Sedentary Behavior and Cognitive Impairment Risk in Chinese Older Adults: Protective Role of Physical Activity

Background: This study aimed to systematically investigate the association between sedentary behavior and cognitive impairment risk based on large-scale data from Chinese older adults, and to examine whether physical activity could buffer the adverse effects of sedentary behavior on cognitive function. Methods: Participants aged 60-79 years were recruited from the 2025 Chinese National Physical Fitness Surveillance database. Daily sedentary behavior and physical activity information was collected through structured questionnaires, and cognitive impairment risk was screened using the AD8 scale. After controlling for potential confounding factors including sex, age group, residence, educational attainment, geographic region, marital status, living arrangement, smoking status, and alcohol consumption, multivariable logistic regression models were employed to analyze the association between sedentary behavior and cognitive impairment risk. Subsequently, stratified analyses were conducted to explore the association strength across different subgroups, and the moderating effect of physical activity on the sedentary-cognition relationship was further examined. Finally, sensitivity analyses were performed to verify the robustness of the findings. Results: This cross-sectional study included 29,046 Chinese older adults aged 60-79 years (mean age 69.2 ± 5.7), with an overall cognitive impairment risk detection rate of 14.0% (4,075/29,046).Multivariable logistic regression analysis adjusted for confounding factors revealed that, compared with the reference group (0-120 min/day of sedentary time), the odds ratios (ORs) for cognitive impairment risk were 1.35 (95% CI: 1.23-1.48),1.62 (1.47-1.79), and 1.89 (1.72-2.07) for sedentary time of 120-180 minutes,180-240 minutes, and ≥240 min/day, respectively, demonstrating a significant dose-response relationship (P <0.001).Stratified analyses indicated that the association between sedentary behavior and cognitive impairment risk showed similar effect sizes in both males and females, but stronger associations were observed among rural residents and the oldest-old (75-79 years) populations. Moderation analysis by physical activity on cognitive function (interaction P = 0.02). Furthermore, various sensitivity analyses confirmed the robustness of these findings. Conclusion: Based on large-scale national data, this study systematically reveals a significant dose-response association between sedentary behavior and cognitive impairment risk among Chinese older adults, whereby longer sedentary time corresponds to greater cognitive impairment risk. Concurrently, physical activity can effectively attenuate the adverse effects of sedentary behavior on cognitive function, demonstrating an important protective role. Rural older adults and the oldest-old populations represent high-risk groups for sedentary-related cognitive impairment and warrant priority attention.