The gut microbiota and mood disorders are both highly complex and yet there are a number of studies showing that gut microbiota alteration has a strong association with symptoms of depression. This article highlights some of these connections and explores ways in which the microbiota may be used to treat depression.
The gut microbiota is important for our mental health. In animal models, altered gut microbiota has been associated with depression. However, the role of the gut microbiota in humans is unclear. It is possible that stress and imbalanced diets also affect the composition of the gut microbiota.
Stress-induced depressive-like behaviors in mice have been shown to be caused by changes in the microbiota. Probiotic intervention can reduce this behavior. Moreover, folic acid has been found to reduce depressive-like behavior.
Early life stress and inflammation are known to contribute to the development of depression. Affected immune and endocrine systems may result in disruption of the gut barrier. This leads to increased permeability and translocation of gut bacterial products, aggravated by the production of LPS.
There is increasing evidence that stress-induced depressive-like behaviors are mediated by the gut microbiota. Several studies have investigated the effects of probiotics and antidepressants on gut microbiota and its role in reducing anxiety-like behaviors.
The gut microbiota plays a critical role in maintaining metabolic integrity and is known to be a potential target for therapeutic intervention. It is believed that microbiome dysbiosis contributes to obesity-related metabolic disorders, including type 2 diabetes.
Dietary fats and carbohydrates have been known to alter microbial composition, but their effects on the gut microbiota are unclear. Some dietary factors may have more profound effects than others. For example, high-fat diets increase the count of total anaerobic microflora, which may lead to disruptions in the circadian rhythm.
Gut microbiota is thought to play a role in the pathogenesis of depression. However, the extent of the relationship between gut microbiota and depression symptoms is still unknown. Therefore, a comprehensive understanding of microbial alterations is necessary to identify effector microbial biomarkers for developing microbiota-based diagnostics.
Microbial changes in patients with MDD and subthreshold depression are different from those found in other forms of depression. In particular, the abundance of Lachnospiraceae, Fusicatenibacter, and Eggerthella were reduced in depressed patients, while those of Coprococcus, Deferribacteria, and Paraprevotella were increased.
The microbiota-gut-brain interaction may also play a role in neurodegenerative diseases. Studies have shown that dysbiosis of microbial species leads to atypical immune signaling. Affected microbial species produce a variety of cytokines, peptides, and endotoxins. These substances influence a number of physiologic functions, including gut permeability, the secretion of IL-1b and TNFa, and NF-kB and MAPK activation.
The gut microbiota has been associated with a variety of psychiatric disorders. However, the molecular pathways linking intestinal microbiota and mood disorders remain unclear. While the use of prebiotic and probiotic formulations has been shown to alleviate depressive phenotypes in animal models of depression, more comprehensive studies are needed to elucidate the effects of these interventions.
Microbiota-based interventions have been shown to improve mood and enhance neurogenesis in mice. A variety of microbes have been found to modulate the function of the central nervous system. These include the Lactobacilli genus, which has been found to promote hippocampal survival. In addition, probiotics have been demonstrated to reduce the effects of chronic stress in mice.
