OTTAWA: People who are fully bilingual and speak both languages every day for most of their lives can delay the onset of dementia by up to four years compared with those who only know one language, Canadian scientists said on Friday.

Researchers said the extra effort involved in using more than one language appeared to boost blood supply to the brain and ensure nerve connections remained healthy -- two factors thought to help fight off dementia.

“We are pretty dazzled by the results,” Professor Ellen Bialystok of Toronto’s York University said in a statement.

“In the process of using ... two languages, you are engaging parts of your brain, parts of your mind that are active and need that kind of constant exercise and activity, and with that experience (it) stays more robust,” she later told CTV television.

The leading cause of dementia among the elderly is Alzheimer’s disease, which gradually destroys a person’s memory. There is no known cure.

Bialystok’s team focused on 184 elderly patients with signs of dementia who attended a Toronto memory clinic between 2002 and 2005. Of the group, 91 spoke only one language while 93 were bilingual.

“The researchers determined that the mean age of onset of dementia symptoms in the monolingual group was 71.4 years, while the bilingual group was 75.5 years,” the statement said.

Bialystok stressed that bilingualism helped delay the start of dementia rather than preventing it altogether.—Reuters