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Relationship between intestinal microbiome composition and depression
More and more people suffer from depression. Mental illness is usually treated with medication (antidepressants) and psychotherapy. There may be other treatment options. Because, as scientists have now found out, an antibiotic reduces depression behavior by changing the composition of the intestinal flora and thereby inhibits an "inflammatory process" in the brain.
Only a few weeks ago, Austrian researchers reported new findings that intestinal bacteria could contribute to mental illness. Now scientists from Germany are also explaining that our psyche is also regulated by the intestinal flora. They also found that an antibiotic can reduce depression behavior.
One of the most common mental illnesses worldwide
As the University of Regensburg wrote in a statement, depression is one of the most common mental illnesses worldwide. About every fifth person is affected once in a lifetime. Depression affects at least 350 million people worldwide. The patients describe an alarming state of mind marked by despair, hopelessness and apathy, a feeling of inner emptiness and often the loss of the beautiful things in life, called anhedonia.
In addition, tiredness, lack of drive and a reduced self-esteem as well as in the worst cases suicidal thoughts and suicidal attempts are added. Nowadays, clinically manifest depression is usually treated with so-called antidepressants, which leads to a reliable improvement in symptoms in many patients. However, the healing process is often hampered by side effects, and 30 percent of patients either respond very late or not at all to treatment.
Our psyche is regulated by various influences: the immune system, the interaction of our hormones, but also the intestinal flora, the microbiome. In fact, our body consists of more bacterial cells in the gut than "own" body cells. The bacteria in the intestinal flora are not only important for digestion - as has been assumed for a long time - the composition of the microbiome also crucially determines our emotional well-being and seems to have changed in depressed patients.
Less depression-like behavior
Neurobiologists led by Prof. Dr. Inga Neumann, Chair of Animal Physiology and Neurobiology at the University of Regensburg, in cooperation with the teams of Prof. Rainer Rupprecht, Chair of Psychiatry and Psychotherapy at the District Clinic of Regensburg, Prof. Andre Gessner from the Institute for Clinical Microbiology and Hygiene at the University Clinic of Regensburg, and Prof. Isabella Heuser, Charite Berlin the exact relationship between emotionality, depression and microbiome in laboratory rats.
The doctoral student Anna-Kristina Schmidtner was able to demonstrate that the composition of the intestinal microbiome differs greatly from normal, non-anxious animals in the rats, which are particularly anxious and also show treatment-resistant depression behavior. If the anxious animals are treated with the antibiotic minocycline, it is not only the intestinal flora that is expected to change significantly. The rats also behave more actively and show less depression-like behavior. The study results were published in the journal "Translational Psychiatry".
The composition of the microbiome changes
But how can an antibiotic influence animal behavior? In addition to its effect on the intestinal bacteria, minocycline in the brain changed so-called glia cells, formerly known as the "putty" of the brain, which regulate numerous brain functions. Depression is associated with activation of the microglia, which is also interpreted as an inflammatory process in the brain.
The team led by Prof. Neumann has now been able to prove that the composition of the microbiome changes after a minocycline treatment: some bacterial families become fewer, others become more common, especially those bacterial families that produce short-chain fatty acids. These enter the bloodstream and can also influence the brain in this way.
According to the scientists, one of these substances - butyrate - can even prevent the activation of microglia in the brain, i.e. it has an anti-inflammatory effect. The antidepressant effect of minocycline is therefore very likely to be attributed to this effect.
Experts from Berlin also reported a few months ago that they had achieved good results for depression with antibiotics, and also "with minocycline, a proven and well-tolerated antibiotic from the group of tetracyclines," said Professor Isabella Heuser, head of the clinic for Psychiatry and psychotherapy of the Charité - Universitätsmedizin Berlin on the Benjamin Franklin campus, in a communication from the Freie Universität (FU) Berlin. This drug has been used successfully for a long time against acne and rheumatism and shows hardly any side effects. (ad)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
- University of Regensburg: More than just a gut feeling - do depressions go through the stomach ?, (accessed: September 18, 2019), University of Regensburg
- Translational Psychiatry: Minocycline alters behavior, microglia and the gut microbiome in a trait-anxiety-dependent manner, (accessed: 18.09.2019), Translational Psychiatry
- Freie Universität Berlin: An antibiotic for depression ?, (accessed: September 18, 2019), Freie Universität Berlin