Type 3 Diabetes Mellitus: A Link Between Alzheimer's Disease and Type 2 Diabetes Mellitus

Nutritional intervention for diabetes mellitus with Alzheimer's disease

The combined disease burden of diabetes mellitus (DM) and Alzheimer's disease (AD) is increasing, and the two diseases share some common pathological changes. However, the pharmacotherapeutic approach to this clinical complexity is limited to symptomatic rather than disease-arresting, with the possible exception of metformin. Whether nutritional intervention might extend or synergize with these effects of metformin is of interest. In particular, dietary patterns with an emphasis on dietary diversity shown to affect cognitive function are of growing interest in a range of food cultural settings. This paper presents the association between diabetes and AD. In addition, the cross-cultural nutritional intervention programs with the potential to mitigate both insulin resistance (IR) and hyperglycemia, together with cognitive impairment are also reviewed. Both dietary patterns and nutritional supplementation showed the effects of improving glycemic control and reducing cognitive decline in diabetes associated with AD, but the intervention specificity remained controversial. Multi-nutrient supplements combined with diverse diets may have preventive and therapeutic potential for DM combined with AD, at least as related to the B vitamin group and folate-dependent homocysteine (Hcy). The nutritional intervention has promise in the prevention and management of DM and AD comorbidities, and more clinical studies would be of nutritional scientific merit.

High-Intensity Interval Training-Induced Hippocampal Molecular Changes Associated with Improvement in Anxiety-like Behavior but Not Cognitive Function in Rats with Type 2 Diabetes

(1) Background: Exercise exerts many neuroprotective effects in diabetes-induced brain disorders. In this study, we investigated the effect of high-intensity interval training (HIIT) on brain molecular changes and cognitive and anxiety-like behaviors in rats with type 2 diabetes. (2) Methods: Twenty-eight adult male rats were divided into four groups (n = 7): control (C), exercise + control (C+EX), diabetes (DM), and diabetes + exercise (DM+EX). Diabetes was induced using a two-month high-fat diet and a single dose of streptozotocin (35 mg/kg) in the DM and DM+EX groups. After, the C+EX and DM+EX groups performed HIIT for eight weeks (five sessions per week, running at 80-100% of VMax, 4-10 intervals) on a motorized treadmill. Then, the elevated plus maze (EPM) and open field test (OFT) were performed to evaluate anxiety-like behaviors. The Morris water maze (MWM) and shuttle box were used to assess cognitive function. The hippocampal levels of beta-amyloid and tau protein were also assessed using Western blot. (3) Results: The hippocampal levels of beta-amyloid and tau protein were increased in the DM group, but HIIT restored these changes. While diabetes led to a significant decrease in open arm time percentage (%OAT) and open arm enters percentage (%OAE) in the EPM, indicating anxiety-like behavior, HIIT restored them. In the OFT, grooming was decreased in diabetic rats, which was restored by HIIT. No significant difference between groups was seen in the latency time in the shuttle box or for learning and memory in the MWM. (4) Conclusions: HIIT-induced hippocampal molecular changes were associated with anxiety-like behavior improvement but not cognitive function in rats with type 2 diabetes.

Relationship between cognitive function in individuals with diabetic foot ulcer and mortality

BACKGROUND

Diabetic foot ulcer (DFU) is a common diabetes mellitus (DM) complication. Individuals with DM and a DFU achieved significantly lower scores in cognitive tests than those without a DFU. We investigated whether baseline cognitive function in individuals with a DFU is a determinant of mortality.

METHODS

A prospective study using data collected during a case-control study conducted in 2010-2012 whereby 90 participants with a DFU (mean age at baseline 58.28 ± 6.95 years, 75.6% male) took the paper and pencil and the NeuroTrax battery of cognitive tests. Depression was assessed, and the DFU status was evaluated. In 2020, information pertaining to participants' vital status (dead/alive) was collected and the relationship between baseline cognitive status and vital status was assessed.

RESULTS

During a median follow-up of 6.8 years (range 0.2-9.5), 39 participants died (43.3%). Individuals alive vs. those who had died during follow-up had a higher global cognitive score at baseline (92.16 ± 10.95 vs. 87.18 ± 12.24, p = 0.045), but increased risk was not found. Individuals who were alive vs. those who had died during follow-up had statistically significantly higher baseline executive function, reaction time and digit symbol substitution test results. However, after adjustment for glycosylated hemoglobin (HbA1c), microvascular and macrovascular complications, no relationship between cognitive tests and mortality remained significant.

CONCLUSIONS

The higher mortality rate among people with type 2 DM and a DFU was not significant after adjustment for HbA1c, micro- and macrovascular complications. There may be common pathophysiological pathways to both DM complications and cognitive impairment, which may contribute to increased mortality. Further studies are warranted.

Diabetes and associated cognitive disorders: Role of the Hypothalamic-Pituitary Adrenal axis

Both diabetes types, types 1 and 2, are associated with cognitive impairments. Each period of life is concerned, and this is an increasing public health problem. Animal models have been developed to investigate the biological actors involved in such impairments. Many levels of the brain function (structure, volume, neurogenesis, neurotransmission, behavior) are involved. In this review, we detailed the part potentially played by the Hypothalamic-Pituitary Adrenal axis in these dysfunctions. Notably, regulating glucocorticoid levels, their receptors and their bioavailability appear to be relevant for future research studies, and treatment development.

The association between sodium-glucose cotransporter 2 inhibitors and incident dementia: A nationwide population-based longitudinal cohort study

BACKGROUND

The association of the use of sodium-glucose cotransporter 2 (SGLT2) inhibitor and incident dementia remains unclear. This study aimed to evaluate the risk of incident dementia with the use of SGLT2 inhibitor.

METHODS

This is a population-based cohort study utilizing Taiwan's National Health Insurance Research Database. Each patient who took SGLT2 inhibitors was assigned to the SGLT2 inhibitor group, whereas 1:1 propensity score-matched randomly selected patients who were nonusers of SGLT2 inhibitors were assigned to the non-SGLT2 inhibitor group. The study outcome was incident dementia.

RESULTS

A total of 976,972 patients newly diagnosed with type 2 diabetes mellitus (DM) between 2011 and 2018 were included in this study. After the patients' propensity score matching by age, sex, duration of DM, comorbidities and drug index date of the patients, a total of 103,247 patients in the SGLT2 inhibitor group and 103,247 in the non-SGLT2 inhibitor group were enrolled for analysis. The SGLT2 inhibitor group was associated with a lower risk of incident dementia (adjusted hazard ratio: 0.89, 95% confidence interval: 0.82-0.96; p = .0021). Diabetic complications were significantly lower in the SGLT2 inhibitor group compared with the non-SGLT2 group. Sensitivity analysis was also consistent with the main analysis.

CONCLUSIONS

Patients with type 2 DM who were prescribed SGLT2 inhibitors were associated with a lower risk of incident dementia compared with those not prescribed SGLT2 inhibitors in real-world practice.

Type 2 Diabetes Mellitus as a Risk Factor for Alzheimer’s Disease: Review and Meta-Analysis

Alzheimer’s disease is the most common type of dementia, reaching 60–80% of case totals, and is one of the major global causes of the elderly population’s decline in functionality concerning daily life activities. Epidemiological research has already indicated that, in addition to several others metabolic factors, diabetes mellitus type 2 is a risk factor of Alzheimer’s disease. Many molecular pathways have been described, and at the same time, there are clues that suggest the connection between type 2 diabetes mellitus and Alzheimer’s disease, through specific genes, autophagy, and even inflammatory pathways. A systematic review with meta-analysis was conducted, and its main goal was to reveal the multilevel connection between these diseases.

Effect of a Community Gerontology Program on the Control of Metabolic Syndrome in Mexican Older Adults

Background: Metabolic syndrome (MS) is highly prevalent in older adults; it constitutes a risk factor for cognitive deterioration, frailty, and Alzheimer’s disease. For this reason, the WHO has pointed out the importance of the implementation of community programs for the training of healthy aging. The aim of this study was to evaluate the effect of a community gerontology program framed in active aging on the control of metabolic syndrome in older adults. Methods: An experimental study was carried out in a convenience sample of 80 older adults diagnosed with MS according to the ATPIII criteria, comprising (1) experimental group (EG), n = 40; (2) control group (CG), n = 40. During a 6-month period, the EG participated in a supervised community gerontology program, and the CG was assessed monthly. Results: A statistically significant decrease was observed in the number of components for the diagnosis of MS. In this regard, of the total of participants with a diagnosis of MS in EG, only 28% maintained the diagnosis of MS (ATPIII ≥ 3 criteria), in contrast to 83% of the CG participants (p < 0.0001). Conclusions: Our findings suggest that health self-care training within the framework of active aging is effective for the control of MS in older adults.

New treatment approaches for Alzheimer's disease: preclinical studies and clinical trials centered on antidiabetic drugs

INTRODUCTION

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) represent two major chronic diseases that affect a large percentage of the population and share common pathogenetic mechanisms, including oxidative stress and inflammation. Considering their common mechanistic aspects, and given the current lack of effective therapies for AD, accumulating research has focused on the therapeutic potential of antidiabetic drugs in the treatment or prevention of AD.

AREAS COVERED

This review examines the latest preclinical and clinical evidence on the potential of antidiabetic drugs as candidates for AD treatment. Numerous approved drugs for T2DM, including insulin, metformin, glucagon-like peptide-1 receptor agonists (GLP-1 RA), and sodium glucose cotransporter 2 inhibitors (SGLT2i), are in the spotlight and may constitute novel approaches for AD treatment.

EXPERT OPINION

Among other pharmacologic agents, GLP-1 RA and SGLT2i have so far exhibited promising results as novel treatment approaches for AD, while current research has centered on deciphering their action on the central nervous system (CNS). Further investigation is crucial to reveal the most effective pharmacological agents and their optimal combinations, maximize their beneficial effects on neurons, and find ways to increase their distribution to the CNS.

Mini Review: Effect of GLP-1 Receptor Agonists and SGLT-2 Inhibitors on the Growth Hormone/IGF Axis

Accumulating evidence supports the early use of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium glucose transporter-2 inhibitors (SGLT-2is) for the treatment of type 2 diabetes. Indeed, these compounds exert numerous pleiotropic actions that favorably affect metabolism and diabetes comorbidities, showing an additional effect beyond glucose control. Although a substantial amount of knowledge has been generated regarding the mechanism of action of both drug classes, much remains to be understood. Growth hormone (GH) is an important driver for multiple endocrine responses involving changes in glucose and lipid metabolism, and affects several tissues and organs (e.g., bone, heart). It acts directly on several target tissues, including skeletal muscle and bone, but several effects are mediated indirectly by circulating (liver-derived) or locally produced IGF-1. In consideration of the multiple metabolic and cardiovascular effects seen in subjects treated with GLP-1RAs and SGLT-2is (e.g., reduction of hyperglycemia, weight loss, free/fat mass and bone remodeling, anti-atherosclerosis, natriuresis), it is reasonable to speculate that GH and IGF-1 may play a about a relevant role in this context. This narrative mini-review aims to describe the involvement of the GH/IGF-1/IGF-1R axis in either mediating or responding to the effects of each of the two drug classes.

A comprehensive review on RAGE-facilitated pathological pathways connecting Alzheimer’s disease, diabetes mellitus, and cardiovascular diseases

Background

Alzheimer’s disease (AD), cardiovascular disease (CVD), and diabetes are some of the most common causes of morbidity and mortality among the aging populations and cause a heavy burden on the worldwide healthcare system. In this review, we briefly highlighted cellular inflammation-based pathways of diabetes mellitus and CVD through receptor for advanced glycation end products AGEs or RAGE leading to Alzheimer’s disease and interrelation between these vascular and metabolic disorders. The articles were retrieved from Google Scholar, Science Direct, and PubMed databases using the following terms: Alzheimer’s; AGEs; RAGE; RAGE in Alzheimer’s; AGEs in Alzheimer’s; RAGE in diabetes; RAGE related pathways of CVD; RAGE in hypertension; RAGE and RAS system; RAGE and oxidative stress.

Main body of the abstract

AD is a neurodegenerative disease characterized by cognitive dysfunction and neuronal cell death. Vascular complications like hypertension, coronary artery disease, and atherosclerosis as well as metabolic syndromes like obesity and diabetes are related to the pathophysiology of AD. RAGE plays significant role in the onset and progression of AD. Amyloid plaques and neurofibrillary tangles (NFT) are two main markers of AD that regulates via RAGE and other RAGE/ligands interactions which also induces oxidative stress and a cascade of other cellular inflammation pathways leading to AD. Though AD and diabetes are two different disorders but may be inter-linked by AGEs and RAGE. In long-term hyperglycemia, upregulated AGEs interacts with RAGE and produces reactive oxygen species which induces further inflammation and vascular complications. Aging, hypercholesterolemia, atherosclerosis, hypertension, obesity, and inflammation are some of the main risk factors for both diabetes and dementia. Chronic hypertension and coronary artery disease disrupt the functions of the blood-brain barrier and are responsible for the accumulation of senile plaques and NFTs.

Short conclusion

RAGE plays a role in the etiology of Aβ and tau hyperphosphorylation, both of which contribute to cognitive impairment. So far, targeting RAGE may provide a potential sight to develop therapies against some metabolic disorders.

Serum Corticosterone and Insulin Resistance as Early Biomarkers in the hAPP23 Overexpressing Mouse Model of Alzheimer's Disease

Increasing epidemiological evidence highlights the association between systemic insulin resistance and Alzheimer’s disease (AD). As insulin resistance can be caused by high-stress hormone levels and since hypercortisolism appears to be an important risk factor of AD, we aimed to investigate the systemic insulin functionality and circulating stress hormone levels in a mutant humanized amyloid precursor protein (APP) overexpressing (hAPP23+/−) AD mouse model. Memory and spatial learning of male hAPP23+/− and C57BL/6 (wild type, WT) mice were assessed by a Morris Water Maze (MWM) test at the age of 4 and 12 months. The systemic metabolism was examined by intraperitoneal glucose and insulin tolerance tests (GTT, ITT). Insulin and corticosterone levels were determined in serum. In the hippocampus, parietal and occipital cortex of hAPP23+/− brains, amyloid-beta (Aβ) deposits were present at 12 months of age. MWM demonstrated a cognitive decline in hAPP23+/− mice at 12 but not at 4 months, evidenced by increasing total path lengths and deteriorating probe trials compared to WT mice. hAPP23+/− animals presented increased serum corticosterone levels compared to WT mice at both 4 and 12 months. hAPP23+/− mice exhibited peripheral insulin resistance compared to WT mice at 4 months, which stabilized at 12 months of age. Serum insulin levels were similar between genotypes at 4 months of age but were significantly higher in hAPP23+/− mice at 12 months of age. Peripheral glucose homeostasis remained unchanged. These results indicate that peripheral insulin resistance combined with elevated circulating stress hormone levels could be potential biomarkers of the pre-symptomatic phase of AD.