The Influence of Birth Cohorts on Future Cognitive Decline

Article type: Research Article

Authors: Turcotte, Valérie^{a; b} | Hudon, Carol^{a; b; c} | Potvin, Olivier^b | Dadar, Mahsa^d | Duchesne, Simon^{b; e; *} | 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] VITAM – Centre de Recherche en Santé Durable, Centre Intégré Universitaire en Santé et Services Sociaux de la Capitale Nationale, Québec, QC, Canada | [d] Department of Psychiatry, Faculty of Medicine, McGill University, Montréal, QC, Canada | [e] Département de Radiologie et Médecine Nucléaire, Faculté de Médecine, Université Laval, Québec, QC, Canada

Correspondence: [*] Correspondence to: Simon Duchesne, PhD, Département de Radiologie et Médecine Nucléaire, Université Laval, 1050 avenue de la Médecine, Québec, QC, G1V 0A6, Canada. Tel.: +1 418 663 5741/Ext. 24777; 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 (https://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 writing of this report. A complete listing of ADNI investigators can be found at:https://adni.loni.usc.edu/wp-content/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf

Abstract: Background:Slowed rates of cognitive decline have been reported in individuals with higher cognitive reserve (CR), but interindividual discrepancies remain unexplained. Few studies have reported a birth cohort effect, favoring later-born individuals, but these studies remain scarce. Objective:We aimed to predict cognitive decline in older adults using birth cohorts and CR. Methods:Within the Alzheimer’s Disease Neuroimaging Initiative, 1,041 dementia-free participants were assessed on four cognitive domains (verbal episodic memory; language and semantic memory; attention; executive functions) at each follow-up visit up to 14 years. Four birth cohorts were formed according to the major historical events of the 20th century (1916–1928; 1929–1938; 1939–1945; 1946–1962). CR was operationalized by merging education, complexity of occupation, and verbal IQ. We used linear mixed-effect models to evaluate the effects of CR and birth cohorts on rate of performance change over time. Age at baseline, baseline structural brain health (total brain and total white matter hyperintensities volumes), and baseline vascular risk factors burden were used as covariates. Results:CR was only associated with slower decline in verbal episodic memory. However, more recent birth cohorts predicted slower annual cognitive decline in all domains, except for executive functions. This effect increased as the birth cohort became more recent. Conclusion:We found that both CR and birth cohorts influence future cognitive decline, which has strong public policy implications.

Keywords: Aging, birth cohorts, cognitive decline, cognitive reserve, generations, neuropsychology

DOI: 10.3233/JAD-220951

Journal: Journal of Alzheimer's Disease, vol. 93, no. 1, pp. 179-191, 2023