New work suggests that the varicella virus could reactivate a dormant herpes infection, leading to the development of Alzheimer’s disease.
A new look at Alzheimer’s disease and neurodegenerative diseases
Largely set aside for more than half a century, the idea that microbial infections are a triggering factor for neurodegenerative diseases experienced a marked resurgence in the 1980s, with several studies establishing links between the onset of the diseaseAlzheimer and herpes simplex viral infections. However, the mechanisms by which this very common virus was likely to influence neurodegeneration remained largely obscure.
In 2020, a landmark study involving an entirely new type of brain model demonstrated precisely how a herpes infection could lead to several pathological hallmarks of Alzheimer’s disease, but the fact that more than two-thirds of the world’s population carries the herpes type I (HSV-1) infection suggested that other factors helped reactivate the virus and set off the cascade of events that caused this form of dementia.
Published in the Journal of Alzheimer’s Diseasethis new research involving researchers from the universities of Oxford and Tufts focused on another common virus associated with Alzheimer’s disease: the varicella zoster virus (VZV). Using the same brain model used two years earlier, the team explored its potential influence on brain cells carrying the herpes virus in its dormant form.
Strikingly, their exposure to BVV led to reactivation of herpes and the formation of toxic plaques usually seen in patients with Alzheimer’s disease. Which did not happen when brain cells exposed to VZV did not carry HSV-1.
One path among others
While the study suggests with certainty that this two-pronged viral mechanism can trigger Alzheimer’s disease, its authors point out that it is probably only one of several pathways, which could potentially intersect. ” Risk factors such as head trauma, obesity or alcohol consumption could also contribute to the reactivation of HSV in brain cells. “Said Dana Cairns, researcher at Tufts University.
Raising fears of an increase in neurodegenerative diseases in the coming decades, SARS-CoV-2 is also able to reactivate VSV and HSV-1. Therefore, the authors of the new study recommend close monitoring of elderly patients who have been infected with the coronavirus.