Interpreting cognitive decline in the face of cognitive reserve: Does bilingualism affect cognitive aging?

Evaluation of the cognitive level of older adults, including decisions about meeting clinical thresholds for dementia, is typically based on behavioral levels of performance. However, individuals with high cognitive reserve will outperform the levels typically associated with their brain structure, providing inaccurate assessments of their status. We define cognitive reserve as the relation between brain integrity and cognitive level, and use the case of bilingualism as a source of cognitive reserve to illustrate how information from only one can distort the interpretation of the individual’s cognitive status.