My grandmother has dementia and I am continually doing research on Alzheimer’s and dementia. This article discusses how speaking more than one language can possibly delay the effects of memory loss;
"If you speak more than one language, you have a better chance of staving off memory loss and, possibly, the mental and physical decline associated with Alzheimer’s disease. New research shows that even learning a new language later in life can delay the onset of dementia.
At the Voice of America, there are many people who speak one, two, three or more languages. Sandra LeMaire, on VOA's Web Desk, speaks four languages fluently..."
http://www.voanews.com/english/news/health/Speaking-Another-Language-Cou...
Source: www.voanews.com