The theory that herpes infections may play a role in triggering or accelerating Alzheimer’s disease has gained interest in recent years, raising the possibility that antiviral medications could slow the progression of symptoms. However, the first clinical trial designed to test this idea has found no evidence to support it.

The trial, conducted by researchers at Columbia University’s Vagelos College of Physicians and Surgeons, found that the commonly used herpes antiviral medication, valacyclovir, did not alter the course of Alzheimer’s in individuals at early stages of the disease. The findings were presented on July 29 at the Alzheimer’s Association International Conference.

Exploring the Link Between Herpes and Alzheimer’s

Herpes simplex viruses HSV1 (cold sores) and HSV2 (genital herpes) infect around 60% to 70% of Americans. Though symptoms may fade after the initial infection, the virus remains latent in the nervous system and can periodically reactivate.

Past studies have noted a potential association between herpes and Alzheimer’s. For example, HSV1 DNA has been found in amyloid plaques in the brains of people with Alzheimer’s, and some observational studies have suggested that individuals treated for herpes had a lower risk of developing Alzheimer’s compared to those who were not treated.

“There was reason to believe valacyclovir might have a therapeutic effect,” said Dr. D.P. Devanand, the trial’s lead investigator and a professor of psychiatry and neurology.

Details of the Clinical Trial

The randomized trial enrolled 120 participants with an average age of 71, all diagnosed with early Alzheimer’s or mild cognitive impairment and confirmed to have Alzheimer’s-related brain changes through imaging or blood biomarkers. All participants had antibodies indicating previous herpes infections, mostly HSV1.

Participants were randomly assigned to receive either daily valacyclovir or a placebo over 18 months. Researchers tracked cognitive function and used brain imaging to monitor amyloid and tau buildup, as well as other structural changes.

At the end of the study, those taking the placebo slightly outperformed the treatment group in cognitive tests. On other measures, the two groups showed no meaningful differences.

“We were hoping to see signs that the medication had a positive effect,” said Devanand. “But that didn’t happen. In some cases, the placebo group even did marginally better.”

The results held consistent across different subgroups based on age, sex, and APOE e4 genetic status.

Conclusion

“Our findings suggest that herpes-targeting antivirals like valacyclovir are not effective for treating early Alzheimer’s in patients with prior HSV infection,” Devanand concluded. “Whether long-term antiviral use following herpes infection might prevent Alzheimer’s remains an open question—one that requires further prospective, controlled trials.”

Source: https://www.cuimc.columbia.edu/news/antiviral-treatment-fails-slow-early-stage-alzheimers