From Yahoo News:

Speaking one or more languages can stall the onset of dementia, according to a new Canadian study. “Our study found that speaking two languages throughout one’s life appears to be associated with a delay in the onset of symptoms of dementia by four years compared to those who speak only one language,” Ellen Bialystok, lead researcher and professor at York University in Toronto, said in a statement.

Her research team examined the medical records of 184 patients with cognitive complaints. Ninety-one spoke one language and 93 were bilingual, speaking a combination of 25 different languages, including Polish, Yiddish, German, Romanian and Hungarian. They found that monolingual patients showed evidence of Alzheimer’s or other forms of dementia at 71.4 years of age on average, while the bilingual group manifested symptoms at 75.5 years.

This difference remained even after considering the possible effects of cultural differences, immigration, formal education, employment and gender on the results. “There are no pharmacological interventions that are this dramatic,” said Morris Freedman, study co-author and an expert on the mechanisms underlying cognitive impairment due to diseases such as Alzheimer’s. The results will be published in the February issue of Neuropsychologia.