Bridging Minds and Microbes: Deciphering the link between Gut Microbiome and Neurological Health
This article explores the complex interaction between the gut microbiome and health, delving into its role in neurological disorders such as Alzheimer’s disease. It highlights the research potential of interventions targeting the gut microbiota to mitigate diseases and promote overall well-being.
Imagine a bustling city on a workday morning with people rushing to attend work, the streets alive with the various modes of transportation, and the hard work of various professions unfolding before your eyes. Likewise, the vast network of bacteria in our bodies can be compared to a busy metropolis where various bacterial communities, such as our gut microbiota, internally promote seamless operations and influence our overall health.
A famous case study investigating the impact of gut microbes on obesity and metabolic traits in mice demonstrates the significance of how our gut health contributes to our overall well-being. Conducted by researchers at Washington University, the study involved genetically identical mice and two human adult twin donors. The lab-grown adult mice were raised in a germ-free environment and fed the same amount of mouse “chow”, which was low in fat, to ensure their gut microbiome was devoid of external microorganisms. Fecal samples were collected from each human twin. One of the twins was lean and the other was obese, despite their identical genetics and similar environment. Researchers performed Fecal Microbiota Transplantation (FMT) to transfer gut microbes from the human twins to the gnotobiotic mice to determine whether differences in the composition of the gut microbiome contributed to obesity. The results showed that the recipient mice developed characteristics resembling their respective donor twin; the mouse with the gut microbiome of the obese twin began to display signs of obesity, and the mice with fecal samples from the lean twin stayed lean, both being on the same diet. This shocking result suggests a significant role of our gut microbiota in metabolism and body fat composition. These insights into the potential contribution of the gut microbiota to physiological disorders highlights the importance of understanding how the microbiome impacts our health.
Considering this study, one may wonder: does our gut health solely influence metabolic diseases such as obesity, or does its impact extend beyond that?
Every living being has a unique set of microbiota, initially determined by our DNA. Our exposure to these microbes begins at the vaginal canal during birth– later, through the mother’s breast milk and diet. Our diet and environment are the biggest influences on our gut microbiome and strongly determine our health. Our bodies consist of both helpful and harmful microbes, and an imbalance could increase the likelihood for disease. This intricate interplay between our gut microbiota and overall health is further explained by the Gut-Brain axis.
The Gut-Brain axis, a bidirectional communication network connecting the central nervous system with the enteric nervous system, offers a deeper understanding of the impact of altered gut microbiota on gastrointestinal and neurological disorders– including Alzheimer’s, Parkinson’s, Multiple Sclerosis, and Autism. This complex system enables the gut and the brain to communicate via various signaling pathways including neural, hormonal, immune, and microbial signaling.
There are several ongoing studies to determine the link between the gut microbiota and various neurological diseases. Alzheimer’s is a progressive and incurable neurodegenerative disease that impacts memory and cognitive functions, impairing one’s ability to perform daily activities. It is characterized by the accumulation of beta-amyloid plaques and tau tangle protein deposits in the brain, leading to damage of neuron function and eventually, death. A study led by Gautam Dantas and Beau Ances at Washington University, investigates the differences in gut microbiomes of Alzheimer’s patients and individuals with normal cognition. They analyzed the gut microbiomes of 164 healthy volunteers aged 68 to 94 and in the sample, 49 showed early signs of Alzheimers. The researchers found distinct differences in the gut microbiome of volunteers with the early signs — in fact, their microbiomes were similar to those with existing Alzheimers, than those with normal cognition. The microbiome changes were also correlated with differing levels of beta-amyloid and tau proteins in the brain, which are associated with Alzheimer’s. However, there were no distinct differences in diets amongst all of the volunteers. This discovery leads to the question of, do the change in microbes lead to change in protein levels in the brain or vice versa? The team is conducting a long-term study with the same volunteers to see if administering beneficial bacteria could decrease the harmful effects of Alzheimer’s or potentially stop it from advancing.
Another exciting study conducted by researchers at the University of California, Davis shows how a ketogenic diet significantly delays Alzheimer’s related memory loss in mice. The study details how a molecule called beta-hydroxybutyrate, or BHB, increases seven-fold on this diet and plays a major role in delaying memory loss. Emerging research suggests that the ketogenic diet, which elevates BHB levels, may have implications for gut microbiome composition and function.
It is important to note that Alzheimer’s can be caused by a number of factors such as genetics, age, oxidative stress and lifestyle. Ongoing research aims to determine if these gut microbiome differences could be a potential cause or giveaway of Alzheimer’s, opening avenues for future research about interventions such as probiotics or fecal transplants, to slow disease progression.
Maintaining a healthy gut microbiome generally refers to having a diverse composition of microorganisms in the gastrointestinal tract and this could be maintained through a balanced and healthy diet, adequate sleep, exercise, stress management, etc. These methods could contribute positively for better health overall and potentially reduce risk of various neurodegenerative diseases such as Alzheimer’s. It is important to acknowledge that much research needs to be done to gain full understanding of the gut-brain axis and its contribution to Alzheimer’s.
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