Education, Occupational Complexity, and Incident Dementia: A COSMIC Collaborative Cohort Study

Article type: Research Article

Authors: Hyun, Jinshil^{a; *} | Hall, Charles B.^{a; b} | Katz, Mindy J.^a | Derby, Carol A.^a | Lipnicki, Darren M.^c | Crawford, John D.^c | Guaita, Antonio^d | Vaccaro, Roberta^d | Davin, Annalisa^d | Kim, Ki Woong^e | Han, Ji Won^f | Bae, Jong Bin^g | Röhr, Susanne^{h; i} | Riedel-Heller, Steffi^h | Ganguli, Mary^j | Jacobsen, Erin^j | Hughes, Tiffany F.^k | Brodaty, Henry^{c; l} | Kochan, Nicole A.^c | Trollor, Julian^{c; m} | Lobo, Antonio^{n; o; p} | Santabarbara, Javier^{n; o; q} | Lopez-Anton, Raul^{n; o; r} | Sachdev, Perminder S.^{c; l} | Lipton, Richard B.^{a; b} | for Cohort Studies of Memory in an International Consortium (COSMIC)

Affiliations: [a] Saul R. Korey Department of Neurology, AlbertEinstein College of Medicine, Bronx, NY, USA | [b] Department of Epidemiology & Population Health, Albert Einstein College of Medicine, Bronx, NY, USA | [c] Centre for Healthy Brain Ageing, University of New South Wales, Sydney, New South Wales, Australia | [d] Golgi Cenci Foundation, Italy | [e] Department of Neuropsychiatry, Seoul National University Bundang Hospital, Seongnam, South Korea | [f] Department of Psychiatry, College of Medicine, Seoul National University, Seoul, South Korea | [g] Department of Brain & Cognitive Sciences, Seoul National University, Seoul, South Korea | [h] Institute of Social Medicine, Occupational Health and Public Health (ISAP), University of Leipzig, Leipzig, Germany | [i] Global Brain Health Institute (GBHI), Trinity College Dublin, Dublin, Ireland | [j] University of Pittsburgh, Pittsburgh, PA, USA | [k] Youngstown State University, Youngstown, OH, USA | [l] Dementia Collaborative Research Centre, University of New South Wales, Sydney, New South Wales, Australia | [m] Department of Developmental Disability Neuropsychiatry, School of Psychiatry, University of New South Wales, Sydney, New South Wales, Australia | [n] Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain | [o] Centro de Investigación Biomédica en Red de Salud Mental, Ministry of Science and Innovation, Spain | [p] Department of Medicine and Psychiatry, Universidad de Zaragoza, Zaragoza, Spain | [q] Department of Preventive Medicine and Public Health, University of Zaragoza, Zaragoza, Spain | [r] Department of Psychology and Sociology, Universidad de Zaragoza, Teruel, Spain

Correspondence: [*] Correspondence to: Jinshil Hyun, Department of Neurology, Albert Einstein College of Medicine, 1225 Morris Park Avenue, Bronx, NY 10461, USA. Tel.: +1 718 568 9854; E-mail: jinshil.hyun@einsteinmed.org.

Abstract: Background:Education and occupational complexity are main sources of mental engagement during early life and adulthood respectively, but research findings are not conclusive regarding protective effects of these factors against late-life dementia. Objective:This project aimed to examine the unique contributions of education and occupational complexity to incident dementia, and to assess the mediating effects of occupational complexity on the association between education and dementia across diverse cohorts. Method:We used data from 10,195 participants (median baseline age = 74.1, range = 58∼103), representing 9 international datasets from 6 countries over 4 continents. Using a coordinated analysis approach, the accelerated failure time model was applied to each dataset, followed by meta-analysis. In addition, causal mediation analyses were performed. Result:The meta-analytic results indicated that both education and occupational complexity were independently associated with increased dementia-free survival time, with 28%of the effect of education mediated by occupational complexity. There was evidence of threshold effects for education, with increased dementia-free survival time associated with ‘high school completion’ or ‘above high school’ compared to ‘middle school completion or below’. Conclusion:Using datasets from a wide range of geographical regions, we found that both early life education and adulthood occupational complexity were independently predictive of dementia. Education and occupational experiences occur during early life and adulthood respectively, and dementia prevention efforts could thus be made at different stages of the life course.

Keywords: Cognitive reserve, coordinated analysis, education, occupational complexity

DOI: 10.3233/JAD-210627

Journal: Journal of Alzheimer's Disease, vol. 85, no. 1, pp. 179-196, 2022