Brain reserve, cognitive reserve, compensation, and maintenance: operationalization, validity, and mechanisms of cognitive resilience.

Significant individual differences in the trajectories of cognitive aging and in age-related changes of brain structure and function have been reported in the past half-century. In some individuals, significant pathological changes in the brain are observed in conjunction with relatively well-preserved cognitive performance. Multiple constructs have been invoked to explain this paradox of resilience, including brain reserve, cognitive reserve, brain maintenance, and compensation. The aim of this session of the Cognitive Aging Summit III was to examine the overlap and distinctions in definitions and measurement of these constructs, to discuss their neural and behavioral correlates and to propose plausible mechanisms of individual cognitive resilience in the face of typical age-related neural declines.