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Updated Review and Meta-Analysis of Probiotics for the Treatment of Clinical Depression: Adjunctive vs. Stand-Alone Treatment.
Nikolova, VL, Cleare, AJ, Young, AH, Stone, JM
Journal of clinical medicine. 2021;10(4)
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Major depressive disorder is a common, complex, and heterogeneous illness that is characterized by persistent low mood and anhedonia, and a combination of sleep disturbances, changes in appetite, feelings of worthlessness or guilt, poor concentration, and suicidal ideation. The aim of this study was to identify and evaluate all current evidence from randomised controlled trials on the efficacy of probiotics in reducing depressive symptoms among people with clinical depression. This study is a review and meta-analysis of randomised controlled trials which included seven studies for qualitative and quantitative analysis. Results demonstrate that probiotics significantly reduce depressive symptoms after eight weeks of use, but only when used in addition to an approved antidepressant. Authors conclude that their findings support the clinical use of probiotics in depressed populations and provides an insight into the mode of administration more likely to yield antidepressant effects.
Abstract
Recent years have seen a rapid increase in the use of gut microbiota-targeting interventions, such as probiotics, for the treatment of psychiatric disorders. The objective of this update review was to evaluate all randomised controlled clinical trial evidence on the efficacy of probiotics for clinical depression. Cochrane guidelines for updated reviews were followed. By searching PubMed and Web of Science databases, we identified 546 new records since our previous review. A total of seven studies met selection criteria, capturing 404 people with depression. A random effects meta-analysis using treatment type (stand-alone vs. adjunctive) as subgroup was performed. The results demonstrated that probiotics are effective in reducing depressive symptoms when administered in addition to antidepressants (SMD = 0.83, 95%CI 0.49-1.17), however, they do not seem to offer significant benefits when used as stand-alone treatment (SMD = -0.02, 95%CI -0.34-0.30). Potential mechanisms of action may be via increases in brain-derived neurotrophic factor (BDNF) and decreases in C-reactive protein (CRP), although limited evidence is available at present. This review offers stronger evidence to support the clinical use of probiotics in depressed populations and provides an insight into the mode of administration more likely to yield antidepressant effects.
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Current Perspectives on Gut Microbiome Dysbiosis and Depression.
Capuco, A, Urits, I, Hasoon, J, Chun, R, Gerald, B, Wang, JK, Kassem, H, Ngo, AL, Abd-Elsayed, A, Simopoulos, T, et al
Advances in therapy. 2020;37(4):1328-1346
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The gut microbiome has been implicated in several neurological disorders; however exact mechanisms are still not fully understood. This review of recent studies, aimed to investigate the relationship between an imbalanced gut microbiome and depression. The authors first looked at the epidemiology of disease, concluding that significant burden needs to be assessed through improved preventative measures. This will depend upon the correct identification of risk factors, and the study focused on the role of the gut microbiome in this through animal and human studies. Imbalances in inflammation through altered gut microbiota, depleted biodiversity and stress induced microbiome changes were all implicated in the development of depression. It was concluded that studies on the role of microbiota in depression remain promising but are small and follow many different methodologies. This study could be used by healthcare professionals to better understand the role of gut microbiota in the development of depression and that ensuring a healthy gut may improve symptoms.
Abstract
The human gut microbiome partakes in a bidirectional communication pathway with the central nervous system (CNS), named the microbiota-gut-brain axis. The microbiota-gut-brain axis is believed to modulate various central processes through the vagus nerve as well as production of microbial metabolites and immune mediators which trigger changes in neurotransmission, neuroinflammation, and behavior. Little is understood about the utilization of microbiome manipulation to treat disease. Though studies exploring the role of the microbiome in various disease processes have shown promise, mechanisms remain unclear and evidence-based treatments for most illnesses have not yet been developed. The animal studies reviewed here offer an excellent array of basic science research that continues to clarify mechanisms by which the microbiome may affect mental health. More evidence is needed, particularly as it relates to translating this work to human subjects. The studies presented in this paper largely demonstrate encouraging results in the treatment of depression. Limitations include small sample sizes and heterogeneous methodology. The exact mechanism by which the gut microbiota causes or alters neuropsychiatric disease states is not fully understood. In this review, we focus on recent studies investigating the relationship between gut microbiome dysbiosis and the pathogenesis of depression. This article is based on previously conducted studies and does not contain any studies with human participants or animals performed by any of the authors.
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Gut Microbiome and Depression: How Microbes Affect the Way We Think.
Limbana, T, Khan, F, Eskander, N
Cureus. 2020;12(8):e9966
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Recent findings have shown that a healthy gut microflora transmits signals to the brain through various pathways, namely the gut-brain axis. With the gut and brain working in a bidirectional relationship, emerging research suggests this could potentially impact stress, anxiety, depression and cognition. Therefore the aim of this review was to determine the role of the gut microbiome in mental health and depression. A total of 26 articles were reviewed and based on these articles, a strong link exists between the gut microbiome and its impact on mental health. Additionally, the literature supports the notion that the gut-brain axis serves as an essential pathway. Based on these findings, the authors agree there is a strong association between the gut microbiome and mental health, while also acknowledging the need to establish a causal link between these two entities. The authors conclude that the microbiome is a promising approach when considering the prevention, treatment and management of mental health diseases in the future.
Abstract
The gut microbiome serves an important role in the human body. Reportedly, one of the benefits of these microflora is on mental health. Once established, food and other dietary sources that enhance quality microbiome content in our gastrointestinal system will be a significant consideration in individuals' day to day lives. This literature review conducted a PubMed search for studies about the gut microbiome and its relation to depression. In using several Medical Subject Heading (MeSH) keywords, relevant literature was selected. A total of 26 articles were selected after applying the inclusion and exclusion criteria, and after checking the articles' accessibility. This literature would like to establish the role of the gut microbiome in depression. This study's findings showed that there is a strong association of microbiome function to mental well-being.
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Gut microbes in neurocognitive and mental health disorders.
Halverson, T, Alagiakrishnan, K
Annals of medicine. 2020;52(8):423-443
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Adequately and effectively treating and managing neurocognitive disorders remains a challenge. Increasing evidence suggests gut microbes may contribute to common mental health disorders through the microbiota-gut-brain axis, and better understanding this interaction could lead to improved clinical outcomes. The aim of this review is to discuss the impact of the gut microbiome on neurocognitive and mental health disorders and the mechanisms by which they act. This review reveals that the gut microbiome can influence brain and intestinal cells and that there is an association between gut dysbiosis with different mental health and neurocognitive disorders. Additionally, evidence shows the antimicrobial effect of current pharmaceutical treatments used in mental disorders may adversely affect the gut microbiome. Based on these findings, the authors conclude the gut microbiome is likely involved in the pathophysiology of neurocognitive and mental health conditions. Treatment strategies focusing on the gut microbiome may have a role in the treatment and management of mental health disorders, however further evidence is needed before applying these strategies in clinical practice.
Abstract
INTRODUCTION As individuals age, the prevalence of neurocognitive and mental health disorders increases. Current biomedical treatments do not completely address the management of these conditions. Despite new pharmacological therapy the challenges of managing these diseases remain.There is increasing evidence that the Gut Microbiome (GM) and microbial dysbiosis contribute to some of the more prevalent mental health and neurocognitive disorders, such as depression, anxiety, obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), schizophrenia, bipolar disorder (BP), and dementia as well as the behavioural and psychological symptoms of dementia (BPSD) through the microbiota-gut-brain axis. Methodology: Scoping review about the effect of gut microbiota on neurocognitive and mental health disorders. RESULTS This scoping review found there is an evolving evidence of the involvement of the gut microbiota in the pathophysiology of neurocognitive and mental health disorders. This manuscript also discusses how the psychotropics used to treat these conditions may have an antimicrobial effect on GM, and the potential for new strategies of management with probiotics and faecal transplantation. CONCLUSIONS This understanding can open up the need for a gut related approach in these disorders as well as unlock the door for the role of gut related microbiota management. KEY MESSAGES Challenges of managing mental health conditions remain in spite of new pharmacological therapy. Gut dysbiosis is seen in various mental health conditions. Various psychotropic medications can have an influence on the gut microbiota by their antimicrobial effect.
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Microbiome-Gut-Brain Axis and Toll-Like Receptors in Parkinson's Disease.
Caputi, V, Giron, MC
International journal of molecular sciences. 2018;19(6)
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Parkinson’s disease (PD) is a progressively debilitating neurodegenerative disease and recently the role of the microbiota-gut-brain axis has gained attention in patients with PD. Research shows that an altered gut microbiota can activate Toll-like receptors (TLRs), receptors involved in the innate immune response, causing an inflammatory cascade in the gut and brain. Based on this knowledge, gut microbiota and TLRs may be potential therapeutic targets for PD. This review sheds light on the current knowledge regarding the association between the microbiota-gut-brain axis and innate immunity via TLR signalling in PD. Increased understanding of this relationship should lead to insights on the pathophysiology of PD, as well as improved dietary and pharmaceutical therapeutic approaches in PD patients. Based on the existing evidence, the authors conclude that through modulating the gut, thus balancing the immune response in PD patients, it may be possible to influence early phases of the neurodegenerative cascade.
Abstract
Parkinson’s disease (PD) is a progressively debilitating neurodegenerative disease characterized by α-synucleinopathy, which involves all districts of the brain-gut axis, including the central, autonomic and enteric nervous systems. The highly bidirectional communication between the brain and the gut is markedly influenced by the microbiome through integrated immunological, neuroendocrine and neurological processes. The gut microbiota and its relevant metabolites interact with the host via a series of biochemical and functional inputs, thereby affecting host homeostasis and health. Indeed, a dysregulated microbiota-gut-brain axis in PD might lie at the basis of gastrointestinal dysfunctions which predominantly emerge many years prior to the diagnosis, corroborating the theory that the pathological process is spread from the gut to the brain. Toll-like receptors (TLRs) play a crucial role in innate immunity by recognizing conserved motifs primarily found in microorganisms and a dysregulation in their signaling may be implicated in α-synucleinopathy, such as PD. An overstimulation of the innate immune system due to gut dysbiosis and/or small intestinal bacterial overgrowth, together with higher intestinal barrier permeability, may provoke local and systemic inflammation as well as enteric neuroglial activation, ultimately triggering the development of alpha-synuclein pathology. In this review, we provide the current knowledge regarding the relationship between the microbiota-gut⁻brain axis and TLRs in PD. A better understanding of the dialogue sustained by the microbiota-gut-brain axis and innate immunity via TLR signaling should bring interesting insights in the pathophysiology of PD and provide novel dietary and/or therapeutic measures aimed at shaping the gut microbiota composition, improving the intestinal epithelial barrier function and balancing the innate immune response in PD patients, in order to influence the early phases of the following neurodegenerative cascade.