Your “gut feeling” could be causing your anxiety.
If you had to guess the organ that has undue influence on your emotions, your mood, what would you guess? The brain? Sure, but what else? The heart- that mythological seat of the soul? Not quite. Ever bothered to consider the poor gut? Well yeah, this cranky guy is the one behind all those hours of endless drama and tantrums (Uh, specifically it’s the trillions of bacteria—the microbiota—that live in your gut though).
For some time now, doctors have observed that patients who have gastrointestinal diseases also suffer from depression and anxiety. In a normal digestive tract, trillions of bacteria are constantly at work to keep your body healthy. They protect against infection, provide nutrition to cells in the digestive system and convert food to energy. However, when the bacteria’s normal functions are disrupted, it can also disrupt your mood and behavior, both of which can lead to anxiety. This link was confirmed in a new study by scientists at the APC Microbiome Institute at University College Cork.
The study specifically addresses the communication between the brain and gut and how it can be influenced by the gastrointestinal microbiota. The discovery relates to gene
regulators called microRNAs – their dysfunction in the brain is believed to be a key factor in anxiety-type illnesses and depression.miRNAs are small nucleotide sequences and have recently emerged as a new class of gene-expression regulators because miRNA-expression levels are altered in patients suffering from depression and anxiety and in animal models of these disorders. The possibility of using miRNAs for the treatment of psychiatric disorders is thus under consideration.
The research demonstrates in animal models that the trillions of bacteria within the gastrointestinal tract can influence microRNAs (miRNAs) in areas of the brain, such as the amygdala and prefrontal cortex that are involved in anxiety and fear-related behaviours.
These miRNAs, which can regulate gene expression, may then act ‘upstream’ of our gut microbes to fine tune physiological processes that are fundamental to the functioning of the central nervous system. Dr Gerard Clarke and Professor John F. Cryan, along with their PhD student Alan Hoban used mice and rats that either had no gut microbes at all or depleted gut microbes.
They later demonstrated through this that the miRNA expression profile is dysregulated in the amygdala and prefrontal cortex brain regions. The amygdala is responsible for the emotional response to fear stimuli, while the prefrontal cortex is the key to higher cognitive functions and in the expression of anxiety and social behaviours.
The team was able to show that some of the miRNA alterations seen could be rescued by adding back the gut microbiome later in life.
This is the first time that the gut microbiome has been so clearly implicated in miRNA expression in both the amygdala and the prefrontal cortex.
The study gives a better understanding of the factors that control miRNA expression and suggests that some of the hurdles impeding the exploitation of their therapeutic potential could be cleared by instead targeting the gut microbiome. Further, it seems to go in hand with an increasing body of the work over the past decade that highlights the influence of our gut bacteria on brain function and behaviour.
It suggests some of the hurdles that stand in the way of exploiting the therapeutic potential of miRNAs could be cleared by instead targeting the microbiome and possibly by consuming “psychobiotics”. These are probiotics containing live bacteria, or prebiotics (foods which support probiotics), with mental health benefits.
“The psychobiotic revolution is coming,” Prof Cryan declared, “and we can now add miRNAs to an expanding range of therapeutic targets in the brain that can potentially be controlled by manipulating the bacteria in our gastrointestinal tract.”
Targeting gut microbes by using psychobiotics “is an appealing prospect”, Dr Clarke added, but more work is needed “before the full benefits of this exciting work can be moved into a clinical setting”.
