People who speak two languages are twice as likely as those who only speak one to regain normal cognitive function after a stroke, according to a new study.

In recent years it has become clear that life experiences modify the way disease expresses itself in the brain, said lead author Dr. Suvarna Alladi, a neurology professor at Nizam's Institute of Medical Sciences in Hyderabad, India.

"One study in Toronto demonstrated that people who could speak two languages had later onset dementia," Alladi told Reuters Health.

Using multiple languages challenges the brain, as it can be harder to find a particular word switching between languages, and this challenge promotes neuroplasticity or "cognitive reserve," which prepares the brain to deal with new challenges, like disease, she said.

Researchers reviewed the medical records of 608 patients in the stroke registry at Alladi's institution between 2006 and 2013. In Hyderabad, Telugu, Urdu, Hindi and English are all common languages and children learn three languages in school, Alladi said.

More than half of the stroke patients spoke at least two languages.

After accounting for other lifestyle factors like smoking, high blood pressure, diabetes, age and education, the researchers found that about 40 percent of those who were bilingual had normal cognitive function after a stroke, compared to 20 percent of those who spoke only one language.

Bilingual people also performed better on tests of attention after a stroke, but there was no difference in the likelihood of experiencing aphasia, or loss of ability to understand or express speech, according to the results in Stroke.

"They develop stroke at the same age but outcomes appear to be better for bilinguals," Alladi said.

Using a second or third language regularly, or speaking it fluently even if you do not use it regularly, seems to provide the benefit to the brain, she said.

"The most important factor would be long-term language use," she said. Learning a second language in school and then never using it may not confer the same benefit, she said.

"The take-home message would be that cognitively stimulating activities are something you can do in midlife to protect yourself. One is speaking two languages, but it could also be playing a musical instrument," or other challenging activities, she said.

"This is heartening because you know that you can do something to protect yourself," Alladi said.

Three languages may be better than two languages, though that is still unclear, "but I suspect the additional positive effects of further languages falls off quickly as more languages are learned," said Fergus Craik of the Rotman Research Institute at Baycrest in Toronto, who was not part of the new study.

He and his colleagues previously found that bilingualism delays the onset of Alzheimer's disease by four to five years.

"People should learn a second language to communicate in a second living situation or to absorb a different culture - or out of interest and enjoyment," Craik told Reuters Health by email. "The neurological benefits are a bonus, not a primary goal."

In many parts of the world, like India, Africa and Europe, speaking multiple languages is already common practice, she said.

"In places where two languages are existing, it's a good idea to encourage that," she said.

SOURCE: http://bit.ly/1MZFqF2 Stroke, online November 19, 2015.