Coevolution of Cognitive and Health Trajectories Among US Older Adults With Cognitive Impairment

OBJECTIVES: Understanding how multiple health aspects coevolve over time in persons with cognitive impairment is critical for clinical care, yet few studies have examined these dynamic interplays. This study investigated the relationship between perceived health status trajectories and cognitive trajectories in PCIs, providing novel insights into how broader health dynamics influence cognitive decline. DESIGN: This is a secondary data analysis with a national representative sample of Medicare beneficiaries in the United States. SETTING AND PARTICIPANTS: Data were from 2569 persons with cognitive impairment in the 2011-2021 National Health and Aging Trends Survey. METHODS: Bayesian dual-trajectory modeling was used to identify distinct trajectories of perceived health and cognition. We examined their sociodemographic and health correlates of each trajectory. Conditional probabilities were estimated to determine how belonging to a specific health status trajectory group influences the likelihood of being in a particular cognitive trajectory group. RESULTS: We identified 5 distinct trajectory groups for health status and cognition. Most participants (73%) exhibited high- to medium-baseline health with stable or moderate decline, 14.2% experienced sharp decline after a high baseline, and 12.9% started low with moderate decline. For cognition, 69.2% showed high-to-medium initial levels with stable or slight decline, 23.6% showed moderate decline, and 7.2% had a low and stable trajectory. Respondents with the most favorable health status trajectories were more likely to have the best cognitive trajectory, whereas those with sharp declining health status experienced worse cognition, despite higher baseline health levels. CONCLUSIONS AND IMPLICATIONS: Stable health trajectories are strongly linked to better cognitive outcomes, whereas sharp health declines predict poorer cognition. Our findings highlight the interconnected biological and behavioral pathways through which health changes may accelerate or mitigate cognitive deterioration, offering insights for targeted interventions and holistic care for persons with cognitive impairment.