Herpesvirus infections, antiviral treatment, and the risk of dementia-a registry-based cohort study in Sweden

Abstract

Introduction: Herpesviruses, including Herpes simplex virus type 1 (HSV1) and varicella zoster-virus (VZV), have been implicated in Alzheimer's disease (AD) development. Likewise, antiviral treatment has been suggested to protect against dementia development in herpes-infected individuals.

Methods: The study enrolled 265,172 subjects aged ≥ 50 years, with diagnoses of VZV or HSV, or prescribed antiviral drugs between 31 December 2005 and 31 December 2017. Controls were matched in a 1:1 ratio by sex and birth year.

Results: Antiviral treatment was associated with decreased risk of dementia (adjusted hazard ratio [HR] 0.89, 95% confidence interval [CI] 0.86 to 0.92), while herpes infection without antiviral drugs increased the risk of dementia (adjusted HR 1.50, 95% CI 1.29 to 1.74).

Discussion: Antiviral treatment was associated with a reduced long-term risk of dementia among individuals with overt signs of herpes infection. This is consistent with earlier findings indicating that herpesviruses are involved in the pathogenesis of AD.

Keywords: Alzheimer's disease; antiviral agents; dementia; herpes simplex; herpes zoster; retrospective cohort study; varicella zoster.

FIGURE 1

Kaplan‐Meier curve of the cumulative incidence of dementia in different groups. “Controls 1” denote controls of the “Herpes, no treatment” group. “Controls 2” denote controls of the “Herpes, with treatment” group. The follow‐up differentiated between subjects, but censors were not drawn in the diagram due to the high number of individuals censored at each time point