Interest in the mysterious connection between gut microbes and the brain has exploded in the scientific world. Researchers are finding that the community of numerous species of bacteria called the microbiome can play a key role in autism, depression, anxiety and cognitive function.
One Link to Autism?
For decades, it has been known that approximately 75 percent of people with autism have some kind of gastrointestinal disorder. This awareness led scientists to explore the relationship between autism and gut bacteria. They discovered the microbiome of autistic people differs markedly from that of people who don’t have this disorder.
One of the specific findings was that the population of the microbe Bacteroides fragilis is smaller in some children with autism. In a 2013 study published in Cell, mice with autistic-like symptoms that were fed B. fragilis experienced improvements in their disorder. They because less anxious, had less repetitive behavior and communicated better with other mice.
The Association with Anxiety and Depression
A further delve into the connection between the mind and the gut gets even more interesting, revealing links with anxiety and depression. A 2010 study published in Neuroscience found bifodobacterium reduced signs of depression in rats. In addition, a 2011 experiment published in the Proceedings of the National Academy of Sciences found lactobacillus alleviated symptoms of depression and anxiety in mice.
While the aforementioned studies were conducted on animals, a small 2015 investigation published in Psychopharmacology discovered the microbiome affects humans in the same way.
A group of 45 volunteers consumed a prebiotic, which is a group of carbohydrates that stimulate the growth of beneficial gut bacteria. In this case, the prebiotic boosted numbers of lactobacillus and bifidobacterium, an advantage that resulted in emotionally healthful effects. The participants had lower levels of the stress hormone cortisol and showed fewer signs of depression.
The Connection with Cognition
Aside from the links with psychological disorders, the microbiome is also connected to cognitive function.
A recent study published in Neuroscience found that harmful effects to gut bacteria led to a significant decrease in cognitive flexibility, a term that denotes the brain’s ability to switch gears in thinking or to adapt to changes in the environment.
Researchers found that the consumption of a high-fat or high-sugar diet produced a greater percentage of “bad” gut bacteria and a lower percentage of the healthful strains of bacteria. These changes correlated with poor performance on cognitive tests, indicating the healthful strains are needed to be able to think in an optimal way.
How Does Gut Bacteria Affect the Brain?
Most scientists believe the therapeutic effect of the microbiome is due to several benefits. Gut microbes generate dopamine, serotonin and gamma-aminobutyric acid (GABA), which are neurotransmitters that promote emotional health.
Some bacteria activate the vagus nerve, the primary neural link between the gut and the brain.
Furthermore, the microbiome is part of the immune system, a part of the body that has an impact on mood.
How Could the Benefits of Gut Bacteria Be Used?
Probiotics are strains of healthful bacteria that enhance the microbiome. Is it conceivable that these agents could be used someday in place of psychiatric drugs like Valium and Prozac? According to some scientists, it’s a possibility.
Antidepressants like Prozac act to increase levels of serotonin, and antianxiety drugs like Valium mimic the effects of GABA.
Considering that the microbiome produces the same benefits of psychiatric drugs but lacks the serious side effects, it has great potential. In the meantime, it’s a good idea to incorporate probiotic foods like yogurt and buttermilk in the diet.
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