The effects of cognitive impairment on 9-year mortality in a community sample
Using 9-year mortality data on a community sample of 3,560 adults aged 40 and over, this study assessed the effects of cognitive functioning and one-year declines in cognitive functioning on mortality controlling for comorbid chronic medical illness, physical disability, and psychiatric illness. The study determined the 9-year vital status and, among the decreased, date of death of respondents who were first interviewed in 1980 by the New Haven Epidemiologic Catchment Area Study. Mortality risk by cognitive functioning, as assessed by the Mini-Mental State Examination (MMSE), was estimated using Cox Proportional Hazards Models controlling for baseline assessments of physical and mental health. For both men and women, lower scores on the MMSE decreased the risk of survival, although the effect was stronger for younger respondents than older respondents. Decline in MMSE scores over the course of one year had no additional effect on mortality beyond the resulting MMSE score. Cause-specific mortality was also examined.