Cognitive functioning in centenarians: A coordinated analysis of results from three countries

Cognitive functions among centenarians in Japan, Sweden, and the United Sta tes are described. Three areas are explored. First, definitions and prevale nce of dementia are compared between Japan and Sweden. Second, levels of co gnitive performances between centenarians and younger age groups are presen ted. Third, interindividual variations in cognitive performances in centena rians and younger persons are compared in Sweden and the United States. The Swedish and Japanese studies show a variation in prevalence of dementia be tween 40% and 63% with a relatively higher prevalence among women. Part of the variance is probably due to differences in sampling and criteria of dem entia, Along with the lower cognitive performance in centenarians, compared with younger age groups, the Swedish and U.S. results show a wider range o f performance among centenarians For those semantic or experientially relat ed abilities that tend to be maintained over the adult life span. In contra st, a smaller range of performance is found for centenarians on those fluid or process-related abilities that have shown a downward age-related trajec tory of performance. Lower variability is probably due to centenarians reac hing the lower performance limit. The conclusions agree with the assumption of a general increase in cognitive differentiation with increasing age, pr imarily in measures of crystallized intelligence. The conclusions point to the general robustness of results across countries, as well as to the relat ive importance of cognition for longevity.