Summary: Recent research suggests that the brain may host its own microbiome, challenging the long-held belief that it is a sterile organ. Studies have discovered bacterial and fungal genetic material in brain tissue, particularly in people with Alzheimer’s disease.
The brain microbiome could be linked to diseases, providing new treatment possibilities. However, much is still unknown about how microbes enter and affect the brain.
Highlights:
- The brain may have its own microbiome, similar to the gut microbiome.
- Studies have found more bacteria and fungi in the brains of Alzheimer’s patients.
- Understanding the brain microbiome could lead to new treatments for brain diseases.
Source: The conversation
The microbes that live in your gut are having their moment in the sun. Even if you haven’t been following the research, you can’t miss the hundreds of ads for probiotics and prebiotics, intended to sell you products to keep your microbiome healthy.
Other microbiomes have also been discovered recently and also play an important role in your health. Your mouth, nasal cavity, skin, and scalp all have their own microbiome. Some have even proposed that the brain has its own microbiome.
The idea that the brain has a microbiome was first suggested in 2013, but it hasn’t gotten much attention. This is primarily due to the long-held belief that the brain is a sterile organ, protected from the rest of the body and the harmful agents that circulate in our blood.
It is also difficult to confirm the presence of microbes. The techniques used rely on the analysis of foreign genetic material, which can be unreliable because these DNA fragments could be the result of contamination.
In healthy brains, the “blood-brain barrier” protects the brain from blood and any harmful substances dissolved in it. However, during aging and in neurological diseases such as Alzheimer’s disease, this protective barrier becomes unstable and blood and harmful substances can enter the brain.
This can cause illness and make damage that has already occurred even worse. Likewise, the immune system becomes less effective as we age. It could also contribute to the presence of microorganisms throughout the body that could have been eliminated by the immune cells of younger people.
The 2013 study mentioned earlier aimed to determine whether microbes could invade the brains of people with HIV/AIDS. They compared brain tissue from people with HIV/AIDS to brain tissue from people without HIV/AIDS.
Surprisingly, they found non-human genetic material indicating the presence of more than 173 types of bacteria and phages (viruses that infect bacteria) in the brains studied.
All of the brain samples tested, taken from patients with different brain disorders, not just people with HIV/AIDS, appeared to contain bacterial genetic material.
A group of researchers from the University of Edinburgh compared the brains of people with Alzheimer’s disease to those of healthy brains. The brains of people with Alzheimer’s disease harbored more bacteria and fungi than those of healthy people. But they found several species of fungi, bacteria and other microorganisms in healthy brains.
The human brain microbiome has been shown to be a subset (approximately 20%) of the gut microbiome. Although more bacteria were found in the brains of people with Alzheimer’s disease, researchers were unable to find a profile of certain bacteria that was only found in diseased brains.
However, this study has not yet been peer-reviewed and published in a scientific journal, so the results should be treated with some caution.
Questions remain
We still don’t have a clear idea of how microorganisms can enter the brain.
One theory proposes that diseases of the mouth, such as gum disease or tooth decay, cause tissue damage that then allows bacteria normally found in the mouth to travel to the brain via the nervous system.
Interestingly, oral bacteria are capable of producing amyloid proteins. It is an important protein in normal brain function, but abnormal clumps of it are found in people with Alzheimer’s disease. Bacteria from the mouth could then invade the brain and cause disease.
The brain microbiome is a recent and exciting idea. With advances in molecular techniques, such as new sequencing technology that helps us understand the genetic code of microorganisms, more microbes will be discovered throughout the body.
It appears that, as with the gut microbiome, a disruption in the balance of microbes present can lead to disease. Nevertheless, this discovery opens the door to potential new therapeutic options for brain diseases such as Alzheimer’s disease.
However, several questions remain. The gut microbiome differs between people, as does the brain microbiome. A comprehensive map of the microbes residing in a healthy brain has not yet been achieved. And we don’t know what controls which microorganisms live in our brains and how they can get in in the first place.
About this research news in neuroscience and microbiome
Author: Janosch Heller
Source: The conversation
Contact: Janosch Heller – The conversation
Picture: Image is credited to Neuroscience News
News Source : neurosciencenews.com
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