The herpes virus appears less often in people with Alzheimer's than in healthy adults.
April 20, 2026
Original Paper
Herpes simplex virus type 1 DNA is less prevalent in persons with Alzheimers disease and genetic factors modify the effect
medRxiv · 10.64898/2026.04.16.26351043
The Takeaway
Scientists have spent years investigating the idea that the common cold sore virus helps trigger the plaques that cause Alzheimer's. This large-scale analysis found that HSV-1 DNA is consistently less frequent in the brains of Alzheimer's patients compared to healthy controls. The relationship is even more complex for people who carry the APOE-e4 risk gene for the disease. This discovery suggests that the virus might not be the villain it was assumed to be in the context of cognitive decline. It forces the entire field of neurobiology to rethink how chronic infections interact with the aging brain. Research may now pivot to how the immune system manages these viruses differently in healthy aging.
From the abstract
INTRODUCTION: Herpes simplex virus-1 (HSV-1) has been implicated in Alzheimers disease (AD). METHODS: Reads from Alzheimers Disease Sequencing Project whole-genome sequencing data collected from brain (2,203 AD; 616 controls) and blood (8,908 AD; 15,768 controls) were aligned to viral genomes. Generalized linear mixed-models tested for the effect of HSV-1 DNA on AD, and we performed GWAS on HSV-1 presence and SNPxHSV-1 interaction effects on AD, adjusting for age, sex, tissue, library preparatio