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  • Max Lee

You Have Bacteria In Your Brain Right Now

Your body is home to around 40 trillion microorganisms that coexist with your cells, collectively known as your microbiome. That’s about as many non-human microorganisms as human cells in your body! Most people have heard about gut bacteria and seen products advertised as being beneficial for the health of your gut. Research has also uncovered the presence of different microbiomes in other organs, including the brain, lungs, skin, and mouth. These microbiomes have a significant impact on health and disease. Organ-specific microbiomes are now recognized as influencers of human genomics and overall health. Each organ's microbiome is unique, comprising bacteria, viruses, fungi, and other microorganisms adapted to their specific environment. For instance, the lung microbiome is distinctly oxygen-rich compared to the gut microbiome. Microbiomes can also induce epigenetic changes, which are modifications that affect gene activity without altering the DNA sequence. These changes can be triggered by microbial metabolites that act as signaling molecules, leading to the addition or removal of chemical groups on DNA or histones. Such modifications can influence inflammation, immune response, and even brain function. 

Emerging research suggests the existence of a brain microbiome, with implications for neurological health. Microorganisms or metabolites can cross the blood-brain barrier, potentially affecting gene expression in brain cells. Despite extensive research, the exact causes of Alzheimer's remain elusive, with genetic, environmental, and lifestyle factors all playing roles. Recently, the potential involvement of microorganisms in Alzheimer's pathogenesis has gained attention. Amyloid-beta, the protein that forms plaques in Alzheimer’s disease, has antimicrobial properties, suggesting it may be part of the brain’s innate immune defense. This hypothesis posits that amyloid-beta is produced in response to microbial invasion [1, 2]. This interaction is being explored in the context of neurodegenerative diseases, mental health disorders, and brain development. 

Exploration of organ-specific microbiomes creates new ways of understanding human health and disease. The relationships between microbiomes and genomics underscore the importance of considering microbial communities as components of the human body just like the human cells they coexist with. Advances in this field would lead to novel therapeutic strategies, personalized medicine approaches, and a deeper understanding of the mechanisms underlying diseases. The future of medicine will no doubt include microbiomes as a key player in genomic and overall health. 


[1] Gosztyla, M. L., Brothers, H. M., & Robinson, S. R. (2018). Alzheimer's Amyloid-β is 

an Antimicrobial Peptide: A Review of the Evidence. Journal of Alzheimer's 

disease: JAD, 62(4), 1495–1506.

[2] Kumar, D. K., Choi, S. H., Washicosky, K. J., Eimer, W. A., Tucker, S., Ghofrani, J., 

Lefkowitz, A., McColl, G., Goldstein, L. E., Tanzi, R. E., & Moir, R. D. (2016). 

Amyloid-β peptide protects against microbial infection in mouse and worm 

models of Alzheimer's disease. Science translational medicine, 8(340), 

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