Gut MicrobiomeS Impact on Brain Function: A New Understanding of Primate Evolution and Neurological Disorders
EVANSTON, Ill. – A groundbreaking study from Northwestern University reveals a direct link between teh gut microbiome and brain function, offering new insights into primate evolution and potential implications for neurological disorders. The research, published in the Proceedings of the National Academy of Sciences (PNAS) on January 5, 2024, demonstrates that differences in gut microbial composition can alter brain activity and gene expression.
The Link between Gut Microbes and brain Evolution
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Humans possess the largest relative brain size among primates, but the metabolic demands of such a complex organ have long been a subject of scientific inquiry. This new study provides the frist empirical evidence showing how the gut microbiome directly influences brain function differences across primate species.
“Our study shows that microbes are acting on traits that are relevant to our understanding of evolution, and particularly the evolution of human brains,” said Katie Amato, associate professor of biological anthropology and principal investigator of the study. Previous research from Amato’s lab established that gut microbes from larger-brained primates generate more metabolic energy in host mice. This new study extends those findings by examining the direct impact of these microbial differences on brain function.
How the Study Was Conducted
Researchers transplanted gut microbes from two large-brain primate species (humans and squirrel monkeys) and one small-brain primate species (macaques) into germ-free mice. After eight weeks, they observed meaningful differences in brain activity between the groups.
Mice harboring microbes from large-brain primates exhibited increased expression of genes associated with energy production and synaptic plasticity – the brain’s ability to strengthen connections between neurons, crucial for learning and memory. Conversely, mice with microbes from smaller-brain primates showed reduced expression of these processes.
“What was super captivating is we were able to compare data we had from the brains of the host mice with data from actual macaque and human brains, and to our surprise, manny of the patterns we saw in brain gene expression of the mice were the same patterns seen in the actual primates themselves,” Amato said. “In other words, we were able to make the brains of mice look like the brains of the actual primates the microbes came from.”
Implications for Neurological Disorders
The study also revealed a surprising correlation between the gut microbes of smaller-brained primates and gene expression patterns associated with neurodevelopmental disorders. Specifically, the researchers observed patterns linked to ADHD,schizophrenia, bipolar disorder, and autism spectrum disorder.
While previous research has suggested a correlation between gut microbiome composition and these conditions, this study provides evidence for a potential causal link. “This study provides more evidence that microbes may causally contribute to these disorders -specifically, the gut microbiome is shaping brain function during advancement,” Amato explained. “Based on our findings, we can speculate that if the human brain is exposed to the actions of the ‘wrong’ microbes, its development will change, and we will see symptoms of these disorders, i.e., if you don’t get exposed to the ‘right’ human microbes in early life, your brain will work differently, and this may lead to symptoms of these conditions.”
Future Research and Clinical Implications
Amato’s team plans to further investigate the mechanisms by which gut microbes influence brain development and function. This includes exploring whether manipulating the gut microbiome could offer therapeutic interventions for neurodevelopmental disorders.
“It’s interesting to think about brain development in species and individuals and investigating whether we can look at cross-sectional, cross-species differences in patterns and discover rules for the way microbes are interacting with the brain, and whether the rules can be translated into development as well,” Amato stated.
Key Takeaways
- The gut microbiome directly impacts brain function and gene expression.
- Microbial differences between primate species correlate with differences in brain activity.
- Gut microbes from smaller-brained primates are associated with gene expression patterns linked to neurodevelopmental disorders.
- This research suggests a potential causal role of the gut microbiome in the development of these disorders.
“Primate gut microbiota induce evolutionarily salient changes in mouse neurodevelopment” was published by the Proceedings of the National Academy of Sciences on January 5, 2024.