A study of 600 stroke victims found that compared to patients who spoke only one language, bilingual stroke patients were more than twice as likely to have normal cognition following their stroke and they also performed better on tests measuring post-stroke attention and function. Forty percent who were multilingual had normal mental functions afterwards, compared to 19 1/2 percent who only speak one language. But the two groups had similar frequencies of aphasia, at 11.8% among monolinguals and 10.5% among bilinguals.
The study was led by Suvarna Alladi, DM of the Nizam Institute of Medical Sciences in Hyderabad, India in collaboration with Edinburgh University's Thomas H. Bak, MD; the study took into account smoking, high blood pressure, diabetes and age, which might have functioned as confounders.
"The only outcome not influenced by bilingualism was the frequency of aphasia," the researchers wrote. "Although this might look surprising at first sight, this finding is in-line with current research, suggesting that the mechanism underlying the protective effect of bilingualism is not because of better linguistic but executive functions acquired through a lifelong practice of language switching."
The study was conducted in Hyderabad because its multi-cultural nature means many languages are commonly spoken, including Hindi, English, Telugu, and Urdu. Because of this, the researchers noted that the findings may not be applicable to bilingual people who live in areas like the U.S., where it is common to speak only one language.
The study, entitled "Impact of bilingualism on cognitive outcome after stroke," was published in the American Heart Association journal Stroke, found "results support the notion of a protective role of bilingualism in the development of post-stroke cognitive impairment".
It is the first time a study has been done looking at the relationship between the number of languages spoken and a patient's cognitive outcome after stroke.
Researchers believe the study, which was funded by the Indian Council of Medical Research, suggests the mental challenge of speaking multiple languages can boost cognitive reserve - an improved ability of the brain to cope with damaging influences such as stroke or dementia.
Co-author Bak said: "Bilingualism makes people switch from one language to another, so while they inhibit one language, they have to activate another to communicate. This switching offers practically constant brain training which may be a factor in helping stroke patients recover."
They conclude, "The mechanism underlying the protective effect of bilingualism is not because of better linguistic but executive functions acquired through a lifelong practice of language switching. The higher scores of bilinguals on attention and fluency domains with no difference in language subscore support this hypothesis. To conclude, our results support the notion of a protective role of bilingualism in the development of poststroke cognitive impairment."
This is yet one more reason to learn a 2nd, and even a 3rd language something Americans are a bit backwards at doing, compared with Europeans.