Mediation of Age-related Cognitive Outcomes by Stroke and Vascular Risk Factors in the Canadian Longitudinal Study on Aging (CLSA)

Anjana J. Menon, Bogna A. Drozdowska, Ryan T. Muir, Michael D. Hill, Philip A. Barber, Eric E. Smith, and Aravind Ganesh

Introduction

Cognition changes with age. Stroke and vascular risk factors can affect brain aging, and many vascular risk factors are modifiable. The objective of this study was to examine whether stroke and vascular risk factors mediate the association between chronological age and cognitive outcomes.

Methods

We used data from the Canadian Longitudinal Study on Aging (CLSA), including 51,338 adults aged 45 to 85 years. The study included two cohorts: the tracking cohort (n = 21,241) and the comprehensive cohort (n = 30,097). Baseline and first follow-up data, approximately three years apart, were analyzed using structural equation modeling. Stroke and vascular risk factors included stroke, TIA, hypertension, diabetes, heart disease, mood disorders, and lifestyle risk factors. Outcomes included baseline cognition and change in cognition.

Results

Stroke and vascular risk factors partially mediated the relationship between age and cognitive outcomes. For baseline cognition, the total effect beta was -0.0086, the direct effect beta was -0.0083, and the indirect effect beta was -0.0002, corresponding to 2.6% mediation. For cognitive change, the total effect beta was -0.01334, the direct effect beta was -0.0123, and the indirect effect beta was -0.001, corresponding to 7.3% mediation.

Conclusion

Stroke and vascular risk factors partially mediated the relationship between age and cognitive outcomes. The mediated proportion was modest but statistically significant for both baseline cognition and change in cognition over follow-up. Preventing and managing vascular risk factors may support healthier cognitive aging.

Key Takeaway

Stroke and vascular risk factors account for a small but statistically significant portion of the relationship between age and cognition in CLSA, highlighting vascular health as a potential target for healthy aging.