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Review
. 2020 Jul 29;10(3):74.
doi: 10.3390/jpm10030074.

The Viral Hypothesis in Alzheimer's Disease: Novel Insights and Pathogen-Based Biomarkers

Sean X Naughton  1 , Urdhva Raval  1 , Giulio M Pasinetti  1   2
Affiliations
Review

The Viral Hypothesis in Alzheimer's Disease: Novel Insights and Pathogen-Based Biomarkers

Sean X Naughton et al. J Pers Med. .

Abstract

Early diagnosis of Alzheimer's disease (AD) and the identification of significant risk factors are necessary to better understand disease progression, and to develop intervention-based therapies prior to significant neurodegeneration. There is thus a critical need to establish biomarkers which can predict the risk of developing AD before the onset of cognitive decline. A number of studies have indicated that exposure to various microbial pathogens can accelerate AD pathology. Additionally, several studies have indicated that amyloid-β possess antimicrobial properties and may act in response to infection as a part of the innate immune system. These findings have led some to speculate that certain types of infections may play a significant role in AD pathogenesis. In this review, we will provide an overview of studies which suggest pathogen involvement in AD. Additionally, we will discuss a number of pathogen-associated biomarkers which may be effective in establishing AD risk. Infections that increase the risk of AD represent a modifiable risk factor which can be treated with therapeutic intervention. Pathogen-based biomarkers may thus be a valuable tool for evaluating and decreasing AD risk across the population.

Keywords: Alzheimer’s disease; bacteria; dementia; virus.

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Conflict of interest statement

The authors declare no conflict of interest. Funding agencies had no role in the writing of this manuscript, or in the decision to publish.

Figures

Figure 1
Figure 1
Involvement of Pathogens in Alzheimer’s disease (AD). Pathogens such as viruses and bacteria can become entrapped by amyloid-β after entering the brain. Amyloid fibrils form in response to certain pathogens, and infection may play a role in accelerating AD pathology by stimulating inflammation and neurodegeneration.
Figure 2
Figure 2
Potential Role of Gut Bacteria in Neurodegeneration. Age-related changes in intestinal permeability and blood brain barrier integrity may allow for penetrance of gut bacteria into the brain and promote the formation of amyloid fibrils. Future studies should focus on the role of gut bacteria as a potential trigger to the amyloid cascade.
See this image and copyright information in PMC

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