A Collaborative Call to Arms
Thirty-one researchers on three continents have teamed up to call for more research into a potential microbiological cause of Alzheimer’s disease
Michael Schubert |
It’s unusual for a scientific proposition to garner so much support that researchers and clinicians from around the world come together to express it. But that’s exactly what happened recently in the Journal of Alzheimer’s Disease, where 31 specialists from locations as varied as Spain, Finland and the United States co-authored an editorial proposing microbes – specifically, herpes simplex virus 1 (HSV1), Chlamydophila pneumoniae and spirochetes – as the major cause of Alzheimer’s disease (1).
“We write to express our concern that one particular aspect of the disease has been neglected,” the authors said, referencing studies implicating HSV1 and bacterial agents in disease-related changes to the brain. The editorial includes evidence for an infectious component of Alzheimer’s disease, including the presence of microbes in the brain, colocalization of pathogen signatures with disease pathology, and the fact that APOE polymorphisms affect susceptibility to both Alzheimer’s and infectious diseases. The editorial also discusses evidence for causation (such as amyloid beta deposition observed after infecting cell cultures and mouse models with HSV1) and mechanism (such as polymorphisms in the human cholesterol 25-hydroxylase gene CH25H, which is selectively upregulated by infection and governs both amyloid beta deposition and Alzheimer’s disease susceptibility).
The proposed Alzheimer’s disease etiology involves the infectious agents’ remaining latent in the central nervous system until they are reactivated by the aging process and the decline of the immune system. Once active, they cause inflammation and neuronal damage that results in dysfunction, amyloid beta induction, and ultimately Alzheimer’s disease. But if this is indeed where the disease originates, what can be done? Because of the personal and public impact of Alzheimer’s, and because so many therapy trials have failed in recent years, the authors are calling for research into the role of infectious agents – both to uncover the cause of Alzheimer’s disease and to explore the potential benefits of antimicrobial therapies.
- RF Itzhaki et al., “Microbes and Alzheimer’s disease”, J Alzheimers Dis, [Epub ahead of print] (2016). PMID: 26967229.