If the benefits of being bilingual spill over to other aspects of cognition, then we would expect to see a lower incidence of Alzheimer’s disease in bilinguals than in monolinguals, or at least a later onset of Alzheimer’s for bilinguals. In fact, there is evidence to support this claim. The psychologist Ellen Bialystok and her colleagues obtained the histories of 184 individuals who had made use of a memory clinic in Toronto. For those who showed signs of dementia, the monolinguals in the sample had an average age at time of onset of 71.4 years. The bilinguals, in contrast, received their diagnosis at 75.5 years, on average.
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But as encouraging as these kinds of studies are, they still have not established exactly how or why differences between bilinguals and monolinguals exist. Because these studies looked back at the histories of people who were already bilingual, the results can only say that a difference between the two groups was found, but not why that difference occurred.
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But even if studying a foreign language is not a magical cure-all, there is one thing it will do: It will make you a better speaker of a foreign language.
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