Association between COVID-19 infection and new-onset dementia in older adults: a systematic review and meta-analysis.

Dec 16, 2024

The relationship between COVID-19 infection and a possible increased likelihood of older adults developing new-onset dementia (NOD) remains elusive.
A thorough search was performed across several databases including MEDLINE/PubMed, PsycINFO, Scopus, medRxiv, and PQDT Global for studies published in English from January 2020 to December 2023. Only original investigations exploring the link between COVID-19 infection and NOD were selected for inclusion. We assessed the risk of developing NOD, using Risk Ratio (RR) for measurement. Control groups were categorized as: (i) a non-COVID cohort with other respiratory infections [control group (C1)]; and (ii) a non-COVID cohort with otherwise unspecified health status [control group (C2)]. Follow-up periods were divided into intervals of 3, 6, 12, and 24 months post-COVID.
11 studies (involving 939,824 post-COVID-19 survivors and 6,765,117 controls) were included in the review. Across a median observation period of 12 months post-COVID, the overall incidence of NOD was about 1.82% in the COVID-infected group, compared to 0.35% in the non-COVID-infected group. The overall pooled meta-analysis showed a significantly increased NOD risk among COVID-19 older adult survivors compared to non-COVID-19 controls (RR = 1.58, 95% CI 1.21-2.08). Similar increased NOD risks were observed in subgroup analyses restricted to an observational period of 12 months (RR = 1.56, 95% CI 1.21-2.01), as well as in five studies that employed propensity score matching to sufficiently and effectively control for multiple confounding covariates (RR = 1.46, 95% CI 1.10-1.94). COVID-19 group and C1 group shared a comparably increased risk of developing NOD (overall RR = 1.13, 95% CI 0.92-1.38).
Under normal circumstances, we believe that COVID-19 infection is likely to be a risk factor for developing NOD in older adults over time. While the increased NOD risk due to COVID-19 infection appears to be similar to that associated with other respiratory infections, it warrants and necessitates investigation with longer observations.

© 2024. The Author(s).

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ABOUT THE EXPERTS

Dan Shan,Congxiyu Wang,Trevor Crawford,Carol Holland
Dan Shan

Centre for Ageing Research, Division of Health Research, Faculty of Health and Medicine, Lancaster University, Health Innovation Campus, Sir John FisBailrigg, Lancasterher Drive, Bailrigg, Lancaster, LA1 4YT, UK. d.shan@lancaster.ac.uk.

Congxiyu Wang

Department of Psychiatry, University of Oxford, Oxford, UK.

Trevor Crawford

Centre for Ageing Research, Department of Psychology, Faculty of Science and Technology, Lancaster University, Lancaster, UK.

Carol Holland

Centre for Ageing Research, Division of Health Research, Faculty of Health and Medicine, Lancaster University, Health Innovation Campus, Sir John FisBailrigg, Lancasterher Drive, Bailrigg, Lancaster, LA1 4YT, UK.