Association between the use of anti-herpetic drugs and subsequent initiation of Alzheimer’s disease drug treatment: Dutch population-based inception cohort study

OBJECTIVES: To examine whether exposure to anti-herpetic drugs (AHDs: acyclovir, valacyclovir, famciclovir) is associated with reduced risk of Alzheimer's disease (AD) treatment initiation. DESIGN: Population-based retrospective matched cohort study. SETTING: University Groningen community pharmacy database IADB.nl, covering approximately 125 Dutch pharmacies (1994-2024). PARTICIPANTS: 262 757 adults aged 50-80 years without prior dementia or AD treatment. Exposed individuals with antiherpetic prescriptions (n=23 887) were matched 1:10 to unexposed controls (n=238 870) by age, sex and calendar time. INTERVENTION: AHDs: acyclovir, valacyclovir, famciclovir. MAIN OUTCOME MEASURES: Initiation of AD drug treatment, defined as at least two prescriptions for rivastigmine, donepezil, galantamine or memantine within 1 year. Cox proportional hazards models estimated HRs with 95% CIs, adjusted for comorbidities and medications. Analyses were stratified by period (1994-2018 vs 2019-2024) and drug type. RESULTS: During follow-up, 2495 participants initiated AD treatment. The age of the participants was 65 (SD 9), and 59% were female. Any AHD exposure was associated with 90% reduced hazard of AD treatment (HR 0.09, 95% CI 0.07 to 0.13, p