Alzheimer’s disease can occur after infection with a very common virus

Researchers from Tufts University in the United States present recent findings that support the hypothesis that Alzheimer’s disease could be caused by a virus.

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[EN VIDÉO] What are the differences between bacteria and viruses?
They are microbes. They are very small and can easily be confused. However, bacteria and viruses are two very different things. And in order to effectively fight the pathogens, it is better to clearly identify them.

Almost 225,000 people in France declare Alzheimer’s disease every year, most after the age of 65. Although this form of dementia is widespread, its origin is still hotly debated in professional circles. However, there are points of consensus: the amyloid plaques and the aggregates of tau protein in which neurons involved in the occurrence symptoms typical of the Alzheimer’s diseaseand theinflammation who seizes the Brain Patients exacerbate this toxicity.

To explain these observations, Several hypotheses are proposed by scientists. factors genetically appear to play an important role in the most common sporadic cases of Alzheimer’s, but deregulation of the synthesis of amyloid proteins or the intervention of a microorganism – a virus mostly – could also have an effect.

experiences in vitro on cultured neurons

A team from Tufts University in the United States presents findings that fall within the framework of the “viral hypothesis” about the origin of Alzheimer’s disease. The latter states that a virus dormant in the brain – usually herpes virus 1 or HSV-1 – is “awakened” by factors that are still poorly defined and triggers the symptoms of Alzheimer’s disease. ” Our results suggest a pathway leading to Alzheimer’s disease, which is caused by infection with the virus VZV this triggers inflammation that wakes up the HSV-1 virus in the brain ‘ says Dana cairnFirst author ofStudy published in Journal of Alzheimer’s Disease.

To support this hypothesis, they infected human neural stem cells with the two viruses and looked for markers specific to Alzheimer’s: amyloid plaques and tau aggregates, gliosis (proliferation of glial cells in the brain) and neuroinflammation. Their results show that the VZV virus alone does not cause the formation of amyloid plaques and tau aggregates like HSV-1, but rather neuroinflammation and gliosis. According to scientists, this indicates an indirect effect of the VZV virus. They also observed that infection of cells in which HSV-1 is dormant by the VZV virus reactivates it and causes changes typical of Alzheimer’s. ” It’s a double whammy of two viruses that are very common and generally harmless, but laboratory studies suggest that if further exposure to VZV awakens dormant HSV-1, it could cause problems. ‘ says Dana Cairns.

These experiments alone are not robust enough to confirm a causal relationship between Alzheimer’s disease and VZV and HSV-1 viruses, although observations point in that direction. Furthermore, the various hypotheses examined regarding the origin of Alzheimer’s disease are not necessarily mutually exclusive. Viral infection, among others, could be a factor to consider in Alzheimer’s disease.

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