Good bacteria to fight depression – Neuroscience News

Summary: Probiotics can support the effects of antidepressants to help relieve symptoms of depression.

Source: University of Basel

Gut flora plays an important role in health, including mental health. Researchers from the University of Basel and the University Psychiatric Clinics Basel (UPK) have shown that probiotics can enhance the effect of antidepressants and help relieve depression.

When he received a visit from what he called “the black dog”, Winston Churchill could barely get out of bed. He had no energy, no interest and no appetite. Although the British Prime Minister did not invent this metaphor for depression, it was he who popularized it.

Experts use drugs and psychotherapy to try to help patients escape the “black dog”, but it persists in some individuals. Researchers are therefore looking for ways to improve existing therapies and develop new ones.

One promising approach is the microbiome-gut-brain axis. By microbiome, we generally mean all the microorganisms that live in or on the human body, such as the intestinal flora. Intestinal bacteria can influence the nervous system, for example via metabolic products.

In a recent study, a research team from the University of Basel and the University Psychiatric Clinics Basel (UPK) showed that probiotics can support treatment with antidepressants.

They reported their findings in the journal Translational psychiatry.

The intestinal flora influences the psyche

It is known from previous studies that patients with depression have a higher than average prevalence of intestinal and digestive problems. If the intestinal flora of people suffering from depression is implanted in mice raised under sterile conditions, that is to say without intestinal flora, the animals also develop depressive-like behavior. For example, they are less energetic and less interested in their surroundings than their peers.

The researchers therefore suspect that the composition of the bacterial community in the gut plays an important role in depressive symptoms.

In their new study, researchers led by Dr. André Schmidt and Professor Undine Lang systematically investigated the effects of probiotics on patients with depression.

All participants were hospitalized at the University Psychiatric Clinics Basel (UPK) and received a probiotic (21 subjects) or a placebo (26 subjects) for 31 days, in addition to antidepressants. Neither the participants nor the study staff knew which preparation the subjects were taking throughout the study period.

The researchers carried out a series of tests on the participants immediately before treatment, at the end of the 31 days and again four weeks later.

Subsequent analysis showed that although depressive symptoms decreased in all participants with systemic antidepressant treatment, there was greater improvement in subjects in the probiotic group than in the placebo group.

In addition, the composition of their intestinal flora changed, at least temporarily: in the probiotic group, an analysis of stool samples revealed an increase in lactic acid bacteria at the end of treatment – ​​an effect which was accompanied a decrease in depressive symptoms.

However, the level of these health-promoting gut bacteria declined again over the next four weeks.

“It may be that four weeks of treatment is not long enough and that it may take longer for the new composition of the intestinal flora to stabilize”, explains Anna-Chiara Schaub, one of the main authors of the study.

Change in the processing of emotional stimuli

Another interesting effect of taking probiotics was observed in relation to brain activity when viewing neutral or fearful faces.

It is known from previous studies that patients with depression have a higher than average prevalence of intestinal and digestive problems. Image is in public domain

The researchers investigated this effect using functional magnetic resonance imaging (fMRI). In patients with depression, certain regions of the brain for emotional processing behave differently than in mentally healthy people.

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 several years, the exact mechanisms have yet to be fully clarified,” says Schaub.

This is another reason why researchers felt it was important to use a wide range of bacteria in the form of probiotics, such as the 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 use the best mix in order to support the treatment of depression”, explains the researcher – even if she holds to point out that probiotics are not suitable as a sole treatment for depression.

About this depression and gut bacteria research news

Author: Angelique Jacobs
Source: University of Basel
Contact: Angelika Jacobs – University of Basel
Image: Image is in public domain

See also

It shows a brain

Original research: Free access.
“Clinical, Gut Microbial, and Neural Effects of Probiotic Complementary Therapy in Depressed Patients: A Randomized Controlled Trial” by Anna-Chiara Schaub et al. Translational psychiatry


Clinical, gut microbial and neural effects of probiotic adjunct therapy in depressed patients: a randomized controlled trial

A promising new therapeutic approach for major depressive disorder (MDD) targets the microbiota-gut-brain (MGB) axis, which is linked to the physiological and behavioral functions affected in MDD.

This is the first randomized controlled trial to investigate whether high-dose, short-term probiotic supplementation reduces depressive symptoms as well as gut microbial and neural changes in depressed patients.

Patients with current depressive episodes took either a multi-strain probiotic supplement or a placebo for 31 days in addition to usual treatment. Assessments took place before, immediately after, and again four weeks after the intervention. The Hamilton Depression Rating Sale (HAM-D) was assessed as the primary outcome.

Quantitative microbiome profiling and neuroimaging were used to detect changes along the MGB axis. In the sample that completed the intervention (probiotics NOT= 21, placebo NOT = 26), HAM-D scores decreased over time, and time-group interactions indicated a greater decrease in probiotics compared to the placebo group.

Probiotics maintained microbial diversity and increased genus abundance Lactobacillusindicating the effectiveness of probiotics in augmenting specific taxa.

The increase in Lactobacilluswas associated with a decrease in depressive symptoms in the probiotics group.

Finally, the activation of the putamen in response to neutral faces was significantly decreased after the probiotic intervention.

Our data imply that supplemental probiotic treatment improves depressive symptoms (HAM-D) as well as changes in the gut microbiota and brain, highlighting the role of the MGB axis in MDD and underscoring the potential of microbiota-related treatment approaches as accessible, pragmatic and non-stigmatizing in MDD.

Trial registration:, identifier: NCT02957591.

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