Large Study Shows People With Dementia Are at Higher Covid-19 Risk

The condition may present both physical and social risk factors that make transmission more likely

A person sits at a table wearing a mask and writing. The room in the nursing home is otherwise empty and has coral-colored walls
Dementia is "the impaired ability to remember, think or make decisions that interferes with doing everyday activities," per the CDC. Photo by Adrià Salido Zarco/NurPhoto via Getty Images

Analysis of millions of health records has found that people with dementia are more likely to catch severe Covid-19, according to a study published on February 9 in the journal Alzheimer’s and Dementia.

The study found that in the first six months of the pandemic, patients with dementia and Covid-19 were more than twice as likely to be hospitalized than those without dementia, and over four times as likely to die, Pam Belluck reports for the New York Times. When risk factors like age, heart disease and asthma were taken into account, the data still show that people with dementia are twice as likely to have caught Covid-19 during the first six months of the pandemic.

“Folks with dementia are more dependent on those around them to do the safety stuff, to remember to wear a mask, to keep people away through social distancing,” says University of Michigan professor of medicine Kenneth Langa, who was not involved in the study, to the New York Times. “There is the cognitive impairment and the fact that they are more socially at risk.”

The researchers used data collected by IBM Watson Health Explorys, which comprises the health records of over 60 million people in the United States. They found records of over 15,000 patients with Covid-19, 810 of whom also had dementia.

The demographic information available in the records showed that black people with dementia were at almost three times the risk of catching Covid-19 than white people with dementia; they were also more likely to be hospitalized. The finding reflects the fact that black people have been disproportionately impacted by the pandemic. The data did not provide information about patients’ job, income or behavior.

"We think that social-economic and behavioral factors may have played important roles here," says Rong Xu, biomedical informatics expert at Case Western and lead author on the study, to Health magazine. "However, we could not test this due to limited social-economic and behavioral information captured in patients' electronic health records."

Dementia is an umbrella term for “the impaired ability to remember, think or make decisions that interferes with doing everyday activities,” per the Centers for Disease Control and Prevention. Alzheimer’s is one common type of dementia, but there are other forms as well. Because people with dementia often need assistance with everyday tasks, they can’t easily socially distance from the people who help them from day to day. Learning new habits, like mask wearing, can also be difficult.

"There will also be greater likelihood for misinterpreting why someone else is wearing a mask and greater challenge for recognition of others who may even be family members if masks are in place,” says Joshua Chodosh, the director of Geriatric Medicine at the New York University Grossman School of Medicine, to Health magazine. All of that is “an impediment to mask wearing,” so risk is higher.

Beyond the social factors that increase the risk of Covid-19 transmission for a person with dementia, there may also be physical symptoms of dementia that put a person more at risk for severe Covid-19. Many people with dementia also have impaired vascular systems, or blood vessels, and research suggests that the coronavirus has a severe impact on a critical layer of the vascular system, Will Stone reported for NPR in November.

University of California, San Francisco neurologist and psychiatrist Kristine Yaffe tells the New York Times that there may be a “frailty element” to people with dementia, which makes them less resilient against infections. For instance, the researchers suggest that if the blood-brain barrier is damaged, that allow the virus to reach the brain more easily than in people without dementia, Misha Gajewski reports for Forbes. A lack of muscle tone and mobility may also indicate that they would have a harder time fighting off an infection.

The researchers acknowledge that their study has limitations. For instance, it may be underestimating the number of people affected by dementia and Covid-19 because it only looks at the health records of people who went to a hospital, so it excludes those who don’t have access to hospital resources.

The Alzheimer’s Association’s chief science officer Maria Carrillo tells the New York Times, “One of the things that has come from this [Covid-19] situation is that we should be pointing out these disparities.”

Get the latest stories in your inbox every weekday.