Will COVID Increase the Risk of Alzheimer’s Disease?

At last count, COVID-19 has infected nearly 100 million people in the US. Over 1 million have died. Worldwide, the case count is over 600 million and more than 6.5 million people have died from this virus. Those numbers are mind boggling, but the devastating impact of the coronavirus may be long lasting. A study published in the Journal of Alzheimer’s Disease (Sept. 13, 2022) suggests there could be a link between infection with COVID and the risk of Alzheimer’s disease.

The Risk of Alzheimer’s Disease and Prior COVID Infection:

Researchers at Case Western Reserve University School of Medicine reviewed electronic health records of 6,245,282 people between February 2, 2020 and May 30, 2021. These were people who were 65 years of age or older and who “had no prior diagnosis of Alzheimer’s disease.”

They were divided into two groups or cohorts. Group 1 contracted COVID-19 during that time frame. There were 410,748 people in this COVID cohort. Group 2 did not catch COVID. There were 5,834,534 people in this “control” cohort.

They then sliced and diced the data to see who developed a diagnosis of Alzheimer’s disease between 2/2/2020 and 5/30/2021.

Here’s the bottom line:

“Older adults with COVID-19 were at significantly increased risk for new diagnosis of Alzheimer’s disease with highest risk in people age ≥85 and in women.”

The absolute numbers are disconcerting but not hair-on-fire alarming. Overall, roughly 1,900 people out of about 400,000 were diagnosed with Alzheimer’s disease in the non-COVID cohort. In the COVID cohort, about 2,700 people out of nearly 400,000 were diagnosed with Alzheimer’s disease. That is an increased relative risk of 69%.

Older women (85 or over) were especially vulnerable, though. Their relative risk of developing a diagnosis of Alzheimer’s disease [AD] after COVID infection was 89% greater than a similar group of older women who did not catch COVID. The absolute numbers were 812 cases of AD out of 61,032 who did not come down with the coronavirus compared to 1,189 cases out of 59,110 women who did catch COVID.

The authors conclude:

“Our findings call for research to understand the underlying mechanisms and for continuous surveillance of long-term impacts of COVID-19 on Alzheimer’s disease.”

Brain Fog and the Risk of Alzheimer’s Disease:

We have received many comments on this website that COVID is not that big a deal. There are still individuals who insist that the flu is worse. But most people who catch influenza do not have to live with persistent symptoms once they get over the infection.

Perhaps you have heard about the symptoms of long COVID. In addition to fatigue and shortness of breath, brain fog is high on the list of common complaints. Visitors to this website have described what it’s like:

Penny describes symptoms of long COVID and brain fog:

“Health professionals don’t exactly know how to treat COVID long haulers. I had COVID in December of 2021. It initially felt like a bad case of bronchitis. Later, I tested positive for COVID.

“Since then, I’ve been dealing with chest pain, headaches and brain fog. It makes me feel super stupid! I have to write everything down. I repeat myself and my family gets annoyed. My taste has been off for months, so I ask others to taste test my cooking.

“My muscles ache and my joints pain me to tears. I have to push myself to get through each day. I’m so exhausted when I wake up and I have to force myself to get up to take my dogs outside. I wonder when this hell is going to end? This isn’t living. It’s existing.”

Marsha describes the difference between the flu and long COVID:

“I had COVID during January and February of 2020. It was not the flu. There are some people who don’t suffer from COVID, but I did. With normal influenza I am pretty sick for about 4-5 days. I run a fever, and stay in bed and sleep. For about three weeks I may not feel 100% but after that, I am back to normal.

“With COVID, I was for sick for about 2 months and had recurring symptoms for about 2 years! COVID was not just a respiratory virus. It seemed to attack every cell in my body. It seemed to destroy my ability to digest food and absorb nutrients so that it was impossible to heal.

“The fatigue was the worst I have ever known and lasted for months. I fainted. My face was numb around my mouth for over a year; I was hoarse for over a year, with kidney and UTI symptoms 4 months later. 20% of my hair fell out. Even a year later, if I talked too much it felt like I was punched in the throat.

“During the first part of COVID, I had a period when my fingertips were purple. I also had COVID toes. I was terribly dizzy for 21 months. Besides that, I had brain fog. There are things to this day that I do not remember and that lasted for 21 months. I lost smell and taste and smelled things that just weren’t there. This virus attacked everything in my body. It’s not the seasonal flu.”

Patty experienced brain fog and worried about dementia:

“I most likely caught COVID in March of 2020. No testing was available at that time for COVID unless you were admitted to the hospital with severe disease. My case was relatively mild, but I experienced terrible brain fog. I could not concentrate well enough to organize a simple budget and pay a few bills. It was not a complex task at all, but I could not hold thoughts in my head long enough to make sure I was not making mistakes.”

“I still feel I have to be careful with some tasks, but I had some degree of attention loss even before COVID struck. I had asked my primary doc way back then if I was experiencing early dementia, but she said no.”

Chris worries about his cognitive ability after COVID:

“I caught COVID in February of 2021. I had an extreme cough, breathing problems, headache and fatigue. After recovery, I experienced loss of smell and taste as well as brain fog. Over a year later, I have recovered some sense of smell but still experience a lack of taste.

“For relaxation I enjoy playing Solitaire and other card games online. After recovery I found myself staring at the screen thinking, what am I supposed to do? This has improved over time; however, I still experience blank moments and forget what I am doing. My ability to concentrate has also declined. It is very worrisome!”

COVID and the Risk of Alzheimer’s Disease:

The investigators do not know whether the coronavirus causes neurodegeneration or accelerates a process that is already underway. One small study published in the journal Alzheimer’s & Dementia (May, 2022) is titled:

“Alzheimer’s-like signaling in brains of COVID-19 patients”

Here is the essence of what they found:

“The mechanisms that lead to cognitive impairment associated with COVID-19 are not well understood.

“In addition to respiratory and cardiac manifestations, it has been reported that approximately one-third of patients with COVID-19 develop neurological symptoms, including headache, disturbed consciousness, and paresthesias. Brain tissue edema, stroke, neuronal degeneration, and neuronal encephalitis have also been reported. In a recent study, diffuse neural inflammatory markers were found in >80% of COVID-19 patient brains, processes which could contribute to the observed neurological symptoms.

“Here we show that SARSCoV2 infection is associated with adrenergic and oxidative stress and activation of the TGF-β signaling pathway in the brains of patients who have succumbed to COVID-19. One consequence of this hyper adrenergic and oxidative state is the development of tau pathology normally associated with AD [Alzheimer’s disease].”

Another epidemiological study published in Alzheimer’s & Dementia (Aug. 2021):  concluded:

“Based on analyses of a nationwide patient EHR [electronic health record] database in the United States we show that patients with dementia had significantly increased risk for COVID-19 compared to patients without dementia.”

The Case Researchers Share Their Thoughts About COVID and the Risk of Alzheimer’s Disease:

The study published in the Journal of Alzheimer’s disease (Sept. 13, 2022) is epidemiological. It cannot establish cause and effect. Nevertheless, it is worrisome.

The Washington Post (September 16, 2022) quotes the Case Western Reserve researchers:

“‘We know that COVID can affect the brain, but I don’t think anyone had looked at new diagnoses of Alzheimer’s,’ said Pamela Davis, one of the study’s co-authors and a research professor at Case Western Reserve University School of Medicine. Colleague Rong Xu said she had expected to see some increase among seniors sickened by covid, but was surprised ‘by the extent of the increase and how rapidly it occurred.’”

Is This a Tempest in a Teapot?

We suspect that we will receive a lot of pushback from visitors who still think COVID is not that big a deal. They will dismiss the Case Western Reserve study as just one report. They would be wrong!

Here is an article that we wrote back in July, 2022 titled:

Will COVID-19 Increase the Risk for Later Dementia?
Neurologists worry that SARS-CoV-2 infection may affect the brain and raise the possibility of later dementia as a consequence.

It was based on data from Denmark (Frontiers in Neurology, June 23, 2022). We also discuss research from Argentina.

The investigators:

“…analyzed data from more than 400 people over 60 years old who had recovered from COVID-19. Of these about 60 percent showed evidence of cognitive impairment, even if their initial infections were mild.”

To read our full article, here is a link.

Final Words:

If the association between long COVID and Alzheimer’s disease is confirmed, the long-lasting impact of the coronavirus could be felt for many years to come. Remember, we are closing in on 100 million COVID infections in the US.

Some researchers estimate that anywhere from 10% to 30% of the people who catch COVID-19 experience some symptoms of long COVID. How many will be vulnerable to the risk of Alzheimer’s disease is anyone’s guess. Even if it is a very small percentage of 100 million, that is still a potentially scary number.

What about you? Have you caught COVID? Have you experienced any long-lasting symptoms? What about brain fog? Please share your experience in the comment section below.

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