Have you ever experienced an upset stomach from nerves before an exam? Has your mood risen after a good meal?
The concept of the gut-brain axis has been studied by the scientific community since the 19th century. Scientists of the stature of Darwin, Beaumont or Cannon studied this connection, which would work in a direct and bidirectional way.
What these scientists discovered was surprising: communication between the gut microbiome and the brain takes place through multiple pathways including the vagus nerve, neuropeptides secreted from the gut, cytokines, tryptophan, and fermentation products of microbial metabolism such as acids. short chain fatty. The brain, for its part, modulates intestinal microbial responses through the secretion of signaling molecules into the intestinal interior.
From all this it has been deduced that the microbiota could play an important role in the functioning of the central nervous system, both when the person is healthy and when they are sick.
The intestinal microbiota has recently become a favorite object of study. An interesting new line of research studies how the microbiota could influence the development of psychiatric and neurological disorders related to stress such as anxiety and depression or behavioral disorders such as autism.
Therefore, could psychobiotics be indicated to improve the symptoms of behavioral disorders, such as autism? Next, we are going to review some of the scientific literature on this line of research.
Studies exploring the relationship between the microbiota and behavioral disorders
A group of scientists from McMaster University in Canada studied in 2011 what could happen when the microbiota was profoundly altered, known as dysbiosis. A group of mice that were shy had their microbiota altered by giving them a potent dose of antibiotics. Well, these mice, who were previously shy, after the antibiotic bomb became adventurous. In short, a change in their microbiota radically modified their behavior.
Two years later, in 2013, Timothy G. Dinan, Professor of Psychiatry and Director of the Department of Psychiatry at University College in Cork (Ireland), Catherine Stanton, nutritionist and John F. Cryan, neuroscientist, coined a new concept: “psychobiotic ”. The psychobiotic was defined as a “living organism that, when consumed in adequate amounts, produces a benefit in the health of patients with mental disorders”.
But let’s not think that all probiotics are capable of producing these effects. As the FAO / WHO said in 2002, it is a class of probiotics capable of producing and releasing neuroactive substances (GABA, serotonin) that act through the brain-intestine axis.
In a recent meta-analysis that included 254 patients, it was found that children with ASD had lower percentages of Akkermansia, Bacteroides, Bifidobacterium and Parabacteroides and higher percentages of Faecalibacterium when compared to controls. Furthermore, a decrease in bacterial diversity has been observed in autistic children.
In another study, this time carried out by Elaine Hsiao’s group, at the University of California, in MIA mice (with autism) it was observed that the dysbiosis caused generated metabolites (4 ethyl-phenyl-sulfate) detectable in serum, which are related to the symptoms of the disease. It has been shown that this can be corrected with the administration of the bacterium Bacteroides fragilis improving behavior problems.
In a recent randomized, double-blind, placebo-controlled study conducted in Taiwan by Liu et al, Lactobacillus plantarum PS128 was administered for 4 weeks in 72 children aged 7 to 15 years with ASD. The results showed that the probiotic strain significantly improved various behavioral symptoms compared to the placebo group . Despite the success obtained, the authors are cautious and state that more studies are needed to better clarify the effects of Lactobacillus plantarum PS128, especially in younger children with ASD who present greater symptoms.
Autism Spectrum Disorders and Probiotics
The origin of autism spectrum disorders (ASD) is still unknown. It is believed to occur in the prenatal stage, at which time important neurological connections are formed. Factors such as infections in the mother during pregnancy have also been involved, but nothing is conclusive. What has been seen in different studies is that the microbiota of people with ASD generally contains a higher content of toxin-producing clostridial groups and less of the Prevotella genus. In addition, a lower proportion of beneficial bacteria such as bifidobacteria and eubacteria have been found.
The probiotic NeuraxBiotic Spectrum could help improve the microbiota of children with ASD, ensuring the safe implantation of the bacterial strain Lactobacillus plantarum PS128 in the stomach and colonization of the intestine. Regarding the improvement in the behavior of these patients, Dr. Guillermo Álvarez, president of the Spanish Society of Microbiota, Probiotics and Prebiotics (SEMIPYP) affirms: “Although we must be cautious and more controlled and more rigorous clinical trials are necessary scientifically, we know that children with digestive disorders by improving these using probiotics, secondarily also do it in the sphere of behavior.
“There is strong evidence that bidirectional communication between the intestine and the brain involves neurological, metabolic, hormonal and immunological signaling pathways, and that the alteration in these systems can favor the appearance of psychiatric disorders or behavioral disorders, among other clinical manifestations.
As I have already pointed out previously, most of this evidence comes from preclinical research , carried out in laboratory animals, and the results cannot be directly extrapolated to humans ”, says Dr. Manuel Martín Carrasco, vice president of the Spanish Society of Pisquiatry.
More information: NeuraxBiotic Spectrum
