by A new study suggests that a single attack 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 patches on the skin, and only on one side of the body.
The disease is caused by the varicella zoster virus (VZV), the same virus that causes chickenpox. When 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 can reactivate as shingles.
Previous studies on shingles and dementia have been conflicting. Some research suggests that shingles increases the risk of dementia, while others suggest that there is no or a negative association.
There is increasing evidence that herpes viruses, including VZV, may affect cognitive decline, the earliest sign of Alzheimer’s disease.
The spots turn into itchy blisters from which fluid oozes
NHS
Researchers at Brigham and Women’s Hospital investigated whether the same is true for shingles.
Corresponding author Sharon Curhan and her team used data from three large, well-characterized studies of men and women over long periods of time:
The study, published in Alzheimer Research & Therapyinvolved 149,327 participants who completed a health questionnaire every two years that included questions about shingles episodes and cognitive decline. They compared those who had shingles with those who did not.
The researchers found that a history of shingles was significantly and independently associated with an approximately 20 percent higher risk of subjective cognitive decline in both women and men.
This risk was higher in men who were carriers of the gene. APOE4which is associated with cognitive impairment and dementia. This association was not present in women.
Researchers do not know the mechanisms linking the virus to cognitive health, but there are several ways it could contribute to cognitive decline.
There is growing evidence that VZV is linked to a vascular disease called VZV vasculopathy, in which the virus damages blood vessels in the brain or body. Curhan’s research group had previously found that shingles is associated with a higher long-term risk of stroke or heart disease.
Other mechanisms that could explain how the virus can cause cognitive decline include the development of inflammation in the brain, direct damage to nerve and brain cells, and the activation of other herpes viruses.
Several mutations in components of the spike protein raise doubts about the effectiveness of the vaccine Getty Images What the study makes clear, however, is that vaccination against shingles is crucial.
Recent studies have shown that shingles vaccination is associated with a reduced risk of dementia.
“Our findings demonstrate the long-term effects of shingles and underscore the importance of public health efforts to prevent and promote shingles vaccination,” Curhan said.
Limitations of this research include that it was an observational study, relied on self-reported information, and included a predominantly white, highly educated population. In future studies, researchers hope to learn more about preventing shingles and its complications.
“We are investigating whether we can identify risk factors that could be modified to reduce the risk of developing shingles,” Curhan said. “We also want to investigate whether the shingles vaccine can help reduce the risk of negative health consequences of shingles, such as cardiovascular disease and cognitive decline.”
