U. MICHIGAN (US)—The memory and cognitive function of seniors in the United States is significantly higher than that of their counterparts across the pond, a University of Michigan study shows.
“The better cognitive performance of U.S. adults was surprising since U.S. adults had a higher prevalence of cardiovascular risk factors, which are generally associated with cognitive decline and poorer mental function,” says Kenneth Langa, University of Michigan professor of medicine and lead author of the study.
Published in the June 25 issue of the journal BMC Geriatrics, the study is the first known international comparison of cognitive function in nationally representative samples of older adults in the United States and England.
Langa and colleagues compared data on 8,299 Americans age 65 and older with 5,276 British seniors. The same cognitive tests were administered to the two groups in the same year. The U.S. advantage in “brain health” was greatest for the oldest old—those age 85 and older.
On a population level, the overall difference in cognitive performance between the two countries was quite large—approaching the magnitude associated with about 10 years of aging. In other words, the cognitive performance of 75-year-olds in the U.S. was as good, on average, as that of 65-year-olds in England.
Higher levels of education and net worth in the United States accounted for some of the better cognitive performance of U.S. adults, according to Langa. Also, U.S. adults reported significantly lower levels of depressive symptoms than English adults, and according to Langa, this may have accounted for some of the U.S. advantage in brain health. Also, fewer than 15 percent of English adults received medication for depression, compared with 75 percent of depressed adults in the United States.
“Future research should explore whether more widespread use of antidepressant medication in the U.S. may be one reason for the lower level of depressive symptoms, and in turn, the better cognitive performance of older U.S. adults compared to older English adults,” Langa adds.
Coauthor David Weir, an economist at Michigan’s Institute for Social Research (ISR) and director of the Health and Retirement Study, notes that other ongoing research by ISR economist Robert Willis suggests there may be a connection between early retirement and early onset of cognitive decline. This provides another possible explanation for lower cognition at older ages in England where retirement occurs earlier than in the United States.
While U.S. adults reported a higher prevalence of hypertension, Langa notes, they also were more likely to be taking medications to treat the condition. A number of studies have shown a link between untreated hypertension and an increased risk for cognitive impairment.
“The fact that the greatest cognitive advantage for U.S. adults was among the oldest-old may support the hypothesis that more aggressive diagnosis and treatment of hypertension, and possibly other cardiovascular risks, leads to less cognitive decline,” Langa says.
“Given the growing number of older adults worldwide,” Langa argues, “future cross-national studies aimed at identifying the medical and social factors that might prevent or delay cognitive decline in older adults would make important and valuable contributions to public health.”
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