Mediating effects of cognitive reserve on the relationship between frailty and cognition in older people without dementia.

Abstract

This study aimed to explore the potential mediating effects of cognitive reserve on the association between frailty and cognition in the older people without dementia. We performed a cross-sectional analysis of data from 3122 community-dwelling older adults (≥ 65-years-old) without dementia of the Cognitive Function and Ageing Study in Wales. A 31-item frailty index was used to assess frailty. A cognitive lifestyle score was constructed to evaluate cognitive reserve, which includes participants' educational level, occupational attainment, and engagement in social and cognitive activities in later life. Linear regression and mediation modeling were used to investigate the relationship between frailty and cognition and the mediating effects of cognitive reserve as well as social and cognitive activities, an alterable component of cognitive reserve for older adults. Frailty was negatively associated with cognition. Cognitive reserve was a mediator of the association between frailty and global cognition (- 1.92; 95% CI: - 2.50, - 1.35), as well as individual cognitive domains, with indirect effects contributing to 13-59% of the total effects. Social and cognitive activities have smaller but similar mediating effects on these associations. Negative effect of frailty on cognition was partially mediated by a reduction in cognitive reserve. Our results support the possibility that enhancing cognitive reserve, especially engagement in social and cognitive activities may protect cognitive health against frailty.