Herpes Simplex Virus and Alzheimer’s Disease: The Present State of Clinical Evidence

Stephanie Toscano Kasabkojian,Francine Papaiordanou,Antonio Carlos Amedeo Vattimo,Analia Luiza Porto Viana,Gabriela Pacheco De Oliveira,Andrea Bauer Bannach,Stevin Zung

doi:10.11648/j.cmr.20211004.13

Abstract

Alzheimer´s disease (AD) and dementia have a probably multifactorial pathogenesis and, accordingly to several studies, human herpes simplex virus type 1 (HSV-1) infection may be related. The purpose of this review is to assess the updated clinical evidence towards the association between herpes infection and AD. We performed a PubMed/MEDLINE database research and included in this review randomized clinical trials on the subject of antivirals effectiveness and AD, and observational case-control studies and observational cohort studies regarding AD diagnosis (using clinical and/or histological methods) and HSV-1 detection (using molecular biology or immunohistochemical techniques). A total of 23 case-control and 3 cohort studies met the predetermined inclusion criteria. The results showed that AD was associated with HSV-1 in 22 of the 26 included studies, with most of them confirming that herpes infection is more prevalent in AD patients, when compared to control patients. A possible link between HSV-1 and AD was discussed and many different interpretations and hypothesis were considered. Evidence from observational studies suggests a possible relationship between the two conditions, but the role of HSV-1 infection in the pathogenesis of AD is not completely understood yet. Well-designed and large clinical trials are necessary to endorse this hypothesis and to consider the use of antiviral drugs as a potential alternative for prevention or reduction in the progression rate of AD in the future.

Highlights

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by a progressive impairment in memory, cognitive performance, daily function and independence [1]
Several studies indicate that human herpes simplex virus type 1 (HSV-1) infection may play a role in the development of Alzheimer’s disease
It was possible to correlate the occurrence of an association between HSV 1 infection and the presence of AD in 22 of the 26 selected studies, in which, infection was more frequent among patients with AD than among controls

Summary

Introduction

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by a progressive impairment in memory, cognitive performance, daily function and independence [1]. The etiopathogenesis of AD remains unclear, but a combination of environmental and genetic factors is believed to be involved in the development of the disease [5]. It is suspected that some infections could contribute to the development of the disease through the interaction between pathogens and genetic/immunologic factors and initiate neuropathological changes [4]. In this context, several studies indicate that human herpes simplex virus type 1 (HSV-1) infection may play a role in the development of Alzheimer’s disease

Objectives

Methods

Results

Conclusion