Herpes drugs linked to fewer starts of Alzheimer’s treatment
Antiviral use was linked to a 90% lower rate of starting Alzheimer’s medication at any given time compared with nonuse.
Our read
Populations- Studied:
- Cohort study of 262,757 adults aged 50-80 years, 3 years, against unexposed individuals
- What changed:
- Alzheimer's disease treatment initiation was 90% lower (HR 0.09) among anti-herpetic drug users compared with unexposed individuals
- The catch:
- Unmeasured education, lifestyle, socioeconomic status, and health-seeking behaviors could confound the association
- In the record:
- One of 6 papers on acyclovir on record: 3 with results in people.
Editor of record: Boris Djordjevic · AgingResearch.News
Dutch adults aged 50–80 without prior dementia or Alzheimer’s drug treatment were studied in a retrospective matched observational cohort of 262,757 people; 59% were women. Using pharmacy records from 1994–2024, researchers compared 23,887 people prescribed herpes antivirals with 238,870 nonusers matched by age, sex and calendar time.
Over three years, 0.17% of antiviral users and 1.03% of nonusers started Alzheimer’s medication. Starting treatment meant receiving at least two prescriptions within one year. The association remained after adjustment for age, sex and health conditions estimated from other prescriptions. All three antivirals studied—acyclovir, valacyclovir and famciclovir—were linked to a lower likelihood of later Alzheimer’s prescriptions. The overall association appeared in both 1994–2018 and 2019–2024.
Why it matters
Herpesviruses becoming active again may contribute to Alzheimer’s disease, a hypothesis the authors said these findings support. They suggested antiviral therapy could have preventive implications.
Caveats
Starting medication was a proxy for Alzheimer’s disease, and the records contained no clinical diagnoses; unrecorded differences in health or prescribing could help explain the association. The cohort excluded people taking immunosuppressants or cancer therapies and did not cover adults outside ages 50–80.
From the paper
- Participants
The overall cohort comprised 238 870 individuals without AHD treatment and 23 887 with AHD treatment.
- Follow-up
Overall, across the 3-year follow-up period, any AHD use resulted in an ARR of 0.86%, corresponding to an NNP of 116, meaning that 116 individuals would need to receive AHD treatment to prevent one case of AD treatment initiation.
- Result
The relative risk at 3 years comparing any AHD use to no AHD use was 0.16 (95% CI 0.11 to 0.21, p<0.001), indicating an 84% reduction in cumulative incidence among AHD users.
- Absolute difference
Overall, across the 3-year follow-up period, any AHD use resulted in an ARR of 0.86%, corresponding to an NNP of 116, meaning that 116 individuals would need to receive AHD treatment to prevent one case of AD treatment initiation.
- Limitation
While Dutch prescribing guidelines restrict these drugs almost exclusively to AD, some degree of misclassification cannot be excluded.
Quoted word for word from the full text on PubMed Central.
The paper
University of Groningen; University Medical Center Groningen
BMJ Open, Jun 15, 2026, Open access
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