Altered fecal microbiota composition in patients with major depressive disorder

Abstract

Studies using animal models have shown that depression affects the stability of the microbiota, but the actual structure and composition in patients with major depressive disorder (MDD) are not well understood. Here, we analyzed fecal samples from 46 patients with depression (29 active-MDD and 17 responded-MDD) and 30 healthy controls (HCs). High-throughput pyrosequencing showed that, according to the Shannon index, increased fecal bacterial α-diversity was found in the active-MDD (A-MDD) vs. the HC group but not in the responded-MDD (R-MDD) vs. the HC group. Bacteroidetes, Proteobacteria, and Actinobacteria strongly increased in level, whereas that of Firmicutes was significantly reduced in the A-MDD and R-MDD groups compared with the HC group. Despite profound interindividual variability, levels of several predominant genera were significantly different between the MDD and HC groups. Most notably, the MDD groups had increased levels of Enterobacteriaceae and Alistipes but reduced levels of Faecalibacterium. A negative correlation was observed between Faecalibacterium and the severity of depressive symptoms. These findings enable a better understanding of changes in the fecal microbiota composition in such patients, showing either a predominance of some potentially harmful bacterial groups or a reduction in beneficial bacterial genera. Further studies are warranted to elucidate the temporal and causal relationships between gut microbiota and depression and to evaluate the suitability of the microbiome as a biomarker.

Modulatory Effects of Gut Microbiota on the Central Nervous System: How Gut Could Play a Role in Neuropsychiatric Health and Diseases

“…109 However, another recent study examined the composition of fecal microbiota in 46 patients with depression and 30 healthy controls, and reported significant differences with increased population of Bacteroidetes, Proteobacteria, and Actinobacteria, and decreased population of Frimicutes in patients with depression. 110 Other evidence that might suggest a role for gut microbiota in the pathogenesis of depression is from studies that have shown certain probiotics can alleviate depressive symptoms in rodent models. Rats that are exposed to stress in early stages of life show behavior traits that are consistent with mood disorder that persists through their adulthood.…”

Vaccinating against depression or anxiety: is it plausible?

“…A clear 'proof of concept' that microorganisms can induce anxiety was demonstrated in mice, by the anxiety-like behavior induced by some enteric bacterial pathogens [7][8][9] (Figure 1). Moreover, inflammation and CMI activation in human subjects with some types of MDD likely result from overgrowth and intestinal translocation of Gram-negative enterobacteria due to a leaky gut [11,13] (Figure 1). More research is needed to identify and/or characterize such kind of pathobionts (potentially pathological microorganisms which, under normal circumstances, live as symbionts) susceptible to induce depression or anxiety in humans.…”

“…Jiang et al [13] recently reported an altered fecal microbiota composition in patients with MDD (Proteobacteria, Bacteroidetes, and Actinobacteria were significantly more abundant, whereas levels of Firmicutes were significantly reduced; it is important to mention that patients were treated with antipsychotics, a study limitation acknowledged by the authors). The overgrowth of the phylum Proteobacteria [13] included the above inflammogenic Enterobacteriaceae identified by Maes et al [11].…”

“…The overgrowth of the phylum Proteobacteria [13] included the above inflammogenic Enterobacteriaceae identified by Maes et al [11]. Moreover, MDD patients had increased levels of the Gram-negative Alistipes of the Rikenellaceae family [13].…”

Breastfeeding and the gut-brain axis: is there a role for melatonin?

“…Enhanced levels of gut permeability and associated alterations in gut microbiota are linked to the etiology and/or course of an array of medical conditions, including multiple sclerosis (13), Parkinson's disease (12), dementia (14), schizophrenia (15), bipolar disorder (16), the autistic spectrum (17) and depression (18). As noted above, the high rates of comorbid depression, often prior to symptom exacerbation, in these conditions suggests that gut-brain axis alterations may mediate some of their associations with such an array of medical presentations via raised levels of depression.…”