Background: Increasing evidence suggests that life course factors such as education and bilingualism may have a protective role against dementia due to Alzheimer disease. This study aimed to compare the effects of education and bilingualism on the onset of cognitive decline at the stage of mild cognitive impairment (MCI). Methods: A total of 115 patients with MCI evaluated in a specialty memory clinic in Hyderabad, India, formed the cohort. MCI was diagnosed according to Petersen's criteria following clinical evaluation and brain imaging. Age at onset of MCI was compared between bilinguals and monolinguals, and across subjects with high and low levels of education, adjusting for possible confounding variables. Results: The bilingual MCI patients were found to have a clinical onset of cognitive complaints 7.4 years later than monolinguals (65.2 vs. 58.1 years; p = 0.004), while years of education was not associated with delayed onset (1-10 years of education, 59.1 years; 11-15 years of education, 62.6 years; >15 years of education, 62.2 years; p = 0.426). Conclusion: The effect of bilingualism is protective against cognitive decline, and lies along a continuum from normal to pathological states. In comparison, the role of years of education is less robust.

Stern Y: Cognitive reserve. Neuropsychologia 2009;47:2015-2028.
Bialystok E, Craik FI, Freedman M: Bilingualism as a protection against the onset of symptoms of dementia. Neuropsychologia 2007;45:459-464.
Alladi S, Bak TH, Duggirala V, Surampudi B, Shailaja M, Shukla AK, Chaudhuri JR, Kaul S: Bilingualism delays age at onset of dementia, independent of education and immigration status. Neurology 2013;81:1938-1944.
Grant A, Dennis NA, Li P: Cognitive control, cognitive reserve, and memory in the aging bilingual brain. Front Psychol 2014;5:1401.
Sharp ES, Gatz M: The relationship between education and dementia: an updated systematic review. Alzheimer Dis Assoc Disord 2011;25:289-304.
Richards M, Deary IJ: A life course approach to cognitive reserve: a model for cognitive aging and development? Ann Neurol 2005;58:617-622.
Roe CM, Xiong C, Miller JP, Morris JC: Education and Alzheimer disease without dementia: support for the cognitive reserve hypothesis. Neurology 2007;68:223-228.
Cobb JL, Wolf PA, Au R, White R, D'Agostino RB: The effect of education on the incidence of dementia and Alzheimer's disease in the Framingham Study. Neurology 1995;45:1707-1712.
Iyer GK, Alladi S, Bak TH, Shailaja M, Mamidipudi A, Rajan A, Gollahalli D, Chaudhuri JR, Kaul S: Dementia in developing countries: does education play the same role in India as in the West? Dement Neuropsychol 2014;8:132-140.
Craik FI, Bialystok E, Freedman M: Delaying the onset of Alzheimer disease: bilingualism as a form of cognitive reserve. Neurology 2010;75:1726-1729.
Zahodne LB, Schofield PW, Farrell MT, Stern Y, Manly JJ: Bilingualism does not alter cognitive decline or dementia risk among Spanish-speaking immigrants. Neuropsychology 2014;28:238-246.
Chertkow H, Whitehead V, Phillips N, Wolfson C, Atherton J, Bergman H: Multilingualism (but not always bilingualism) delays the onset of Alzheimer disease: evidence from a bilingual community. Alzheimer Dis Assoc Disord 2010;24:118-125.
Ardila A, Bertolucci PH, Braga LW, Castro-Caldas A, Judd T, Kosmidis MH, Matute E, Nitrini R, Ostrosky-Solis F, Rosselli M: Illiteracy: the neuropsychology of cognition without reading. Arch Clin Neuropsychol 2010;25:689-712.
Bak TH, Alladi S: Can being bilingual affect the onset of dementia? Future Neurol 2014;9:101-103.
Green DW, Abutalebi J: Language control in bilinguals: the adaptive control hypothesis. J Cogn Psychol (Hove) 2013;25:515-530.
Schweizer TA, Ware J, Fischer CE, Craik FI, Bialystok E: Bilingualism as a contributor to cognitive reserve: evidence from brain atrophy in Alzheimer's disease. Cortex 2012;48:991-996.
Perani D, Farsad M, Ballarini T, Lubian F, Malpetti M, Fracchetti A, Magnani G, March A, Abutalebi J: The impact of bilingualism on brain reserve and metabolic connectivity in Alzheimer's dementia. Proc Natl Acad Sci USA 2017;114:1690-1695.
Arenaza-Urquijoe EM, Landeaua B, Joie RL, Mevel K, Mézenge F, Perrotin A, Desgranges B, Bartrés-Faze D, Eustache F, Chételat G: Relationships between years of education and gray matter volume, metabolism and functional connectivity in healthy elders. Neuroimage 2013;83:450-457.
Marques P, Moreira P, Magalhães R, Costa P, Santos N, Zihl J, Soares J, Sousa N: The functional connectome of cognitive reserve. Hum Brain Mapp 2016;37:3310-3322.
Rolstad S, Nordlund A, Eckerström C, Gustavsson MH, Zetterberg H, Wallin A: Biomarkers in relation to cognitive reserve in patients with MCI - proof of concept. Dement Geriatr Cogn Disord 2009;27:194-200.
Estanga A, Ecay-Torres M, Ibañez A, Izagirre A, Villanua J, Garcia-Sebastian M, Iglesias Gaspar MT, Otaegui-Arrazola A, Iriondo A, Clerigue M, Martinez-Lage P: Beneficial effect of bilingualism on Alzheimer's disease CSF biomarkers and cognition. Neurobiol Aging 2017;50:144-151.
Bak TH, Alladi S: Bilingualism, dementia and the tale of many variables: why we need to move beyond the Western World. Commentary on Lawton et al (2015) and Fuller-Thomson (2015). Cortex 2016;74:315-317.
Braak H, Braak E: Staging of Alzheimer's disease-related neurofibrillary changes. Neurobiol Aging 1995;16:271-278.
Petersen RC: Mild cognitive impairment as a diagnostic entity. J Intern Med 2004;256:183-194.
Vemuri P, Weigand SD, Przybelski SA, Knopman DS, Smith GE, Trojanowski JQ, Shaw LM, Decarli CS, Carmichael O, Bernstein MA, Aisen PS, Weiner M, Petersen RC, Jack CR Jr; Alzheimer's Disease Neuroimaging Initiative: Cognitive reserve and Alzheimer's disease biomarkers are independent determinants of cognition. Brain 2011;134(pt 5):1479-1492.
Ossher L, Bialystok E, Craik FI, Murphy KJ, Troyer AK: The effect of bilingualism on amnestic mild cognitive impairment. J Gerontol B Psychol Sci Soc Sci 2013;68:8-12.
Bialystok E, Craik FI, Binns MA, Ossher L, Freedman M: Effects of bilingualism on the age of onset and progression of MCI and AD: evidence from executive function tests. Neuropsychology 2014;28:290-304.
Alladi S, Shailaja M, Mridula KR, Haritha CA, Kavitha N, Khan SA, Divyaraj G, Kaul S: Mild cognitive impairment: clinical and imaging profile in a memory clinic setting in India. Dement Geriatr Cogn Disord 2014;37:113-124.
Alladi S, Mekala S, Chadalawada SK, Jala S, Mridula R, Kaul S: Subtypes of dementia: a study from a memory clinic in India. Dement Geriatr Cogn Disord 2011;32:32-38.
Alladi S, Bak TH, Shailaja M, Gollahalli D, Rajan A, Surampudi B, Hornberger M, Duggirala V, Chaudhuri JR, Kaul S: Bilingualism delays the onset of behavioural but not aphasic forms of frontotemporal dementia. Neuropsychologia 2017;99:207-212.
Mohanty AK: Bilingualism in a Multilingual Society: Psychosocial and Pedagogical Implications. Mysore, Central Institute of Indian Languages, 1994.
Bak TH: The impact of bilingualism on cognitive ageing and dementia: finding a path through a forest of confounding variables; in Bialystok E, Sullivan MD (eds): Aging and Bilingualism. Linguistic Approaches to Bilingualism. Amsterdam, John Benjamins Publishing, 2016, vol 6, pp 205-226.
Alladi S, Bak TH, Mekala S, Rajan A, Chaudhuri JR, Mioshi E, Krovvidi R, Surampudi B, Duggirala V, Kaul S: Impact of bilingualism on cognitive outcome after stroke. Stroke 2016;47:258-261.
Rao SL, Subbakrishna DK, Gopukumar K: NIMHANS Neuropsychology Battery - 2004 Manual, ed 1. Bangalore, NIMHANS, 2004, pp 6-201.
Bialystok E, Craik FI, Luk G: Lexical access in bilinguals: effects of vocabulary size and executive control. J Neurolinguistics 2008;21:522-538.
Vasanta D: (Re)searching multilingualism in India: a critical review of concepts. J Indian Speech Hear Assoc 2011;25:71-81.
Lynch JW, Kaplan GA, Shema SJ: Cumulative impact of sustained economic hardship on physical, cognitive, psychological and social functioning. N Engl J Med 1997;337:1889-1895.
Bak TH, Nissan JJ, Allerhand MM, Deary IJ: Does bilingualism influence cognitive aging? Ann Neurol 2014;75:959-963.
Hughes TF, Snitz BE, Ganguli M: Should mild cognitive impairment be subtyped? Curr Opin Psychiatry 2011;24:237-242.
Farias ST, Mungas D, Reed BR, Harvey D, De Carli C: Progression of mild cognitive impairment to dementia in clinic- vs community-based cohorts. Arch Neurol 2009;66:1151-1157.
Vega-Mendoza M, West H, Sorace A, Bak TH: The impact of late, non-balanced bilingualism on cognitive performance. Cognition 2015;137:40-46.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.