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Multilingual people have advantages in avoiding dementia, study suggests

CHARYZMATYCZNA STARSZA PANI
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Drawn from the Nun Study, new research suggests that those who speak four or more languages have better chance of keeping brain healthy.

Dementia and Alzheimer’s disease continue to afflict older people and put strains on their families. A new study suggests that learning foreign languages may offer a way to keep one’s brain healthy into older adulthood.

In looking at a well-known study conducted with Catholic religious sisters several years ago, researchers found that only 6% of nuns studied who spoke four or more languages developed dementia, while 31% of those who only spoke one language developed dementia.

The research, led by Suzanne Tyas, a public health professor at the University of Waterloo in Ontario, examined the health outcomes of 325 Roman Catholic nuns who were members of the School Sisters of Notre Dame in the United States. The data were drawn from a larger, internationally recognized study examining the sisters, known as the Nun Study.

“The Nun Study is unique: It is a natural experiment, with very different lives in childhood and adolescence before entering the convent, contrasted with very similar adult lives in the convent,” said Tyas. “This gives us the ability to look at early-life factors on health later in life without worrying about all the other factors, such as socioeconomic status and genetics, which usually vary from person to person during adulthood and can weaken other studies.”

Tyas pointed out that language is a complex ability of the human brain, and “switching between different languages takes cognitive flexibility. So it makes sense that the extra mental exercise multilinguals would get from speaking four or more languages might help their brains be in better shape than monolinguals.”

The researchers also examined 106 samples of the nuns’ written work and compared it to the broader findings. They found that written linguistic ability affected whether the individuals were at greater risk of developing dementia. For example, idea density—the number of ideas expressed succinctly in written work—helped reduce the risk even more than multilingualism.

“This study shows that while multilingualism may be important, we should also be looking further into other examples of linguistic ability,” said Tyas. “In addition, we need to know more about multilingualism and what aspects are important—such as the age when a language is first learned, how often each language is spoken, and how similar or different these languages are. This knowledge can guide strategies to promote multilingualism and other linguistic training to reduce the risk of developing dementia.”

The study was published in the Journal of Alzheimer’s Disease.