Herpes Causes Alzheimers In Some People

Herpes is the dreaded 'gift that keeps on giving'. But could it also be taking our memories? Decades of research show a striking correlation between Alzheimer's disease risk and infection with Herpes Simplex Virus 1 (HSV1) in people carrying a specific gene. Now, newly-available epidemiological data provide a causal link between HSV1 infection and senile dementia -- raising the tantalizing prospect of a simple, effective preventive treatment for one of humanity's costliest disorders.

From here.

Alzheimer's disease isn't the only cause of dementia in the elderly, but it is probably the most common. And, while it may have more than once cause, some cases, at least, are caused by a Herpes infection that interacts with a particular gene. If this causes even a significant share of Alzheimer's cases, this dreaded disease could be greatly curtailed. And this may be a huge share of the cases:

"HSV1 could account for 50% or more of Alzheimer's disease cases," says Professor Itzhaki, who has spent over 25 years at the University of Manchester investigating a potential link. 

HSV1 is better known as the cause of cold sores. Itzhaki has shown previously that cold sores occur more frequently in carriers of APOE-ε4 -- a gene variant that confers increased risk of Alzheimer's. 

"Our theory is that in APOE-ε4 carriers, reactivation is more frequent or more harmful in HSV1-infected brain cells, which as a result accumulate damage that culminates in development of Alzheimer's."

Best of all, anti-viral drugs can be effective, even after someone is infected:

[A]ntiviral drugs drastically reduce risk of senile dementia in patients with severe herpes infections.

There is no herpes vaccine for reasons both commercial and technical, but the commercial reasons have involved the fact that even though two-thirds of adults in the world under age fifty have been infected with the virus, that it is often asymptomatic for long periods of time and has seemingly mild symptoms when it does manifest itself. But, like HPV, for which vaccination became a higher priority when we learned that it caused cancer and not just genital warts, an HSV vaccine may become a higher priority now that we know that it is so closely associated with Alzheimer's disease. 

The paper is:

Ruth F. Itzhaki. "Corroboration of a Major Role for Herpes Simplex Virus Type 1 in Alzheimer’s Disease." Frontiers in Aging Neuroscience (2018); 10 DOI: 10.3389/fnagi.2018.00324

This potential medical breakthrough that could have a massive impact on public health isn't unique either. For example, great progress is being made in the cheap and effective treatment of sepsis, another major killer in the First World.