Research progress of gut microbiota and frailty syndrome

Abstract

Frailty is a clinical syndrome caused by homeostasis imbalance. It is characterized by marked vulnerability to endogenous or exogenous stressors, reduced self-care ability, and increased mortality risk. This aging-related syndrome is common in individuals older than 65 years and carries an increased risk for poor health outcomes. These include falls, incident disability, incapacity, and mortality. In addition, it can result in a poor prognosis for other comorbidities. With the aging population, frailty increases the burden of adverse health outcomes. Studies on frailty are at their infancy. In addition, there is a lack of thorough understanding of its pathogenesis. Several studies have suggested that frailty is caused by chronic inflammation due to enhanced intestinal permeability following gut microbiota imbalance as well as pathogen-related antibodies entering the circulation system. These result in musculoskeletal system disorders and neurodegenerative diseases. However, this assumption has not been validated in large cohort-based studies. Several studies have suggested that inflammation is not the only cause of frailty. Hence, further studies are necessary to extend our understanding of its pathogenesis. This review summarizes the research findings in the field and expands on the possible role of the gut microbiota in frailty syndrome.

Prevalence of Frailty and Its Association with Depressive Symptoms among European Older Adults from 17 Countries: A 5-Year Longitudinal Study

“…As a result, musculoskeletal system disorders and neurodegenerative diseases might develop. All of the above can predispose individuals to frailty [ 50 , 51 ]. Regarding depression, gut microbiota can affect the nervous system through the gut–brain axis, which consists of the immune system, vagus nerve, and neuroendocrine system, all of which can modify and control cognitive functions such as depression [ 51 , 52 ].…”

“…All of the above can predispose individuals to frailty [ 50 , 51 ]. Regarding depression, gut microbiota can affect the nervous system through the gut–brain axis, which consists of the immune system, vagus nerve, and neuroendocrine system, all of which can modify and control cognitive functions such as depression [ 51 , 52 ]. Taken together, both of the presented physiological pathways to frailty and depression (i.e., inflammatory markers and microbiota) indicate a bidirectional association between frailty and depression.…”

Expanded insights into the neural component of the activity-based anorexia animal model — morphological changes in the enteric nervous system and altered pain perception

“…Another factor with a recognized impact on the ENS function and structure is the gut microbiota [71]. Besides its influence on postnatal development, experimental depletion of microbiota leads to the degeneration of enteric neurons in adults.…”

Frailty and transplant-free survival of patients with liver cirrhosis: A meta-analysis

“…findings also suggested that cirrhotic patients with frailty may be at high risk for receiving invasive treatments, which may be another potential reason for the poor long-term clinical outcomes of these patients [45]. Pathophysiologically, frailty has been related to upregulated inflammatory response, impaired systemic immune dysfunction, and gut microbiota disorder [46][47][48], which may also partly explain the association between frailty and poor TFS in patients with cirrhosis. Studies are warranted to determine the molecular pathways involved.…”