Risk of new-onset dementia following COVID-19 infection: a systematic review and meta-analysis

Abstract

Background Emerging evidence suggests coronavirus disease 2019 (COVID-19) infection may increase the risk of developing dementia, although studies have reported conflicting findings. This meta-analysis aimed to synthesise the literature on the association between COVID-19 and the risk of new-onset dementia. Methods PubMed, Embase and Web of Science were searched for cohort studies or case–control studies that investigated new-onset dementia development among adult COVID-19 survivors compared to individuals without COVID-19 infection from inception to 9 November 2023. Studies that exclusively involved populations younger than 18 years, with known dementia or lacked adequate data about the risk of dementia were excluded. Two authors independently conducted the screening of eligible studies, data extraction and risk of bias assessment. The primary outcome was new-onset dementia following COVID-19 infection. Data were pooled using random-effects models, with hazard ratios (HRs) and 95% confidence intervals (CIs) calculated. Results A total of 15 retrospective cohort studies encompassing 26 408 378 participants were included. Pooled analysis indicated COVID-19 was associated with an increased risk of new-onset dementia (HR = 1.49, 95% CI: 1.33–1.68). This risk remained elevated when compared with non-COVID cohorts (HR = 1.65, 95% CI: 1.39–1.95), and respiratory tract infection cohorts (HR = 1.29, 95% CI: 1.12–1.49), but not influenza or sepsis cohorts. Increased dementia risk was observed in both males and females, as well as in individuals older than 65 years (HR = 1.68, 95% CI: 1.48–1.90), with the risk remaining elevated for up to 24 months. Conclusion This meta-analysis demonstrates a significant association between COVID-19 infection and increased risk of developing new-onset dementia, which underscores the need for cognitive monitoring and early intervention for COVID-19 survivors to address potential long-term neurological impacts.