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What’s the Connection Between Viral Infections and Dementia?

What is at the root cause of Alzheimer's disease? New research suggests a connection between viral infections and dementia. Let's fight back!

Drug companies, the Alzheimer’s Association and the FDA have placed almost all their chips on the beta-amyloid theory of Alzheimer’s disease. Billions have been spent on anti-amyloid drugs such as aducanumab (Aduhelm) and lecanemab (Leqembi). Read more about this potentially misguided approach at this link. While beta-amyloid may indeed be part of the story, we have long wanted to know what amyloid is actually doing in the brain. What triggers the formation of this sticky protein in the first place? Some researchers suggest that there is a connection between viral infections and dementia and that beta-amyloid formation is the body’s reaction to invasion. They postulate that it may be part of an immune reaction that runs amok.

Viral Infections and Dementia!

NIH researchers have just reported on a relationship between viral infections and neurodegenerative diseases (Neuron, Jan. 11, 2023). They analyzed data from over 300,000 people in a Finnish biobank (FinnGen) and almost 500,000 people in the UK biobank.

These were individuals who had been diagnosed with a variety of neurodegenerative diseases such as Alzheimer’s disease, generalized dementia, vascular dementia, ALS, Parkinson’s disease and multiple sclerosis. Investigators compared these people to individuals who did not have any such neurological diseases.

The Associations between Viral Infections and Dementia:

The authors introduce their research this way:

“Recent research has shown a definitive association between an increased risk of multiple sclerosis and prior infection with the Epstein-Barr virus (EBV). Additional concerns regarding the potential short and long-term cognitive impact of the current coronavirus pandemic have raised the priority of investigating the potential connection between viral exposures and neuroinflammation and/or neurodegeneration.”

They found that exposure to viral diseases was associated with an increased risk of neurodegeneration. Viral encephalitis was closely linked to Alzheimer’s disease. When patients had influenza with pneumonia, they were more likely to develop 5 of the 6 neurodegenerative diseases studied.

Shingles, caused by the varicella-zoster herpes virus, and intestinal viral infections were also associated with brain disorders.

The authors point out that this can be a delayed process:

“Some of these exposures were associated with an increased risk of neurodegeneration up to 15 years after infection.”

What About Herpes Viral Infections and Dementia?

The authors of this research linking viral infections and dementia point out that:

“The results described above are supported by recent findings in the literature, which suggest an association between herpes simplex virus (HSV) encephalitis and AD [Alzheimer’s disease], AD and hepatitis, genital warts and dementia, EBV and dementia, and MS and HSV. Since the discovery of an association of the 1918 flu pandemic, caused by H1N1 influenza A, with postencephalitic parkinsonism, a link between influenza and PD has been debated. A recent study using Danish data found an association between influenza and PD with an odds ratio of 1.73 up to 10 years after virus exposure. This is very similar to the hazard ratio for influenza and pneumonia in FinnGen which was 1.72.”

Preventing Viral Infections and Dementia:

The NIH investigators go on to note that “vaccines are currently available for some of these viruses, including influenza, shingles (varicella-zoster), and pneumonia.”

They suggest that vaccination might partially reduce the risk of developing neurodegenerative diseases:

“Influenza and pneumonia vaccination has been found to reduce risk for AD and PD. Shingles (varicella-zoster) vaccination is associated with a reduced risk of dementia, AD, and PD in both the United States and Wales.”

They also suggest that antiviral drugs might be beneficial:

“These findings also suggest additional avenues to explore for both the treatment and prevention of NDDs. In addition to vaccination, some studies suggest that using antivirals may reduce the risk of dementia in HSV positive patients25 or in patients with varicella-zoster virus.”

This Is NOT New!

We have written a lot about the possible connection between viral infections and dementia. Several years ago we interviewed a Harvard research who believed that beta-amyloid has both antiviral and antimicrobial properties. He suggested that the formation of amyloid plaque was the body’s way of fighting off infection. You can listen to this intriguing interview at this link.

More recently, we interviewed Donald Weaver, MD, PhD. He is a senior scientist at the Krembil Brain Institute at the University Health Network, Toronto, Ontario, Canada. He is a professor of Medicine (Neurology), Chemistry, and Pharmaceutical Sciences at the University of Toronto and a neurologist at the Toronto Western Hospital. His research suggests that Alzheimer’s disease might be an autoimmune disease and that many things could trigger this reaction, including viral infections. You can listen to this recent podcast at this link.

Final Words:

We think it is time to think differently about Alzheimer’s disease and dementia. Most of the drugs that have been developed to rid the brain of amyloid plaque have fizzled. Even the new ones that have been approved by the FDA, Aduhem and Leqembi, have not restored memory or been proven to reverse dementia.

Perhaps it is time to explore the connection between viral infections and dementia. Why does the body form amyloid plaque? Could vaccination help prevent some cases of Alzheimer’s disease? What about antiviral medications? If the NIH and the Alzheimer’s Association begin funding novel approaches to preventing or treating dementia, perhaps we might make more progress against this devastating disease!

What do you think? Please share your thoughts in the comment section below.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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  • Levine, K.S., et al, "Virus exposure and neurodegenerative disease risk across national biobanks," Neuron, Jan. 11, 2023, doi: 10.1016/j.neuron.2022.12.029
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