Dementia, osteoporosis and fragility fractures: Intricate epidemiological relationships, plausible biological connections, and twisted clinical practices.

Dementia, osteoporosis, and fragility fractures are chronic diseases, often co-existing in older adults. These conditions pose severe morbidity, long-term disability, and mortality, with relevant socioeconomic implications. While in the research arena, the discussion remains on whether dementia is the cause or the consequence of fragility fractures, healthcare professionals need a better understanding of the interplay between such conditions from epidemiological and physiological standpoints. With this review, we summarized the available literature surrounding the relationship between cognitive impairment, dementia, and both low bone mineral density (BMD) and fragility fractures. Given the strength of the bi-directional associations and their impact on the quality of life, we shed light on the biological connections between brain and bone systems, presenting the main mediators, including gut microbioma, and pathological pathways leading to the dysregulation of bone and brain metabolism. Ultimately, we synthesized the evidence about the impact of available pharmacological treatments for the prevention of fragility fractures on cognitive functions and individuals' outcomes when dementia coexists. Vice versa, the effects of symptomatic treatments for dementia on the risk of falls and fragility fractures are explored. Combining evidence alongside clinical practice, we discuss challenges and opportunities related to the management of older adults affected by cognitive impairment or dementia and at high risk for fragility fracture prevention, which leads to not only an improvement in patient health-related outcomes and survival but also a reduction in healthcare cost and socio-economic burden.

Akkermansia muciniphila: key player in metabolic and gastrointestinal disorders.

OBJECTIVE: Gut microbiota has a key role in host metabolic regulation and immune response, and its dysbiosis represents one of the main causes of gastrointestinal diseases. In this scenario, Akkermansia muciniphila is a crucial player in keeping the integrity of the gastrointestinal tract. MATERIALS AND METHODS: This review focuses on the correlation between gut microbiota and intestinal homeostasis, primarily exploring A. muciniphila and its involvement in the development of metabolic disorders and gastrointestinal diseases. RESULTS: Akkermansia muciniphila belongs to the Verrucomicrobia phylum, and it colonizes the mucus layer in the gastrointestinal tract, representing 1 to 4% of the fecal microbiota. It stimulates mucosal microbial networks, and it improves intestinal barrier function, providing crucial host immunological responses. Several studies have demonstrated the possible involvement of A. muciniphila in the development of intestinal and metabolic disorders. Indeed, adipose and glucose metabolisms are influenced by A. muciniphila, and its levels inversely correlate to inflammatory conditions, such as inflammatory bowel disease, obesity, and diabetes. Conversely, its therapeutic administration decreases their development. CONCLUSIONS: A. muciniphila exerts a key role in the maintenance of intestinal health and in host metabolic modulation. Future studies could open new horizons towards its potential therapeutic applications in gastrointestinal and extra-intestinal diseases.