Cognitive reserve: the evolution of the conceptual framework

Abstract

Brain and Cognitive reserve concept is a theoretical general framework introduced to explain individual differences to withstand brain damages. Several behavioural and neuroimaging studies support the evidence that lifestyles act on brain plasticity modulating the impact of neurological insults. However, once that AD is clinically evident, the protective benefits of premorbid experience are assumed to be substantially decreased. This review presents an overview of the principal literature focused on reserve mechanisms. The evolution of the conceptual framework is considered, passing from brain and cognitive to neural reserve's hypothesis. Interactions between reserve mechanisms and AD-related biomarkers are reported. In particular this review is focussed on the neuroimaging (MRI) studies. MRI provides the opportunity to investigate in vivo structural and functional brain changes. Several studies reported here assessed the impact of reserves on brain resilience. Literature supports the hypothesis that reserves impact on neurodegenerative process in the early phase of AD. Moreover, studies fit with the existence of a "neural reserve", characterised by specific neural networks and their efficiency. It remains to be demonstrated whether interventions later in life can modulate this brain resilience.