According to a recent study published in the Journal of Alzheimer's disease, herpes simplex virus (HSV) is associated with an increased risk of Alzheimer's disease. Researchers from Tufts University in the United States and Oxford University in the United Kingdom used a three-dimensional human tissue culture model simulating the brain to prove that varicella zoster virus (VZV, which usually causes varicella and herpes zoster) may activate another common HSV, thus initiating the early stage of Alzheimer's disease. Researchers found that HSV-1, a virus that causes oral herpes, normally "sleeps" in brain neurons, and if neurons are infected with VZV, they "wake up" HSV-1, leading to tau and β Amyloid accumulation, which ultimately leads to loss of neuronal signal function, is a hallmark feature of Alzheimer's disease patients. The repeated cycle of HSV-1 activation leads to more inflammation, plaques and accumulation of neuronal and cognitive damage in the brain. The results show that one of the pathways of Alzheimer's disease is caused by VZV infection, which generates inflammatory triggers and wakes up HSV in the brain. Although studies have demonstrated a link between VZV and HSV-1 activation, other inflammatory events in the brain may also wake up HSV-1 and lead to Alzheimer's disease. Researchers pointed out that some patients with COVID-19 have experienced the long-term neurological effects of novel coronavirus, especially in the elderly, VZV and HSV-1 can be reactivated after infection with covid-19. In these cases, close attention should be paid to possible subsequent cognitive effects and neurodegeneration. According to the data of the World Health Organization, it is estimated that 3.7 billion people under the age of 50 are infected with HSV-1. In most cases, it is latent in nerve cells. When activated, it causes nerve and skin inflammation, forming painful open ulcers and blisters. Most carriers will have very mild symptoms or even no symptoms before the virus enters dormancy. Varicella zoster virus is also common, and about 95% of people have been infected with varicella before the age of 20. VZV is a kind of herpes virus, which can also stay in the body and find a way to enter nerve cells before dormancy. At the later stage of life, VZV can be reactivated to cause herpes zoster, which is a disease characterized by blisters and nodules on the skin, forming a band pattern, which may be very painful and last for weeks or even months. The link between HSV-1 and Alzheimer's disease occurs only when HSV-1 reactivation leads to ulcers, blisters, and other inflammatory conditions. (outlook new era)