Lifelong bilingualism, cognitive reserve and Alzheimer's disease A review of findings

Increasing our understanding about neuroprotective lifestyle variables has become a practical imperative in our aging society. Cognitive reserve (CR) refers to the use brain resources in a way that allows for coping with neuropathology and maintaining cognitive functioning. A growing body of evidence suggests that bilingualism may represent a form of CR against Alzheimer's disease (AD). The purpose of the present review is to summarize both behavioral and neuro-imaging evidence for bilingualism as a reserve variable against AD. The potential influences of literacy, intelligence, immigration status are discussed. Evidence is reviewed suggesting that bilingualism may delay clinical AD symptoms by protecting against age-related declines in the brain's executive control circuitry. It is suggested that such potential beneficial effects within executive control systems may enable bilinguals to circumvent the typical effects of AD pathology on symptom expression for several years.