Dementia is an age-independent risk factor for severity and death in COVID-19 inpatients

Introduction Dementia has been associated with COVID-19 prevalence, but whether this reflects higher infection, older age of patients, or disease severity remains unclear. Methods We investigated a cohort of 12,863 UK Biobank community-dwelling individuals > 65 years old (1814 individuals >= 80 years old) tested for COVID-19. Individuals were stratified by age to account for age as a confounder. Risk factors were analyzed for COVID-19-positive diagnosis, hospitalization, and death. Results All-cause dementia, Alzheimer's disease (AD), and Parkinson's disease (PD) were associated with COVID-19-positive diagnosis, and all-cause dementia and AD remained associated in individuals >= 80 years old. All-cause dementia, AD, or PD were not risk factors for overall hospitalization, but increased the risk of hospitalization of COVID-19 patients. All-cause dementia and AD increased the risk of COVID-19-related death, and all-cause dementia was uniquely associated with increased death in >= 80-year-old patients. Discussion All-cause dementia and AD are age-independent risk factors for disease severity and death in COVID-19.