in Boston.
“There is a lot of evidence that [people] with cognitive decline are at highest risk of later developing dementia, so it is likely that preventing or delaying cognitive decline today will help reduce risk of dementia tomorrow,” says Grodstein, who was not involved in the research but wrote an editorial accompanying the study.
Next page: More research needed