The average score for the 8,299 American participants was 12.8, while the 5,276 English subjects only averaged 11.4 out of 24. This difference approaches the magnitude associated with about 10 years of aging. In other words, 75-year-olds in the U.S. had memories as good, on average, as 65-year-olds in England. According to Langa, "Higher levels of education and net worth in the U.S. probably accounted for some of the better cognitive performance. Furthermore, U.S. adults reported significantly lower levels of depressive symptoms than English adults".
Transatlantic differences in aggressiveness of cardiovascular disease treatment are also suggested as possible explanations for the English adults' poor showing.
Full bibliographic information: Cognitive health among older adults in the United States and in England Kenneth M Langa, David J Llewellyn, Iain A Lang, David R Weir, Robert B Wallace, Mohammed U Kabeto and Felicia A Huppert BMC Geriatrics (in press)