Experts working at Tufts University in the USA have unveiled recent findings validating the possibility that Alzheimer’s disease might be caused by a virus.
Bacteria and viruses: what makes them different?
Both viruses and bacteria are microbes. Thus, the latter are small and it happens to confuse them easily. However, these are two very different things. In order to perfectly combat those who cause disease, it is preferable to carry out a clear, relevant and precise identification.
Approximately 225,000 individuals in the country are affected by Alzheimer’s annually, the majority once they reach the age of 65. If this type of dementia is recurrent, its origin is still subject to lively debate within the scientific community. Nevertheless, the experts agree on several points: the amyloid plaques and the Tau protein aggregates present in the neurons have a role in the onset of classic symptoms of Alzheimer’s. L’inflammation gaining the brains of sick people enlarges this toxic side.
What is the explanation for such a phenomenon? Different possibilities are given by the experts. Genetic factors seem to play a major role in the sporadic situations of Alzheimer’s disease, which are the most recurrent. However, here is another possible cause of the occurrence of the disease: a deregulation of the synthesis of amyloid proteins or the action of a micro-organism, which is often similar to a virus.
VZV or the virus varicella zoster belongs to the herpesvirus family. Nearly 90% of the international population has been in contact with the latter at least once. It is known to cause two diseases: chickenpox and shingles. After that, it takes refuge and remains in the brain. As the years progress, it can increase tenfold and have an impact on health.
Performing in vitro tests on cultured neurons
Experts from the American University of Tufts, in the USA, unveil conclusions integrating what is called the viral hypothesis on the origin of Alzheimer’s. The latter claims that a virus present in the brain – most of the time herpes virus 1 or HSV-1 – or “activated” by still vague aspects, and generates the symptoms of Alzheimer’s.
The findings expose a pathway that might cause Alzheimer’s. In the latter, we learn that infection with the VZV virus causes inflammation. The consequence would be the activation of the HSV-1 virus in the brain.
Sufficient experiences?
Scientists performed the infection of human neural stem cells with the use of two viruses. Then, they went in search of different markers specific to Alzheimer’s: amyloid plaques and Tau aggregates, gliosis (this is the multiplication of glial cells in the brain), not to mention neuro-inflammation. Their findings reveal that the unique VZV virus does not cause the conception of amyloid plaques and Tau aggregates, in the same way as HSV-1. Indeed, this would cause neuro-inflammation and gliosis. This means, according to experts, that it would then be an indirect effect of the VZV virus.
Furthermore, they discovered that infection of cells, where HSV-1 is present, by the virus VZV activates the latter once more and causes classic Alzheimer’s changes. It is a double effect of two common and generally not very dangerous viruses. However, laboratory reports claim that a second exposure to VZV results in the activation of HSV-1 already present. And there, unfortunately, it might cause serious health problems.
These tests alone turn out to be insufficient and not strong enough to validate a causal link between Alzheimer’s and the VZV and HSV-1 viruses, even if the experiments tend to validate this.
