Broadband Access, Internet Use, and General Cognition in Middle-Aged and Older Adults: Longitudinal Study.

Background: Internet use may support cognitive health in aging populations, but the digital divide in access and use might worsen inequalities. Objective: This study aimed to examine whether internet use mediates the long-term relationship between broadband access and cognitive function among middle-aged and older adults in China. Methods: Using 3-wave data (2015-2020) from the China Health and Retirement Longitudinal Study (N=6063), we applied parallel-process latent growth curve models to analyze trajectories of broadband access, internet use, and general cognition, adjusting for sociodemographic and time-varying covariates. Results: Baseline broadband access predicted initial internet use (β=0.453; P<.001), and broadband access increases strongly forecasted rises in internet use (β=0.625; P<.001). Increased internet use was associated with improved baseline general cognition (β=0.470; P<.001) and more significant cognitive improvements over time (β=0.444; P=.006). Older age, lower educational level, and rural residence were correlated with lower initial digital engagement; however, participants from rural areas demonstrated a greater adoption rate. Health status and social activities initially positively influenced outcomes; however, their impact diminished by the final wave. Conclusions: These findings demonstrate that internet use mediates the longitudinal relationship between broadband access and cognitive resilience. The observed cascading growth trajectories suggest that gradually bridging the digital divide may help mitigate cognitive decline.