Human brains, presumably mammal brains in general, do not have microbiomes. If they did, they would look like Donald Sutherland in that movie.
Also, a microbiome is not the same thing as an infection. A microbiome is a mutualistic (or similar) ecology of multi-celled organisms or part thereof (like, your gut or your eyeballs or something) and microbes, probably including multiple species or varieties. Brains do not have that. If there are microbes in the brain it is an infection.
There is some interesting research out there possibly linking infections and Alzheimers. It is unfortunately being couched in terms of microbiomes. Why? Mainly because science reporters are generally not scientists, so they don’t bump on errors like that? Maybe. But in this case, there seems to be an actual project that claims to be actually mapping out the brain’s microbiome, including “helpful” organisms.
Neurodegenerative diseases (i.e. Alzheimer’s and Huntington’s) often involves the formation of aggregates of proteins in a patients’ brain, correlated with the process of degeneration. Some of these proteins are unique to the specific disease and others are commonly found in healthy individuals but also occur intertwined with the disease-linked types. Until now, these “common proteins” were thought to be an effect of sampling the tissues and were ignored as background. A new paper out today in PLoS Biology suggests, however, that these protein aggregates may be linked to aging. The main reason to think this is that they are found more widely (in a phyologenetic sense) than previously expected … having been isolated in Caenorhabditis elegans, the laboratory classic roundworm model. And, in C. elegans, they seem to be linked to aging. Continue reading Aggregate Proteins and Brain Aging: Interesting new findings→