Alzheimer disease

Alzheimer Disease: Herpes Simplex Virus 1 Is a Major Risk

Herpes simplex virus type 1 (HSV1) is a major risk factor for Alzheimer disease (AD), suggesting that antiherpes antiviral drugs may be effective AD therapies, according to the author of a new research review.1

 

In examining data from past studies, Ruth F. Itzhaki, PhD, concluded that people who are HSV-seropositive have a much higher risk of developing senile dementia (SD) than people who are HSV-seronegative—findings she called “striking.” Moreover, antiviral treatment significantly decreases the chance of developing SD among patients who are HSV-seropositive.

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“It should be stressed that these results apply only to those with severe cases of HSV1 or [varicella-zoster virus] infection, but when considered with the over 150 publications that strongly support an HSV1 role in AD, they greatly justify usage of antiherpes antivirals to treat AD,” Itzhaki wrote.

 

Three of the studies included in the review examined Taiwan’s National Health Insurance Research Database, which includes records for 99.9% of that country’s population. All 3 showed a positive correlation between HSV and the development of AD.

 

In one of those studies, researchers compared 8362 participants aged 50 years or older who were newly diagnosed with HSV1 or HSV2 infections with 25,086 participants aged 50 years or older who had no HSV infection.2 The researchers traced the incidence of dementia development in both groups between 2001 and 2010 and found that those infected with HSV has a 2.56-fold greater risk for developing SD. Participants with HSV1 developed SD more often than did participants with HSV2.

 

Of those participants who were HSV-infected, 7,215 had been treated with an antiherpes agent  such as acyclovir, famciclovir, ganciclovir, idoxuridine, penciclovir, tromantadine, valaciclovir, and valganciclovir. The participants who were HSV-infected and vaccinated had a significant reduction—almost 10-fold—in SD compared with the participants who were HSV-infected and not vaccinated.

 

Itzhaki wrote that the type and duration of antiviral treatment and the stage at which its use would be most effective are important considerations in AD treatment.

 

“Research data on a microbial cause of Alzheimer disease have been ignored or dismissed for 3 decades; very unfortunately for those who developed Alzheimer disease during that period and who therefore had no chance of benefitting from the information,” Itzhaki concluded. “Surely, now is the time to rectify the situation by determining—and then using—the best means of treatment at hand.”1

 

—Colleen Murphy

 

References:

  1. Itzhaki RF. Corroboration of a major role for herpes simplex virus type 1 in Alzheimer’s disease. [published online October 19, 2018]. Front Aging Neurosci. https://doi.org/10.3389/fnagi.2018.00324.

 

  1. Tzeng N-S, Chung C-H, Lin F-H, et al. Anti-herpetic medications and reduced risk of dementia in patients with herpes simplex virus infections—a nationwide, population-based cohort study in Taiwan. Neurotherapeutics. 2018;15(2):417-429. https://doi.org/10.1007/s13311-018-0611-x.