A new study suggests a single episode of shingles can predict the onset of dementia years in advance. Shingles is an infection that causes a painful red rash. It can appear as blotches on your skin, on one side of your body only. It’s caused by the varicella zoster virus (VZV), the same virus that causes chickenpox. After a person has chickenpox, the virus stays in their body for the rest of their life. Most of the time, our immune system keeps the virus at bay. Years and even decades later, the virus may reactivate as shingles. Previous studies of shingles and dementia have been conflicting. …