A large-scale study showing that the chickenpox virus, the cause of herpes zoster, is not related to dementia is of interest.
According to a Medicalnewstoday press release, Dr Charlotte Warren Gash of the UK used data from the Danish National Register to examine the link between the incidence of shingles and the risk of dementia.
The researchers looked at data on hospital diagnoses and drug prescriptions to identify individuals over 40 years of age diagnosed with shingles and dementia from January 1997 to December 2017. The study compared 247,305 people with herpes zoster and nearly 1.25 million people of the general population, age and sex-matched.
They found that a previous diagnosis of herpes zoster was associated with a slightly reduced risk of dementia in individuals compared to the general population. The association between herpes zoster and dementia due to Alzheimer’s disease was also similar to that observed in all-cause dementia.
Dr Sigrun Alba Johannesdottir Humidt, study author and epidemiologist at Aarhus University Hospital in Denmark, said: “This was unexpected and we cannot explain the reasons for the findings of this study. “It may be because we missed the diagnosis of shingles in patients with undiagnosed dementia because we might not find medical records for herpes.
“Another possibility is that the antiviral drugs used to treat herpes zoster actually prevent the onset of dementia, but our data do not allow us to investigate this further,” she continued.
Dr. M. Arfan Ikram, an epidemiologist at Erasmus University Medical Center in the Netherlands, was not surprised by this and said, “The research team did not find a link between herpes zoster infection and dementia, perhaps unexpectedly,” in an interview with the media. He said that any effect they found would also be negligible. “A role for infectious diseases in dementia risk has been reported, but it is likely to be only a small fraction,” he said.
In this study, the researchers also found that shingles infection was associated with inflammation of the cranial nerves or central nervous system.