Dementia significantly increases risk of COVID-19 infection, mortality

February 9, 2021

Dementia sufferers bear a higher COVID-19 risk. (AP Photo/Alexander Zemlianichenko)

People with dementia are at a significantly higher risk of contracting COVID-19 and experiencing more severe outcomes of the disease, including death, regardless of other factors, according to a study published in Alzheimer's & Dementia on Tuesday.

Study co-author Pamela B. Davis, a member of the Center for Clinical Investigation at Case Western Reserve University, said her findings illustrate the importance of providing vaccines to people with dementia, which is most commonly caused by Alzheimer's disease.

“We kind of expected that folks with dementia would have an increased risk of acquisition, and probably for severity of COVID-19, but we were a little bit surprised that dementia was such an independent risk factor,” Davis told The Academic Times.

The study notes that the reason for this is likely that patients with dementia experience recent memory loss before succumbing to long-term loss. It is possible patients with dementia are simply unable to comply with necessary precautions against COVID-19, Davis emphasized.

“We speculate that folks with dementia may have difficulty in following the recommendations to wear a mask, clean your hands and socially distance,” she said. “Recent memory is one of the first things that goes, and the instructions to do this are relatively recent.”

Davis explained that the team’s research started off as a medical record analysis of individuals with Alzheimer’s, aiming to single out which drugs could impact the course of dementia, in general. 

When COVID-19 emerged about midway through that study, lead author Rong Xu, from the Center for Artificial Intelligence at Case Western Reserve, began shifting attention to the fact that many risk factors for the virus are the same as those for dementia.

“What surprised us, when we looked at the data, was that even after [Xu] controlled for the other risk factors, including nursing-home living, there was still an excess risk for patients with dementia,” Davis said.

In conducting the study, the team analyzed the de-identified records of an astounding 61.9 million adult and senior patients across all 50 states in the U.S. More than 1 million had a confirmed diagnosis of dementia, and over 15,000 were COVID-19 patients. 

After adjusting for external risk factors like age and other serious health conditions, the researchers found that patients with dementia, as a stand-alone factor, are at a much higher risk for COVID-19, particularly those with vascular dementia. The conclusion was based on the study's adjusted-odds ratio.

Vascular dementia is a form of the condition that results from damaged blood vessels in the brain, often due to multiple strokes. There is a great deal of research to support that COVID-19 impacts blood vessels, leading Davis to infer a connection between the virus and this type of dementia.

While Davis considered this to be one potential biological component of why patients with dementia are at higher risk, she highlighted that there is likely another aspect yet to be identified, especially because increased symptom-severity and mortality rates cannot be due to the obstacles posed by memory loss. 

Davis stresses that COVID-19 vaccines should be supplied to those with dementia going forward. For instance, she commended Ohio Gov. Mike DeWine's decision to place individuals residing in congregate living facilities, who often have dementia, in the highest-priority group 1A for the vaccine

It should also be noted that while the study isolated dementia as a factor, it additionally revealed that when demographics come into play, Black people with dementia are much more likely than white individuals with the condition to acquire COVID-19, adding to a large body of research about communities that are most susceptible to the disease. 

In one study published last week, unbiased machine learning algorithms statistically confirmed widely reported data suggesting that racially segregated U.S. counties have disproportionately high levels of COVID-19 infections and mortalities.

Policymakers and physicians must pay attention to which populations need the most support, Davis insisted.

“There are lots of classes of patients who are vulnerable,” she said, “and it's incumbent on us, in medicine, to make sure they are protected.”

The paper, “COVID-19 and dementia: Analyses of risk, disparity, and outcomes from electronic health records in the US,” was published Feb. 9 in Alzheimer's & Dementia. The authors include QuanQiu Wang, Pamela B. Davis and Rong Xo, Case Western Reserve University; Mark E. Gurney, CEO of Tetra Therapeutics. The lead author was Rong Xo.

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