Learning another language 'could protect against dementia'

One study found that, among people who did eventually get dementia, those who were bilingual throughout their lives developed the disease three to four years later.
Dr Ellen Bialystok, of York University in Toronto, Canada, and two colleagues examined hospital records of patients diagnosed with a variety of different types of dementia.
They found: "In spite of being equivalent on a variety of cognitive and other factors, the bilinguals experienced onset and symptoms and were diagnosed approximately three to four years later than the monolinguals.
"Specifically, monolingual patients were diagnosed on average at age 75.4 years and bilinguals at age 78.6 years.

http://www.telegraph.co.uk/health/healthnews/9173552/Learning-another-language-could-protect-against-dementia.html