{"id":2364,"date":"2020-06-24T15:15:27","date_gmt":"2020-06-24T15:15:27","guid":{"rendered":"https:\/\/www.danielleal.pt\/?p=2364"},"modified":"2020-06-25T14:26:53","modified_gmt":"2020-06-25T14:26:53","slug":"the-relationship-between-depression-and-anxiety-and-the-intestinal-microbiota","status":"publish","type":"post","link":"https:\/\/danielleal.pt\/en\/the-relationship-between-depression-and-anxiety-and-the-intestinal-microbiota\/","title":{"rendered":"The Relationship between Depression and Anxiety and the Intestinal Microbiota"},"content":{"rendered":"

The intestinal microbiome is certainly one of the most fascinating areas of scientific research nowadays. The systemic implications of our intestinal ecosystem are very profound and diverse, and they include the brain and the entire neuro-behavioral axis.<\/span><\/p>\n

The idea that what goes on in the gut stays in the gut, is part of the past.<\/b> There are more microorganisms in our gut than human cells in the whole body. This community of microbes has a fundamental role in maintaining health, through different mechanisms. In this article, we will focus on the interaction of the microbiota with the brain – the so-called gut-brain axis<\/b> – and its contribution to neuropsychiatric conditions, such as anxiety and depression.<\/span><\/p>\n

Is there evidence suggesting an association between neuropsychiatric disorders and the microbiota?<\/span><\/strong><\/p>\n

There are several studies demonstrating an effect of intestinal microbiota on depression and anxiety, including some that have looked at therapeutic interventions, such as prebiotics and probiotics.<\/span><\/p>\n

In a particularly elegant study, published in 2016, researchers decided to transplant fecal material from 34 patients with depression into mice. (1<\/span><\/a>) The study included a control arm in which the fecal transplant donors were healthy individuals. The mice that received depressed donors fecal transplants developed depressive behaviors, such as anhedonia, and increased anxiety.<\/b> The control group mice showed no significant changes in their behavior. This is an animal study, which should never be seen as the best scientific evidence, but it is nonetheless fascinating.<\/span><\/p>\n

In turn, a retrospective study in the United Kingdom, sought to relate diagnoses of depression and anxiety, with the prescription of antibiotics in the previous year. (2<\/span><\/a>) The goal of the study was to understand whether individuals who took antibiotics were more likely to be diagnosed with one of the aforementioned conditions. The sample collected was quite large (about 200,000 patients with depression and 15,000 with anxiety). It was showed that taking antibiotics contributed to an increased risk of 25% for the diagnosis of depression and 17% for anxiety.<\/b> Repeated courses of antibiotics further increased the risk (up to 50%). Since taking antibiotics is a disruptive factor of the microbiota, this association suggests the existence of a relationship between the variables, although it cannot establish causality.<\/b><\/span><\/p>\n

How can the microbiota influence the brain?<\/span><\/strong><\/p>\n

We should think of the microbiota as a group of workers that inhabits our intestines, with which we can establish a relationship of symbiosis (in which both parties benefit) or dysbiosis (in which there is damage to the host). With regard to the central nervous system, the microbiota can interfere with its functioning, through the following routes:<\/span><\/p>\n