Bacterial Infection and Alzheimer's Disease: A Meta-Analysis

Abstract

The possibility of an infectious etiology for Alzheimer's disease (AD) has been repeatedly postulated over the past three decades. We provide the first meta-analysis to address the relationship between bacterial infection and AD. Studies examining the association between AD and spirochetal bacteria or Chlamydophila pneumoniae (Cpn) were identified through a systematic search of the databases MEDLINE, EMBASE, PubMed, and Google Scholar. Data combined from 25 relevant, primarily case-control studies demonstrated a statistically significant association between AD and detectable evidence of infection of either bacterial group. We found over a ten-fold increased occurrence of AD when there is detectable evidence of spirochetal infection (OR: 10.61; 95% CI: 3.38-33.29) and over a four-fold increased occurrence of AD in a conservative risk estimate (OR: 4.45; 95% CI: 2.33-8.52). We found over a five-fold increased occurrence of AD with Cpn infection (OR: 5.66; 95% CI: 1.83-17.51). This study shows a strongly positive association between bacterial infection and AD. Further detailed investigation of the role of bacterial infection is warranted.

Neuroinflammation and Infection: Molecular Mechanisms Associated with Dysfunction of Neurovascular Unit

“…The late-age development of AD is purposely due to the activity of infections that initially occurred during the childhood (Khachaturian, 1985). In AD, the association of chronic infections with progressive neurodegeneration was clearly demonstrated by recent studies (Maheshwari and Eslick, 2015). Chronic spirochetal infections can induce β-amyloid accumulation in the brain, cause dementia and reproduce the clinical, pathological, and biological hallmarks of AD (Miklossy, 2011).…”

“…Chronic spirochetal infections can induce β-amyloid accumulation in the brain, cause dementia and reproduce the clinical, pathological, and biological hallmarks of AD (Miklossy, 2011). Thus, infections by spirochete bacteria have significant potentials in developing AD (De Chiara et al, 2012; Hill et al, 2014; Maheshwari and Eslick, 2015). Different species of spirochetes, such as T. socranskii, T. pectinovorum, T. denticola, T. maltophilum, T. medium, T. amylovorum , and Borrelia burgdorferi (causing Lyme disease) are found in the brain of AD patients (Burgdorfer et al, 1982; Riviere et al, 2002).…”

The human-specificCASP4gene product contributes to Alzheimer-related synaptic and behavioural deficits

“…Other studies have shown, although inconsistently, the presence of infectious pathogens in the brains of AD (85,86). These pathogens include virus, fungi and LPS-bearing gramnegative bacteria such as Chlamydophila pneumoniae, spirochetes, and Porphyromonas gingivalis.…”

Spirochetal Lipoproteins and Immune Evasion

“…Better understanding of spirochetal lipoproteins and their regulatory mechanisms may provide insight into clinical outcomes arising from spirochetal infections. For example, spirochetal infections may increase the risk of Alzheimer’s disease (43). …”