New Alzheimer’s diagnoses are more common among seniors who have had Covid-19, study finds


A recent study of more than 6 million people over the age of 65 found that seniors with Covid-19 had a significantly higher risk of being diagnosed with Alzheimer’s disease within a year.

The study does not show that Covid-19 causes Alzheimer’s, but it adds to the growing body of research on the links between coronavirus infection and cognitive function.

“In the Alzheimer’s disease brain, pathology begins to emerge about 20 years before the onset of symptoms,” said Dr. David Holtzman, a neurologist who directs an Alzheimer’s disease research laboratory at Washington University School of Medicine in St. Louis. People would need to be followed for decades after a Covid-19 infection to prove causation, he said.

Instead, a Covid-19 infection can cause inflammation that can exacerbate changes already occurring in the brain, experts say.

“The brain has its own immune response to the pathology involved [Alzheimer’s] the disease progresses,” said Holtzman, who was not part of the new study. “When there are other things in the body that cause inflammation that can affect the brain, what probably happens is that it can exacerbate the process that’s already happening.”

Other viruses can cause similar inflammation, experts say.

Covid “is another one of a dozen potential risk factors that I talk to my patients about,” said Dr. Richard Isaacson, a neurologist and director of Florida Atlantic University’s Center for Brain Health. He was not involved in the new study, but is a researcher focused on preventing the risks of Alzheimer’s disease.

“I tell people to get the tetanus vaccine. I tell people to get their annual flu shots and Pneumovax,” and to exercise and eat a brain-healthy diet.

However, “when there’s smoke, there’s sometimes fire,” he said. “I really think this is something that should at least be addressed.”

The latest study, published last week in the Journal of Alzheimer’s Disease, found that there were about seven new diagnoses of Alzheimer’s disease for every 1,000 seniors who had a documented case of Covid-19 in the past year, compared with about five new diagnoses. in every 1,000 that didn’t.

Heather Snyder, vice president of medical and scientific relations for the Alzheimer’s Association, said the study’s findings could have broader implications for the pandemic.

“The pandemic led to severe delays for people seeking medical diagnoses such as Alzheimer’s, meaning these results could be driven by those who had Alzheimer’s when they were infected but had not yet sought a formal diagnosis,” he said.

The study’s authors, along with Snyder and other experts, identify this work as a call for more research into the mechanisms underlying Alzheimer’s disease that may explain the association.

In the new study, the Alzheimer’s diagnosis was “mostly tentative,” said Dr. Eliezer Masliah, director of the Division of Neuroscience at the National Institute on Aging at the National Institutes of Health.

Masliah, who was not involved in the research, said there is evidence that Covid-19 “can cause cognitive impairment”, but there are new ways to definitively confirm the link to Alzheimer’s.

A next step would be to follow people who are at risk of Alzheimer’s after a Covid-19 infection to monitor the biomarkers found in the blood and brain over the long term.

“In the next two years, we will have very important information,” Masliah said. And it’s a “very important issue” to watch, given the size of the disease.

“Imagine how many millions of people over 60 or 65, like me, have had Covid. Say 5% or 10% or even 1% of them are at risk,” he said.

“Wow. We’re looking at a lot of people who could have a very large epidemic of Alzheimer’s disease that we have in the coming years.’

About 6.5 million people over the age of 65 are living with Alzheimer’s, according to Alzheimer’s Association estimates. And it was the seventh leading cause of death in the US in 2020, according to data from the US Centers for Disease Control and Prevention.

“Alzheimer’s disease is a serious and challenging disease, and we thought we could turn it around by reducing general risk factors such as high blood pressure, heart disease, obesity, and a sedentary lifestyle,” said Dr. Pamela Davis, lead author of the study. at Case Western Reserve University and co-author of the new study.

“Now, so many people in the US have had Covid, and the long-term effects of Covid are still emerging. It’s important to continue to monitor the impact of this disease on future disability.”