In 2010, A A Colorado university lecturer began to experience troubling signs of cognitive decline.
The lecturer – a 63-year-old virological immunologist whose identity remained anonymous – suffered from disturbing symptoms, including memory disorders, loss of concentration and reading difficulties. While lecturing to students, he stated that he had difficulty concentrating and was often unable to complete sentences without interruption. However, medical tests, including a brain biopsy, did not reveal the source of the problem, and over the next four years the symptoms continued to worsen.
His decline would likely have continued had he not heard about a case of encephalitis, a stern inflammation of the brain caused by reactivation of the varicella-zoster virus, most often associated with chickenpox in children and, later in life, shingles.
Recalling that his own symptoms had been preceded by a brief case of shingles, subsequent tests confirmed that the patient had indeed had reactivation of varicella-zoster. So he decided to treat the problem with acyclovir, an antiviral drug commonly prescribed to patients with shingles. To the amazement of his colleagues, the Colorado lecturer’s symptoms quickly resolved and his cognitive function returned to normal.
This is an extraordinary case study, published in 2016inspired neurovirologists to delve deeper into the connection between shingles and brain aging. For decades, shingles has been associated primarily with a type of nerve pain known as postherpetic neuralgia, which can be so severe that this was once quoted as the leading cause of pain-related suicides among older people. Now, research is beginning to reveal the devastating effects of shingles on brain health.
According to Andrew Bubak, an assistant professor of neurology at the University of Colorado, Anschutz, the true burden of the varicella-zoster virus “is completely underestimated. But it is a virus that can be easily treated.”
In recent years, a growing number of studies have shown that the shingles vaccine appears to be able to protect the aging body and brain, something that dementia specialists are taking note of. In April 2025 important examination researchers at Stanford University suggested that vaccination against shingles could prevent one in five fresh cases of dementia. More recent research also linked shingles vaccination to slowing biological aging in various ways.
One explanation for these findings is that the vaccine may stimulate the immune system in broadly beneficial ways. While there is probably some truth to this, additional research is increasingly pointing to the value of avoiding shingles (or reactivating the varicella-zoster virus) in the first place, and two separate studies have found a link between shingles and shingles self-reported cognitive decline AND dementia.
Neurovirologists say this fresh data highlights the importance of avoiding infection by vaccinating children against chickenpox – given to children in the US since 1995 and introduced in the UK in January 2026 – as well as through the adult shingles vaccine and booster doses later in life.
Before chickenpox vaccinations began routinely in the United States, more than 90 percent of children contracted the chickenpox virus during childhood. Once infected, the virus takes up residence in the peripheral nervous system – the neurons that connect the brain and spinal cord to the limbs and organs – where it remains dormant, sometimes for decades.
Varicella-zoster can be reactivated in the body under the influence of various triggering factors, including: acute stress Down concussion, Covid-19 co-infectionimmunosuppressive drugs and general aging immune system. In many cases, such reactivations may be completely asymptomatic, e.g some research suggesting that many of us may unknowingly experience repeated “subclinical” reactivations – the virus emerging from dormancy without causing noticeable symptoms – in mid- to later life.