Role of Microbes in Alzheimer’s Disease Demands Research and Testing, Scientists Say in Editorial

An editorial by a large number of senior Alzheimer’s researchers urges the scientific community to take a serious look at evidence pointing to the contribution of microbes in the development of Alzheimer’s disease – and calling for more clinical research.

Published online in the Journal of Alzheimer’s Disease by 31 international scientists, the editorial suggests that certain microorganisms — a common virus and two specific types of bacteria — are major causes of a large proportion of all Alzheimer’s cases.

The editorial summarizes extensive published research showing that microbes are likely implicated in dementia, and contribute to the buildup of amyloid beta. This body of work has been dismissed as controversial and largely ignored by the scientific community. As a result, proposals for funding relevant clinical trials have been continuously refused, hindering research. More than 400 clinical Alzheimer’s trials investigating other concepts, however, were funded and returned disappointing results over the past decade.

Opposition to new research findings is likely as old as science itself. Similar opposition was voiced when researchers proposed that viruses might cause certain cancers, or that bacteria can cause stomach ulcers — concepts that were proved valid and are mainstream today, allowing for more effective treatments of these conditions. Likewise, clinical trials of antimicrobial drugs in patients with Alzheimer’s disease could provide a clearer picture of the potential role microbes play in the development of dementia.

Professor Douglas Kell at the University of Manchester’s School of Chemistry and Manchester Institute of Biotechnology contributed to the editorial. He noted that supposedly sterile blood has been observed to contain dormant microbes — a finding with long-reaching implications for blood transfusions.

“We are saying there is incontrovertible evidence that Alzheimer’s Disease has a dormant microbial component, and that this can be woken up by iron dysregulation. Removing this iron will slow down or prevent cognitive degeneration – we can’t keep ignoring all of the evidence,” Professor Kell said in a press release.

Professor Resia Pretorius at the University of Pretoria, a co-author, added: “The microbial presence in blood may also play a fundamental role as causative agent of systemic inflammation, which is a characteristic of Alzheimer’s disease — particularly, the bacterial cell wall component and endotoxin, lipopolysaccharide. Furthermore, there is ample evidence that this can cause neuroinflammation and amyloid-β plaque formation.”

Dr. James Pickett, head of Research at Britain’s Alzheimer’s Society, commented on the editorial in a statement online: “A large number of different microbes including viruses, bacteria and fungi have been found in the brains of older people — but there do appear to be more of them in the brains of people who have died with Alzheimer’s disease. While these observations are interesting and warrant further research, there is currently insufficient evidence to tell us that microbes are responsible for causing Alzheimer’s disease in the vast majority of cases. We would like to reassure people that there remains no convincing evidence that Alzheimer’s disease is contagious or can be passed from person to person like a virus.”

“Given the enormous global impact of dementia, there is intense interest from the research community to understand all the potential contributing factors. We welcome research that explores all possible avenues and have committed £100 million over the next decade to more fully understand the causes of dementia and to improve diagnosis, treatment and prevention of the condition,” Dr. Pickett said.

According to the editorial, research into potential microbial causes of Alzheimer’s disease will likely have implications for the future treatment of Parkinson’s and other progressive neurological diseases.