New research has found that catching shingles could increase a person’s risk of developing Alzheimer’s disease.
The infection wakes up another herpes virus that is normally harmless and lays dormant in our bodies – this ‘chain reaction’ is linked to a dramatic build-up of dangerous plaque in the brain.
Shingles is the subsequent infection following chickenpox, which occurs when a person is first exposed to varicella zoster virus (VZV).
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Using brain cells grown in a lab, researchers led by the University of Oxford examined what impact VZV has on the brain. While it did not directly cause the changes associated with Alzheimer’s, it was found to reactivate another virus, HSV-1, which led to a quick build-up of proteins that cause harm in the brain.
It follows research that has showed that older people with high levels of HSV-1 in their brain are much more at risk of developing Alzheimer’s.
Study author Dana Cairns, from Tufts University in Massachusetts, said: “It’s a one-two punch of two viruses that are very common and usually harmless.
“But the lab studies suggest that if a new exposure to VZV wakes up dormant HSV-1, they could cause trouble.”
Professor Ruth Itzhaki, from the University of Manchester, also worked on the study and said: “This striking result appears to confirm that, in humans, infections such as VZV can cause an increase in inflammation in the brain, which can reactivate dormant HSV-1.
“The damage in the brain by repeated infections over a lifetime would lead eventually to the development of AD/dementia.
“This would mean vaccines could play a greater role than just protecting against a single disease, because they could also indirectly, by reducing infections, provide some protection against Alzheimer’s.”
The study has been published in the Journal of Alzheimer’s Disease.
