Aerobic physical activity is associated with lower pneumonia and COVID-19 mortality in adults with cognitive...

Cardiovascular disease and pneumonia are major causes of death in dementia, but cause-specific mortality has rarely been examined in clinically confirmed cognitive-impairment cohorts. In this nationwide retrospective cohort study, 116,563 individuals with clinically confirmed mild cognitive impairment or dementia in the Korean Dementia Relief Center registry (2016-2021) were linked to health screening and death registry data. Aerobic physical activity (APA) was quantified in metabolic-equivalent minutes per week (MET·min/week). Cox proportional hazards and Fine-Gray models estimated adjusted hazard ratios (HRs) and subdistribution HRs (sHRs). The Benjamini-Hochberg procedure controlled the false discovery rate (FDR) across 18 cause-specific comparisons. During 400,500 person-years of follow-up (mean, 3.4 years), 5022 participants (4.31%) died. Compared with inactivity, low, moderate, and high APA were associated with lower all-cause mortality (HR [95% CI], 0.728 [0.652-0.813], 0.704 [0.636-0.781], and 0.636 [0.590-0.687], respectively). High APA was associated with lower pneumonia mortality (sHR, 0.554; 95% CI, 0.437-0.702) and COVID-19 mortality (sHR, 0.520; 0.368-0.735). These point estimates were numerically lower than for ischemic heart disease and cerebrovascular disease (sHRs, 0.613 and 0.630). Pneumonia mortality was lower across all APA levels after FDR control (q ≤ 0.023). The E-value for the high APA-pneumonia association was 3.01. APA was associated with lower mortality even at modest activity levels, especially for pneumonia deaths. Achievable activity goals may therefore merit prospective evaluation as part of supportive care for adults with cognitive impairment. Because APA may also indicate preserved physiological reserve, these findings do not establish causality and require confirmation using repeated, objective activity measurements.