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IOWA CITY — Patients with Alzheimer ’s disease who contract COVID-19 appear to be more likely to die from the respiratory infection than do COVID-19 patients who don’t have the neurodegenerative disease, according to new University of Iowa research that could hold implications for ethical vaccine distribution and global policy decisions.
“Our results provide evidence that caution may be required when providing care for patients with Alzheimer ’s disease to prevent COVID-19, and consideration of this patient population when determining the ethics of vaccination priority, including in younger patients diagnosed with (Alzheimer’s),” according to the recent study involving seven UI researchers. The study noted that “much of the global at-risk population remains unvaccinated.”
The new study, published in the October edition of the Journal of Alzheimer’s Disease, found Alzheimer’s patients with COVID-19 are 20 percent more likely to die from the virus than others — an important finding as ongoing mutations and variants “will likely remain a major threat in the coming years.”
“Our work could also help guide health care decisions on global COVID-19 policy, as well as for caring for Alzheimer’s disease patients through future pandemics,” according to the study, which said its findings also could hold relevance for other respiratory illnesses involving similar risk factors.
UI researchers conducted the study earlier this year by tapping a health research database containing medical records, with identifying information removed, of more than 50 million patients — mostly from the United States — through Feb. 17, meaning the data came before widespread vaccination and variant spread.
Although vaccines have loosened the pandemic’s grip on this country, with many Americans resuming mostly normal activities, UI neurologist and neuroscientist Qiang Zhang — who co-authored the study — told The Gazette his team’s research indicates Alzheimer’s patients might want to keep their guard up.
“Based on the study’s results, it's probably best to recommend patients with Alzheimer's disease try to practice social distancing and take the vaccination and maybe put masks on in indoor settings with a high density of people,” he said. “Because, if you get COVID, you have a higher chance of dying from COVID — compared to other people.”
From the massive health care database, UI researchers analyzed about 380,000 patients who contracted COVID — and identified 4,174 who had Alzheimer’s; 2,765 who had vascular dementia; and 610 who had less common types of dementia.
Researchers adjusted for risk variables like age, sex, race, ethnicity and other comorbidities like obesity and diabetes and found “the odds of mortality from COVID-19 were significantly elevated in the Alzheimer’s group.”
“This would mean that all other factors being equal, a patient with Alzheimer’s would have an about 20 percent increased chance of COVID-19 mortality,” according to the study.
Where Alzheimer’s is the most common kind of dementia — occurring when proteins and fibers build up and block or destroy nerve cells in a brain — vascular dementia is the second-most common, occurring when blood vessels are blocked or damaged, leading to mini-strokes or brain bleeding.
“Interestingly, for vascular dementia, we used a similar approach … and found that the odds of dying from COVID-19 was not consistently increased among patients with vascular dementia,” according to the study, which — while not aimed at answering the question of “why” — attempted an explanation.
“There are several possibilities for the association between Alzheimer’s, COVID-19, and mortality,” according to the study. “Indeed, SARS-CoV2 can invade the central nervous system, and COVID-19 patients frequently have neurological impairments, which may be compounded in neurodegenerative conditions like Parkinson’s disease and Alzheimer’s.”
UI researchers in a 2020 study found COVID-19 patients with Parkinson’s were nearly 30 percent more likely to die from the virus than others. Zhang told The Gazette that, in general, pneumonia and respiratory-type diseases are a “major cause of mortality” in those with Alzheimer’s.
As to why that might be, Zhang said varying levels of care might be to blame.
Because one major cause of pneumonia is aspiration — when food, liquid or other particles are breathed into the lungs — Alzheimer’s patients receiving insufficient care are more likely to aspirate.
The UI research also confirmed other studies’ findings that men are about 44 percent more likely to die from COVID-19 than women; Black patients are 37 percent more likely to die from the virus; those with diabetes are 39 percent more likely to die from COVID-19; and patients with metastatic cancer were 72 percent more likely to die from it.
Research limitations include a lack of globally diversity, which would account for varying access to care and treatment strategies; no details on the severity of a patient’s Alzheimer’s or level of care; no information on a patient’s “do not resuscitate” wishes; and no data on medication a patient was taking.
“Some medications may reduce the COVID-19-related mortality … while others — or the conditions they treat — may be associated with increased risk of death,” according to the study. “It is possible that patients with Alzheimer’s are treated differently by the health care system or are more likely to have advanced directives.”
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