Metformin vs sulfonylurea use and risk of dementia in US veterans aged ≥65 years with diabetes

Effect of metformin in hypothalamic astrocytes from an immunocompromised mice model

Astrocytes are glial cells that play key roles in neuroinflammation, which is a common feature in diabetic encephalopathy and aging process. Metformin is an antidiabetic compound that shows neuroprotective properties, including in inflammatory models, but astroglial signaling pathways involved are still poorly known. Interferons α/β are cytokines that participate in antiviral responses and the lack of their signaling increases susceptible to viral infections. Here, we investigated the effects of metformin on astrocytes from hypothalamus, a crucial brain region related to inflammatory processes. Astrocyte cultures were derived from interferon α/β receptor knockout (IFNα/βR-/-) and wild-type (WT) mice. Metformin did not change the expression of glial fibrillary acidic protein but caused an anti-inflammatory effect by decreasing pro-inflammatory cytokines (tumor necrosis factor-α and interleukin-1β), as well as increasing gene expression of anti-inflammatory proteins interleukin-10 and Nrf2 (nuclear factor erythroid derived 2 like 2). However, nuclear factor κB p65 and cyclooxygenase 2 were downregulated in WT astrocytes and upregulated in IFNα/βR-/- astrocytes. AMP-activated protein kinase (AMPK), a molecular target of metformin, was upregulated only in WT astrocytes, while sirtuin 1 increased in both mice models. The expression of inducible nitric oxide synthase was decreased in WT astrocytes and heme oxygenase 1 was increased in IFNα/βR-/- astrocytes. Although loss of IFNα/βR-mediated signaling affects some effects of metformin, our results support beneficial roles of this drug in hypothalamic astrocytes. Moreover, paradoxical response of metformin may involve AMPK. Thus, metformin can mediate glioprotection due its effects on age-related disorders in non-diabetic and diabetic encephalopathy individuals.

Glycated Hemoglobin A1c Time in Range and Dementia in Older Adults With Diabetes

Importance

Individuals with diabetes commonly experience Alzheimer disease and related dementias (ADRD). Factors such as hypoglycemia, hyperglycemia, and glycemic variability have been associated with increased risk of ADRD. Traditional glycemic measures, such as mean glycated hemoglobin A1c (HbA1c), may not identify the dynamic and complex pathophysiologic factors in the association between diabetes and ADRD. The HbA1c time in range (TIR) is a previously developed measure of glycemic control that expresses HbA1c stability over time within specific ranges. This measure may inform the current understanding of the association between glucose levels over time and ADRD incidence.

Objective

To examine the association between HbA1c TIR and incidence of ADRD in older veterans with diabetes.

Design, Setting, and Participants

The study sample for this cohort study was obtained from administrative and health care utilization data from the Veterans Health Administration and Medicare from January 1, 2004, to December 31, 2018. Veterans 65 years or older with diabetes were assessed. Participants were required to have at least 4 HbA1c tests during the 3-year baseline period, which could start between January 1, 2005, and December 31, 2014. Data analysis was conducted between July and December 2023.

Main Outcomes and Measures

Hemoglobin A1c TIR was calculated as the percentage of days during baseline in which HbA1c was in individualized target ranges based on clinical characteristics and life expectancy, with higher HbA1c TIR viewed as more favorable. The association between HbA1c TIR and ADRD incidence was estimated. Additional models considered ADRD incidence in participants who were above or below HbA1c target ranges most of the time.

Results

The study included 374 021 veterans with diabetes (mean [SD] age, 73.2 [5.8] years; 369 059 [99%] male). During follow-up of up to 10 years, 41 424 (11%) developed ADRD. Adjusted Cox proportional hazards regression models showed that lower HbA1c TIR was associated with increased risk of incident ADRD (HbA1c TIR of 0 to <20% compared with ≥80%: hazard ratio, 1.19; 95% CI, 1.16-1.23). Furthermore, the direction of out-of-range HbA1c levels was associated with incident ADRD. Having greater time below range (≥60%, compared with ≥60% TIR) was associated with significantly increased risk (hazard ratio, 1.23; 95% CI, 1.19-1.27). Findings remained significant after excluding individuals with baseline use of medications associated with hypoglycemia risk (ie, insulin and sulfonylureas) or with hypoglycemia events.

Conclusions and Relevance

In this study of older adults with diabetes, increased HbA1c stability within patient-specific target ranges was associated with a lower risk of ADRD. Lower HbA1c TIR may identify patients at increased risk of ADRD.

Metformin-induced changes in the gut microbiome and plasma metabolome are associated with cognition in men

BACKGROUND

An altered gut microbiome characterized by reduced abundance of butyrate producing bacteria and reduced gene richness is associated with type 2 diabetes (T2D). An important complication of T2D is increased risk of cognitive impairment and dementia. The biguanide metformin is a commonly prescribed medication for the control of T2D and metformin treatment has been associated with a significant reduction in the risk of dementia and improved cognition, particularly in people with T2D.

AIM

To investigate the associations of metformin use with cognition exploring potential mechanisms by analyzing the gut microbiome and plasma metabolome using shotgun metagenomics and HPLC-ESI-MS/MS, respectively.

METHODS

We explored two independent cohorts: an observational study (Aging Imageomics) and a phase IV, randomized, double-blind, parallel-group, randomized pilot study (MEIFLO). From the two studies, we analyzed four study groups: (1) individuals with no documented medical history or medical treatment (n = 172); (2) people with long-term T2D on metformin monotherapy (n = 134); (3) people with long-term T2D treated with oral hypoglycemic agents other than metformin (n = 45); (4) a newly diagnosed T2D subjects on metformin monotherapy (n = 22). Analyses were also performed stratifying by sex.

RESULTS

Several bacterial species belonging to the Proteobacteria (Escherichia coli) and Verrucomicrobia (Akkermansia muciniphila) phyla were positively associated with metformin treatment, while bacterial species belonging to the Firmicutes phylum (Romboutsia timonensis, Romboutsia ilealis) were negatively associated. Due to the consistent increase in A. muciniphila and decrease in R.ilealis in people with T2D subjects treated with metformin, we investigated the association between this ratio and cognition. In the entire cohort of metformin-treated T2D subjects, the A.muciniphila/R.ilealis ratio was not significantly associated with cognitive test scores. However, after stratifying by sex, the A.muciniphila/R. ilealis ratio was significantly and positively associated with higher memory scores and improved memory in men. Metformin treatment was associated with an enrichment of microbial pathways involved in the TCA cycle, and butanoate, arginine, and proline metabolism in both cohorts. The bacterial genes involved in arginine metabolism, especially in production of glutamate (astA, astB, astC, astD, astE, putA), were enriched following metformin intake. In agreement, in the metabolomics analysis, metformin treatment was strongly associated with the amino acid proline, a metabolite involved in the metabolism of glutamate.

CONCLUSIONS

The beneficial effects of metformin may be mediated by changes in the composition of the gut microbiota and microbial-host-derived co-metabolites.

Intricacies of aging and Down syndrome

Down syndrome is the most frequently occurring genetic condition, with a substantial escalation in risk associated with advanced maternal age. The syndrome is characterized by a diverse range of phenotypes, affecting to some extent all levels of organization, and its progeroid nature - early manifestation of aspects of the senile phenotype. Despite extensive investigations, many aspects and mechanisms of the disease remain unexplored. The current review aims to provide an overview of the main causes and manifestations of Down syndrome, while also examining the phenomenon of accelerated aging and exploring potential therapeutic strategies.

Heterogeneous treatment effects of sodium-glucose cotransporter 2 inhibitors on risk of dementia in people with type 2 diabetes: A population-based cohort study

INTRODUCTION

Sodium-glucose cotransporter 2 (SGLT2) inhibitors exhibit potential benefits in reducing dementia risk, yet the optimal beneficiary subgroups remain uncertain.

METHODS

Individuals with type 2 diabetes (T2D) initiating either SGLT2 inhibitor or sulfonylurea were identified from OneFlorida+ Clinical Research Network (2016-2022). A doubly robust learning was deployed to estimate risk difference (RD) and 95% confidence interval (CI) of all-cause dementia.

RESULTS

Among 35,458 individuals with T2D, 1.8% in the SGLT2 inhibitor group and 4.7% in the sulfonylurea group developed all-cause dementia over a 3.2-year follow-up, yielding a lower risk for SGLT2 inhibitors (RD, -2.5%; 95% CI, -3.0% to -2.1%). Hispanic ethnicity and chronic kidney disease were identified as the two important variables to define four subgroups in which RD ranged from -4.3% (-5.5 to -3.2) to -0.9% (-1.9 to 0.2).

DISCUSSION

Compared to sulfonylureas, SGLT2 inhibitors were associated with a reduced risk of all-cause dementia, but the association varied among different subgroups.

HIGHLIGHTS

New users of sodium-glucose cotransporter 2 (SGLT2) inhibitors were significantly associated with a lower risk of all-cause dementia as compared to those of sulfonylureas. The association varied among different subgroups defined by Hispanic ethnicity and chronic kidney disease. A significantly lower risk of Alzheimer's disease and vascular dementia was observed among new users of SGLT2 inhibitors compared to those of sulfonylureas.

Unveiling the impact of aging on BBB and Alzheimer's disease: Factors and therapeutic implications

Alzheimer's disease (AD) is a highly prevalent neurodegenerative condition that has devastating effects on individuals, often resulting in dementia. AD is primarily defined by the presence of extracellular plaques containing insoluble β-amyloid peptide (Aβ) and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein (P-tau). In addition, individuals afflicted by these age-related illnesses experience a diminished state of health, which places significant financial strain on their loved ones. Several risk factors play a significant role in the development of AD. These factors include genetics, diet, smoking, certain diseases (such as cerebrovascular diseases, obesity, hypertension, and dyslipidemia), age, and alcohol consumption. Age-related factors are key contributors to the development of vascular-based neurodegenerative diseases such as AD. In general, the process of aging can lead to changes in the immune system's responses and can also initiate inflammation in the brain. The chronic inflammation and the inflammatory mediators found in the brain play a crucial role in the dysfunction of the blood-brain barrier (BBB). Furthermore, maintaining BBB integrity is of utmost importance in preventing a wide range of neurological disorders. Therefore, in this review, we discussed the role of age and its related factors in the breakdown of the blood-brain barrier and the development of AD. We also discussed the importance of different compounds, such as those with anti-aging properties, and other compounds that can help maintain the integrity of the blood-brain barrier in the prevention of AD. This review builds a strong correlation between age-related factors, degradation of the BBB, and its impact on AD.

Novel targets and therapies of metformin in dementia: old drug, new insights

Dementia is a devastating disorder characterized by progressive and persistent cognitive decline, imposing a heavy public health burden on the individual and society. Despite numerous efforts by researchers in the field of dementia, pharmacological treatments are limited to relieving symptoms and fail to prevent disease progression. Therefore, studies exploring novel therapeutics or repurposing classical drugs indicated for other diseases are urgently needed. Metformin, a first-line antihyperglycemic drug used to treat type 2 diabetes, has been shown to be beneficial in neurodegenerative diseases including dementia. This review discusses and evaluates the neuroprotective role of metformin in dementia, from the perspective of basic and clinical studies. Mechanistically, metformin has been shown to improve insulin resistance, reduce neuronal apoptosis, and decrease oxidative stress and neuroinflammation in the brain. Collectively, the current data presented here support the future potential of metformin as a potential therapeutic strategy for dementia. This study also inspires a new field for future translational studies and clinical research to discover novel therapeutic targets for dementia.

Metformin mitigates dementia risk among individuals with type 2 diabetes

This mini-narrative review explores the relationship between diabetes and dementia, focusing on the potential mitigating role of metformin in reducing cognitive decline among individuals with type 2 diabetes. The interplay of factors such as glycemic control, diabetic complications, and lifestyle influences characterises diabetes-related dementia. This review emphasises the significance of comprehensive diabetes management in addressing the heightened risk of dementia in this population. Methodologically, the review synthesises evidence from 23 studies retrieved through searches on PubMed, Embase, Google Scholar, and Scopus. Current evidence suggests a predominantly positive association between metformin use and a reduced risk of dementia in individuals with diabetes. However, the review shows the complex nature of these outcomes, revealing variations in results in some studies. These discrepancies show the importance of exploring dose-response relationships, long-term effects, and demographic diversity to unravel the complexities of metformin's impact on cognitive health. Limitations in the existing body of research, including methodological disparities and confounding variables, necessitate refined approaches in future studies. Large-scale prospective longitudinal studies and randomised controlled trials focusing specifically on cognitive effects are recommended. Propensity score matching and exploration of molecular mechanisms can enhance the validity of findings in clinical practice. From a clinical perspective, metformin can serve as a potential adjunctive therapy for individuals with diabetes at risk of cognitive decline.

Risk of Dementia and Alzheimer's Disease Associated With Antidiabetics: A Bayesian Network Meta-Analysis

INTRODUCTION

Dementia risk is substantially elevated in patients with diabetes. However, evidence on dementia risk associated with various antidiabetic regimens is still limited. This study aims to comprehensively investigate the risk of dementia and Alzheimer's disease (AD) associated with various antidiabetic classes.

METHODS

Cochrane Central Register of Controlled Trials, Embase, MEDLINE (PubMed), and Scopus were searched from inception to March 2024 (PROSPERO CRD 42022365927). Observational studies investigating dementia and AD incidences after antidiabetic initiation were identified. Bayesian network meta-analysis was performed to determine dementia and AD risks associated with antidiabetics. Preferred Reporting Items for Systematic Reviews-Network Meta-Analyses (PRISMA-NMA) guidelines were followed. Statistical analysis was performed and updated in November 2023 and March 2024, respectively.

RESULTS

A total of 1,565,245 patients from 16 studies were included. Dementia and AD risks were significantly lower with metformin and sodium glucose co-transporter-2 inhibitors (SGLT2i). Metformin displayed the lowest risk of dementia across diverse antidiabetics, whereas α-glucosidase inhibitors demonstrated the highest risk. SGLT2i exhibited the lowest dementia risk across second-line antidiabetics. Dementia risk was significantly higher with dipeptidyl peptidase-4 inhibitor (DPP4i), metformin, sulfonylureas, and thiazolidinediones (TZD) compared to SGLT2i in the elderly (≥75 years). Dementia risk associated with metformin was substantially lower, regardless of diabetic complication status or baseline A1C.

DISCUSSION

Metformin and SGLT2i demonstrated lower dementia risk than other antidiabetic classes. Patient-specific factors may affect this relationship and cautious interpretation is warranted as metformin is typically initiated at an earlier stage with fewer complications. Hence, further large-scaled clinical trials are required.

Initiation of Statins for Primary Prevention in Heart Failure With Preserved Ejection Fraction

Background

Statins are highly effective for primary prevention of atherosclerotic cardiovascular disease (ASCVD) and mortality. Data on the benefit of statins in adults with heart failure with preserved ejection fraction (HFpEF) and without ASCVD are limited.

Objectives

The purpose of this study was to determine whether statins are associated with a lower risk of mortality and major adverse cardiovascular events (MACE) in HFpEF.

Methods

Veterans Health Administration data from 2002 to 2016, linked to Medicare and Medicaid claims and pharmaceutical data, were collected. Patients had a new HFpEF diagnosis and no known ASCVD or prior statin use at baseline. Cox proportional hazards models were fit to evaluate the association of new statin use with outcomes (all-cause mortality and MACE). Propensity score overlap weighting (PSW) was used to balance baseline characteristics.

Results

Among 7,970 Veterans, 47% initiated a statin over a mean 6.0-year follow-up. At HFpEF diagnosis, mean age was 69 ± 12 years, 96% were male, 67% were White, 14% were Black, and mean EF was 60% ± 6%. Before PSW, statin users were younger with more prevalent metabolic syndrome, arthritis, and other chronic conditions. All characteristics were balanced after PSW. There were 5,314 deaths and 4,859 MACE events. After PSW, the hazard for all-cause mortality for statin users vs nonusers was 22% lower (HR: 0.78; 95% CI: 0.73-0.83). The HR for MACE was 0.79 (95% CI: 0.74-0.84), 0.69 (95% CI: 0.60-0.80) for all-cause hospitalization, and 0.72 (95% CI: 0.59-0.88) for HF hospitalization.

Conclusions

New statin use was associated with reduced all-cause mortality, MACE, and hospitalization in Veterans with HFpEF without prevalent ASCVD.

Metformin, Cognitive Function, and Changes in the Gut Microbiome

The decline in cognitive function and the prevalence of neurodegenerative disorders are among the most serious threats to health in old age. The prevalence of dementia has reached 50 million people worldwide and has become a major public health problem. The causes of age-related cognitive impairment are multiple, complex, and difficult to determine. However, type 2 diabetes (T2D) is linked to an enhanced risk of cognitive impairment and dementia. Human studies have shown that patients with T2D exhibit dysbiosis of the gut microbiota. This dysbiosis may contribute to the development of insulin resistance and increased plasma lipopolysaccharide concentrations. Metformin medication mimics some of the benefits of calorie restriction and physical activity, such as greater insulin sensitivity and decreased cholesterol levels, and hence may also have a positive impact on aging in humans. According to recent human investigations, metformin might partially restore gut dysbiosis related to T2D. Likewise, some studies showed that metformin reduced the risk of dementia and improved cognition, although not all studies are concordant. Therefore, this review focused on those human studies describing the effects of metformin on the gut microbiome (specifically the changes in taxonomy, function, and circulating metabolomics), the changes in cognitive function, and their possible bidirectional implications.

DPP-4 inhibition by linagliptin ameliorates age-related mild cognitive impairment by regulating microglia polarization in mice

Extensive preclinical evidence demonstrates a causative link between insulin signaling dysfunction and the pathogenesis of Alzheimer's disease (AD), and diabetic drugs may represent a promising approach to fighting AD. However, it remains to be determined which antidiabetic drugs are more effective in preventing cognitive impairment. Thus, the present study investigated the effect of dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin on cognitive impairment in middle-aged mice by comparing it with the effect of metformin. We found that DPP-4 activity increased in the hippocampus of middle-aged mice, and DPP-4 was mainly expressed by microglia rather than astrocytes and oligodendrocytes. DPP-4 directly regulated M1/M2 microglia polarization following LPS or IL-4 stimulation, while DPP-4 inhibitor, linagliptin, suppressed M1-polarized activation and induced M2-polarized activation. Both linagliptin and metformin enhanced cognitive ability, increased hippocampal synaptic plasticity and neurogenesis, and decreased age-related oxidative stress and inflammation by regulating microglia polarization in the hippocampus of middle-aged mice. The combination of linagliptin and metformin showed a maximum protective effect compared to the individual drugs alone. Loss of macrophage inflammatory protein-1α (MIP-1α), a DPP-4 substrate, abrogated the cognitive protection and anti-inflammation effects of linagliptin. Therefore, the current investigation exhibits a potential utility for DPP-4 inhibition in attenuating microglia-mediated inflammation and preventing mild cognitive impairment (MCI) in middle-aged mice, and the effect was partly mediated by MIP-1α.

The impact of sodium-glucose co-transporter-2 inhibitors on dementia and cardiovascular events in diabetic patients with atrial fibrillation

AIMS

The effectiveness of sodium-glucose co-transporter-2 inhibitors (SGLT2i) on incident dementia in patients with diabetes and atrial fibrillation (AF) remains unknown. This study aimed to investigate the association between SGLT2i and the risk of incident dementia in diabetic patients with AF, and to explore the interactions with oral anticoagulants or dipeptidyl peptidase-4 inhibitors (DPP4i).

MATERIALS AND METHODS

We conducted a cohort study using Taiwan's National Health Insurance Research Database. Patients with diabetes and AFwithout a prior history of established cardiovascular diseases, were identified. Using propensity score matching, 810 patients receiving SGLT2i were matched with 1620 patients not receiving SGLT2i. The primary outcome was incident dementia, and secondary outcomes included composite cardiovascular events and mortality.

RESULTS

After up to 5 years of follow-up, SGLT2i use was associated with a significantly lower risk of incident dementia (hazard: 0.71, 95% confidence interval: 0.51-0.98), particularly vascular dementia (HR: 0.44, 95% CI: 0.24-0.82). SGLT2i was related to reduced risks of AF-related hospitalisation (HR: 0.72, 95% CI: 0.56-0.93), stroke (HR: 0.75, 95% CI: 0.60-0.94), and all-cause death (HR: 0.33, 95% CI: 0.24-0.44). The protective effects were consistent irrespective of the concurrent use of non-vitamin K antagonist oral anticoagulants (NOACs) or DPP4i.

CONCLUSIONS

In diabetic patients with AF, SGLT2i was associated with reduced risks of incident dementia, AF-related hospitalisation, stroke, and all-cause death. The protective effects were independent of either concurrent use of NOACs or DPP4i.

Heterogeneous treatment effects of metformin on risk of dementia in patients with type 2 diabetes: A longitudinal observational study

INTRODUCTION

Little is known about the heterogeneous treatment effects of metformin on dementia risk in people with type 2 diabetes (T2D).

METHODS

Participants (≥ 50 years) with T2D and normal cognition at baseline were identified from the National Alzheimer's Coordinating Center database (2005-2021). We applied a doubly robust learning approach to estimate risk differences (RD) with a 95% confidence interval (CI) for dementia risk between metformin use and no use in the overall population and subgroups identified through a decision tree model.

RESULTS

Among 1393 participants, 104 developed dementia over a 4-year median follow-up. Metformin was significantly associated with a lower risk of dementia in the overall population (RD, -3.2%; 95% CI, -6.2% to -0.2%). We identified four subgroups with varied risks for dementia, defined by neuropsychiatric disorders, non-steroidal anti-inflammatory drugs, and antidepressant use.

DISCUSSION

Metformin use was significantly associated with a lower risk of dementia in individuals with T2D, with significant variability among subgroups.

Diabetes, antidiabetic medications and risk of dementia: A systematic umbrella review and meta-analysis

AIMS

The objective of this umbrella review and meta-analysis was to evaluate the effect of diabetes on risk of dementia, as well as the mitigating effect of antidiabetic treatments.

MATERIALS AND METHODS

We conducted a systematic umbrella review on diabetes and its treatment, and a meta-analysis focusing on treatment. We searched MEDLINE/PubMed, Embase, PsycINFO, CINAHL and the Cochrane Library for systematic reviews and meta-analyses assessing the risk of cognitive decline/dementia in individuals with diabetes until 2 July 2023. We conducted random-effects meta-analyses to obtain risk ratios and 95% confidence intervals estimating the association of metformin, thiazolidinediones, pioglitazone, dipeptidyl peptidase-4 inhibitors, α-glucosidase inhibitors, meglitinides, insulin, sulphonylureas, glucagon-like peptide-1 receptor agonists (GLP1RAs) and sodium-glucose cotransporter-2 inhibitors (SGLT2is) with risk of dementia from cohort/case-control studies. The subgroups analysed included country and world region. Risk of bias was assessed with the AMSTAR tool and Newcastle-Ottawa Scale.

RESULTS

We included 100 reviews and 27 cohort/case-control studies (N = 3 046 661). Metformin, thiazolidinediones, pioglitazone, GLP1RAs and SGLT2is were associated with significant reduction in risk of dementia. When studies examining metformin were divided by country, the only significant effect was for the United States. Moreover, the effect of metformin was significant in Western but not Eastern populations. No significant effect was observed for dipeptidyl peptidase-4 inhibitors, α-glucosidase inhibitors, or insulin, while meglitinides and sulphonylureas were associated with increased risk.

CONCLUSIONS

Metformin, thiazolidinediones, pioglitazone, GLP1RAs and SGLT2is were associated with reduced risk of dementia. More longitudinal studies aimed at determining their relative benefit in different populations should be conducted.

A multimodal precision-prevention approach combining lifestyle intervention with metformin repurposing to prevent cognitive impairment and disability: the MET-FINGER randomised controlled trial protocol

BACKGROUND

Combining multimodal lifestyle interventions and disease-modifying drugs (novel or repurposed) could provide novel precision approaches to prevent cognitive impairment. Metformin is a promising candidate in view of the well-established link between type 2 diabetes (T2D) and Alzheimer's Disease and emerging evidence of its potential neuro-protective effects (e.g. vascular, metabolic, anti-senescence). MET-FINGER aims to test a FINGER 2.0 multimodal intervention, combining an updated FINGER multidomain lifestyle intervention with metformin, where appropriate, in an APOE ε4-enriched population of older adults (60-79 years) at increased risk of dementia.

METHODS

MET-FINGER is an international randomised, controlled, parallel-group, phase-IIb proof-of-concept clinical trial, where metformin is included through a trial-within-trial design. 600 participants will be recruited at three sites (UK, Finland, Sweden). Participants at increased risk of dementia based on vascular risk factors and cognitive screening, will be first randomised to the FINGER 2.0 intervention (lifestyle + metformin if eligible; active arm) or to receive regular health advice (control arm). Participants allocated to the FINGER 2.0 intervention group at risk indicators of T2D will be additionally randomised to receive metformin (2000 mg/day or 1000 mg/day) or placebo. The study duration is 2 years. The changes in global cognition (primary outcome, using a Neuropsychological Test Battery), memory, executive function, and processing speed cognitive domains; functional status; lifestyle, vascular, metabolic, and other dementia-related risk factors (secondary outcomes), will be compared between the FINGER 2.0 intervention and the control arm. The feasibility, potential interaction (between-groups differences in healthy lifestyle changes), and disease-modifying effects of the lifestyle-metformin combination will be exploratory outcomes. The lifestyle intervention is adapted from the original FINGER trial (diet, physical activity, cognitive training, monitoring of cardiovascular/metabolic risk factors, social interaction) to be consistently delivered in three countries. Metformin is administered as Glucophage®XR/SR 500, (500 mg oral tablets). The metformin/placebo treatment will be double blinded.

CONCLUSION

MET-FINGER is the first trial combining a multimodal lifestyle intervention with a putative repurposed disease-modifying drug for cognitive impairment prevention. Although preliminary, its findings will provide crucial information for innovative precision prevention strategies and form the basis for a larger phase-III trial design and future research in this field.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT05109169).

Incident dementia risk among patients with type 2 diabetes receiving metformin versus alternative oral glucose-lowering therapy: an observational cohort study using UK primary healthcare records

INTRODUCTION

4.2 million individuals in the UK have type 2 diabetes, a known risk factor for dementia and mild cognitive impairment (MCI). Diabetes treatment may modify this association, but existing evidence is conflicting. We therefore aimed to assess the association between metformin therapy and risk of incident all-cause dementia or MCI compared with other oral glucose-lowering therapies (GLTs).

RESEARCH DESIGN AND METHODS

We conducted an observational cohort study using the Clinical Practice Research Datalink among UK adults diagnosed with diabetes at ≥40 years between 1990 and 2019. We used an active comparator new user design to compare risks of dementia and MCI among individuals initially prescribed metformin versus an alternative oral GLT using Cox proportional hazards regression controlling for sociodemographic, lifestyle and clinical confounders. We assessed for interaction by age and sex. Sensitivity analyses included an as-treated analysis to mitigate potential exposure misclassification.

RESULTS

We included 211 396 individuals (median age 63 years; 42.8% female), of whom 179 333 (84.8%) initiated on metformin therapy. Over median follow-up of 5.4 years, metformin use was associated with a lower risk of dementia (adjusted HR (aHR) 0.86 (95% CI 0.79 to 0.94)) and MCI (aHR 0.92 (95% CI 0.86 to 0.99)). Metformin users aged under 80 years had a lower dementia risk (aHR 0.77 (95% CI 0.68 to 0.85)), which was not observed for those aged ≥80 years (aHR 0.95 (95% CI 0.87 to 1.05)). There was no interaction with sex. The as-treated analysis showed a reduced effect size compared with the main analysis (aHR 0.90 (95% CI 0.83 to 0.98)).

CONCLUSIONS

Metformin use was associated with lower risks of incident dementia and MCI compared with alternative GLT among UK adults with diabetes. While our findings are consistent with a neuroprotective effect of metformin against dementia, further research is needed to reduce risks of confounding by indication and assess causality.

No association between metformin initiation and incident dementia in older adults newly diagnosed with diabetes

BACKGROUND

Metformin has been suggested to reduce dementia risk; however, most epidemiologic studies have been limited by immortal time bias or confounding due to disease severity.

OBJECTIVES

To investigate the association of metformin initiation with incident dementia using strategies that mitigate these important sources of bias.

METHODS

Residents of Ontario, Canada ≥66 years newly diagnosed with diabetes from January 1, 2008 to December 31, 2017 entered this retrospective population-based cohort. To consider the indication for metformin monotherapy initiation, people with hemoglobin A1c of 6.5%-8.0% and estimated glomerular filtration rate ≥45 mL/min/1.73 m2 were selected. Using the landmark method to address immortal time bias, exposure was grouped into "metformin monotherapy initiation within 180 days after new diabetes diagnosis" or "no glucose-lowering medications within 180 days." To address disease latency, 1-year lag time was applied to the end of the 180-day landmark period. Incident dementia was defined using a validated algorithm for Alzheimer's disease and related dementias. Adjusted hazard ratios (aHR) and confidence intervals (CIs) were estimated from propensity-score weighted Cox proportional hazard models.

RESULTS

Over mean follow-up of 6.77 years from cohort entry, metformin initiation within 180 days after new diabetes diagnosis (N = 12,331; 978 events; 65,762 person-years) showed no association with dementia risk (aHR [95% CI] = 1.05 [0.96-1.15]), compared to delayed or no glucose-lowering medication initiation (N = 22,369; 1768 events; 117,415 person-years).

CONCLUSION

Early metformin initiation was not associated with incident dementia in older adults newly diagnosed with diabetes. The utility of metformin to prevent dementia was not supported.

Metformin: The Winding Path from Understanding Its Molecular Mechanisms to Proving Therapeutic Benefits in Neurodegenerative Disorders

Metformin, a widely prescribed medication for type 2 diabetes, has garnered increasing attention for its potential neuroprotective properties due to the growing demand for treatments for Alzheimer's, Parkinson's, and motor neuron diseases. This review synthesizes experimental and clinical studies on metformin's mechanisms of action and potential therapeutic benefits for neurodegenerative disorders. A comprehensive search of electronic databases, including PubMed, MEDLINE, Embase, and Cochrane library, focused on key phrases such as "metformin", "neuroprotection", and "neurodegenerative diseases", with data up to September 2023. Recent research on metformin's glucoregulatory mechanisms reveals new molecular targets, including the activation of the LKB1-AMPK signaling pathway, which is crucial for chronic administration of metformin. The pleiotropic impact may involve other stress kinases that are acutely activated. The precise role of respiratory chain complexes (I and IV), of the mitochondrial targets, or of the lysosomes in metformin effects remains to be established by further research. Research on extrahepatic targets like the gut and microbiota, as well as its antioxidant and immunomodulatory properties, is crucial for understanding neurodegenerative disorders. Experimental data on animal models shows promising results, but clinical studies are inconclusive. Understanding the molecular targets and mechanisms of its effects could help design clinical trials to explore and, hopefully, prove its therapeutic effects in neurodegenerative conditions.

The potential protective effect of aqueous extract of Acanthophyllum glandulosum root on Streptozotocin-induced diabetes in mice

Purpose

Treatment of diabetes using traditional medicine has attracted attention in recent decades because of its unique benefits. Acanthophyllum glandulosum is known as an herb with therapeutic potential. This research explored the likely protective effects of Acanthophyllum Glandulosum Root (AGR) in mice with Streptozotocin-induced type 2 diabetes mellitus (T2DM) to provide complementary therapy.

Methods

Diabetes was induced by a single injection of Streptozotocin (STZ) in mice. STZ-diabetic mice were treated with oral dosages of AGR (25, 50, 100, and 200 mg/kg) on different experiment days. During the experiment, the effect of a topical extract of AGR on Glucose level, serum lipid profile, and liver and kidney biomarkers, with the histopathological assessment of heart, kidney, spleen, and liver, were investigated. The gene expression level of inflammation biomarkers (Tumour Necrosis Factor-alpha (TNF-α) and interleukin-1 (IL-1)), apoptosis factor (Caspase3), glucose regulatory genes (Glucose transporter (GLUT) 4 and 2), and lipid regulatory gene (Adenosine 50-monophosphate protein-kinase (AMPK)) were investigated.

Results

Administration of AGR to STZ-diabetic mice decreased blood glucose level (p < 0.01), normalized the lipid profile (p < 0.01), improved the serum level of kidney (p < 0.01) and liver biomarkers (p < 0.01), and normalized Kidney hypertrophy (p < 0.01), inflammation (p < 0.001), and apoptosis (p < 0.01). The AGR effect was better at 100 mg/kg than Metformin (100 mg/kg) on healing T2DM condition in mice.

Conclusion

AGR possesses anti-inflammatory, antioxidant, anti-hyperglycemic, anti-hyperlipidemic, and anti-glycation activity, thus exhibiting a protective function in STZ-induced diabetic mice. Further in vitro and in vivo works are necessary, especially to elucidate the mechanism of action of AGR at the cellular and molecular levels.

Dementia risk in patients with type 2 diabetes: Comparing metformin with no pharmacological treatment

INTRODUCTION

Metformin has been suggested as a therapeutic agent for dementia, but the relevant evidence has been partial and inconsistent.

METHODS

We established a national cohort of 210,237 type 2 diabetes patients in the UK Clinical Practice Research Datalink. Risks of incident dementia were compared between metformin initiators and those who were not prescribed any anti-diabetes medication during follow-up.

RESULTS

Compared with metformin initiators (n = 114,628), patients who received no anti-diabetes medication (n = 95,609) had lower HbA1c and better cardiovascular health at baseline. Both Cox regression and propensity score weighting analysis showed metformin initiators had lower risk of dementia compared to those non-users (adjusted hazard ratio = 0.88 [95% confidence interval: 0.84-0.92] and 0.90 [0.84-0.96]). Patients on long-term metformin treatment had an even lower risk of dementia.

DISCUSSION

Metformin may act beyond its glycemic effect and reduce dementia risk to an even lower level than that of patients with milder diabetes and better health profiles.

HIGHLIGHTS

Metformin initiators had a significantly lower risk of dementia compared with patients not receiving anti-diabetes medication. Compared with metformin initiators, diabetes patients not receiving pharmacological treatment had better glycemic profiles at baseline and during follow-up. Patients on long-term metformin treatment had an even lower risk of subsequent dementia incidence. Metformin may act beyond its effect on hyperglycemia and has the potential of being repurposed for dementia prevention.

Anti-diabetics and the Prevention of Dementia: A Systematic Review

Type 2 diabetes mellitus (T2DM) is a worldwide epidemic that is only increasing as the years progress, and as of 2019, affecting over 37 million. T2DM is a chronic condition caused by reduced insulin secretion and increased insulin resistance. Due to insulin not operating at optimal conditions, blood glucose rises and remains high, thus disturbing metabolic hemostasis. Many complications can arise from T2DM, such as coronary vascular disease, kidney damage, eye damage, and, quite significantly, dementia. It is theorized that dementia from T2DM stems from the fact that the brain is susceptible to hyperglycemic conditions, which are promoted by the increase in insulin resistance of target cells in the central nervous system. This directly affects cognitive processes and memory, which correlates to decreased temporal and front lobes volume. The risk of diabetic complications can be minimized with therapeutic interventions such as oral-antidiabetic (OAD) agents and insulin. Several OADs are on the market, but the first-line agent is metformin, a biguanide that decreases glucose production and increases insulin sensitivity. This paper aims to determine if currently prescribed OADs can help slow cognitive decline and reduce the risk and incidence of dementia as a complication of T2DM. Studies found that, for the most part, all OADs except sulfonylureas (SU) significantly slowed the decline of cognitive function and reduced the risk and incidence of dementia. SU's were shown to increase the risk of dementia in most studies. Of all the OADs, thiazolidinediones may be the most beneficial drug class for reducing the risk of dementia in T2DM patients. Future research should focus on whether early intervention with specific classes of OADs can not only improve glycemic control, leading to decreased hyperglycemia but also prevent the build-up of damaged brain tissue and help to reduce the risk and incidence of dementia in patients with T2DM.

Association of sulfonylureas with the risk of dementia: A population-based cohort study

BACKGROUND

Sulfonylureas are oral glucose-lowering medications positioned as a second-line therapy for type 2 diabetes. Evidence relating them to cognitive decline has been mixed. The objective was to determine whether sulfonylurea use was associated with a differential risk of dementia compared with dipeptidyl peptidase-4 (DPP4) inhibitor use.

METHODS

Using administrative data from residents in Ontario, Canada, adults aged ≥66 years who were new users of a sulfonylurea or a DPP4 inhibitor from June 14, 2011, to March 31, 2021 entered this population-based retrospective cohort study. Dementia was ascertained using a validated algorithm for Alzheimer's disease and related dementias. Propensity-score weighted Cox proportional hazards models were used to obtain adjusted hazard ratios (aHR) and confidence intervals (CI) for time to incident dementia. The observation window started at 1 year after cohort entry to mitigate protopathic bias due to delayed diagnosis. The primary analysis used an intention-to-treat exposure definition. A separate propensity-score weighted analysis was conducted to explore within-class differences in dementia risk among sulfonylurea new users selected from the primary cohort.

RESULTS

Among 107,806 DPP4 inhibitor new users and 37,030 sulfonylurea new users, sulfonylureas compared with DPP4 inhibitors were associated with a higher risk of dementia (18.4/1000 person-years; aHR [95% CI] = 1.09 [1.04-1.15]) over a mean follow-up of 4.82 years from cohort entry. Glyburide compared to gliclazide exhibited a higher dementia risk (aHR [95% CI] = 1.17 [1.03-1.32]).

CONCLUSION

New use of a sulfonylurea especially glyburide was associated with a higher dementia risk compared with new use of a DPP4 inhibitor in older adults with diabetes.

Comparison on cognitive outcomes of antidiabetic agents for type 2 diabetes: A systematic review and network meta-analysis

We aimed to summarise current evidence on different antidiabetic drugs to delay cognitive impairment, including mild cognitive impairment, dementia, Alzheimer's disease (AD) and vascular dementia, among subjects with type 2 diabetes mellitus (T2DM). Medline, Cochrane and Embase databases were searched from inception to 31 July 2022. Two investigators independently reviewed and screened trials comparing antidiabetic drugs with no antidiabetic drugs, placebo, or other active antidiabetic drugs on cognitive outcomes in T2DM. Data were analysed using meta-analysis and network meta-analysis. Twenty-seven studies met the inclusion criteria, including 3 randomised controlled trials, 19 cohort studies and 5 case-control studies. Compared with non-user, SGLT-2i (OR 0.41 [95% CI 0.22-0.76]), GLP-1RA (OR 0.34 [95% CI 0.14-0.85]), thiazolidinedione (OR 0.60 [95% CI 0.51-0.69]), and DPP-4i (OR 0.78 [95% CI 0.61-0.99]) users had a decreased risk of dementia, whereas sulfonylurea (OR 1.43 [95% CI 1.11-1.82]) increased dementia risk. Network meta-analysis showed that SGLT-2i was most likely to rank best (SUCRA = 94.4%), GLP-1 RA second best (SUCRA = 92.7%), thiazolidinedione third best (SUCRA = 74.7%) and DPP-4i fourth best (SUCRA = 54.9%), while sulfonylurea second worst (SUCRA = 20.0%) for decreasing dementia outcomes, by synthesising evidence from direct and indirect comparisons of multiple intervention. Evidence suggests the effects of SGLT-2i ≈ GLP-1 RAs > thiazolidinedione > DPP-4i for delaying cognitive impairment, dementia and AD outcomes, whereas sulfonylurea was associated with the highest risk. These findings provide evidence for evaluating the optional treatment for clinical practice. PROSPERO REGISTRATION: Registration no. CRD42022347280.

Exploring the mechanism of metformin action in Alzheimer's disease and type 2 diabetes based on network pharmacology, molecular docking, and molecular dynamic simulation

Background

Metformin, which has been shown to be highly effective in treating type 2 diabetes (T2D), is also believed to be valuable for Alzheimer's disease (AD). Computer simulation techniques have emerged as an innovative approach to explore mechanisms.

Objective

To study the potential mechanism of metformin action in AD and T2D.

Methods

The chemical structure of metformin was obtained from PubChem. The targets of metformin were obtained from PubChem, Pharm Mapper, Batman, SwissTargetPrediction, DrugBank, and PubMed. The pathogenic genes of AD and T2D were retrieved from the GeneCards, OMIM, TTD, Drugbank, PharmGKB, and DisGeNET. The intersection of metformin with the targets of AD and T2D is represented by a Venn diagram. The protein-protein interaction (PPI) and core targets networks of intersected targets were constructed by Cytoscape 3.7.1. The enrichment information of GO and Kyoto Encyclopedia of Gene and Genomics (KEGG) pathways obtained by the Metascape was made into a bar chart and a bubble diagram. AutoDockTools, Pymol, and Chem3D were used for the molecular docking. Gromacs software was used to perform molecular dynamics (MD) simulation of the best binding target protein.

Results

A total of 115 key targets of metformin for AD and T2D were obtained. GO analysis showed that biological process mainly involved response to hormones and the regulation of ion transport. Cellular component was enriched in the cell body and axon. Molecular function mainly involved kinase binding and signal receptor regulator activity. The KEGG pathway was mainly enriched in pathways of cancer, neurodegeneration, and endocrine resistance. Core targets mainly included TP53, TNF, VEGFA, HIF1A, IL1B, IGF1, ESR1, SIRT1, CAT, and CXCL8. The molecular docking results showed best binding of metformin to CAT. MD simulation further indicated that the CAT-metformin complex could bind well and converge relatively stable at 30 ns.

Conclusion

Metformin exerts its effects on regulating oxidative stress, gluconeogenesis and inflammation, which may be the mechanism of action of metformin to improve the common pathological features of T2D and AD.

The development and benefits of metformin in various diseases

Metformin has been used for the treatment of type II diabetes mellitus for decades due to its safety, low cost, and outstanding hypoglycemic effect clinically. The mechanisms underlying these benefits are complex and still not fully understood. Inhibition of mitochondrial respiratory-chain complex I is the most described downstream mechanism of metformin, leading to reduced ATP production and activation of AMP-activated protein kinase (AMPK). Meanwhile, many novel targets of metformin have been gradually discovered. In recent years, multiple pre-clinical and clinical studies are committed to extend the indications of metformin in addition to diabetes. Herein, we summarized the benefits of metformin in four types of diseases, including metabolic associated diseases, cancer, aging and age-related diseases, neurological disorders. We comprehensively discussed the pharmacokinetic properties and the mechanisms of action, treatment strategies, the clinical application, the potential risk of metformin in various diseases. This review provides a brief summary of the benefits and concerns of metformin, aiming to interest scientists to consider and explore the common and specific mechanisms and guiding for the further research. Although there have been countless studies of metformin, longitudinal research in each field is still much warranted.

Systemic Metabolism and Mitochondria in the Mechanism of Alzheimer's Disease: Finding Potential Therapeutic Targets

Elderly people over the age of 65 are those most likely to experience Alzheimer's disease (AD), and aging and AD are associated with apparent metabolic alterations. Currently, there is no curative medication against AD and only several drugs have been approved by the FDA, but these drugs can only improve the symptoms of AD. Many preclinical and clinical trials have explored the impact of adjusting the whole-body and intracellular metabolism on the pathogenesis of AD. The most recent evidence suggests that mitochondria initiate an integrated stress response to environmental stress, which is beneficial for healthy aging and neuroprotection. There is also an increasing awareness of the differential risk and potential targeting strategies related to the metabolic level and microbiome. As the main participants in intracellular metabolism, mitochondrial bioenergetics, mitochondrial quality-control mechanisms, and mitochondria-linked inflammatory responses have been regarded as potential therapeutic targets for AD. This review summarizes and highlights these advances.

The Correlation between Metformin Use and Incident Dementia in Patients with New-Onset Diabetes Mellitus: A Population-Based Study

The evidence of metformin's effect on dementia is conflicting. This study investigates the association between metformin use and the risk of dementia among patients with diabetes mellitus (DM). This study included patients with new-onset DM between 2002 and 2013. We divided the patients into patients who used metformin and patients who did not. Two models were used to assess metformin use: the cumulative defined daily dose (cDDD) of metformin use and the intensity of metformin use. This study with 3-year and 5-year follow-ups investigated the risk of dementia among patients with DM who used metformin. At the 3-year follow-up, patients who received cDDD < 300 had an odds ratio (OR) of developing dementia of 0.92 (95% confidence interval [CI] = 0.89-0.96); patients who used metformin at intensities <10 and 10-25 DDD/month had ORs of 0.92 (95% CI: 0.87-0.97) and 0.92 (95% CI: 0.85-1.00), respectively. Metformin use at cDDD 300-500 (OR = 0.80, 95% CI = 0.56-1.15) or >500 (OR = 1.48, 95% CI = 0.48-4.60) or at an intensity >25 DDD/month (OR = 0.84, 95% CI = 0.60-1.18) were not associated with an incident of dementia. There were similar results at the 5-year follow-up. Patients with a low intensity of metformin use had a lower risk of dementia. However, higher doses of metformin with higher intensity exhibited no protective role in dementia. Prospective clinical trials are warranted to evaluate the actual underlying mechanisms between metformin dosage and the risk of dementia.

Diabetic vascular diseases: molecular mechanisms and therapeutic strategies

Vascular complications of diabetes pose a severe threat to human health. Prevention and treatment protocols based on a single vascular complication are no longer suitable for the long-term management of patients with diabetes. Diabetic panvascular disease (DPD) is a clinical syndrome in which vessels of various sizes, including macrovessels and microvessels in the cardiac, cerebral, renal, ophthalmic, and peripheral systems of patients with diabetes, develop atherosclerosis as a common pathology. Pathological manifestations of DPDs usually manifest macrovascular atherosclerosis, as well as microvascular endothelial function impairment, basement membrane thickening, and microthrombosis. Cardiac, cerebral, and peripheral microangiopathy coexist with microangiopathy, while renal and retinal are predominantly microangiopathic. The following associations exist between DPDs: numerous similar molecular mechanisms, and risk-predictive relationships between diseases. Aggressive glycemic control combined with early comprehensive vascular intervention is the key to prevention and treatment. In addition to the widely recommended metformin, glucagon-like peptide-1 agonist, and sodium-glucose cotransporter-2 inhibitors, for the latest molecular mechanisms, aldose reductase inhibitors, peroxisome proliferator-activated receptor-γ agonizts, glucokinases agonizts, mitochondrial energy modulators, etc. are under active development. DPDs are proposed for patients to obtain more systematic clinical care requires a comprehensive diabetes care center focusing on panvascular diseases. This would leverage the advantages of a cross-disciplinary approach to achieve better integration of the pathogenesis and therapeutic evidence. Such a strategy would confer more clinical benefits to patients and promote the comprehensive development of DPD as a discipline.

Metformin Attenuates Tau Pathology in Tau-Seeded PS19 Mice

Accumulation of neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau is a histopathological hallmark of Alzheimer's disease (AD) and related tauopathies. Growing evidence demonstrated that tau pathology in AD spreads in a prion-like manner. Previous studies showed that metformin might have a positive effect on cognition. However, the underlying mechanisms are still unknown. Therefore, the present study aimed to investigate the effects of metformin on tau propagation. Brain extracts containing tau aggregates were unilaterally injected into the hippocampus and the overlying cerebral cortex of PS19 mice. Metformin was administrated through drinking water for four months, and we observed tau spreading in the brain of tau-seeded PS19 mice. Metformin inhibited the spreading of tau pathology in the ipsilateral hemisphere, attenuated tau pathology in the contralateral hemisphere, and reduced the hyperphosphorylation of tau at Ser202/Thr205, Thr231, and Ser422 sites in the soluble fraction and Ser202/Thr205, Ser262, Thr396, Thr231, and Ser422 sites in the insoluble fraction of tau-seeded PS19 mice brains. Metformin did not affect tau kinases or phosphatase 2A protein levels but reduced mTORC1 protein levels. Additionally, metformin reduced learning and memory deficits of the tau-seeded PS19 mice. These findings indicate that metformin reduced tau hyperphosphorylation, attenuated tau pathology in tau-seeded PS19 mice, and improved learning and memory deficits. These findings highlight the potential mechanisms underlying the beneficial effects of metformin on cognition, implying that metformin could be a promising drug for the prevention and early treatment of AD.

Type 2 diabetes mellitus and cognitive function: understanding the connections

PURPOSE OF REVIEW

To review the connection between type 2 diabetes and cognitive dysfunction, including its epidemiology, potential mechanisms of pathophysiology, risk factors, possible prevention, and treatment considerations.

RECENT FINDINGS

Diabetes is a risk factor for mild cognitive decline, in addition to Alzheimer's disease and vascular dementia. Duration of diabetes, concomitant vascular or associated co-morbidities, hyper- and hypoglycemia may lead to worsening cognitive dysfunction. Unfortunately, there is a lack of evidence-based guidance on the prevention of cognitive dysfunction in the diabetes population. Studies of diabetes medications, including metformin, glucagon-like peptide-1 (GLP-1) receptor agonists, and sodium-glucose cotransporter-2 inhibitors (SGLT2) have shown some benefit with cardiovascular morbidity and may affect cognition. In the absence of clearly defined preventive tools, diabetes practice guidelines recommend annual cognitive screening as standard of care in adults with diabetes aged 65 years or older.

SUMMARY

People living with diabetes are at risk for significant decline in cognitive function. Epidemiology and risk factors are well defined. Prevention and treatment strategies are limited and require further study.

Association of Sodium-Glucose Cotransporter 2 Inhibitors With Time to Dementia: A Population-Based Cohort Study

OBJECTIVE

Type 2 diabetes (T2D) increases dementia risk, but clear evidence to recommend interventions that can mitigate that risk remains lacking. This population-based retrospective cohort study aimed to determine whether new use of sodium-glucose cotransporter 2 (SGLT2) inhibitors compared with dipeptidyl peptidase 4 (DPP-4) inhibitors was associated with lower dementia risk.

RESEARCH DESIGN AND METHODS

Ontario residents aged ≥66 years who were new users of an SGLT2 inhibitor or a DPP-4 inhibitor from 1 July 2016 to 31 March 2021 entered the cohort. Incident dementia was identified using a validated algorithm for Alzheimer's disease and related dementias. Propensity score-weighted Cox proportional hazards models were used to obtain adjusted hazard ratios (aHR) and CIs for time to incident dementia. To address reverse causality and disease latency, the observation window started at 1-year lag time from cohort entry. The primary analysis followed intention-to-treat exposure definition, and a secondary as-treated analysis was performed.

RESULTS

Among 106,903 individuals, SGLT2 inhibitors compared with DPP-4 inhibitors were associated with lower risk of dementia (14.2/1,000 person-years; aHR 0.80 [95% CI 0.71-0.89]) over a mean follow-up of 2.80 years from cohort entry. When stratified by different SGLT2 inhibitors, dapagliflozin exhibited the lowest risk (aHR 0.67 [95% CI 0.53-0.84]), followed by empagliflozin (aHR 0.78 [95% CI 0.69-0.89]), whereas canagliflozin showed no association (aHR 0.96 [95% CI 0.80-1.16]). The as-treated analysis observed a larger association (aHR 0.66 [95% CI 0.57-0.76]) than the intention-to-treat analysis.

CONCLUSIONS

SGLT2 inhibitors showed an association with lower dementia risk in older people with T2D. Randomized controlled trials are warranted.

Causal inference in medical records and complementary systems pharmacology for metformin drug repurposing towards dementia

Metformin, a diabetes drug with anti-aging cellular responses, has complex actions that may alter dementia onset. Mixed results are emerging from prior observational studies. To address this complexity, we deploy a causal inference approach accounting for the competing risk of death in emulated clinical trials using two distinct electronic health record systems. In intention-to-treat analyses, metformin use associates with lower hazard of all-cause mortality and lower cause-specific hazard of dementia onset, after accounting for prolonged survival, relative to sulfonylureas. In parallel systems pharmacology studies, the expression of two AD-related proteins, APOE and SPP1, was suppressed by pharmacologic concentrations of metformin in differentiated human neural cells, relative to a sulfonylurea. Together, our findings suggest that metformin might reduce the risk of dementia in diabetes patients through mechanisms beyond glycemic control, and that SPP1 is a candidate biomarker for metformin's action in the brain.

The potential benefit of metformin to reduce delirium risk and mortality: a retrospective cohort study

PURPOSE

Metformin has been reported to improve age-related disorders, including dementia, and to lower mortality. This study was conducted to investigate whether metformin use lower delirium risk, as well as long-term mortality.

METHODS

In this retrospective cohort study, previously recruited 1,404 subjects were analyzed. The relationship between metformin use and delirium, and the relationship between metformin use and 3-year mortality were investigated.

MAIN FINDINGS

242 subjects were categorized into a type 2 diabetes mellitus (DM)-without-metformin group, and 264 subjects were categorized into a DM-with-metformin group. Prevalence of delirium was 36.0% in the DM-without-metformin group, and 29.2% in the DM-with-metformin group. A history of metformin use reduced the risk of delirium in patients with DM (OR, 0.50 [95% CI, 0.32 to 0.79]) after controlling for confounding factors. The 3-year mortality in the DM-without-metformin group (survival rate, 0.595 [95% CI, 0.512 to 0.669]) was higher than in the DM-with-metformin group (survival rate, 0.695 [95% CI, 0.604 to 0.770]) (p=0.035). A history of metformin use decreased the risk of 3-year mortality after adjustment for confounding factors (HR, 0.69 [95% CI, 0.48 to 0.98]).

CONCLUSIONS

Metformin use may lower the risk of delirium and mortality in DM patients.

Comparative effect of metformin versus sulfonylureas with dementia and Parkinson's disease risk in US patients over 50 with type 2 diabetes mellitus

INTRODUCTION

Type 2 diabetes is a risk factor for dementia and Parkinson's disease (PD). Drug treatments for diabetes, such as metformin, could be used as novel treatments for these neurological conditions. Using electronic health records from the USA (OPTUM EHR) we aimed to assess the association of metformin with all-cause dementia, dementia subtypes and PD compared with sulfonylureas.

RESEARCH DESIGN AND METHODS

A new user comparator study design was conducted in patients ≥50 years old with diabetes who were new users of metformin or sulfonylureas between 2006 and 2018. Primary outcomes were all-cause dementia and PD. Secondary outcomes were Alzheimer's disease (AD), vascular dementia (VD) and mild cognitive impairment (MCI). Cox proportional hazards models with inverse probability of treatment weighting (IPTW) were used to estimate the HRs. Subanalyses included stratification by age, race, renal function, and glycemic control.

RESULTS

We identified 96 140 and 16 451 new users of metformin and sulfonylureas, respectively. Mean age was 66.4±8.2 years (48% male, 83% Caucasian). Over the 5-year follow-up, 3207 patients developed all-cause dementia (2256 (2.3%) metformin, 951 (5.8%) sulfonylurea users) and 760 patients developed PD (625 (0.7%) metformin, 135 (0.8%) sulfonylurea users). After IPTW, HRs for all-cause dementia and PD were 0.80 (95% CI 0.73 to 0.88) and 1.00 (95% CI 0.79 to 1.28). HRs for AD, VD and MCI were 0.81 (0.70-0.94), 0.79 (0.63-1.00) and 0.91 (0.79-1.04). Stronger associations were observed in patients who were younger (<75 years old), Caucasian, and with moderate renal function.

CONCLUSIONS

Metformin users compared with sulfonylurea users were associated with a lower risk of all-cause dementia, AD and VD but not with PD or MCI. Age and renal function modified risk reduction. Our findings support the hypothesis that metformin provides more neuroprotection for dementia than sulfonylureas but not for PD, but further work is required to assess causality.

Use of oral diabetes medications and the risk of incident dementia in US veterans aged ≥60 years with type 2 diabetes

INTRODUCTION

Studies have reported that antidiabetic medications (ADMs) were associated with lower risk of dementia, but current findings are inconsistent. This study compared the risk of dementia onset in patients with type 2 diabetes (T2D) treated with sulfonylurea (SU) or thiazolidinedione (TZD) to patients with T2D treated with metformin (MET).

RESEARCH DESIGN AND METHODS

This is a prospective observational study within a T2D population using electronic medical records from all sites of the Veterans Affairs Healthcare System. Patients with T2D who initiated ADM from January 1, 2001, to December 31, 2017, were aged ≥60 years at the initiation, and were dementia-free were identified. A SU monotherapy group, a TZD monotherapy group, and a control group (MET monotherapy) were assembled based on prescription records. Participants were required to take the assigned treatment for at least 1 year. The primary outcome was all-cause dementia, and the two secondary outcomes were Alzheimer's disease and vascular dementia, defined by International Classification of Diseases (ICD), 9th Revision, or ICD, 10th Revision, codes. The risks of developing outcomes were compared using propensity score weighted Cox proportional hazard models.

RESULTS

Among 559 106 eligible veterans (mean age 65.7 (SD 8.7) years), the all-cause dementia rate was 8.2 cases per 1000 person-years (95% CI 6.0 to 13.7). After at least 1 year of treatment, TZD monotherapy was associated with a 22% lower risk of all-cause dementia onset (HR 0.78, 95% CI 0.75 to 0.81), compared with MET monotherapy, and 11% lower for MET and TZD dual therapy (HR 0.89, 95% CI 0.86 to 0.93), whereas the risk was 12% higher for SU monotherapy (HR 1.12 95% CI 1.09 to 1.15).

CONCLUSIONS

Among patients with T2D, TZD use was associated with a lower risk of dementia, and SU use was associated with a higher risk compared with MET use. Supplementing SU with either MET or TZD may partially offset its prodementia effects. These findings may help inform medication selection for elderly patients with T2D at high risk of dementia.

Metformin use is associated with a reduced risk of cognitive impairment in adults with diabetes mellitus: A systematic review and meta-analysis

Objective

Controversy exists regarding the impact of metformin and whether it prevents or promotes the incidence of cognitive dysfunction. This systematic review and meta-analysis were conducted to identify the effect of metformin therapy on cognitive function in patients with diabetes.

Methods

Electronic databases (PubMed, EMBASE, PsycINFO, the Cochrane Library, and Web of Science) were systematically searched by two investigators from the date of inception until March 1, 2022. The study followed PRISMA guidelines. Inclusion criteria were defined according to the PECOSmodel. Eligible studies investigated cognitive dysfunction in metformin users compared with non-users in adults with diabetes. Only observational study designs (such as cohort, cross-section, and case-control) were included.

Results

A systematic search identified 1,839 articles, of which 28 (17 cohort, 8 case-control, and 3 cross-sectional studies) were included in the meta-analysis. Metformin reduced the occurrence of cognitive impairment in patients with diabetes [unadjusted hazard ratio (HR) = 0.67, 95% CI: 0.62–0.73; adjusted hazard ratio (aHR) = 0.92, 95% CI: 0.85–0.99]. In addition, the use of metformin was associated with a decreased risk of dementia (HR = 0.64, 95% CI: 0.59–0.69; aHR = 0.90, 95% CI: 0.84–0.96), while a random-effects meta-analysis indicated no significant effect of metformin on the risk of Alzheimer's disease (AD) (HR = 0.85, 95% CI: 0.60–1.22; aHR = 1.10, 95% CI: 0.95–1.28).

Conclusion

Metformin therapy decreased the occurrence risk of cognitive decline in patients with diabetes mellitus. Moreover, the use of metformin by adults with diabetes for the prevention of dementia, but not AD, is supported by the available evidence.

Factors Associated With Mild Cognitive Impairment in Patients With Type 2 Diabetes: A Cohort Study

Background

Cognitive dysfunction is increasingly recognized as an important comorbidity of diabetes mellitus (DM).

Objective

The purpose of this study was to determine the prevalence and predictors of cognitive decline in individuals with type 2 diabetes mellitus (T2DM).

Methods

This cohort study included patients with type 2 diabetes mellitus aged between 40 and 75 years and with a duration of the evolution of diabetes that is greater than five years admitted in endocrinology consultation of the Sheikh Khalifa ibn Zaid Hospital in Casablanca, Morocco. For each patient, we collected clinical characteristics and biological assessments. All subjects provided screening test results as defined by the Mini-Mental State Examination (MMSE).

Results

We included a total of 100 patients with diabetes between May and September 2021. The median age of the patients was 65 years (interquartile range (IQR): 59-70 years), 65% were males, and the median duration of diabetes was 15 years (IQR: 9-20 years). The most common cardiovascular risk factors (CVRFs) were hypertension (72.7%) and dyslipidemia (53%). The most common complications of diabetes were peripheral neuropathy (50%), diabetic retinopathy (DR) (39%), peripheral artery disease (33%), and coronary artery disease (27%). Cognitive impairment was present in 47.5% of our patients. For the multivariate analysis, we found that the decrease in the MMSE score is associated with the increase in age (p-value = 0.004) and the occurrence of diabetic retinopathy (p-value < 0.001), dyslipidemia (p-value = 0.006), and elevated creatinine (p-value < 0.001).

Conclusion

It is necessary to consider the cognitive decline of patients with diabetes as one of the most important complications of this disease because of its impact on the evolution and compliance of these patients.

Metformin and Dementia Risk: A Systematic Review with Respect to Time Related Biases

Background:

When studying drug effects using observational data, time-related biases may exist and result in spurious associations. Numerous observational studies have investigated metformin and dementia risk, but have reported inconsistent findings, some of which might be caused by unaddressed time-related biases. Immortal time bias biases the results toward a “protective” effect, whereas time-lag and time-window biases can lead to either a “detrimental” or “protective” effect.

Objective:

To conduct a systematic review examining time-related biases in the literature on metformin and dementia.

Methods:

The electronic databases PubMed, Web of Science, and ProQuest were searched for the terms “Metformin” AND (“dementia” OR “Alzheimer’s Disease” OR “cognitive impairment"). These databases were searched from inception through 09/24/2021. Only English language articles and human research were eligible.

Results:

Seventeen studies were identified: thirteen cohort studies, two case-control studies, and two nested case-control studies. Eleven (64.7%) studies reported a reduced risk of dementia associated with metformin use; two (11.8%) suggested metformin increased dementia risk, while four (23.5%) concluded no significant associations. Eight (61.5%) of thirteen cohort studies had immortal time bias or did not clearly address it. Fifteen (88.2%) of seventeen reviewed studies had time-lag bias or did not clearly address it. Two (50.0%) of four case-control studies did not explicitly address time-window bias. The studies that addressed most biases concluded no associations between metformin and dementia risk.

Conclusion:

None of the reviewed studies clearly addressed relevant time-related biases, illustrating time-related biases are common in observational studies investigating the impact of anti-diabetic medications on dementia risk.

Actions of Metformin in the Brain: A New Perspective of Metformin Treatments in Related Neurological Disorders

Metformin is a first-line drug for treating type 2 diabetes mellitus (T2DM) and one of the most commonly prescribed drugs in the world. Besides its hypoglycemic effects, metformin also can improve cognitive or mood functions in some T2DM patients; moreover, it has been reported that metformin exerts beneficial effects on many neurological disorders, including major depressive disorder (MDD), Alzheimer’s disease (AD) and Fragile X syndrome (FXS); however, the mechanism underlying metformin in the brain is not fully understood. Neurotransmission between neurons is fundamental for brain functions, and its defects have been implicated in many neurological disorders. Recent studies suggest that metformin appears not only to regulate synaptic transmission or plasticity in pathological conditions but also to regulate the balance of excitation and inhibition (E/I balance) in neural networks. In this review, we focused on and reviewed the roles of metformin in brain functions and related neurological disorders, which would give us a deeper understanding of the actions of metformin in the brain.

Metformin and the risk of dementia based on an analysis of 396,332 participants

Background:

AMPK has attracted widespread interest as a potential therapeutic target for age-related diseases, given its key role in controlling energy homeostasis. Metformin (Met) has historically been used to treat Type 2 diabetes and has been shown to counteract age-related diseases. However, studies regarding the relationship between Met and a variety of age-related classifications of cognitive decline have reported mixed findings.

Objective:

To assess the potential effect of Met on the onset of dementia and discuss the possible biological mechanisms involved.

Methods:

This study was registered in the PROSPERO database (CRD420201251468). PubMed, Embase, and Cochrane Library were searched from inception to 25 May 2021, for population-based cohort studies. Effect estimates with 95% confidence intervals (CIs) were pooled using the random-effects model. Meta-regression and subgroup analyses were performed to explore sources of heterogeneity and the stability of the results.

Results:

Fourteen population-based cohort studies (17 individual comparisons) involving 396,332 participants were identified. Meta-analysis showed that Met exposure was significantly associated with reduced risk of all subtypes of dementias [relative risk (RR) = 0.79, 95% CI = 0.68–0.91; p < 0.001]. Conversely, no significant reduction in risk was observed for those who received Met monotherapy at the onset of vascular dementia (VD), Parkinson’s disease (PD), and Alzheimer’s disease (AD). The effect was more prominent in patients who had long-term Met exposure (⩾4 years) (RR = 0.38, 95% CI = 0.32–0.46; p < 0.001), while no such significant effect was found with short-term Met exposure (1–2 years) (RR = 1.20, 95% CI = 0.87–1.66; p < 0.001). Moreover, no association was observed for Met exposure in participants of European descent (RR = 1.01, 95% CI = 0.66–1.54; p = 0.003) compared with those from other countries.

Conclusion:

Based on the evidence from population-based cohort studies, our findings suggest that the AMPK activator, Met, is a potential geroprotective agent for dementias, particularly among long-term Met users. Due to the significant heterogeneity among the included studies, we should interpret the results with caution.

Metabolic hormones mediate cognition

Recent biochemical and behavioural evidence indicates that metabolic hormones not only regulate energy intake and nutrient content, but also modulate plasticity and cognition in the central nervous system. Disruptions in metabolic hormone signalling may provide a link between metabolic syndromes like obesity and diabetes, and cognitive impairment. For example, altered metabolic homeostasis in obesity is a strong determinant of the severity of age-related cognitive decline and neurodegenerative disease. Here we review the evidence that eating behaviours and metabolic hormones-particularly ghrelin, leptin, and insulin-are key players in the delicate regulation of neural plasticity and cognition. Caloric restriction and antidiabetic therapies, both of which affect metabolic hormone levels can restore metabolic homeostasis and enhance cognitive function. Thus, metabolic hormone pathways provide a promising target for the treatment of cognitive decline.

Association Between Metformin and Alzheimer's Disease: A Systematic Review and Meta-Analysis of Clinical Observational Studies

BACKGROUND

As one of the widely used drugs for the management of type 2 diabetes mellites (T2DM), metformin is increasingly believed to delay cognitive deterioration and therapeutically for Alzheimer's disease (AD) patients especially those with T2DM. However, studies of the potential neuroprotective effects of metformin in AD patients have reported contradictory results.

OBJECTIVE

This study aimed to evaluate the association between metformin and the risk of developing AD.

METHODS

We systematically searched the PubMed, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov databases to identify clinical observational studies on the relationship between AD risk and metformin use published before December 20, 2021. Two investigators independently screened records, extracted data, and assessed the quality of the studies. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated using random-effect models.

RESULTS

After screening a total of 1,670 records, we included 10 studies involving 229,110 participants. The meta-analysis showed no significant association between AD incidence and metformin exposure (OR 1.17, 95% CI 0.88-1.56, p = 0.291). However, subgroup analysis showed that among Asians, the risk of AD was significantly higher among metformin users than those who did not (OR 1.71, 95% CI 1.24-2.37, p = 0.001).

CONCLUSION

The available evidence does not support the idea that metformin reduces risk of AD, and it may, in fact, increase the risk in Asians. Further well-designed randomized controlled trials are required to understand the role played by metformin and other antidiabetic drugs in the prevention of AD and other neurodegenerative diseases.

The effect of metformin on cognitive function: A systematic review and meta-analysis

Most people are familiar with metformin as a diabetic treatment option. Different positive benefits have been found for it, in addition to its anti-diabetes properties. Cognitive function enhancement is the most recent characteristic that has been studied. This study aimed to look at the evidence on the effects of metformin on cognitive performance. Web of Science, PubMed, Scopus, the Cochrane Library, EMBASE, and PsycINFO databases were searched systematically. After eliminating duplicates and irrelevant documents, the findings were screened. The documents that remained were scanned and data were extracted. Nineteen studies were qualified for meta-analysis after evaluating 3827 identified records. There was no significant relationship between metformin therapy and cognitive performance in none of the studies including cross-sectionals, cohorts, and clinical trials (p > 0.05). Results show that metformin has no significant effect on improving cognitive function or protecting against any dementia including vascular dementia and Alzheimer's disease, and cognitive impairment as well.

Glucose-lowering drugs, cognition, and dementia: The clinical evidence

Type 2 diabetes mellitus (T2DM) is an important risk factor for dementia. The possibility to mitigate this risk by controlling T2DM is compelling; however, different glucose-lowering drugs have different effects on the brain by virtue of their different mechanisms of action. The clinical and epidemiological data appear mixed, warranting careful critical evaluation of the human studies. Here we examine the evidence in the context of dementia prevention and treatment, both for people with and without T2DM. We discuss the evidence on this scaffold of research directions, identifying methodological complexities in the extant literature (e.g. comparator discrepancies, changes in the therapeutic landscape), and the implications of different outcome measures (e.g. neuropsychological). We consider possible implications of cerebrovascular protection vs. effects on progression of neurodegenerative proteinopathy, and we present a research roadmap for glucose-lowering drugs in cognitive neurology, including neuroimaging, and fluid biomarkers. We conclude that there is great potential to advance personalized strategies to prevent and treat dementia with glucose-lowering drugs.

Association Between Specific Type 2 Diabetes Therapies and Risk of Alzheimer’s Disease and Related Dementias in Propensity-Score Matched Type 2 Diabetic Patients

Objective

We sought to determine the impact of Type 2 Diabetes Mellitus (T2D) anti-hyperglycemic medications (A-HgM) on risk of Alzheimer’s disease (AD) and related dementias (ADRD) outcomes including vascular dementia, and non-AD dementia such as frontotemporal, Lewy body, and mixed etiology dementias.

Research Design and Methods

This retrospective cohort study used the US-based Mariner claims dataset. 1,815,032 T2D participants 45 years and older with records 6 months prior and at least 3 years after the diagnosis of T2D were included. Claims were surveyed for a diagnosis of AD and ADRD 12 months post T2D diagnosis. A propensity score approach was used to minimize selection bias. Analyses were conducted between January 1st and February 28th, 2021.

Results

In this cohort study A-HgM exposure was associated with decreased diagnosis of AD (RR, 0.61; 95% CI, 0.59–0.62; p < 0.001), vascular dementia (RR, 0.72; 95% CI, 0.69–0.74; p < 0.001) and non-AD dementia (RR, 0.67; 95% CI, 0.66–0.68; p < 0.001). Metformin was associated with the greatest risk reduction and insulin with the least reduction in risk compared to patients not receiving A-HgM for ADRD risk. Of interest, patients with a diagnosis of AD, while either on metformin or insulin, were older in age and predominately female, than individuals on these drugs that did not develop AD. Mean (SD) follow-up was 6.2 (1.8) years.

Conclusion

After controlling for age, sex, and comorbidities, A-HgM in patients with T2D was associated with a reduced risk of AD and ADRD. These findings provide evidence in support of T2D as a risk factor for AD and ADRD and the beneficial impact of early and effective control of hyperglycemia to mitigate risk.

Metformin versus sulphonylureas for new onset atrial fibrillation and stroke in type 2 diabetes mellitus: a population-based study

AIMS

To gain insights on the cardiovascular effects of metformin and sulphonylurea, the present study compares the rates of incident atrial fibrillation, stroke, cardiovascular mortality and all-cause mortality between metformin and sulphonylurea users in type 2 diabetes mellitus.

METHODS

This was a retrospective population-based cohort study of type 2 diabetes mellitus patients receiving either sulphonylurea or metformin monotherapy between January 1, 2000, and December 31, 2019. The primary outcome was new-onset AF or stroke. Secondary outcomes were cardiovascular, non-cardiovascular and all-cause mortality. Propensity score matching (1:2 ratio) between sulphonylurea and metformin users was performed, based on demographics, CHA-DS-VASc score, past comorbidities and medication use. Cox regression was used to identify significant risk factors. Competing risk analysis was conducted using cause-specific and subdistribution hazard models. Sensitivity analyses using propensity score stratification, high-dimensional propensity score and inverse probability of treatment weighting were conducted. Subgroup analyses were conducted for age and gender in the matched cohort.

RESULTS

A total of 36,228 sulphonylurea users and 72,456 metformin users were included in the propensity score-matched cohort. Multivariable Cox regression showed that sulphonylurea users had higher risks of incident AF (hazard ratio [HR]: 2.89, 95% confidence interval [CI]: 2.75-3.77; P < 0.0001), stroke (HR: 3.23, 95% CI: 3.01-3.45; P < 0.0001), cardiovascular mortality (HR: 3.60, 95% CI: 2.62-4.81; P < 0.0001) and all-cause mortality (HR: 4.35, 95% CI: 3.16-4.75; P < 0.0001) compared to metformin users. Similarly, significant results were observed using cause-specific and subdistribution hazard models. Sensitivity analysis using techniques based on the propensity score also yielded similar results.

CONCLUSIONS

Sulphonylurea use was associated with higher risks of incident AF, stroke, cardiovascular mortality and all-cause mortality compared to metformin. Males and patients older than 65 years with sulphonylurea use were exposed to the highest risks.

Potential role of Drug Repositioning Strategy (DRS) for management of tauopathy

Tauopathy is a term that has been used to represent a pathological condition in which hyperphosphorylated tau protein aggregates in neurons and glia which results in neurodegeneration, synapse loss and dysfunction and cognitive impairments. Recently, drug repositioning strategy (DRS) becomes a promising field and an alternative approach to advancing new treatments from actually developed and FDA approved drugs for an indication other than the indication it was originally intended for. This paradigm provides an advantage because the safety of the candidate compound has already been established, which abolishes the need for further preclinical safety testing and thus substantially reduces the time and cost involved in progressing of clinical trials. In the present review, we focused on correlation between tauopathy and common diseases as type 2 diabetes mellitus and the global virus COVID-19 and how tau pathology can aggravate development of these diseases in addition to how these diseases can be a risk factor for development of tauopathy. Moreover, correlation between COVID-19 and type 2 diabetes mellitus was also discussed. Therefore, repositioning of a drug in the daily clinical practice of patients to manage or prevent two or more diseases at the same time with lower side effects and drug-drug interactions is a promising idea. This review concluded the results of pre-clinical and clinical studies applied on antidiabetics, COVID-19 medications, antihypertensives, antidepressants and cholesterol lowering drugs for possible drug repositioning for management of tauopathy.

Deciphering the Roles of Metformin in Alzheimer's Disease: A Snapshot

Alzheimer’s disease (AD) is a prevalent neurodegenerative disease predominantly affecting millions of elderly people. To date, no effective therapy has been identified to reverse the progression of AD. Metformin, as a first-line medication for Type 2 Diabetes Mellitus (T2DM), exerts multiple beneficial effects on various neurodegenerative disorders, including AD. Evidence from clinical studies has demonstrated that metformin use contributes to a lower risk of developing AD and better cognitive performance, which might be modified by interactors such as diabetic status and APOE-ε4 status. Previous mechanistic studies have gradually unveiled the effects of metformin on AD pathology and pathophysiology, including neuronal loss, neural dysfunction, amyloid-β (Aβ) depositions, tau phosphorylation, chronic neuroinflammation, insulin resistance, impaired glucose metabolism and mitochondrial dysfunction. Current evidence remains ambiguous and even conflicting. Herein, we review the current state of knowledge concerning the mechanisms of metformin in AD pathology while summarizing current evidence from clinical studies.