A recent paper by Bialystok et al in Neuropsychologia (vol. 45, pgs. 459 to 464) 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% were immigrants. Our memory clinic, in Montreal Canada, has the advantage of having a large set of individuals who are either multilingual immigrants to Canada, or who are nonimmigrants but raised in both official languages of Canada—French and English. We thus attempted to replicate the above findings using a larger cohort in a different setting. We examined age at diagnosis of Alzheimer disease and age at symptom onset for all unilingual versus multilingual participants, and then for those who were nonimmigrant English/French bilinguals. Overall, we found a small but significant protective effect of more than 2 languages spoken, but we 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 Bialystok et al with 2 or more languages delaying the diagnosis of Alzheimer disease by almost 5 years. A trend toward the same effect was also seen in nonimmigrants whose first language was French. In contrast, in nonimmigrants whose first language was English, no such effect was found. These results are discussed in relation to the earlier findings and the theory of cognitive reserve.
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§Research Centre, Institut Universitaire de Gériatrie
∥Department of Neurology and Neurosurgery
*Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, and Jewish General Hospital/ McGill University Memory Clinic, Jewish General Hospital
†Division of Geriatric Medicine, Department of Medicine, McGill University
‡Department of Clinical Neurosciences, Sir Mortimer B. Davis -Jewish General Hospital
¶Department of Psychology/Centre for Research in Human Development, Concordia University, Montreal, Qubec, Canada
♯Department of Epidemiology and Biostatistics and Occupational Health, McGill University; Division of Clinical Epidemiology, McGill University Health Centre
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Received for publication March 30, 2009
accepted July 26 2009
Dr Chertkow is supported by operating grants from the CIHR (Canadian Institutes for Health Research). Dr Chertkow is a “chercheur national” of the FRSQ (Fonds de la Recherche en Santé du Québec).
Reprints: Howard Chertkow, MD, Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, and Jewish General Hospital/McGill University Memory Clinic, Jewish General Hospital, McGill University, Montreal, Quebec, Canada, H3T-1E2 (e-mail email@example.com).