title: Delaying onset of dementia: are two languages enough?
abstract: There is an emerging literature suggesting that speaking two or more languages may significantly delay the onset of dementia. Although the mechanisms are unknown, it has been suggested that these may involve cognitive reserve, a concept that has been associated with factors such as higher levels of education, occupational status, social networks, and physical exercise. In the case of bilingualism, cognitive reserve may involve reorganization and strengthening of neural networks that enhance executive control. We review evidence for protective effects of bilingualism from a multicultural perspective involving studies in Toronto and Montreal, Canada, and Hyderabad, India. Reports from Toronto and Hyderabad showed a significant effect of speaking two or more languages in delaying onset of Alzheimer's disease by up to 5 years, whereas the Montreal study showed a significant protective effect of speaking at least four languages and a protective effect of speaking at least two languages in immigrants. Although there were differences in results across studies, a common theme was the significant effect of language use history as one of the factors in determining the onset of Alzheimer's disease. Moreover, the Hyderabad study extended the findings to frontotemporal dementia and vascular dementia.
authors: Department of Medicine, Division of Neurology, Baycrest, Toronto, ON, Canada M6A 2E1 ; Department of Medicine, Division of Neurology, Mt. Sinai Hospital, Toronto, ON, Canada M5G 1X5 ; Rotman Research Institute, Baycrest, 3560 Bathurst Street, Toronto, ON, Canada M6A 2E1 ; Department of Medicine (Neurology), University of Toronto, Toronto, Canada M5G 2C4.
authors: Morris
authors: M
authors: Freedman
authors: Department of Neurology, Nizam's Institute of Medical Sciences, Punjagutta, Hyderabad 500 082, India.
authors: Suvarna
authors: S
authors: Alladi
authors: Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research and Jewish General Hospital/McGill University Memory Clinic, Jewish General Hospital, 3744 Chemin de la Côte-Sainte-Catherine, Montreal, QC, Canada H3T 1E2 ; Division of Geriatric Medicine, Department of Medicine, McGill University, Canada H3T 1E2 ; Department of Clinical Neurosciences, Sir Mortimer B. Davis-Jewish General Hospital, Canada H3T 1E2.
authors: Howard
authors: H
authors: Chertkow
authors: Rotman Research Institute, Baycrest, 3560 Bathurst Street, Toronto, ON, Canada M6A 2E1 ; Department of Psychology, York University, 4700 Keele Street, Toronto, ON, Canada M3J IP3.
authors: Ellen
authors: E
authors: Bialystok
authors: Rotman Research Institute, Baycrest, 3560 Bathurst Street, Toronto, ON, Canada M6A 2E1 ; Department of Psychology, University of Toronto, Toronto, ON, Canada M5S 3G3.
authors: Fergus I M
authors: FI
authors: Craik
authors: Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research and Jewish General Hospital/McGill University Memory Clinic, Jewish General Hospital, 3744 Chemin de la Côte-Sainte-Catherine, Montreal, QC, Canada H3T 1E2 ; Department of Psychology/Centre for Research in Human Development, Concordia University, 7141 Sherbrooke Street West, Montreal, QC, Canada H4B 1R6 ; Centre for Research on Brain, Language, and Music, McGill University, Montreal, Canada H3G 2A8.
authors: Natalie A
authors: NA
authors: Phillips
authors: Department of Linguistics, University College of Arts & Social Sciences, Osmania University, Hyderabad 500 007, India.
authors: Vasanta
authors: V
authors: Duggirala
authors: Centre for Neural and Cognitive Sciences, University of Hyderabad, Gachibowli, Hyderabad 500 046, India.
authors: Surampudi Bapi
authors: SB
authors: Raju
authors: Human Cognitive Neuroscience and Centre for Cognitive Aging and Cognitive Epidemiology School of Philosophy, Psychology and Language Sciences, University of Edinburgh, 7 George Square, Edinburgh EH8 9JZ, UK ; Centere for Clinical Brain Sciences, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK.
authors: Thomas H
authors: TH
authors: Bak
mesh_terms: D017668:Age of Onset; D058245:Cognitive Reserve; D003704:Dementia / Q000517:prevention & control* / Q000523:psychology; D006801:Humans; D007802:Language; D019303:Multilingualism