June 28, 2009 -- In a study likely to ignite barroom arguments in both nations, American seniors performed significantly better on cognition and memory tests than their British counterparts -- indicating that older Yanks may be more mentally agile, researchers reported.
In tests of almost 14,000 residents over 65 on both sides of the Atlantic, Americans scored an average 13.2 on a 24-point cognitive scale, compared with 11.7 for comparable Britons, according to Dr. Kenneth Langa of the University of Michigan and colleagues.
Reporting online in the journal BMC Geriatrics, the researchers called the findings especially surprising because the Americans, in their sample, tended to have more cardiovascular disease and diabetes and were far more likely to be alcohol-abstinent -- all factors that would work against health in old age.
They had no definite explanation for the difference, but they pointed out that the United States sample was generally better educated and wealthier, and had a lower prevalence of depression.
The Americans also were somewhat more likely to take medication to treat high blood pressure.
A related clue, the researchers said, was that Americans 85 and older did particularly well in the testing relative to their British counterparts. The mean U.S. and British scores in this age group were 10.1 and 8.3, respectively. The differences were narrower in younger age ranges.
"The fact that the greatest cognitive advantage for U.S. adults in our study was among the oldest-old may also support the hypothesis that more aggressive diagnosis and treatment of hypertension, and possibly other cardiovascular risks, in the U.S. in middle-age and older adults leads to less significant cognitive decline among the oldest-old," the researchers wrote in the study.
Given the enormous health and cost implications of dementia, they added, research to confirm that more aggressive management of cardiovascular disease could improve cognition "could pay significant public health dividends."
U.S., U.K. Seniors Go Head-to-Head in Cognitive Tests
Their study drew on two survey research projects conducted simultaneously in the U.S. and Britain, both of which included the same test of cognitive function.
The projects were the U.S. Health and Retirement Study, with 8,299 participants older than 65, and the English Longitudinal Study of Aging, which involved 5,276 people over 65. Both studies collected information about health status, history and behaviors and included an eight-item assessment of depressive symptoms in the previous year.
The cognition test was a basic word-recall exercise. Given lists of nouns, participants were asked to repeat them immediately, and then again five minutes later after they had answered other survey questions.
Langa and colleagues found that the delayed recall test showed the greatest difference between seniors in the two countries: 4.3 for the U.S. and 3.3 for Britain, representing a 24 percent relative difference.
Performance on the immediate recall test was closer -- 5.3 versus 4.8 on average -- but still significantly different.
The researchers noted several limitations to the study, in addition to the different modes of survey administration in the two countries.
Response rates were considerably higher in the U.S. study, and there were also differences in the methods for recruiting proxy respondents for sample members unable to respond directly.
Both studies also relied on respondents to provide information on health status, history, and behaviors.
Still, Dr. Reisa Sperling, a neurologist at Harvard Medical School who was not involved in the study, suggested that the findings "may have 'real-world' significance."
"I found the difference in education and wealth particularly interesting, and I would speculate that the differences in 'cognitive reserve' may explain some of the observed differences in cognitive performance," she said.
But another neurologist, Dr. Charles DeCarli, of the University of California, Davis, said the methodological differences between the U.S. and British data were a major weakness in the study. In particular, he cited the fact that the two studies administered their surveys in different ways. For example, in Britain, they were all conducted in person, whereas the U.S. study used both telephone and fact-to-face contacts.
Study Points to Importance of Preventive Medicine
DeCarli noted in an e-mail that the 70 percent of U.S. participants who responded by telephone could have written down the word lists to aid their memories.
He also pointed out that there could be national differences in the accuracy of self-reported health status.
DeCarli agreed that "increased health care services for chronic diseases may be beneficial" for cognitive function, but he added that primary prevention is even more important.
"Most of the cost of American health care relates to medical procedures and not preventive medicine," he said.
This article was developed in collaboration with ABC News.