Association between cognitive reserve dimensions and frailty among older adults: A structured narrative review

Frailty is a broadly investigated geriatric condition, which is characterized by an increased vul- nerability to stressors. It represents an extremely relevant public health issue, increasingly conceptualized in a multidimensional perspective. The concept of cognitive reserve (CR), as originally conceptualized by Stern, has been developed in the past decades as a potential fac- tor able to determine individual differences in cognitive vulnerability and trajectories occur- ring with aging. Our purpose was to provide a comprehensive review of the literature exploring the relationship between CR dimensions, selected according to the Stern model, and frailty status. A review of the literature on the association between potential CR dimen- sions and frailty was carried out through PubMed, Web of Knowledge and Scopus. CR expressed in terms of education, occupation, premorbid intelligence quotient and leisure time activities was associated with frailty in both cross-sectional and longitudinal observations. The majority of reviewed evidence suggests a potential protective role of CR factors against the onset and the worsening of frailty among older adults. To the best of our knowledge, this is the first attempt to provide a comprehensive overview regarding the association between CR dimensions and frailty. Education, occupation, premorbid intelligence quotient and leisure time activities are able to interact with the general concept of frailty, rather than simply affect- ing the cognitive trajectory towards dementia. The lack of a unique and operationalized approach to the assessment of CR, as well as the wide heterogeneity of frailty evaluation tools and criteria, denote some methodological critical issues that need to be overcome.