The Gut and Mental Health: Are They Connected?

Medical experts have come to understand that the bacteria that lives in our digestive tract has an impact on our overall health, it is generally accepted that the balance and variety of these bacteria affect gastrointestinal conditions like IBS and Crohn’s Disease, as well as skin issues, obesity and diabetes.  But interestingly, more and more research is showing the apparent connection because our gut “health” and our mental health, as well as other conditions like Autism and Multiple Schlerosis.

Neuroscientists are beginning to better understand gut bacteria’s influence on the brain.  Correlations have been found between the composition of the gut microbiome and behavioral conditions, like autism, in research from the California Institute of Technology in Pasadena.   In a study, these researchers were able to show that the presence of certain bacteria could identify those more prone to depression and anxiety disorders.  According to Sarkis Mazmanian, a microbiologist at the California Institute of Technology, the immune system plays a part, as well as the vagus nerve, which connects the brain to the digestive tract.

A study, from the University College Cork in Ireland, found that mice born by caesarean section, which contained different microbes than mice born naturally, had mental health symptoms including increased anxiety and symptoms of depression. Researchers concluded that the animals’ inability to pick up their mothers’ vaginal microbes during birth may cause lifelong changes in mental health.

Another study from the California Institute of Technology found that mice with some features of autism had lower levels of a common gut bacterium called Bacteroides fragiles than normal mice.  The symptoms these mice displayed included signs of stress, antisocial behavior in addition to the gastrointestinal symptoms marked by autism.  In addition, feeding the mice B. fragilis reversed their symptoms.   In the opposite direction, these researchers also found that the symptomatic mice had higher levels of a bacterial metabolite called 4-ethylphenylsulphate (4EPS) in their blood, and by injecting that into normally behaved mice they caused the same behavioral problems.  Another study out of Caltech has shown that certain bacteria in the gut are important for the production of peripheral serotonin.

Research out of the Massachusetts Institute of Technology (MIT) has shown that ha strain of Lactobacillus reuteri, ingested in yogurt or in a supplement can increase levels of the feel-good hormone oxytocin, thereby improving mood and general health.

While the research is ongoing, the potential treatments have been referred to as “psychobiotics,” a term coined by Ted Dinan, a psychiatrist at the University of Cork that is involved in many of the studies, now in humans too.

Use of therapeutic psychobiotics are years away from reaching the market, but the potential impact is extraordinary – if it is proven that that abnormal gut bacteria have a role in causing mental disorders, it may be possible to create effective treatments by addressing a gut imbalance first.