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Viruses can interact to trigger Alzheimer’s

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Viruses can interact to trigger Alzheimer's

A study from Tuft’s suggests that very common viruses such as Varicella and Herpes may combine to cause Alzheimer’s Disease (1).

Tufts University in Medford, Massachusetts researchers have shown that the virus responsible for chickenpox and shingles (Varicella) can interact with the Herpes 1 virus, a virus that can cause cold sores, but which lies dormant in the nerve cells for decades. Up to 80 percent of American adults are estimated to be carriers of Herpes 1. 

Almost all of us has had chicken pox; unfortunately, the virus then remains dormant in 95% of us. Age and a declining immune system (caused by age, stress, immunosuppression) can reawaken this virus (varicella) later in life and people then develop shingles (Varicella Zoster Virus, or VZV). 

VZV has been previously linked to Alzheimer’s Disease by causing neuroinflammation. 

In this study researchers found that when VZV becomes activated appearing as shingles, it can in turn reactivate dormant herpes simplex virus type 1, or HSV-1. And a significant amount of research has shown an association between activated HSV-1 and Alzheimer’s.

In the research, Varicella was not seen to cause neuroinflammation on its own, and there was no tau protein tangle and no build up of amyloid plaque. But where there was dormant HSV-1 in the neurons, the Varicella axctivated it, and amyloid plaque and tau proteins grew, with a reduction of eclectic transmission.

Dr Ruth Itzhaki of Oxford University stated that it was becoming increasingly clear that infection, and viruses in particular, played a significant role in Alzheimer’s Disease. Professor David Kaplan, who with Dana Cairns of Tufts, led the study, concluded that researchers should be looking at ways of preventing these viruses taking a hold in humans to prevent diseases such as Alzheimer’s. 

More vaccines are one likely solution.

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  1. Journal of Alzheimer’s Disease, vol. 88, no. 3, pp. 1189-1200, 2022; 25 May 2022; https://content.iospress.com/articles/journal-of-alzheimers-disease/jad220287