Sedentary behavior and cognitive impairment risk in older Chinese adults: effect modification by physical activity

Based on a nationally representative sample, this study aimed to analyze the association between sedentary behavior (SB) and cognitive impairment risk (CIR) among older Chinese adults, identify high-risk populations, and examine the effect modification of physical activity (PA) on this association.

A total of 29,046 older adults aged 60-79 years were included from the 2025 China Sixth National Physical Fitness Surveillance database. SB and PA information were collected through structured questionnaires, and CIR was screened using the Ascertain Dementia 8 (AD8) scale. Multivariable logistic regression models were applied to analyze the association between SB and CIR, adjusting for confounding factors including sex, age, residential setting, educational attainment, geographic region, marital status, living arrangement, smoking status, and alcohol consumption. Stratified analyses were conducted to identify high-risk subgroups, and the effect modification by PA on the SB-CIR association was examined.

The overall CIR detection rate was 14.0% (4,075/29,046). After adjusting for confounding factors, using the 0-120 min/day SB group as the reference, the odds ratios (ORs) for CIR were 1.35 (95% CI: 1.23-1.48), 1.62 (1.47-1.79), and 1.89 (1.72-2.07) for SB of 120-180 min/day, 180-240 min/day, and ≥ 240 min/day, respectively, demonstrating a significant dose-response association (p < 0.001). The association was stronger among rural-dwelling and oldest-old (75-79 years) adults. Significant effect modification by PA on the SB-CIR association was observed (p for interaction = 0.02).

SB was significantly associated with CIR among older Chinese adults, and PA may modify the strength of this association. These findings suggest that rural-dwelling and oldest-old adults are populations warranting particular attention.