Abstract
Few studies have systematically explored the association between cognitive decline and mortality among the aged (above 80 years old) and also have limited evidence of the potential effect modifiers between them. Therefore, this study included 14,891 aged (mean age: 90.3±7.5 years) and 10,904 aged deaths with 34,486 person-years were observed. Cognitive decline was continuous and stratified into ten categories. Potential effect modifiers were identified as age, sex, blood pressure (BP) and high BP related diseases, including hypertension and cardiovascular disease (CVD) mortality. Cox proportional hazards model was used to evaluate the relationship between them after adjusting for demographic characteristics, socioeconomic status, lifestyle factors, leisure activities and health conditions. Compared to those with maintained high normal cognitive function, participants who have declined to severe cognitive impairment from a high normal cognitive function, low normal cognitive function and mild cognitive impairment have 55%, 56% and 63% mortality risks respectively. The multivariable-adjusted model indicated that the aged with decreasing one more point in MMSE score per year, had around 4% higher risk of mortality. There was a significant association of interaction of cognitive decline-mortality and sex (P=0.013) as well as hypertension (P=0.004) but with no significant association among age (P=0.277), high BP (P=0.082), and CVD mortality (P=0.058). Our findings suggest that periodic screen cognitive decline and strengthen BP control may be necessary for public health.