An analysis of nearly 62 million electronic medical records found that adults with dementia are at a significantly higher risk of contracting coronavirus disease 2019 (COVID-19) and that Black adults with dementia are at an even greater risk.

The investigators used de-identified population-level electronic health record data from 360 hospitals and 317,000 providers across 50 states, representing 20% of the US population. At the time of the analysis, the study population consisted of 61,916,260 adult and senior patients, including 1,064,960 who had dementia, 15,770 with COVID-19, and 810 with both dementia and COVID-19.

In addition to finding an association between dementia and COVID-19 diagnosis, the investigators found the strongest effect for vascular dementia, followed by presenile dementia, Alzheimer disease, senile dementia, and post-traumatic dementia.

The investigators noted that this heightened risk could not be entirely explained by characteristics such as old age, living in a nursing home, and other characteristics common to both patients with dementia and heightened COVID-19 risk. After adjusting for those factors, they found that Americans with dementia were still twice as likely to have gotten COVID-19 as of late summer 2020.

The investigators also noted significant demographic factors affecting COVID-19 risk among patients with dementia. Black patients with dementia were more likely to be infected with COVID-19 than white patients with dementia after adjusting for age, sex, and COVID-19 risk factors and with similar racial disparity for Alzheimer disease and vascular dementia.

Interestingly, the authors said similar racial disparity was observed for patients with dementia without adjusting for COVID-19 risk factors, suggesting that factors other than known COVID-19 risk factors may have contributed to the increased risk among Black patients with dementia. Sex in general had no additional effects on the risk of COVID-19 in patients with dementia, age had no additional effects, and senior patients with vascular dementia were less likely to be infected by COVID-19 than adults younger than 65 years of age with vascular dementia.

Furthermore, the researchers found that the overall hospitalization risk over a 6-month period for 15,770 adult and senior patients with COVID-19 was 25.17%. Among 810 patients with COVID-19 and dementia, 59.26% were hospitalized. This was higher for Black patients (73.08%) than for white patients (53.85%).

Similarly, the 6-month mortality risk for adults and senior patients with COVID-19 was 5.64% but was 20.99% among the patients with COVID-19 and dementia. This statistic was similar for Black and white patients, with mortality risks of 23.08% and 19.23%, respectively.

In considering why there might be an association between dementia and COVID-19, the investigators noted the frequent brain complications caused by the virus. In addition to reports of direct impacts, such as encephalitis, thrombotic events, and brain invasion, the brain is also affected by organ failure elsewhere caused by COVID-19.

Based on these complications and autopsy findings, the team hypothesized that preexisting dementia, especially with involvement of blood vessels in the brain, may predispose patients to a greater risk of morbidity and mortality from COVID-19.

Wang Q, Davis P, Gurney M, and Xu R. COVID-19 and dementia: Analyses of risk, disparity, and outcomes from electronic health records in the US. Journal of the Alzheimer’s Association; February 9, 2021. Accessed February 9, 2021.