Loneliness, Dementia Status, and Their Association with All-Cause Mortality Among Older US Adults

Article type: Research Article

Authors: Georgescu, Michael F.^{a; 1; 2} | Beydoun, May A.^{a; 1; 2} | Ashe, Jason^a | Maino Vieytes, Christian A.^a | Beydoun, Hind A.^{b; c} | Evans, Michele K.^{a; 3} | Zonderman, Alan B.^{a; 3}

Affiliations: [a] Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Intramural Research Program, NIA/NIH/IRP, Baltimore, MD, USA | [b] U.S. Department of Veterans Affairs, VA National Center on Homelessness Among Veterans, Washington, DC, USA | [c] Department of Management, Policy, and Community Health, School of Public Health, University of Texas Health Science Center at Houston, Houston, TX, USA

Correspondence: [*] Correspondence to: May A. Beydoun, PhD, MPH, NIH Biomedical Research Center, National Institute on Aging, IRP, 251 Bayview Blvd, Suite 100, 04B118, Baltimore, MD 21224, USA. Fax: +1 410 558 8236; E-mail: baydounm@mail.nih.gov.

Note: [1] These authors contributed equally to this work.

Note: [2] MFG and MAB had full access to the data used in this manuscript and completed all the statistical analyses.3

Note: [3] Co-senior authors.

Abstract: Background:Loneliness, dementia, and mortality are interconnected. Objective:We aimed at understanding mediating pathways and interactions between loneliness and dementia in relation to mortality risk. Methods:The study tested bi-directional relationships between dementia, loneliness, and mortality, by examining both interactions and mediating effects in a large sample of older US adults participating in the nationally representative Health and Retirement Study. Out of≤6,468 older participants selected in 2010, with mean baseline age of 78.3 years and a follow-up time up to the end of 2020, 3,298 died at a rate of 64 per 1,000 person-years (P-Y). Cox proportional hazards and four-way decomposition models were used. Results:Algorithmically defined dementia status (yes versus no) was consistently linked with a more than two-fold increase in mortality risk. Dementia status and Ln(odds of dementia) were strongly related with mortality risk across tertiles of loneliness score. Loneliness z-score was also linked to an elevated risk of all-cause mortality regardless of age, sex, or race or ethnicity, and its total effect (TE) on mortality was partially mediated by Ln(odds of dementia), z-scored, (≤40% of the TE was a pure indirect effect). Conversely, a small proportion (<5%) of the TE of Ln(odds of dementia), z-scored, on mortality risk was explained by the loneliness z-score. Conclusions:In sum, dementia was positively associated with all-cause mortality risk, in similar fashion across loneliness score tertiles, while loneliness was associated with mortality risk. TE of loneliness on mortality risk was partially mediated by dementia odds in reduced models.

Keywords: Aging, Alzheimer’s disease, cohort studies, dementia, loneliness, mortality

DOI: 10.3233/JAD-231359

Journal: Journal of Alzheimer's Disease, vol. 99, no. 2, pp. 753-772, 2024