In 2010, a university lecturer from Colorado started experiencing worrying signs of cognitive decline.
The lecturer—a 63-year-old viral immunologist whose identity has been kept anonymous—suffered alarming symptoms, including impaired memory, waning concentration, and difficulty reading. While giving lectures to students, he found he had difficulty focusing and was often unable to finish sentences without pausing. But medical tests, including a brain biopsy, failed to get to the source of the problem, and over the next four years, his symptoms continued to progress.
His decline would have likely continued unabated had he not heard about a case of encephalitis—serious brain inflammation caused by a reactivation of the varicella-zoster virus, most commonly associated with childhood chickenpox and, later in life, shingles.
Remembering that his own symptoms had been preceded by a brief case of shingles, subsequent tests confirmed the patient had indeed experienced a reactivation of varicella-zoster. And so he decided to treat the problem with a course of acyclovir, an antiviral drug commonly prescribed to shingles patients. To his colleagues’ amazement, the Colorado lecturer’s symptoms quickly faded away and his cognition returned to normal.
This remarkable case study, published in 2016, has inspired neurovirologists to look deeper into the connection between shingles and brain aging. For decades, shingles has been predominantly associated with a form of nerve pain known as postherpetic neuralgia, which can be so severe that it was once cited as the leading cause of pain-related suicide in the elderly. Now, research is starting to reveal the devastating impact that shingles can have on brain health.
According to Andrew Bubak, assistant professor of neurology at the University of Colorado Anschutz, the true burden of varicella-zoster “is totally underestimated. But it’s a very treatable virus.”
In recent years, increasing numbers of studies have shown that the shingles vaccine appears to be capable of protecting the aging body and brain, and dementia specialists are taking note. In April 2025, a major study by researchers at Stanford University suggested vaccination against shingles could prevent one in five new cases of dementia. More recent studies have also linked getting a shingles vaccine to slower biological aging across a variety of measures.
One explanation given for the findings is that the vaccine might be stimulating the immune system in a broadly beneficial manner. While there is likely some truth in this, additional research increasingly points to the value of avoiding shingles (or reactivations of the varicella-zoster virus) in the first place, with two separate studies finding associations between shingles and self-reported cognitive decline and dementia.
Neurovirologists believe this emerging data underlines the importance of avoiding infection, through the childhood chickenpox vaccination—given to children in the US since 1995 and introduced in the UK in January 2026—and through the adult shingles vaccine and booster jabs in later life.
Before the US started routinely vaccinating against chickenpox, more than 90 percent of children acquired the varicella-zoster virus in childhood. Following the infection, the virus takes up position in the peripheral nervous system—the neurons linking the brain and spinal cord to the limbs and organs—where it stays dormant, sometimes for decades.
Varicella-zoster can reactivate in the body following various triggers, which range from acute stress to concussion, co-infections with Covid-19, immunosuppressive medications, and the general aging of the immune system. In many cases, such reactivations may be completely symptomless, with some studies suggesting many of us could unknowingly experience repeated “subclinical” reactivations—the virus reawakening from its dormant state without inducing visible symptoms—in mid- to later life.
