Association between Allostatic Load and Stroke Risk: A Cross-Sectional and Longitudinal Analysis

Background: Allostatic load (AL) is a composite measure representing the cumulative physiological burden of chronic stress. While AL has been implicated in various chronic diseases, its specific association with stroke—particularly in Chinese older adults—remains underexplored. This study aimed to investigate the cross-sectional and longitudinal relationships between AL and stroke risk, and to examine the role of hypertension in this association. Methods: We used data from the China Health and Retirement Longitudinal Study (CHARLS), tracking participants aged 45 and older from 2011 to 2018. The analysis included 6,300 people. AL was built from 11 biomarkers across four body systems and grouped into low, moderate, and high burden levels. We first used cross-sectional analysis and logistic regression to see how baseline AL related to stroke. Then, we went further to see whether changes in AL over time—what we call AL trajectories—affected future stroke risk. Results: Looking at the cross-sectional data, high AL was clearly tied to higher stroke risk (OR = 2.093, 95% CI: 1.329–3.367). But here’s the thing—once we adjusted for hypertension, that link weakened and became non-significant. Mediation analysis showed that hypertension actually explained about 44.75% of AL’s total effect on stroke. Longitudinally, each one-unit rise in AL was associated with an 11.6% increase in stroke risk (OR = 1.116, 95% CI: 1.051–1.184). We also found that people whose AL worsened—or stayed high over time—faced a significantly higher stroke risk compared to those with consistently low AL. Conclusion: High AL is independently associated with an increased risk of stroke in Chinese older adults. Hypertension plays a significant mediating role in this relationship. In addition, increases or persistently elevated AL over time further elevate stroke risk. These findings highlight the potential of AL as a valuable indicator for stroke risk stratification and prevention.