Metformin, Cognitive Function, and Changes in the Gut Microbiome

IUPHAR review: From gut to brain: The role of gut dysbiosis, bacterial amyloids, and metabolic disease in Alzheimer's disease

Gut microbial dysbiosis, or altered gut microbial communities, in Alzheimer's Disease suggests a pathogenic role for gut inflammation and microbial products in shaping a neuroinflammatory environment. Similarly, metabolic diseases, such as obesity and diabetes, are also associated with an increased risk of Alzheimer's Disease. As the metabolic landscape shifts during gut inflammation, and gut inflammation in turn impacts metabolic processes, we explore how these interconnected pathways may contribute to the progression of Alzheimer's Disease. Additionally, we discuss the role of bacterial amyloids produced by gut microbes, which may exacerbate amyloid aggregation in the brain and contribute to neurodegenerative processes. Furthermore, we highlight potential therapeutic strategies aimed at reducing gut inflammation, improving metabolic health, and decreasing amyloid content as a means to mitigate Alzheimer's Disease progression. These approaches, targeting the gut-brain-metabolic axis, could offer promising avenues for delaying or preventing cognitive decline in affected individuals.

Metformin and Cognitive Performance in Patients With Type 2 Diabetes: An Umbrella Review

Contradictory results for the association between metformin intake and changes in cognitive function have been reported. We attempted to overview systematic reviews and meta-analyses showing the role of metformin, as mono or combination therapy, in cognitive performance alterations among patients with type 2 diabetes mellitus (T2DM) and to determine the quality of the evidence as well. To find the English-written reviews, a literature search was conducted on PubMed, Web of Science, Scopus, Cochrane Library, Trip, and Google Scholar by May 1, 2023. The literature search unearthed 2672 records, 10 of which were included in the study. Metformin may provide cognitive benefits for patients with type 2 diabetes, as evidence suggests potential improvements in memory and a reduced risk of neurodegenerative diseases. Even though the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) score alterations correspond to raising concerns about cognitive decline, Mini-Mental State Examination (MMSE) and selective reminding test (SRT) score improvements support metformin's role in improving specific cognitive domains. As such, metformin may exert differential impacts on various aspects of cognitive performance in these patients. However, the inconsistency and low quality of current evidence point toward the need for accurate research to elucidate whether metformin's cognitive effects are protective, neutral, or context-dependent based on patient profiles.

The gut microbiome across the lifespan: how diet modulates our microbial ecosystem from infancy to the elderly

This comprehensive review examines the impact of dietary patterns on gut microbiome composition and diversity from infancy to old age, linking these changes to age-related health outcomes. It investigates how the gut microbiome develops and changes across life stages, focusing on the influence of dietary factors. The review explores how early-life feeding practices, including breastfeeding and formula feeding, shape the infant gut microbiota and have lasting effects. In elderly individuals, alterations in the gut microbiome are associated with increased susceptibility to infections, chronic inflammation, metabolic disorders and cognitive decline. The critical role of diet in modulating the gut microbiome throughout life is emphasised, particularly the potential benefits of probiotics and fortified foods in promoting healthy ageing. By elucidating the mechanisms connecting food systems to gut health, this review provides insights into interventions that could enhance gut microbiome resilience and improve health outcomes across the lifespan.

Metformin's Effects on Cognitive Function from a Biovariance Perspective: A Narrative Review

This study examines the effects of metformin on brain functions focusing on the variability of the results reported in the literature. While some studies suggest that metformin may have neuroprotective effects in diabetic patients, others report an insignificant impact of metformin on cognitive function, or even a negative effect. We propose that this inconsistency may be due to intrinsic cellular-level variability among individuals, which we term "biovariance". Biovariance persists even in demographically homogeneous samples due to complex and stochastic biological processes. Additionally, the complex metabolic actions of metformin, including its influence on neuroenergetics and neuronal survival, may produce different effects depending on individual metabolic characteristics.

The Anti-Aging Mechanism of Metformin: From Molecular Insights to Clinical Applications

Aging represents a complex biological phenomenon marked by the progressive deterioration of physiological functions over time, reduced resilience, and increased vulnerability to age-related diseases, ultimately culminating in mortality. Recent research has uncovered diverse molecular mechanisms through which metformin extends its benefits beyond glycemic control, presenting it as a promising intervention against aging. This review delves into the anti-aging properties of metformin, highlighting its role in mitochondrial energy modulation, activation of the AMPK-mTOR signaling pathway, stimulation of autophagy, and mitigation of inflammation linked to cellular aging. Furthermore, we discuss its influence on epigenetic modifications that underpin genomic stability and cellular homeostasis. Metformin's potential in addressing age-associated disorders including metabolic, cardiovascular, and neurodegenerative diseases is also explored. The Targeting Aging with Metformin (TAME) trial aims to provide key evidence on its efficacy in delaying aging in humans. Despite these promising insights, significant challenges persist in gaining a more comprehensive understanding into its underlying mechanisms, determining optimal dosing strategies, and evaluating long-term safety in non-diabetic populations. Addressing these challenges is crucial to fully realizing metformin's potential as an anti-aging therapeutic.

The oral-gut microbiota axis: a link in cardiometabolic diseases

The oral-gut microbiota axis plays a crucial role in cardiometabolic health. This review explores the interactions between these microbiomes through enteric, hematogenous, and immune pathways, resulting in disruptions in microbial balance and metabolic processes. These disruptions contribute to systemic inflammation, metabolic disorders, and endothelial dysfunction, which are closely associated with cardiometabolic diseases. Understanding these interactions provides insights for innovative therapeutic strategies to prevent and manage cardiometabolic diseases.

Metformin in Antiviral Therapy: Evidence and Perspectives

Metformin, a widely used antidiabetic medication, has emerged as a promising broad-spectrum antiviral agent due to its ability to modulate cellular pathways essential for viral replication. By activating AMPK, metformin depletes cellular energy reserves that viruses rely on, effectively limiting the replication of pathogens such as influenza, HIV, SARS-CoV-2, HBV, and HCV. Its role in inhibiting the mTOR pathway, crucial for viral protein synthesis and reactivation, is particularly significant in managing infections caused by HIV, CMV, and EBV. Furthermore, metformin reduces oxidative stress and reactive oxygen species (ROS), which are critical for replicating arboviruses such as Zika and dengue. The drug also regulates immune responses, cellular differentiation, and inflammation, disrupting the life cycle of HPV and potentially other viruses. These diverse mechanisms suppress viral replication, enhance immune system functionality, and contribute to better clinical outcomes. This multifaceted approach highlights metformin's potential as an adjunctive therapy in treating a wide range of viral infections.

Recognition of mild cognitive impairment in older adults using a polynomial regression model based on prefrontal cortex hemoglobin oxygenation

AIM

This study employed a three-minute game-based intelligence test (GBIT) to create a hemoglobin polynomial regression model for early identification of mild cognitive impairment (MCI) in older adults.

METHODS

210 older adult participants were recruited from community centers in the central region of Taichung City. Working memory (WM) performance in older adults was assessed during GBIT, while hemoglobin responses were measured by near-infrared spectroscopy (NIRS). Variables included oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb). Data sequences underwent a fitting procedure using a transformed cubic polynomial function. The transformed coefficients were used as predictors of a logistic regression model to recognize MCI in older adults.

RESULTS

This study confirmed the relationship between age and cognitive performance. The findings demonstrate that the NIRS cubic polynomial function trends during the GBIT test showed significant changes in older adults, increasing with age. Logistic regression analysis identified age and the orientation (coefficient a) of HHb as the main factors for recognizing MCI. The model achieved an overall precision of 83.33 % (sensitivity = 75.00 %; specificity = 84.68 %) with the formula: ln (Odds [MCI]) = -1.64 + 0.57 × HHb_a + 1.40 × age.

CONCLUSIONS

NIRS hemoglobin response characteristics during GBIT may serve as an efficient indicator of MCI in older adults. These findings may advance the field of cognitive health evaluation, resulting in earlier detection of cognitive deterioration in older adults.

Synergistic Interplay of Diet, Gut Microbiota, and Insulin Resistance: Unraveling the Molecular Nexus

This comprehensive review explores the intricate relationship between gut microbiota, diet, and insulin resistance, emphasizing the novel roles of diet-induced microbial changes in influencing metabolic health. It highlights how diet significantly influences gut microbiota composition, with different dietary patterns fostering diverse microbial communities. These diet-induced changes in the microbiome impact human metabolism by affecting inflammation, energy balance, and insulin sensitivity, particularly through microbial metabolites like short-chain fatty acids (SCFAs). Focusing the key mediators like endotoxemia and systemic inflammation, and introduces personalized microbiome-based therapeutic strategies, it also investigates the effects of dietary components-fiber, polyphenols, and lipids-on microbiota and insulin sensitivity, along with the roles of protein intake and amino acid metabolism. The study compares the effects of Western and Mediterranean diets on the microbiota-insulin resistance axis. Therapeutic implications, including probiotics, fecal microbiota transplantation (FMT), and personalized diets, are discussed. Key findings reveal that high-fat diets, especially those rich in saturated fats, contribute to dysbiosis and increased intestinal permeability, while high-fiber diets promote beneficial bacteria and SCFAs. The review underscores the future potential of food and microbiota interventions for preventing or managing insulin resistance.

Metformin's dual impact on Gut microbiota and cardiovascular health: A comprehensive analysis

Cardiovascular diseases (CVD) cause significant global morbidity, mortality and public health burden annually. CVD alters richness, diversity, and composition of Gut microbiota along with RAS and histopathological differences. Present study explores Metformin role in mitigating doxorubicin induced cardiovascular toxicity/remodeling. Animals were divided into 4 groups with n=6: Group I (N. Control) free access to diet and water; Group II (MET. Control) on oral Metformin (250 mg/kg) daily; Group III (DOX. Control) alternate day intraperitoneal Doxorubicin (3 mg/kg) totaling 18 mg/kg; Group IV (DOX. MET. Control) received both daily oral Metformin (250 mg/kg) and alternate day Doxorubicin (3 mg/kg). Gut microbial analysis was made from stool before animals were sacrificed for biochemical and histopathological analysis. Significant alterations were observed in ɑ and β-diversity with new genus from Firmicutes, specifically Clostridia_UCG-014, Eubacterium ruminantium, and Tunicibacter, were prevalent in both the DOX. Control and DOX.MET groups. Proteobacteria, represented by Succinivibrio, were absent in all groups. Additionally, Parabacteroides from the Bacteroidia phylum was absent in all groups except the N. control. In the DOX.MET Control group, levels of Angiotensin II ( 7.75± 0.49 nmol/min, p<0.01) and Renin (2.60±0.26 ng/ml/hr) were significantly reduced. Conversely, levels of CK-MB, Fibrinogen, Troponin, CRP ( p < 0.0001), and TNFɑ (p < 0.05) were elevated. Histopathological examination revealed substantial cardiac changes, including Fibrinogen and fat deposition and eosinophilic infiltration, as well as liver damage characterized by binucleated cells and damaged hepatocytes, along with altered renal tissues in the DOX.MET.Control group. The findings suggest that MET. significantly modifies gut microbiota, particularly impacting the Firmicutes and Proteobacteria phyla. The reduction in Angiotensin II levels, alongside increased inflammatory markers and myocardial damage, highlights the complex interactions and potential adverse effects associated with MET therapy on cardiovascular health.

Overview of Psychiatric Medications in the Pipeline in Phase III Trials as of June 1, 2024: A Systematic Review

Objective

This systematic review provides an overview of psychiatric medications in the late stages of development (Phase III clinical trials) as of June 1, 2024. It details the mechanisms of action, efficacy, dosing, and adverse effects of these medications.

Methods

We searched the PubMed database for Phase III studies of psychiatric medications published until June 1, 2024, using the keywords "psychiatric" OR "psychopharm*" AND "medic*" OR "pharm*". Our review encompassed medications currently undergoing Phase III clinical trials and those that have completed Phase III but are awaiting approval from the United States Food and Drug Administration (FDA). We independently analyzed the identified studies and reached a consensus on the medications to be included in this systematic review.

Results

As of June 1, 2024, a total of 89 pipeline drug trials were identified, including nine for schizophrenia, five for bipolar disorders, 25 for depressive disorders, 11 for anxiety disorders, five for post-traumatic stress disorder (PTSD), one for obsessive compulsive disorder (OCD), two for eating disorders, two for sleep-wake disorders, three for sexual dysfunctions, one for substance-related and addictive disorders, 22 for neurocognitive disorders, and three for neurodevelopmental disorders, specifically attention deficit hyperactivity disorder (ADHD).

Conclusion

The psychiatric medications in the pipeline as of June 1, 2024, demonstrate significant promise in treating psychiatric disorders.

Electron transport chain capacity expands yellow fever vaccine immunogenicity

Vaccination has successfully controlled several infectious diseases although better vaccines remain desirable. Host response to vaccination studies have identified correlates of vaccine immunogenicity that could be useful to guide development and selection of future vaccines. However, it remains unclear whether these findings represent mere statistical correlations or reflect functional associations with vaccine immunogenicity. Functional associations, rather than statistical correlates, would offer mechanistic insights into vaccine-induced adaptive immunity. Through a human experimental study to test the immunomodulatory properties of metformin, an anti-diabetic drug, we chanced upon a functional determinant of neutralizing antibodies. Although vaccine viremia is a known correlate of antibody response, we found that in healthy volunteers with no detectable or low yellow fever 17D viremia, metformin-treated volunteers elicited higher neutralizing antibody titers than placebo-treated volunteers. Transcriptional and metabolomic analyses collectively showed that a brief course of metformin, started 3 days prior to YF17D vaccination and stopped at 3 days after vaccination, expanded oxidative phosphorylation and protein translation capacities. These increased capacities directly correlated with YF17D neutralizing antibody titers, with reduced reactive oxygen species response compared to placebo-treated volunteers. Our findings thus demonstrate a functional association between cellular respiration and vaccine-induced humoral immunity and suggest potential approaches to enhancing vaccine immunogenicity.

Anti-Aging Drugs and the Related Signal Pathways

Aging is a multifactorial biological process involving chronic diseases that manifest from the molecular level to the systemic level. From its inception to 31 May 2022, this study searched the PubMed, Web of Science, EBSCO, and Cochrane library databases to identify relevant research from 15,983 articles. Multiple approaches have been employed to combat aging, such as dietary restriction (DR), exercise, exchanging circulating factors, gene therapy, and anti-aging drugs. Among them, anti-aging drugs are advantageous in their ease of adherence and wide prevalence. Despite a shared functional output of aging alleviation, the current anti-aging drugs target different signal pathways that frequently cross-talk with each other. At present, six important signal pathways were identified as being critical in the aging process, including pathways for the mechanistic target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), nutrient signal pathway, silent information regulator factor 2-related enzyme 1 (SIRT1), regulation of telomere length and glycogen synthase kinase-3 (GSK-3), and energy metabolism. These signal pathways could be targeted by many anti-aging drugs, with the corresponding representatives of rapamycin, metformin, acarbose, nicotinamide adenine dinucleotide (NAD+), lithium, and nonsteroidal anti-inflammatory drugs (NSAIDs), respectively. This review summarized these important aging-related signal pathways and their representative targeting drugs in attempts to obtain insights into and promote the development of mechanism-based anti-aging strategies.