Dysbiosis: A Potential Precursor to the Development of a Depressive Disorder

Circulating B vitamins metabolites in depressive disorders - connections with the microbiota-gut-brain axis

PURPOSE

In this review, we aim to summarize recent information about the association of B vitamins with immune-metabolic aspects of depression and their connection with the gut-brain axis.

VIEWS

B vitamins may alter depressive symptoms by many various mechanisms such as reducing oxidative stress, inflammation, gut permeability, controlling epigenetics, modifying the microbiome, and stimulating it to produce many beneficial substances such as short-chain fatty acids or neurotransmitters: norepinephrine, dopamine, serotonin, gamma-aminobutyric acid, and acetylcholine.

CONCLUSIONS

Specifically, vitamins B1 (thiamine), B6 (pyridoxine), B9 (folate), and B12 (cyanocobalamin), B2 (riboflavin) have been observed to affect depression. Given probiotic's capability to produce vitamins from the B group, and modify intestinal function, inflammation, or metabolic dysfunction, their supplementation might be a possible treatment method for the immunometabolic form of depression. Thus, the intake of certain probiotic bacterial strains simultaneously with controlling the required daily intake of B vitamins may positively affect the course of depression. Circulating B vitamins metabolite levels, especially B9, B12, and B6 may also be biomarkers of depression. Further investigation is needed to find stronger evidence on this topic.

Exploring gender differences in the relationship between gut microbiome and depression - a scoping review

Background

Major depressive disorder (MDD) exhibits gender disparities, and emerging evidence suggests the involvement of the gut microbiome, necessitating exploration of sex-specific differences.

Methods

A review was conducted, encompassing a thorough examination of relevant studies available in Medline via Ovid, Embase via OvidSP, CINAHL, and PsycINFO databases from their inception to June 2023. The search strategy employed specific keywords and Medical Subject Headings (MeSH) terms tailored to major depressive disorder in women, encompassing unipolar depression, depressive symptoms, and dysbiosis.

Results

Five studies were included. Among the four studies, alterations in alpha (n=1) and beta diversity (n=3) in the gut microbiome of individuals with MDD were revealed compared to controls. Gender-specific differences were observed in four studies, demonstrating the abundance of specific bacterial taxa and highlighting potential sex-specific implications in MDD pathophysiology. Correlation analyses (n=4) indicated associations between certain bacterial taxa and the severity of depressive symptoms, with varying patterns between males and females. Studies (n=3) also highlighted promising findings regarding the potential utility of microbial markers in diagnosing MDD, emphasizing the crucial role of sex stratification in understanding the disease pathophysiology.

Conclusions

The findings underscore the importance of recognizing gender-specific differences in the composition of the gut microbiome and its relationship with MDD. Further comprehensive robust studies are required to unravel the intricate mechanisms underlying these disparities.

Systematic identification of the role of gut microbiota in mental disorders: a TwinsUK cohort study

Mental disorders are complex disorders influenced by multiple genetic, environmental, and biological factors. Specific microbiota imbalances seem to affect mental health status. However, the mechanisms by which microbiota disturbances impact the presence of depression, stress, anxiety, and eating disorders remain poorly understood. Currently, there are no robust biomarkers identified. We proposed a novel pyramid-layer design to accurately identify microbial/metabolomic signatures underlying mental disorders in the TwinsUK registry. Monozygotic and dizygotic twins discordant for mental disorders were screened, in a pairwise manner, for differentially abundant bacterial genera and circulating metabolites. In addition, multivariate analyses were performed, accounting for individual-level confounders. Our pyramid-layer study design allowed us to overcome the limitations of cross-sectional study designs with significant confounder effects and resulted in an association of the abundance of genus Parabacteroides with the diagnosis of mental disorders. Future research should explore the potential role of Parabacteroides as a mediator of mental health status. Our results indicate the potential role of the microbiome as a modifier in mental disorders that might contribute to the development of novel methodologies to assess personal risk and intervention strategies.

Prebiotics for depression: how does the gut microbiota play a role?

Depression, a mood disorder characterized by persistent feelings of sadness and aversion to activity that can interfere with daily life, is a condition of great concern. Prebiotics, which are non-digestible substances selectively utilized by host microorganisms for health benefits, have gained attention for their potential to improve overall wellness and alleviate various disorders including depression. This study aims to review clinical trials utilizing carbohydrate-type prebiotics such as inulin-type fructans, galactooligosaccharides (GOS), human milk oligosaccharides, resistant starch, prebiotic phytochemicals including epigallocatechin gallate (EGCG), chlorogenic acids, resveratrol, and prebiotic lipids (n-3 polysaturated fatty acids) to determine their effects on depression. Our findings suggest that GOS at a daily dosage of 5 g and eicosapentaenoic acid at or less than 1 g can effectively mitigate depressive symptoms. While EGCG exhibits potential antidepressant properties, a higher dosage of 3 g/d may be necessary to elicit significant effects. The plausible mechanisms underlying the impact of prebiotics on depression include the synthesis of neurotransmitters, production of short-chain fatty acids, and regulation of inflammation.

Vitality Revisited: The Evolving Concept of Flourishing and Its Relevance to Personal and Public Health

Human flourishing, the state of optimal functioning and well-being across all aspects of an individual's life, has been a topic of philosophical and theological discussion for centuries. In the mid-20th century, social psychologists and health scientists began exploring the concept of flourishing in the context of health and high-level wellness. However, it is only in recent years, in part due to the USD 43 million Global Flourishing Study including 22 countries, that flourishing has entered the mainstream discourse. Here, we explore this history and the rapid acceleration of research into human flourishing, defined as "the relative attainment of a state in which all aspects of a person's life are good" by the Harvard University's Flourishing Program. We also explore the construct of "vitality", which refers to a sense of aliveness, energy, and motivation; we contend that this has been neglected in the flourishing movement. We explore why incorporating measures of vitality, together with a broader biopsychosocial approach, considers all dimensions of the environment across time (the total exposome), which will greatly advance research, policies, and actions to achieve human flourishing.