Research has shown that there is a gut-brain connection with indirect chemical signaling and communication. Now, an animal study has found much more direct interaction that could strengthen the gut-brain connection.
Mice on a high-fat diet had weaker gut barriers, and bacteria could reach the brain without ever entering the blood system, using the vagus nerve as a shortcut. When mice were on a high-fat diet, not only were their microbiomes altered, their guts were also more permeable. When the mice reverted to a normal diet, the bacteria left their brains. They were able to “clean” the mice’s brains by switching them to a healthier diet.
The mice in the study were germ-free to begin with and fed a diet similar to the Western diet. It was 45 percent carbs and 35 percent fat for nine days. Similar diets cause “leaky gut” in humans. In the mice, the intestinal barriers started to break down.
We know that the gut-brain connection is a two-way connection — they impact each other. This new study deepens the link between gut health and neurodegenerative concerns like dementia and Parkinson’s. However, it does not show that gut microbes directly cause neurological problems.
In mice models of Alzheimer’s, Parkinson’s and autism, the mice had the bacteria in their brains without any dietary changes. That strengthens the researchers’ belief in the gut-brain connection in neurological health.
The researchers said that this shows how much of an impact the gut has on health. “It suggests that the development of neurological conditions may be initiated in the gut,” said co-principal investigator Dr. David Weiss, of Emory Univ. “This may shift the focus of new interventions for brain conditions with the gut as the new target of the therapy. That potential anatomical shift of the target could have an unbelievable impact on how people with neurological conditions benefit from therapies.”
Animal research is not the same as a human trial. We cannot draw final conclusions from the work. However, it can give researchers a clearer idea of what to look for. We know that the Western diet damages the human gut and makes it more permeable. Seeing it do the same thing in mice and learning that bacteria can use that as a backdoor to the brain means it may also happen in humans. Researchers can now hone in more intensely on their questions. If the research has the same results in humans, it is comforting to know that the results were reversible. When the mice ate a healthier diet, their guts became stronger, and the bacteria vanished from their brains.
