Cognitive functioning and health as determinants of mortality in an older population

The authors studied whether the ability of cognitive functioning to predict mortality is pervasive or specific, and they considered the role of health in the cognition-mortality association. Data were taken from a sample of 2 ,380 persons aged 55-85 years who took part in the Netherlands' Longitudina l Aging Study Amsterdam in 1992-1993. Five cognitive measures were distingu ished: general cognitive functioning, information processing speed, fluid i ntelligence, learning, and proportion retained. Mortality data were obtaine d during an average follow-up period of 1,215 days. Cox proportional hazard s regression models revealed that all cognitive functions predicted mortali ty independent of age, sex, education, and depressive symptoms. When health (self-rated health, medication use, physical performance, functional limit ations, lung function, specific chronic diseases) was also taken into accou nt, information processing speed, fluid intelligence, and proportion retain ed remained independent predictors of mortality; whereas the ability of gen eral cognitive functioning and learning to determine mortality was lost. Th e authors concluded that the ability of cognitive functioning to predict mo rtality is pervasive to all cognitive functions that were included in the s tudy when age, sex, education, and depressive symptoms are considered and i s more specific to some functions when also controlling for health.