Cognitive decline and risk of all-cause mortality in older women: a cohort study

BACKGROUND: With global population aging and an increasing prevalence of cognitive decline, the association between cognitive change as a dynamic process and all-cause mortality remains insufficiently investigated. We therefore aimed to assess the association of cognitive decline on all-cause mortality in older women. METHODS: We analyzed data originating from the cognitive cohort of the Women's Health Study established in 1998. 6,377 US-based women aged ≥ 65 years and currently or formerly employed in health-related professions were enrolled at baseline. Women with complete information on 4-year global cognitive performance change were eligible for our analysis and assigned to quintiles according to change in global cognitive performance. Follow-up for all-cause mortality was administered until December 31, 2022. Multivariable adjusted Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% CIs of the effect of cognitive change on the risk of all-cause mortality. Secondary analyses evaluated the risk in the lowest 20% and 10% of the cognitive change distribution, and according to verbal memory changes. RESULTS: 5,214 women with a mean age of 66.1 years (SD 4.0) were included in the analyses. Women were followed for an average of 13.4 person years and 3,333 deaths were observed. When compared to the 5th quintile with the greatest improvement, the adjusted HR for all-cause mortality was 0.96 (95%CI [0.86-1.08]) for the 4th, 1.04 (95%CI [0.93-1.16]) for the 3rd, 1.15 (95%CI [1.04-1.29]) for the 2nd, and 1.37 (95%CI [1.23-1.52]) for the 1st quintile characterized by the greatest decline. Similar patterns were observed for verbal memory change. Risk was further elevated when comparing the worst 20% (HR: 1.32 (95%CI [1.21-1.43])) and 10% (HR: 1.44 (95%CI [1.29-1.60])) to all other participants. CONCLUSION: Cognitive decline over four years was associated with an increased risk of mortality among older women. Further studies should explore whether declines earlier in life or among men are also associated with an increased risk of mortality.