Can COVID-19 Cause Alzheimer’s?
Since 2020, more than 100 million Americans have had their brush with COVID-19. Early on in the pandemic, scientists discovered that the virus responsible for COVID, SARS-CoV-2, doesn’t just affect the lungs: It also has the potential to reach other parts of the body, including the blood vessels, the heart, and the brain.
One early study, for example, found that a year after a COVID infection, a person is 42 percent more likely to have ongoing memory impairment, confusion, or a combination of neurological symptoms we’ve come to know as brain fog. At least one in 10 people who’ve had COVID continue to experience symptoms—including brain fog, cognitive impairment, and problems with memory—for years after the initial infection.
Some researchers have drawn similarities between both the brain changes and symptoms of COVID and Alzheimer’s disease, leading to a provocative question: Could COVID-19 speed up the progression or cause Alzheimer’s disease?
How does COVID-19 affect the brain?
Research has shown that COVID-19 can infiltrate the brain and infect the neurons themselves. This in turn activates the brain’s immune system, which consists of a cellular line of defense made up of cells called astrocytes and microglia. But in some cases, something in this immune response to COVID goes awry, and the immune system overreacts. This can lead to inflammation, cell death and brain damage—not so different from what is seen in the brains of people with neurodegenerative diseases like Alzheimer’s.
That’s what happens in COVID-19. In Alzheimer’s, the process is not so different: the brain’s microglia activate in response to build-ups of an Alzheimer’s biomarker protein called beta-amyloid, that gets in the way of neural activity and eventually leads to the die-off of brain cells. The microglia and astrocytes release more signals to the rest of the brain’s immune system, which causes more inflammation and more damage.
Here’s where the two conditions really overlap: Scientists are still studying how COVID impacts the brain, but some research indicates that the virus may also cause the build-up of problematic proteins, not so different from beta-amyloid, in brain cells—and that may be what’s driving these Alzheimer’s-like cognitive symptoms some people experience after a COVID infection.
COVID and Alzheimer’s risk
Another question scientists are asking is: Could getting COVID—with all this brain inflammation and possible protein build-up—now make you more likely to develop Alzheimer’s later in life?
Researchers are looking back at people infected early in the pandemic to see what percentage of them have gone on to develop cognitive dysfunction, Alzheimer’s or other forms of dementia. While scientists aren’t sure yet if COVID-19 can cause Alzheimer’s, some data already suggests it can increase the risk in the short term.
One study tracked post-COVID risk for two years in 1.2 million people. The researchers found that people who recovered from COVID-19 had a higher chance of developing dementia two years down the line — their risk rose from a 10-percent chance to a 13-percent chance. Scientists will need to follow people who were infected with COVID-19 long-term to determine whether they are at a higher risk of Alzheimer’s or other forms of dementia.
Meanwhile, a mounting body of evidence indicates that some bacterial and viral infections may ultimately lead to neurodegenerative diseases like multiple sclerosis or Alzheimer’s.
Protect the brain by protecting against COVID
Vaccines and boosters, N95 masks, and air quality and ventilation are all ways to help avoid COVID infection — and doing so can help you lower your risk for cognitive issues down the line.