黑料吃瓜群网

New research has found further evidence that the herpes virus responsible for cold sores can also cause聽Alzheimer鈥檚, and that antiviral drugs drastically reduce risk of senile dementia in patients with severe herpes infections. The in raises the tantalising prospect of a simple, effective preventive treatment for one of humanity鈥檚 costliest disorders.

The HSV1 theory of Alzheimer鈥檚 disease

Herpes viruses are the dreaded 鈥榞ift that keeps on giving鈥�. They remain lifelong in our neurons and immune cells, reactivating and resurfacing in characteristic blisters when we鈥檙e run down by stress or illness. Most people are infected by Herpes Simplex Virus 1 (HSV1) by the time they reach old age.

But what happens to infected neurons in our brain during this reactivation?

鈥淗SV1 could account for 50% or more of Alzheimer鈥檚 disease cases,鈥� said Professor Ruth Itzhaki, who has spent over 25 years at the investigating a potential link.聽

HSV1 is better known as the cause of cold sores. Prof Itzhaki has shown previously that cold sores occur more frequently in carriers of APOE-蔚4 鈥� a gene variant that confers increased risk of Alzheimer鈥檚.

鈥淥ur theory is that in APOE-蔚4 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鈥檚.鈥�

Proving the theory

Few countries collect the population data required to test this theory 鈥� for example, to find out whether antiviral treatments reduce dementia risk.

In Taiwan, however, researchers have done just that. There, 99.9% 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鈥�2018 three studies were published describing Taiwanese data on the development of senile dementia 鈥� of which Alzheimer鈥檚 is the main cause 鈥� and the treatment of patients with marked overt signs of infection with HSV or varicella zoster virus (VZV, the chickenpox virus).

鈥淭he striking results include evidence that the risk of senile dementia is much greater in those who are infected with HSV, and that antiherpes antiviral treatment causes a dramatic decrease in number of those subjects severely affected by HSV1 who later develop dementia.鈥�

Previous findings from Prof Itzhaki鈥檚 own research group provide a mechanistic link which supports these epidemiological findings. They found that HSV1 causes protein deposits characteristic of Alzheimer鈥檚: 鈥榩laques鈥� between neurons, and 鈥榯angles鈥� inside of them.

鈥淰iral DNA is located very specifically within plaques in postmortem brain tissue from Alzheimer鈥檚 sufferers. The main proteins of both plaques and tangles accumulate also in HSV1-infected cell cultures 鈥� and antiviral drugs can prevent this.鈥�

Towards a cure

鈥淚t should be stressed that the results of these Taiwanese studies apply only to severe HSV1 (or VZV) infections, which are rare,鈥� admitted Prof Itzhaki. 鈥淚deally, we would study dementia rates amongst people who have suffered mild HSV1 infection, including herpes labialis (cold sores) or mild genital herpes, but these are far less likely to be documented.鈥�

Although further work is needed to confirm and define a causal link between HSV1 infection and Alzheimer鈥檚, Prof Itzhaki is enthusiastic about the treatment prospects.

鈥淐onsidering that over 150 publications strongly support an HSV1 role in Alzheimer鈥檚, these Taiwan findings greatly justify usage of antiherpes antivirals 鈥� which are safe and well-tolerated 鈥� to treat Alzheimer鈥檚 disease.

鈥淭hey also incentivise development of an HSV1 vaccine, which would likely be the most effective treatment.鈥�

This echoes the growing use worldwide of human papillomavirus (HPV) vaccination to prevent cervical cancer 鈥� another virus-disease link which emerged in a similar process of research.

Image credit: 漏stock.adobe.com/au/pathdoc