JAMA December 2026 Valacyclovir Treatment of Early Symptomatic Alzheimer Disease The VALAD Randomized Clinical Trial

This randomized clinical trial, called VALAD, investigated whether the antiviral drug valacyclovir could be an effective treatment for individuals diagnosed with early symptomatic Alzheimer disease who also tested positive for the herpes simplex virus (HSV). The study was motivated by evidence suggesting a potential link between HSV and the etiology of Alzheimer disease. Researchers compared a valacyclovir group and a placebo group over 78 weeks, using the ADAS-Cognitive Subscale scoreas the primary measure of efficacy, along with secondary measures like changes in daily living activities and brain amyloid and tau levels via PET scans. Ultimately, the results indicated that valacyclovir was not efficaciousand, in fact, showed a trend toward greater cognitive worsening compared to the placebo, leading to the conclusion that the drug is not recommended for this patient population.