Read a Wall Street Journal article that describes how people who speak multiple languages appear to have brains that resist some of the early symptoms and brain damage of dementia. The article, Building a More Resilient Brain, describes how a concept called cognitive reserve, often well-developed in bilingual individuals, may enable the brain to continue working even when damage or stress occurs.
Researchers who have examined the brains of dementia patients have found that the dementia damage in bilingual and non-bilingual individuals is roughly the same, however, the more severe and observable symptoms of the disease appear to be delayed by several years in people who speak another language. The reporter, Shirley Wang, details these statistics in the online article which also features an interesting chart and video.
As Our Parents Age So Do We 