Menopause and Alzheimer's disease susceptibility: Exploring the potential mechanisms

The gut microbiota in menopause: Is there a role for prebiotic and probiotic solutions?

The gut microbiota, comprising a diverse array of microorganisms in the gastrointestinal tract, has emerged as a key player in human health. Emerging research indicates that this gut microbial composition is influenced by sex. These sex differences are not necessarily static and likely alter across the life course in response to several factors including changing hormone profile. As such, the menopause transition-a pivotal phase in female ageing in which the hormone profile changes dramatically is receiving increasing attention. Declining estrogen which occurs during menopause appears to influence the microbiota, which may in turn contribute to menopause-related conditions such as weight gain, bone health, cancer risk and cognitive health. The modulation of estrogen through the gut's 'estrobolome', a collection of bacterial genes involved in estrogen metabolism, may offer explanation for some of the interindividual differences observed during menopause (e.g. length, symptoms and disease risk). Therapeutic modulation of the gut microbiota therefore represents a potential approach towards managing menopausal symptoms. Indeed, prebiotics and probiotics such as Lactobacillus have been shown to increase bacterial diversity and improve metabolic and overall health in menopausal women. However, evidence remains limited regarding the specific underlying mechanisms, highlighting an urgent need for a research focus in the area. This review summarizes the current understanding of the gut microbiota's role in menopausal health and the potential of prebiotics and probiotics as therapeutic interventions. Further research into gut microbiota modulation may enable more effective, personalised treatments for menopause-associated health challenges, and supporting women's health into older ages.

The Role of Astrocytes in the Molecular Pathophysiology of Schizophrenia: Between Neurodevelopment and Neurodegeneration

Schizophrenia is a chronic and severe psychiatric disorder affecting approximately 1% of the global population, characterized by disrupted synaptic plasticity and brain connectivity. While substantial evidence supports its classification as a neurodevelopmental disorder, non-canonical neurodegenerative features have also been reported, with increasing attention given to astrocytic dysfunction. Overall, in this study, we explore the role of astrocytes as a structural and functional link between neurodevelopment and neurodegeneration in schizophrenia. Specifically, we examine how astrocytes contribute to forming an aberrant substrate during early neurodevelopment, potentially predisposing individuals to later neurodegeneration. Astrocytes regulate neurotransmitter homeostasis and synaptic plasticity, influencing early vulnerability and disease progression through their involvement in Ca2⁺ signaling and dopamine-glutamate interaction-key pathways implicated in schizophrenia pathophysiology. Astrocytes differentiate via nuclear factor I-A, Sox9, and Notch pathways, occurring within a neuronal environment that may already be compromised in the early stages due to the genetic factors associated with the 'two-hits' model of schizophrenia. As a result, astrocytes may contribute to the development of an altered neural matrix, disrupting neuronal signaling, exacerbating the dopamine-glutamate imbalance, and causing excessive synaptic pruning and demyelination. These processes may underlie both the core symptoms of schizophrenia and the increased susceptibility to cognitive decline-clinically resembling neurodegeneration but driven by a distinct, poorly understood molecular substrate. Finally, astrocytes are emerging as potential pharmacological targets for antipsychotics such as clozapine, which may modulate their function by regulating glutamate clearance, redox balance, and synaptic remodeling.

Associations of dietary protein and amino acid intakes with disability-adjusted life years for Alzheimer's disease in Japanese people

BackgroundThe number of patients with dementia is increasing worldwide. In Japan, dementia is the most significant reason recognized for people requiring nursing care. Protein is one of the possible preventive nutrients for dementia; however, adequate intake levels can differ according to usual protein intakes and protein sources.ObjectiveThis study examined the relationships between disability-adjusted life years (DALYs) for Alzheimer's disease and protein or amino acid intakes.MethodsGlobal Burden of Disease Study data (DALYs for each sex and age group in each year) and de-identified individual records from the National Health and Nutrition Survey Japan (data from 46,831 subjects) from 2001 to 2019 were used. Multiple regression analyses were conducted to assess the relationships between DALYs and protein or amino acid intakes with lifestyle factors and sociodemographic index as confounding factors.ResultsHigher protein-to-energy ratios were correlated with lower DALYs in women in their 70 s (partial regression coefficient [Coeff.] = -349.488, p = 0.034), in men in their 60 s (Coeff. = -51.484), and in both sexes combined in their 60 s (Coeff. = -26.696, p = 0.015) even after adjusting for other possible nutrient intakes. Additionally, elevated isoleucine, lysine, tyrosine, histidine, arginine, alanine, asparagine, and glycine levels were correlated with lower DALYs in women in their 70 s (Coeff. = -2.752 to -0.141).ConclusionsAdequate protein and specific amino acid intakes may be associated with DALYs for Alzheimer's disease.

Unveiling FOXO3's metabolic contribution to menopause and Alzheimer's disease

The increasing prevalence of Alzheimer's disease (AD) calls for a comprehensive exploration of its complex etiology, with a focus on sex-specific vulnerability, particularly the heightened susceptibility observed in postmenopausal women. Neurometabolic alterations during the endocrine transition emerge as early indicators of AD pathology, including reduced glucose metabolism and increased amyloid-beta (Aβ) deposition. The fluctuating endocrine environment, marked by declining estradiol levels and reduced estrogen receptor beta (ERβ) activity, further exacerbates this process. In this context, here we explore the potential of forkhead box O3 (FOXO3) as a critical mediator linking metabolic disturbances to hormonal decline. We propose that FOXO3 plays a key role in the intersection of menopause and AD, given its dysregulation in both AD patients and postmenopausal women, modulating cellular metabolism through interactions with the AMPK/AKT/PI3K pathways. This relationship highlights the intersection between hormonal changes and increased AD susceptibility. This review aims to open a discussion on FOXO3's contribution to the metabolic dysregulation seen in menopause and its impact on the progression of AD. Understanding the functional role of FOXO3 in menopause-associated metabolic changes could lead to targeted therapeutic strategies, offering novel insights for managing for this condition.