Towards an understanding of healthy cognitive ageing: The importance of lifestyle in Cognitive Reserve Theory and the Scaffolding Theory of Aging and Cognition

The World Health Organization (WHO) aims to improve our understanding of the factors that promote healthy cognitive ageing and combat dementia. Therefore, ageing theories that consider individual ageing trajectories are of paramount importance to meet the WHO’s aim. Both the revisited Scaffolding Theory of Aging and Cognition (STAC-r) and Cognitive Reserve theory (CR) offer theoretical frameworks for the mechanisms of cognitive ageing and the positive influence of an engaging lifestyle. STAC-r additionally considers adverse factors, such as depression. Currently, it is unclear which of the two theories best explains the compensation mechanism of age-related cognitive decline. This review provides an essential discussion of the similarities and differences between these prominent cognitive ageing theories, their implications for intervention methods and neurodegenerative disease, and significant shortcomings that have not yet been addressed. This review will direct researchers to common insights in the field and to intervention targets and testable hypotheses for future research. Future research should investigate the potential use of STAC-r in neurodegenerative diseases and provide clarity as to what combination of factors build CR, including their relative importance and when in life they are most effective.