Here are our key takeaways from the study “Association between herpes simplex virus type 1 and the risk of Alzheimer’s disease: a retrospective case–control study” published in BMJ Open on May 20, 2025.
READ STUDY HERE.
Herpes Cure Advocacy welcomes the findings of this new retrospective case–control study as further confirmation of the urgent need to elevate herpes simplex virus type 1 (HSV-1) as a public health priority. The study’s conclusion—that HSV-1 infection is significantly associated with an increased risk of Alzheimer’s disease—reinforces growing evidence that chronic viral infections may play a key role in neurodegenerative processes. For decades, HSV-1 has been underestimated and stigmatized, limiting public and scientific discourse. Yet, research like this highlights the virus’s broader systemic implications and the potential for prevention or mitigation through early detection, therapeutic intervention, or even vaccination. This study deepens the case for investing in herpes cure research—not only to address the direct symptoms and stigma of the disease, but also to understand its possible contribution to other health issues such as long-term cognitive decline. It is a call for collaborative, multidisciplinary research that includes the voices of patients and advocates.
🧠 Scientific Implications
- Supports the viral hypothesis of Alzheimer’s disease, particularly the role of HSV-1 in neuroinflammation and amyloid-beta plaque formation.
- Suggests antiherpetic therapy might be a preventive strategy for AD in HSV-1 positive patients.
- Causality not established—only associations shown.
- Reinforces the need for further research, including prospective studies and mechanistic investigations.
🔬 Study Objective
- Investigate the association between herpes simplex virus type 1 (HSV-1) and Alzheimer’s disease (AD) using large-scale U.S. administrative claims data.
- Assess whether antiherpetic medications reduce the risk of AD among those diagnosed with HSV-1.
📊 Study Design
- Retrospective matched case–control study using the IQVIA PharMetrics Plus claims database.
- Included 344,628 matched pairs (AD patients vs. controls), aged ≥50 years.
- Matched on age, sex, region, database entry year, and healthcare visit frequency.
- Analysis also extended to AD-related dementias (ADRD) and other herpesviruses.
📈 Key Findings
- HSV-1 significantly increases AD risk:
- HSV-1 diagnosis was more common in AD patients (0.44%) vs. controls (0.24%).
- Adjusted odds ratio (OR) = 1.80 (95% CI: 1.65 to 1.96), indicating an 80% increased risk of AD in HSV-1 patients.
- HSV-1 diagnosis was more common in AD patients (0.44%) vs. controls (0.24%).
- Risk increases with age:
- Stronger association in older age groups (75+ years: OR = 2.10).
- Stronger association in older age groups (75+ years: OR = 2.10).
- Antiherpetic medication may reduce AD risk:
- Among HSV-1 patients, those who took antiherpetic drugs had a 17% lower risk of developing AD.
- Adjusted hazard ratio (HR) = 0.83 (95% CI: 0.74 to 0.92).
- Among HSV-1 patients, those who took antiherpetic drugs had a 17% lower risk of developing AD.
- Other herpesviruses:
- HSV-2 and VZV were also associated with increased AD risk.
- CMV showed no significant association.
- COPD (a non-infectious comparator) was more common in controls.
- HSV-2 and VZV were also associated with increased AD risk.
⚠️ Study Limitations
- Asymptomatic HSV-1 infections likely underreported.
- Possible diagnosis misclassification for both HSV and early AD.
- Claims data may miss older adults (65+) covered by Medicare.
- Importantly, causality is not established—only associations shown.
NOTE: As of May 2025, Gilead is supporting two Phase 1 clinical trials for two different antiviral therapies.
Disclaimer: This post was drafted by the HCA team with the support of ChatGPT.