Half of all Alzheimer’s cases could be caused by herpes virus, says scientist

THE herpes virus could account for at least half of all cases of Alzheimer’s disease, a scientist has claimed.

There are two types of herpes simplex virus (HSV): HSV1, also known as oral herpes, which causes cold sores and blisters around the mouth and on the face; and HSV2, which is generally responsible for genital herpes outbreaks.

Professor Ruth Itzhaki, who has spent more than 25 years at the University of Manchester in England investigating a potential link, looked to Taiwan as few countries collect the population data required to test the theory.

In Taiwan, 99.9pc of the population is enrolled in a National Health Insurance Research Database, which is being extensively mined for information on microbial infections and disease.

In 2017 and 2018, three studies were published describing Taiwanese data on the development of senile dementia – of which Alzheimer’s is the main cause – and the treatment of patients with marked overt signs of infection with HSV or varicella zoster virus (VZV – the chickenpox virus).

Prof Itzhaki said: “The striking results include evidence that the risk of senile dementia is much greater in those who are infected with HSV, and that anti-herpes antiviral treatment causes a dramatic decrease in the number of those subjects severely affected by HSV1 who later develop dementia.

“HSV1 could account for 50pc or more of Alzheimer’s disease cases.”

The results of the studies apply only to severe HSV1 (or VZV) infections, which are rare.

‘The risk of senile dementia is much greater in those infected with HSV’