According to a study by Tufts University and the University of Oxford, the varicella zoster virus (VZV), which may activate the herpes simplex virus (HSV), may help trigger the first stages of Alzheimer’s disease.
As published in the Journal of Alzheimer’s Disease, HSV-1 affects the neurons in the brain and upon activation may result in the accumulation of tau and amyloid beta proteins, widely believed to be found in Alzheimer’s patients.
From the study: “We infected human-induced neural stem cell (hiNSC) cultures with HSV-1 and/or VZV and sought the presence of AD-related phenotypes such as amyloid-β (Aβ) and P-tau accumulation, gliosis, and neuroinflammation.”
“Cells infected with VZV did not show the main AD characteristics, Aβ and P-tau accumulation, which HSV-1 does cause, but did show gliosis and increased levels of pro-inflammatory cytokines, suggesting that VZV’s action relating to AD/dementia is indirect.”
What the authors concluded: “Our results are consistent with the suggestion that shingles causes reactivation of HSV1 in brain and with the protective effects against AD of various vaccines, as well as the decrease in herpes labialis reported after certain types of vaccination. They support an indirect role for VZV in AD/dementia via reactivation of HSV-1 in brain.”