Cognitive reserve: implications for assessment and intervention.

The concept of reserve is used to explain the observation that some individuals function better than others in the presence of brain pathology. This article reviews the concept of reserve from its theoretical basis to the implication of reserve for clinical practice. A distinction between brain reserve, referring to individual differences in the anatomic substrate, and cognitive reserve, referring to differences in the flexibility or adaptivity of cognitive networks, is useful. Epidemiologic evidence indicates that a set of life exposures including higher educational and occupational attainment, and engaging in leisure activities is associated with a lower risk of incident dementia, suggesting that these life exposures may enhance cognitive reserve. This provides a basis for controlled clinical studies that can test specific exposures that may enhance reserve. The concept of cognitive reserve also has important implications for clinical practice in terms of diagnosis and prognosis.