New research shows that probiotics can help relieve depression

Good bacteria to fight depression

Intestinal microbiome plays an important role in health, including mental health. Researchers at the University of Basel and the University of Basel Psychiatric Clinic (UPK) have shown that probiotics support the effects of antidepressants and help relieve depression.

Depression is a very common problem in modern society. In fact, according to the CDC, 18.5% of adults surveyed in the United States in 2019 had symptoms of depression that were mild, moderate, or severe in the previous 2 weeks.

It may come as a surprise to many that scientists have discovered that your intestinal flora, the trillions of bacteria and other microbes that live in your digestive tract, can contribute to depression. However, this is not surprising, as your gut microbiome is known to play an important role in health and is associated with weight loss, autism, COVID-19 severity, ALS, and the safety and effectiveness of medications.

Winston Churchill could barely get out of bed when a man who called him a “black dog” visited. He had no energy, no interest, no appetite. Although this metaphor for depression was not invented by the British Prime Minister, it made it popular.

Experts use medications and psychotherapy to help patients avoid the “black dog,” but it persists in some people. Therefore, scientists are looking for ways to improve existing therapies and develop new ones.

One of the most promising methods is the microbiome-intestinal-brain axis. A microbiome is generally understood to be all the microorganisms that live in or on the human body, such as the intestinal flora. Intestinal bacteria can affect the nervous system, for example, through metabolic products.

A recent study by the University of Basel and the University of Basel Psychiatric Clinic (UPK) showed that probiotics support treatment with antidepressants. They reported their findings in the journal on June 3, 2022 Translational psychiatry.

Illustration of human intestinal microbiome

Illustration of human intestinal microbiome.

Intestinal flora affects the psyche

Previous studies have shown that people with depression have a higher than average prevalence of gastrointestinal problems. If the intestinal flora of people with depression is implanted in mice grown under sterile conditions, that is, in the absence of intestinal flora, the animals will develop depression-like behavior. For example, they are less energetic and less interested in the environment than their peers. Therefore, researchers suspect that the composition of the bacterial community in the gut plays an important role in the symptoms of depression.

“With additional knowledge about the specific effects of some bacteria, it may be possible to use the best mix to optimize bacterial selection and support the treatment of depression.” – Anna-Chiara Shaub

In their new study, researchers led by Drs. Andre Schmidt and Professor Undin Lang have observed the effects of probiotics on depression. All participants were hospitalized in the psychiatric clinics (UPK) of the University of Basel and, in addition to antidepressants, were given probiotics (21 subjects) or placebo (26 subjects) for 31 days. Neither the participants nor the researchers knew how the subjects were prepared during the study. The researchers performed a series of tests on participants before, at the end of 31 days and after another four weeks.

Subsequent analysis showed that although general antidepressant treatment reduced depressive symptoms in all participants, there was a significant improvement in the probiotic group compared to the placebo group.

In addition, the composition of their intestinal flora changed at least temporarily: in the probiotic group, the analysis of fecal samples revealed an increase in milk.[{” attribute=””>acid bacteria at the end of treatment – an effect that was accompanied by a reduction in depressive symptoms. However, the level of these health-promoting gut bacteria decreased again over the following four weeks. “It may be that four weeks of treatment is not long enough and that it takes longer for the new composition of the intestinal flora to stabilize,” explains Anna-Chiara Schaub, one of the lead authors of the study.

Change in the processing of emotional stimuli

Another interesting effect of taking probiotics was seen in relation to brain activity when viewing neutral or fearful faces. The researchers investigated this effect using functional magnetic resonance imaging (fMRI). In patients with depression, certain brain regions for emotional processing behave differently than in individuals with good mental health. After four weeks of probiotics, this brain activity normalized in the probiotic group but not in the placebo group.

“Although the microbiome-gut-brain axis has been the subject of research for a number of years, the exact mechanisms are yet to be fully clarified,” says Schaub. This was another reason why the researchers believed it was important to use a wide range of bacteria in the form of probiotics, such as formulations already available on the market. “With additional knowledge of the specific effect of certain bacteria, it may be possible to optimize the selection of bacteria and to use the best mix in order to support treatment for depression,” says the researcher – although she is keen to emphasize that probiotics are not suitable as a sole treatment for depression.

Reference: “Clinical, gut microbial and neural effects of a probiotic add-on therapy in depressed patients: a randomized controlled trial” by Anna-Chiara Schaub, Else Schneider, Jorge F. Vazquez-Castellanos, Nina Schweinfurth, Cedric Kettelhack, Jessica P. K. Doll, Gulnara Yamanbaeva, Laura Mählmann, Serge Brand, Christoph Beglinger, Stefan Borgwardt, Jeroen Raes, André Schmidt and Undine E. Lang, 3 June 2022, Translational Psychiatry.
DOI: 10.1038/s41398-022-01977-z

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