Aging, neurocognitive reserve, and the healthy brain

Healthy older adults experience a general decrement in physical and cognitive abilities with advancing age. The severity of these behavioral and neurocognitive declines is highly variable within the aged population. The Neurocognitive Reserve Hypothesis has been proposed in the cognitive and clinical neuroscience of aging to suggest that mentally-stimulating activities and life-long experiences may provide reserve-a protective mechanism that increases the brain's capacity to cope with age-related pathology. This model of the neurocognitive reserve hypothesis has successfully provided a theoretical account for the disjunction between the degree of observed brain damage/pathology and the clinical manifestations of that damage, both structurally and functionally. This article briefly reviews the behavioral and neuroimaging evidence that neurocognitive reserve shapes age-related and individual differences in neurocognitive processes, patterns of neural activation, brain structures and neural networks. Moreover, existing theoretical frameworks proposed in the aging literature are introduced to complement the understanding of neurocognitive reserve in normal and pathological aging. Finally, we report preliminary functional and structural neuroimaging results to support the hypothesis that neurocognitive reserve is a neural resource that mitigates not only the effects of cognitive decline caused by neurological diseases and/or psychiatric disorders, but also those caused by the general aging process. We conclude that there is currently limited understanding of the mechanisms underlying neurocognitive reserve; however, the concept provides a dynamic view for understanding the nature of resilience and our ability to adapt as we age to cope with brain pathology and damage. Future studies may consider decoding the individualized factors potentially underpinning neurocognitive reserve's beneficial contribution to protecting against accelerated cognitive decline and to promoting psychological resilience with advanced aging.