New Study Links Herpes to Getting Alzheimer's Disease

Analysis of a Taiwanese study led UK-based researchers to discover a causal link between herpes and Alzheimer's disease.
Shelby Rogers

Alzheimer's disease remains one of the most mysterious and devastating mental diseases around. However, new reports from several groups of researchers are finding an unexpected link that could help medical professionals better understand Alzheimer's disease.

Scientists from the Universities of Manchester and Edinburgh did further analysis of a Taiwanese study that uncovered a causal link between the herpes virus infection and Alzheimer's disease.

The original Taiwanese paper looked at subjects who'd suffered severe herpes infections and were then treated with very strong antiviral drugs. That study discovered the risk of getting dementia after being treated with those antiviral drugs was reduced by a factor of 10.

"This article and two others by different research groups in Taiwan provide the first population evidence for a causal link between herpes virus infection and Alzheimer's disease, a hugely important finding," said Professor Ruth Itzhaki of the University of Manchester.

The recent commentary from the UK-based team appeared in a recent edition of the Journal of Alzheimer's Disease. In the commentary, the team says the Taiwanese research could be the strongest evidence of a causal link between herpes and Alzheimer's, something that would support over three decades of work done by Itzhaki.

"I believe we are the first to realise the implications of these striking data on this devastating condition which principally affects the elderly. No effective treatments are yet available," Itzhaki said.

The scale and rate at which people contract both herpes and Alzheimer's means researchers are working fast to discover as much as they can about potential correlations between the two, and thus, get started on treatment plans. 

"Almost 30 million people worldwide suffer from it and sadly, this figure will rise as longevity increases," Itzhaki said. "But we believe that these safe and easily available antivirals may have a strong part to play in combating the disease in these patients. It also raises the future possibility of preventing the disease by vaccination against the virus in infancy."

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"Successful treatment by a specific drug, or successful vaccination against the putative microbe, are the only ways to prove that a microbe is the cause of a non- infectious human disease," the professor continued.

The herpes simplex virus (or HSV1) infects most humans during their young adulthood. It then remains in the body in a dormant form for life. The virus's trademark cold sores and other physical indicators happen sporadically in humans.


The Taiwanese study observed over 8,300 subjects over the age of 50 who were newly diagnosed with a severe HSV infection. The team then compared them with a control group of over 25,000 people who didn't have the infection. The Asia-based team then monitored the development of dementia of both groups for 10 years, between 2000 and 2010.

They found that when they compared those within the HSV group treated with antiviral therapy compared to those who didn't get any, there was a dramatic reduction in dementia over the 10 years.

Professor Richard Lathe said, "Not only is the magnitude of the antiviral effect remarkable, but also the fact that -- despite the relatively brief duration and the timing of treatment -- in most patients severely affected by HSV1 it appeared to prevent the long-term damage in brain that results in Alzheimer's."

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