Health. Does shingles increase the risk of dementia?

Shingles mainly affects people over 50 years old. Very painful, this viral infectious disease is “due to the reactivation of the varicella-zoster virus of the herpes-virus family, occurring long after chickenpox”, describes the Health Insurance.

In detail, for shingles to appear, the varicella-zoster virus, which has remained “asleep” at the root of the nerves at the level of the nerve ganglia, must multiply there. Then, it “runs along the nerve fibers to cause a painful skin or mucous rash on the territory innervated by these fibers”, she continues.

A surprising finding

Studies have suggested that this reactivation of the varicella virus could constitute a risk factor for dementia in the elderly. To find out for sure, the team of Sigrun Alba Johannesdottir Schmidt from Aarhus University Hospital in Denmark obtained the medical data of nearly 250,000 people who had been treated in hospital for shingles. They formed a parallel control group of people of the same age – average age 64 – who had never been treated for this disease.

After comparing the occurrence of dementia in the two groups, the scientists found no significant difference. Participants who suffered from shingles were 9.7% to develop dementia twenty years later, while the others were 10.3%.

More surprisingly, the researchers observed that the shingles group even had a 7% lower risk compared to the control group, once the other health factors involved in the risk of dementia were taken into account (diabetes, cancer, head trauma).

“We were surprised by these results,” say the authors, for whom the reasons for this finding remain unknown.

Vaccination recommended

These results should not call into question the recommendation to vaccinate seniors against this disease. Because if nearly 90% of shingles heal without sequelae, certain complications may appear, including persistent pain, bacterial superinfection or even an extension of shingles on several parts of the body, including the central nervous system, in the event of immunosuppression.

Moreover, the authors of the study noted that in the latter case, although rare, an increase in the risk of dementia was clearly observed.

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