New Canadian research has found that having a strong ability for learning languages may help to reduce an individual's risk of developing dementia.
Carried out by researchers at the University of Waterloo, the new study looked at 325 Roman Catholic nuns in the United States who were taking part in the larger, internationally recognized Nun Study, which is a longitudinal study of religious sisters aged 75 and over.
The nuns were asked to report on how many languages they spoke, and 106 samples of the nuns' written work was also provided for analysis.
The findings, published in the Journal of Alzheimer's Disease, showed that just six percent of the nuns who spoke four or more languages developed dementia, compared to 31 percent of those who only spoke one language.
However, speaking two or three languages did not appear to have a significant effect on reducing dementia risk in this study, a finding which goes against those found in some previous studies.
When the researchers analyzed the nuns' written work, they found that written linguistic ability appeared to have an even greater effect on reducing dementia risk than the ability to speak different languages.
"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," explained lead author Suzanne 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."
"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," says Tyas.
"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."