Multilingualism (But Not Always Bilingualism) Delays the Onset of Alzheimer Disease: Evidence From a Bilingual Community

The authors note that an earlier study suggested that early bilingualism produced a statistically significant 4.1-year delay in onset of memory loss symptoms in older individuals with Alzheimer disease, possibly reflecting an increase in the cognitive reserve of these individuals. That study focused on multilingual elderly patients of whom 90 percent were immigrants. The authors’ Montreal memory clinic has the advantage of having a large set of individuals who are either multilingual immigrants to Canada, or who are non-immigrants but raised in both official languages of Canada—French and English. They thus attempted to replicate the earlier findings using a larger cohort in a different setting. The authors examined age at diagnosis of Alzheimer disease and age at symptom onset for all unilingual versus multilingual participants, and then for those who were non-immigrant English/French bilinguals. Overall, the authors found a small but significant protective effect of more than two languages spoken, but they found no significant benefit in bilinguals overall in relation to age at diagnosis or age at symptom onset. However, in the immigrant group, the results mirrored those of the earlier study with two or more languages delaying the diagnosis of Alzheimer disease by almost 5 years. A trend toward the same effect was also seen in non-immigrants whose first language was French. In contrast, in non-immigrants whose first language was English, no such effect was found. Their results are discussed in relation to the earlier findings and the theory of cognitive reserve.

Alzheimer Disease & Associated Disorders : An International Journal

Vol. 24

no. 2

118-125

April 2010

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