Birth Cohorts and Cognitive Reserve Influence Cognitive Performances in Older Adults

Article type: Research Article

Authors: Turcotte, Valérie^{a; b} | Potvin, Olivier^b | Dadar, Mahsa^{b; c} | Hudon, Carol^{a; b} | Duchesne, Simon^{b; c; *} | for the Alzheimer’s Disease Neuroimaging Initiative¹

Affiliations: [a] École de psychologie, Faculté des Sciences Sociales, Université Laval, Québec, QC, Canada | [b] CERVO Brain Research Centre, Centre Intégré Universitaire en Santé et Services Sociaux de la Capitale Nationale, Québec, QC, Canada | [c] Département de Radiologie et Médecine Nucléaire, Faculté de Médecine, Université Laval, Québec, QC, Canada

Correspondence: [*] Correspondence to: Simon Duchesne, PhD, Université Laval, Département de Radiologie et Médecine Nucléaire, 1050 Avenue de la Médecine, Québec, QC, G1V 0A6, Canada. Tel.: +1 418 663 5741 ext. 4777; E-mail: simon.duchesne@fmed.ulaval.ca.

Note: [1] Data used in preparation of this article were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database (http://adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or wri-ting of this report. A complete listing of ADNI investigators can be found at: http://adni.loni.usc.edu/wp-content/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf

Abstract: Background:Evidence suggests birth cohort differences in cognitive performance of older adults. Proxies of cognitive reserve (CR), such as educational attainment and occupational complexity, could also partly account for these differences as they are influenced by the sociocultural environment of the birth cohorts. Objective:To predict cognitive performance using birth cohorts and CR and examine the moderating influence of CR on cognitive performance and structural brain health association. Methods:Using ADNI data (n = 1628), four birth cohorts were defined (1915–1928; 1929–1938; 1939–1945; 1946–1964). CR proxies were education, occupational complexity, and verbal IQ. We predicted baseline cognitive performances (verbal episodic memory; language and semantic memory; attention capacities; executive functions) using multiple linear regressions with CR, birth cohorts, age, structural brain health (total brain volume; total white matter hyperintensities volume) and vascular risk factors burden as predictors. Sex and CR interactions were also explored. Results:Recent birth cohorts, higher CR, and healthier brain structures predicted better performance in verbal episodic memory, language and semantic memory, and attention capacities, with large effect sizes. Better performance in executive functions was predicted by a higher CR and a larger total brain volume, with a small effect size. With equal score of CR, women outperformed men in verbal episodic memory and language and semantic memory in all cohorts. Higher level of CR predicted better performance in verbal episodic memory, only when total brain volume was lower. Conclusion:Cohort differences in cognitive performance favor more recent birth cohorts and suggests that this association may be partly explained by proxies of CR.

Keywords: Aging, birth cohorts, cognition, cognitive impairments, cognitive reserve, generations

DOI: 10.3233/JAD-215044

Journal: Journal of Alzheimer's Disease, vol. 85, no. 2, pp. 587-604, 2022