How common viruses can cause Alzheimer’s
In interaction, the viruses of the shingles-infection and Herpes simplex virus (HSV) inflammation and accumulation of Alzheimer’s-associated proteins cause in the brain. This mechanism appears to be responsible for the previously identified association between herpesviruses and Alzheimer’s.
researchers of Tufts University and the University of Oxford have demonstrated how that Varizella-Zoster-Virus and Herpes simplex virus early stages of Alzheimer can trigger. The corresponding study results were published in the “Journal of Alzheimer´s Disease” released.
Varicella zoster virus and HSV-1 widespread
Estimated 3.7 billion People under the age of 50 are included HSV-1 infectedthe virus, the Lippenherpes caused, reports the research team, citing figures from the World Health Organization (WHO).
After the first infection, the virus usually remains asymptomatic and lies dormant in the nerve cells. However, it can be activated again and cause corresponding symptoms. The correlations established so far between HSV-1 and the Alzheimer’s disease were only at one reactivation detectable by HSV-1.
That Varizella-Zoster-Virus is also extremely widespread and round 95 percent of people have already been infected before the age of 20, with the initial infection usually manifesting itself as chickenpox, the team explains. The virus can also remain in the body and cause shingles if it is reactivated.
Alzheimer’s and herpes viruses
In earlier studies, a Link between herpesviruses and Alzheimer’s found, but the underlying mechanisms remain unclear.
It became clear that HSV-1 (one of the main variants of the virus) lies dormant in the neurons of the brain and, upon reactivation, leads to the accumulation of tau and amyloid beta proteins as well as the loss of neural functions can lead, which are typical features of Alzheimer’s disease.
There is “a body of evidence linking HSV to an increased risk of Alzheimer’s disease in patients”stressed Professor David Kaplan of the School of Engineering in the Tufts University.
“We know that there is an association between HSV-1 and Alzheimer’s disease, and there is evidence that varicella-zoster viruses are involved, but we did not know the sequence of events that trigger the viruses to cause the disease to set in motion”so Kaplan further.
Investigation in the brain model
To examine the cause and effect relationship between the viruses and Alzheimer’s, the researchers have one three-dimensional human tissue culture model made of small, six-millimeter-wide silk protein-collagen sponges that mimic the brain.
The sponges were colonized with neural stem cells that functioning neurons grew up that were able to transmit signals to each other in a network, just as happens in the brain.
Some of the stem cells also formed Gliazellenwhich are typically found in the brain and help keep neurons alive and functioning, the research team reports.
Varicella-zoster viruses reactivate HSV-1
In the case of an infection alone with varicella-zoster viruses no education of the characteristic Alzheimer’s proteins tau and beta-amyloid have been detectable and the function of the neurons has not suffered.
However, the neurons already housed dormant HSV-1the varicella-zoster virus led to their reactivationaccompanied by a dramatic increase of the tau and beta amyloid proteins. At the same time, the neural signals began to slow down.
“It is a double whammy of two viruses that are very common and usually harmless”according to the study author Dana Cairns from Tufts University. The study shows that problems can arise when new exposure to varicella-zoster virus wakes up dormant HSV-1.
HSV-1 activation promotes Alzheimer’s
Professor Kaplan adds that varicella-zoster viruses are known from many clinical cases to inflammation in the brain trigger, possibly leading to activation of dormant HSV and increased inflammation.
Repeated cycles of HSV-1 activation could lead to further inflammation in the brain, leading to the formation of Plaques and to the accumulation of neuronal and cognitive damage lead, explain the researchers.
Vaccination might help
Furthermore, it is known that a Vaccination against varicella zoster virus to prevent chicken pox and shingles too Reduced risk of dementia. The vaccine may help break the cycle of viral reactivation, inflammation and neuronal damage.
Similar mechanisms in COVID-19?
Finally, the researchers also point out the long-term neurological effects that follow an infection with the Coronavirus SARS-CoV-2-Virus may occur. (please refer COVID-19 as a trigger of Alzheimer-like dementia?) These could be related to the fact that both varicella zoster viruses and HSV-1 can be reactivated by COVID-19. (fp)
Author and source information
This text corresponds to the specifications of medical specialist literature, medical guidelines and current studies and has been checked by medical professionals.
Sources:
- Dana Cairns, Ruth F. Itzhaki, David L. Kaplan: Potential Involvement of Varicella Zoster Virus in Alzheimer’s Disease via Reactivation of Quiescent Herpes Simplex Virus Type 1; in: Journal of Alzheimer´s Disease (veröffentlicht 20.06.2022), content.iospress.com
- Tufts University: Common viruses may be triggering the onset of Alzheimer’s disease (veröffentlicht 29.06.2022), eurekalert.org
Important NOTE:
This article contains general advice only and should not be used for self-diagnosis or treatment. He can not substitute a visit at the doctor.