There is a strong link between the common herpes simplex virus type 1 (HSV-1) and an increased risk of Alzheimer’s disease, study shared.
The research suggests that antiviral medication might slightly reduce the chances of developing the condition in those infected.
Scientists from Gilead Sciences and the University of Washington in Seattle analysed health records of nearly 690,000 people aged over 50, comparing those with and without Alzheimer’s between 2006 and 2021. Their findings were published in the journal BMJ Open.
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People who had a history of HSV-1 infection were found to be 80% more likely to develop Alzheimer’s than those without the virus, even after adjusting for other factors.
HSV-1 is the virus commonly responsible for cold sores and can remain dormant in the body for years.
The researchers also found that people with HSV-1 who were treated with antiviral drugs had a 17% lower risk of developing Alzheimer’s.
Out of 2,330 people with a known HSV-1 infection, 40% received antivirals such as aciclovir, a drug used in the UK for treating herpes viruses.
Other viruses, including HSV-2 and varicella zoster (which causes chickenpox and shingles), were also linked to a higher risk of Alzheimer’s in the study. However, the exact reason for this link is still unclear.
Experts believe inflammation caused by these viral infections may play a role in triggering Alzheimer’s. Previous studies have found HSV-1 DNA in the brain plaques associated with the disease.
While some researchers praised the study’s size and quality, others warned against jumping to conclusions.
They noted that most Alzheimer’s cases did not involve HSV-1 and that the reduction in risk from antivirals was relatively small.
Health experts agree that more research is needed to understand how viruses affect brain health.
Though the findings are promising, they do not yet prove that treating cold sores or other herpes infections will prevent Alzheimer’s.
