Later-Life Cognitive Trajectories and Risk of Death: Results from a 6-Year Longitudinal Study of 7082 Chinese

Abstract

Background and objectives: To identify cognitive decline trajectories in a Chinese elderly population, explore the associations between these trajectories and mortality, and further identify risk factors related to certain trajectories of cognitive decline.

Design: Prospective cohort study.

Setting: The group-based trajectory modeling and Cox proportional hazards models were conducted to explore the association between cognitive trajectory groups and mortality, while multinomial logistic regression models were constructed to estimate potential risk factors.

Participants: We included 7082 participants aged 65 years or above in three consecutive but non-overlapping cohorts of the Chinese Longitudinal Healthy Longevity Survey with the Chinese version of the Mini-Mental State Examination up to 6 years. Participants were subsequently followed for a median (IQR) of 2.89 (1.38-3.12) years to obtain their survival status and date of death.

Measurements: Chinese version of the Mini-Mental State Examination was used to measure participants' cognitive function.

Results: Through use of group-based trajectory modeling, we determined three cognitive trajectory groups. Then, after adjusting for confounding factors, we found a monotonic and positive association between cognitive decline and mortality risk. Meanwhile, the association varied among elderly populations in different age groups and BMI categories, but did not differ by sex, smoking, drinking and exercising. Older seniors, females and those with poorer baseline cognitive function and less social participation tended to be more likely to be in the unfavorable trajectory groups.

Conclusion: We found that the faster the cognitive decline, the higher the mortality, especially among those aged 65-79 years and those overweight. Our findings suggested the importance of implement better monitoring of the cognitive function of the elderly population.

Keywords: Chinese older adults; Cognitive function; group-based trajectory modeling; mortality; trajectory group.