The Microbiome of the Brain
If you’ve been listening to our show, which has been around for nearly two decades, you’ve heard us discuss the importance of the microbiome. This is the collection of bacteria, fungi, and other microbes that live on and in our bodies. And they outnumber our cells.
Now we know they’re also inside our brains. For years scientists held that the brain was sterile and devoid of microbes. We have the blood-brain barrier as an effective “wall” against microbes. However, researchers report finding bacteria and fungi in people’s brains. And there’s evidence that microbial brain infections may lead to dementia and Alzheimer’s.
For example, oral bacteria have been found in the spinal fluid and brains of Alzheimer’s patients. One theory is the disruption of the oral microbiome leads to inflammation that could play a part in how oral bacteria travel to the brain. In another case, a patient diagnosed with Alzheimer’s also had a fungal infection. After he was treated with an antimicrobial, his dementia symptoms went away.
Scientists have found the genetic material of nearly 200 different bacteria and viruses in the brains of people with neurological diseases. These people also had greater numbers of microbes in their brains. It’s important to note that there are people with neurologic diseases where no microbes were found. But if the link is credible, could treating dementia be as easy as taking antimicrobials?
More Information
The role of microbiome-host interactions in the development of Alzheimer´s disease
Alzheimer`s disease (AD) is the most prevalent cause of dementia. It is often assumed that AD is caused by an aggregation of extracellular beta-amyloid and intracellular tau-protein, supported by a recent study showing reduced brain amyloid levels and reduced cognitive decline under treatment with a beta-amyloid-binding antibody.
The brain microbiome: could understanding it help prevent dementia?
Long thought to be sterile, our brains are now believed to harbour all sorts of micro-organisms, from bacteria to fungi. How big a part do they play in Alzheimer’s and similar diseases?
The Role of Microbiome in Brain Development and Neurodegenerative Diseases
Hundreds of billions of commensal microorganisms live in and on our bodies, most of which colonize the gut shortly after birth and stay there for the rest of our lives. In animal models, bidirectional communications between the central nervous system and gut microbiota (Gut-Brain Axis) have been extensively studied, and it is clear that changes in microbiota composition play a vital role in the pathogenesis of various neurodevelopmental and neurodegenerative disorders, such as Autism Spectrum Disorder, Alzheimer's disease, Parkinson's disease, Multiple Sclerosis, Amyotrophic Lateral Sclerosis, anxiety, stress, and so on.