Type 2 diabetes and late-onset Alzheimer's disease

The identification of biomarkers for Alzheimer's disease using a systems biology approach based on lncRNA-circRNA-miRNA-mRNA ceRNA networks

In addition to being the most prevalent form of neurodegeneration among the elderly, AD is a devastating multifactorial disease. Currently, treatments address only its symptoms. Several clinical studies have shown that the disease begins to manifest decades before the first symptoms appear, indicating that studying early changes is crucial to improving early diagnosis and discovering novel treatments. Our study used bioinformatics and systems biology to identify biomarkers in AD that could be used for diagnosis and prognosis. The procedure was performed on data from the GEO database, and GO and KEGG enrichment analysis were performed. Then, we set up a network of interactions between proteins. Several miRNA prediction tools including miRDB, miRWalk, and TargetScan were used. The ceRNA network led to the identification of eight mRNAs, four circRNAs, seven miRNAs, and seven lncRNAs. Multiple mechanisms, including the cell cycle and DNA replication, have been linked to the promotion of AD development by the ceRNA network. By using the ceRNA network, it should be possible to extract prospective biomarkers and therapeutic targets for the treatment of AD. It is possible that the processes involved in DNA cell cycle and the replication of DNA contribute to the development of Alzheimer's disease.

Association Between Type 2 Diabetes Mellitus and Alzheimer's Disease: Common Molecular Mechanism and Therapeutic Targets

Diabetes mellitus (DM) and Alzheimer's disease (AD) rates are rising, mirroring the global trend of an aging population. Numerous epidemiological studies have shown that those with Type 2 diabetes (T2DM) have an increased risk of developing dementia. These degenerative and progressive diseases share some risk factors. To a large extent, the amyloid cascade is responsible for AD development. Neurofibrillary tangles induce neurodegeneration and brain atrophy; this chain reaction begins with hyperphosphorylation of tau proteins caused by progressive amyloid beta (Aβ) accumulation. In addition to these processes, it seems that alterations in brain glucose metabolism and insulin signalling lead to cell death and reduced synaptic plasticity in AD, before the onset of symptoms, which may be years away. Due to the substantial evidence linking insulin resistance in the brain with AD, researchers have coined the name "Type 3 diabetes" to characterize the condition. We still know little about the processes involved, even though current animal models have helped illuminate the links between T2DM and AD. This brief overview discusses insulin and IGF-1 signalling disorders and the primary molecular pathways that may connect them. The presence of GSK-3β in AD is intriguing. These proteins' association with T2DM and pancreatic β-cell failure suggests they might be therapeutic targets for both disorders.

Development and validation of a risk prediction model for mild cognitive impairment in elderly patients with type 2 diabetes mellitus

BACKGROUND

The prevalence of mild cognitive impairment (MCI) is steadily increasing among elderly people with type 2 diabetes (T2DM). This study aimed to create and validate a predictive model based on a nomogram.

METHODS

This cross-sectional study collected sociodemographic characteristics, T2DM-related factors, depression, and levels of social support from 530 older adults with T2DM. We used LASSO regression and multifactorial logistic regression to determine the predictors of the model. The performance of the nomogram was evaluated using calibration curves, receiver operating characteristics (ROC), and decision curve analysis (DCA).

RESULTS

The nomogram comprised age, smoking, physical activity, social support, depression, living alone, and glycosylated hemoglobin. The AUC for the training and validation sets were 0.914 and 0.859. The DCA showed good clinical applicability.

CONCLUSIONS

This predictive nomogram has satisfactory accuracy and discrimination. Therefore, the nomogram can be intuitively and easily used to detect MCI in elderly adults with T2DM.

Molecular mechanisms linking type 2 diabetes mellitus and late-onset Alzheimer's disease: A systematic review and qualitative meta-analysis

Research evidence indicating common metabolic mechanisms through which type 2 diabetes mellitus (T2DM) increases risk of late-onset Alzheimer's dementia (LOAD) has accumulated over recent decades. The aim of this systematic review is to provide a comprehensive review of common mechanisms, which have hitherto been discussed in separate perspectives, and to assemble and evaluate candidate loci and epigenetic modifications contributing to polygenic risk linkages between T2DM and LOAD. For the systematic review on pathophysiological mechanisms, both human and animal studies up to December 2023 are included. For the qualitative meta-analysis of genomic bases, human association studies were examined; for epigenetic mechanisms, data from human studies and animal models were accepted. Papers describing pathophysiological studies were identified in databases, and further literature gathered from cited work. For genomic and epigenomic studies, literature mining was conducted by formalised search codes using Boolean operators in search engines, and augmented by GeneRif citations in Entrez Gene, and other sources (WikiGenes, etc.). For the systematic review of pathophysiological mechanisms, 923 publications were evaluated, and 138 gene loci extracted for testing candidate risk linkages. 3 57 publications were evaluated for genomic association and descriptions of epigenomic modifications. Overall accumulated results highlight insulin signalling, inflammation and inflammasome pathways, proteolysis, gluconeogenesis and glycolysis, glycosylation, lipoprotein metabolism and oxidation, cell cycle regulation or survival, autophagic-lysosomal pathways, and energy. Documented findings suggest interplay between brain insulin resistance, neuroinflammation, insult compensatory mechanisms, and peripheral metabolic dysregulation in T2DM and LOAD linkage. The results allow for more streamlined longitudinal studies of T2DM-LOAD risk linkages.

Mitigating diabetes associated with reactive oxygen species (ROS) and protein aggregation through pharmacological interventions

Diabetes mellitus, a complex metabolic disorder, presents a growing global health challenge. In 2021, there were 529 million diabetics worldwide. At the super-regional level, Oceania, the Middle East, and North Africa had the highest age-standardized rates. The majority of cases of diabetes in 2021 (>90.0%) were type 2 diabetes, which is largely indicative of the prevalence of diabetes in general, particularly in older adults (K. L. Ong, et al., Global, regional, and national burden of diabetes from 1990 to 2021, with projections of prevalence to 2050: a systematic analysis for the Global Burden of Disease Study 2021, Lancet, 2023, 402(10397), 203-234). Nowadays, slowing the progression of diabetic complications is the only effective way to manage diabetes with the available therapeutic options. However, novel biomarkers and treatments are urgently needed to control cytokine secretion, advanced glycation end products (AGEs) production, vascular inflammatory effects, and cellular death. Emerging research has highlighted the intricate interplay between reactive oxygen species (ROS) and protein aggregation in the pathogenesis of diabetes. In this scenario, the main aim of this paper is to provide a comprehensive review of the current understanding of the molecular mechanisms underlying ROS-induced cellular damage and protein aggregation, specifically focusing on their contribution to diabetes development. The role of ROS as key mediators of oxidative stress in diabetes is discussed, emphasizing their impact on cellular components and signaling. Additionally, the involvement of protein aggregation in impairing cellular function and insulin signaling is explored. The synergistic effects of ROS and protein aggregation in promoting β-cell dysfunction and insulin resistance are examined, shedding light on potential targets for therapeutic intervention.

Obesity, diabetes and their metabolic correlates in middle-aged adults with Down syndrome

BACKGROUND

Obesity in adults without Down syndrome is associated with an adverse metabolic profile including high prevalence of pre-diabetes and diabetes, high levels of insulin, non-high-density lipoprotein (HDL) cholesterol, leptin and high-sensitivity C-reactive protein (hsCRP) and low levels of HDL and adiponectin. We examined whether obesity in middle-aged adults with Down syndrome is also related to an adverse metabolic profile.

METHODS

This cross-sectional study included 143 adults with Down syndrome, with a mean age of 55.7 ± 5.7 years and 52.5% women. Body mass index (BMI) was classified as underweight (BMI < 18.5 kg/m2 ), normal (BMI 18.5-24.9 kg/m2 ), overweight (BMI 25-29.9 kg/m2 ) and obese (BMI ≥ 30 kg/m2 ). Diabetes was ascertained by history or by haemoglobin A1c (HbA1c) as normal glucose tolerance (HbA1c < 5.7%), pre-diabetes (HbA1c 5.7-6.4%) and diabetes (HbA1c ≥ 6.5%). We measured non-fasting lipids, hsCRP, insulin, adiponectin and leptin.

RESULTS

The majority of the sample had an overweight (46.9%) or obesity (27.3%) status. However, there was a relatively low prevalence of pre-diabetes (9.8%) and diabetes (6.9%). Overweight and obesity status were not associated with lower HDL and adiponectin and higher insulin, non-HDL cholesterol and hsCRP as expected in adults without Down syndrome. However, overweight and obesity were strongly associated with higher leptin (P < 0.001).

CONCLUSIONS

The only metabolic correlate of obesity in middle-aged adults with Down syndrome was high leptin levels. Our findings are limited by non-fasting laboratory tests but suggest that middle-aged adults with Down syndrome do not have the adverse metabolic profile related to obesity found in adults without Down syndrome.

Reinstated Activity of Human Tau-induced Enhanced Insulin Signaling Restricts Disease Pathogenesis by Regulating the Functioning of Kinases/Phosphatases and Tau Hyperphosphorylation in Drosophila

Tauopathies such as Alzheimer's disease (AD), Frontotemporal dementia, and parkinsonism linked to chromosome 17 (FTDP-17), etc. are characterized by tau hyperphosphorylation and distinguished accumulation of paired helical filaments (PHFs)/or neurofibrillary tangles (NFTs) in a specific-neuronal subset of the brain. Among different reported risk factors, type 2 diabetes (T2D) has gained attention due to its correlation with tau pathogenesis. However, mechanistic details and the precise contribution of insulin pathway in tau etiology is still debatable. We demonstrate that expression of human tau causes overactivation of insulin pathway in Drosophila disease models. We subsequently noted that tissue-specific downregulation of insulin signaling or even exclusive reduction of its growth-promoting sub-branch effectively reinstates the overactivated insulin signaling pathway in human tau expressing cells, which in turn restricts pathogenic tau hyperphosphorylation and aggregate formation. It was further noted that restored tau phosphorylation was achieved due to a reestablished balance between the levels of different kinase(s) (GSK3β and ERK/P38 MAP kinase) and phosphatase (PP2A). Taken together, our study demonstrates a precise involvement of the insulin pathway and associated molecular events in the pathogenesis of human tauopathies in Drosophila, which will be immensely helpful in developing novel therapeutic options against these devastating human brain disorders. Moreover, our study reveals an interesting link between tau etiology and aberrant insulin signaling, which is a characteristic feature of Type 2 Diabetes.

A Potential Role for the Ketogenic Diet in Alzheimer's Disease Treatment: Exploring Pre-Clinical and Clinical Evidence

Given the remarkable progress in global health and overall quality of life, the significant rise in life expectancy has become intertwined with the surging occurrence of neurodegenerative disorders (NDs). This emerging trend is poised to pose a substantial challenge to the fields of medicine and public health in the years ahead. In this context, Alzheimer's disease (AD) is regarded as an ND that causes recent memory loss, motor impairment and cognitive deficits. AD is the most common cause of dementia in the elderly and its development is linked to multifactorial interactions between the environment, genetics, aging and lifestyle. The pathological hallmarks in AD are the accumulation of β-amyloid peptide (Aβ), the hyperphosphorylation of tau protein, neurotoxic events and impaired glucose metabolism. Due to pharmacological limitations and in view of the prevailing glycemic hypometabolism, the ketogenic diet (KD) emerges as a promising non-pharmacological possibility for managing AD, an approach that has already demonstrated efficacy in addressing other disorders, notably epilepsy. The KD consists of a food regimen in which carbohydrate intake is discouraged at the expense of increased lipid consumption, inducing metabolic ketosis whereby the main source of energy becomes ketone bodies instead of glucose. Thus, under these dietary conditions, neuronal death via lack of energy would be decreased, inasmuch as the metabolism of lipids is not impaired in AD. In this way, the clinical picture of patients with AD would potentially improve via the slowing down of symptoms and delaying of the progression of the disease. Hence, this review aims to explore the rationale behind utilizing the KD in AD treatment while emphasizing the metabolic interplay between the KD and the improvement of AD indicators, drawing insights from both preclinical and clinical investigations. Via a comprehensive examination of the studies detailed in this review, it is evident that the KD emerges as a promising alternative for managing AD. Moreover, its efficacy is notably enhanced when dietary composition is modified, thereby opening up innovative avenues for decreasing the progression of AD.

Risk of Neurodegenerative Diseases in Elderly Koreans with an Initial Diagnosis of Type 2 Diabetes: A Nationwide Retrospective Cohort Study

Type 2 diabetes (T2D) and neurodegenerative diseases (NDs) are common among elderly individuals. Growing evidence has indicated a strong link between T2D and NDs, such as Alzheimer's disease. However, previous studies have limitations in exploring the epidemiological relationship among these diseases as a group of NDs rather than as a specific type of ND. We aimed to investigate the risk of NDs in elderly Koreans who were first diagnosed with T2D and determine the association between T2D and NDs. We conducted a retrospective longitudinal cohort study of patients with who were initially diagnosed with T2D using the Korean National Health Information Database. The study participants were categorized into a T2D group (n = 155,459) and a control group (n = 155,459), aged 60-84 years, that were matched for age, sex, and comorbidities. We followed the participants for 10 years to investigate the incidence of NDs. The Cox proportional hazards regression model was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for NDs. The numbers of patients diagnosed with ND at the end of follow-up were as follows: 51,096/155,459 (32.9%) in the T2D group and 44,673/155,459 (28.7%) in the control group (χ2 = 622.53, p < 0.001). The incidences of NDs in the T2D and control groups were 44.68 (95% CI: 44.29, 45.07) and 36.89 (95% CI: 36.55, 37.24) cases per 1,000 person-years at risk, respectively. The overall incidence of NDs was higher in the T2D group than that in the control group (HR: 1.23, 95% CI: 1.22, 1.25, p < 0.001). This study revealed a higher incidence of NDs in elderly Koreans who were initially diagnosed with T2D. This suggests that T2D is a risk factor for NDs in elderly Koreans.

FMNL2 regulates gliovascular interactions and is associated with vascular risk factors and cerebrovascular pathology in Alzheimer's disease

Alzheimer's disease (AD) has been associated with cardiovascular and cerebrovascular risk factors (CVRFs) during middle age and later and is frequently accompanied by cerebrovascular pathology at death. An interaction between CVRFs and genetic variants might explain the pathogenesis. Genome-wide, gene by CVRF interaction analyses for AD, in 6568 patients and 8101 controls identified FMNL2 (p = 6.6 × 10-7). A significant increase in FMNL2 expression was observed in the brains of patients with brain infarcts and AD pathology and was associated with amyloid and phosphorylated tau deposition. FMNL2 was also prominent in astroglia in AD among those with cerebrovascular pathology. Amyloid toxicity in zebrafish increased fmnl2a expression in astroglia with detachment of astroglial end feet from blood vessels. Knockdown of fmnl2a prevented gliovascular remodeling, reduced microglial activity and enhanced amyloidosis. APP/PS1dE9 AD mice also displayed increased Fmnl2 expression and reduced the gliovascular contacts independent of the gliotic response. Based on this work, we propose that FMNL2 regulates pathology-dependent plasticity of the blood-brain-barrier by controlling gliovascular interactions and stimulating the clearance of extracellular aggregates. Therefore, in AD cerebrovascular risk factors promote cerebrovascular pathology which in turn, interacts with FMNL2 altering the normal astroglial-vascular mechanisms underlying the clearance of amyloid and tau increasing their deposition in brain.

Early Prediction of a Pre-Symptomatic Neurodegeneration Disorder by Measuring Macrophage Inhibitory Factor Level in Diabetic Patients

BACKGROUND

The relationship between diabetes mellitus and neurodegenerative disorders has been of great interest. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine in which a variety of signaling cascades are activated through it. MIF has been involved in the pathogenesis of several diseases and can predict early pre-symptomatic stages of neurodegeneration in diabetic patients.

OBJECTIVE

To investigate whether serum MIF could predict brain neurodegeneration at the early pre-symptomatic stages in diabetic patients.

METHODS

We examined adults with type 2 diabetes mellitus and compared with normal control adults using a short form of the IQCODE and biochemical examination, including assessment of HA1C, fasting blood glucose, lipid profile, and MIF which was measured by ELISA technique. Correlations between parameters were studied. Computational PathLinker bioinformatic tool was used to search for potential pathway reconstructions for the insulin/amyloid-β/MIF signaling.

RESULTS

We demonstrated that MIF level was increased in the serum at the early pre-symptomatic stages of neurodegenerative disorder in diabetic patients. In addition, network analysis demonstrates that insulin receptor substrate 1 can ameliorate amyloid-β protein precursor through COP9 signalosome complex subunit 5 that enhances MIF elevation.

CONCLUSION

Diagnosis processes could not be used as routine examinations for still pre-symptomatic neurodegenerative disorders. This may be due to the time constraints and the heavy dependence on the physician's experience. Therefore, serum MIF level could predict brain neurodegeneration at the early pre-symptomatic stages in diabetic patients which may support its potential utility as a clinically useful biomarker.

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.

Hemorrhagic stroke outcomes of KApSR patients with co-morbid diabetes and Alzheimer's disease

Background

Vascular risk factors, such as diabetes mellitus (DM), are associated with poorer outcomes following many neurodegenerative diseases, including hemorrhagic stroke and Alzheimer's disease (AD). Combined AD and DM co-morbidities are associated with an increased risk of hemorrhagic stroke and increased Medicare costs. Therefore, we hypothesized that patients with DM in combination with AD, termed DM/AD, would have increased hemorrhagic stroke severity.

Methods

Kentucky Appalachian Stroke Registry (KApSR) is a database of demographic and clinical data from patients that live in Appalachia, a distinct region with increased health disparities and stroke severity. Inpatients with a primary indication of hemorrhagic stroke were selected from KApSR for retrospective analysis and were separated into four groups: DM only, AD only, neither, or both.

Results

Hemorrhagic stroke patients (2,071 total) presented with either intracerebral hemorrhage (ICH), n=1,448, or subarachnoid hemorrhage (SAH), n=623. When examining all four groups, subjects with AD were significantly older (AD+, 80.9±6.6 yrs) (DM+/AD+, 77.4±10.0 yrs) than non AD subjects (DM-/AD-, 61.3±16.5 yrs) and (DM+, 66.0±12.5 yrs). A higher percentage of females were among the AD+ group and a higher percentage of males among the DM+/AD+ group. Interestingly, after adjusting for multiple comparison, DM+/AD+ subjects were ten times as likely to suffer a moderate to severe stroke based on a National Institute of Health Stroke (NIHSS) upon admission [odds ratio (95% CI)] compared to DM-/AD- [0.1 (0.02-0.55)], DM+ [0.11 (0.02-0.59)], and AD+ [0.09(0.01-0.63)]. The odds of DM+/AD+ subjects having an unfavorable discharge destination (death, hospice, long-term care) was significant (P<0.05) from DM-/AD- [0.26 (0.07-0.96)] when adjusting for sex, age, and comorbidities.

Conclusions

In our retrospective analysis utilizing KApSR, regardless of adjusting for age, sex, and comorbidities, DM+/AD+ patients were significantly more likely to have had a moderate or severe stroke leading to an unfavorable outcome following hemorrhagic stroke.

Long-term dysglycemia as a risk factor for faster cognitive decline during aging: A 12-year follow-up study

AIMS

This longitudinal study evaluated associations between glucose metabolism and cognitive performance during a 12-year follow-up.

METHODS

We included 714 subjects, which were followedfrom the age 55 to 70 years. Using oral glucose tolerance tests the population was classified as normoglycemic (NGT) and based on WHO diagnostic criteria for diabetes and prediabetes. Cognitive performance was assessed with a verbal fluency (category) test and wordlist learning tests of CERAD-nb, a verbal fluency (letter) test, and trail-making tests A and B.

RESULTS

Compared to the normal group subjects with long-lasting prediabetes showed significantly greater decline (4.6 versus 2.9 words) on the verbal fluency (category) test (p = 0.041); subjects with long-lasting type 2 diabetes showed significantly greater decline (13 versus 6 s) on the trail making A test (p = 0.021) and on the wordlist learning test (3.3 versus 1.7 words) (p = 0.013); and a combined group of subjects with prediabetes or incident type 2 diabetes showed significantly greater cognitive decline (3.8 versus 2.9 words) in the verbal fluency (category) test (p = 0.039).

CONCLUSION

Prediabetes was associated with cognitive decline during aging. This finding should be incorporated into prevention strategies, because both type 2 diabetes and dementia are increasing world-wide.

Mild Cognitive Impairment and Donepezil Impact Mitochondrial Respiratory Capacity in Skeletal Muscle

Alzheimer's Disease (ad) associates with insulin resistance and low aerobic capacity, suggestive of impaired skeletal muscle mitochondrial function. However, this has not been directly measured in AD. This study ( n  = 50) compared muscle mitochondrial respiratory function and gene expression profiling in cognitively healthy older adults (CH; n = 24) to 26 individuals in the earliest phase of ad-related cognitive decline, mild cognitive impairment (MCI; n  = 11) or MCI taking the ad medication donepezil (MCI + med; n  = 15). Mitochondrial respiratory kinetics were measured in permeabilized muscle fibers from muscle biopsies of the vastus lateralis. Untreated MCI exhibited lower lipid-stimulated skeletal muscle mitochondrial respiration (State 3, ADP-stimulated) than both CH ( P = .043) and MCI + med (P = .007) groups. MCI also exhibited poorer mitochondrial coupling control compared to CH (P = .014). RNA sequencing of skeletal muscle revealed unique differences in mitochondrial function and metabolism genes based on both MCI status (CH vs MCI) and medication treatment (MCI vs MCI + med). MCI + med modified over 600 skeletal muscle genes compared to MCI suggesting donepezil powerfully impacts the transcriptional profile of muscle. Overall, skeletal muscle mitochondrial respiration is altered in untreated MCI but normalized in donepezil-treated MCI participants while leak control is impaired regardless of medication status. These results provide evidence that mitochondrial changes occur in the early stages of AD, but are influenced by a common ad medicine. Further study of mitochondrial bioenergetics and the influence of transcriptional regulation in early ad is warranted.

Antidiabetic Drugs in Alzheimer's Disease and Mild Cognitive Impairment: A Systematic Review

INTRODUCTION

Considering that Alzheimer's disease (AD) and diabetes mellitus share pathophysiological features and AD remains with no cure, antidiabetic drugs like intranasal insulin, glitazones, metformin, and liraglutide are being tested as a potential treatment.

OBJECTIVE

The aim of this systematic review was to assess the efficacy of antidiabetic drugs in patients with AD, mild cognitive impairment (MCI), or subjective cognitive complaints (SCCs). Cognition was studied as the primary outcome and modulation of AD biomarkers, and imaging was also assessed as a secondary outcome.

METHODS

We conducted a search in the electronic databases PubMed/MEDLINE, EMBASE, and Scopus seeking clinical trials evaluating the effect on cognition of antidiabetic drugs in patients with AD, MCI, or SCCs.

RESULTS

A total of 23 articles were found eligible. Intranasal regular insulin improved verbal memory in most studies, especially in apoE4- patients, but results in other cognitive domains were unclear. Detemir improved cognition after 2 months of treatment, but it did not after 4 months. Pioglitazone improved cognition in diabetic patients with AD or MCI in 3 clinical trials, but it is controversial as 2 other studies did not show effect. Metformin and liraglutide showed promising results, but further research is needed as just 2 clinical trials involved each of these drugs. Almost all drugs tested were shown to modulate AD biomarkers and imaging.

CONCLUSIONS

Intranasal insulin, pioglitazone, metformin, and liraglutide are promising drugs that could be useful in the treatment of AD. However, many questions remain to be answered in future studies, so no particular antidiabetic drug can currently be recommended to treat AD.

Clusterin and Its Role in Insulin Resistance and the Cardiometabolic Syndrome

The cardiometabolic syndrome involves a clustering of metabolic and cardiovascular factors which increase the risk of patients developing both Type 2 Diabetes Mellitus and cardio/cerebrovascular disease. Although the mechanistic underpinnings of this link remain uncertain, key factors include insulin resistance, excess visceral adiposity, atherogenic dyslipidemia, and endothelial dysfunction. Of these, a state of resistance to insulin action in overweight/obese patients appears to be central to the pathophysiologic process. Given the increasing prevalence of obesity-related Type 2 Diabetes, coupled with the fact that cardiovascular disease is the number one cause of mortality in this patient population, a more thorough understanding of the cardiometabolic syndrome and potential options to mitigate its risk is imperative. Inherent in the pathogenesis of insulin resistance is an underlying state of chronic inflammation, at least partly in response to excess adiposity. Within obese adipose tissue, an immunomodulatory shift occurs, involving a preponderance of pro-inflammatory immune cells and cytokines/adipokines, along with antigen presentation by adipocytes. Therefore, various adipokines differentially expressed by obese adipocytes may have a significant effect on cardiometabolism. Clusterin is a molecular chaperone that is widely produced by many tissues throughout the body, but is also preferentially overexpressed by obese compared lean adipocytes and relates strongly to multiple components of the cardiometabolic syndrome. Herein, we summarize the known and potential roles of circulating and adipocyte-specific clusterin in cardiometabolism and discuss potential further investigations to determine if clusterin is a viable target to attenuate both metabolic and cardiovascular disease.

Propionate and Alzheimer's Disease

Propionate, a short-chain fatty acid, serves important roles in the human body. However, our review of the current literature suggests that under certain conditions, excess levels of propionate may play a role in Alzheimer's disease (AD). The cause of the excessive levels of propionate may be related to the Bacteroidetes phylum, which are the primary producers of propionate in the human gut. Studies have shown that the relative abundance of the Bacteroidetes phylum is significantly increased in older adults. Other studies have shown that levels of the Bacteroidetes phylum are increased in persons with AD. Studies on the diet, medication use, and propionate metabolism offer additional potential causes. There are many different mechanisms by which excess levels of propionate may lead to AD, such as hyperammonemia. These mechanisms offer potential points for intervention.

Race/Ethnic Disparities in Mild Cognitive Impairment and Dementia: The Northern Manhattan Study

BACKGROUND

Variability in dementia rates across racial and ethnic groups has been estimated at 60%. Studies suggest disparities in Caribbean Hispanic and Black populations, but community-based data are limited.

OBJECTIVE

Estimate the prevalence of mild cognitive impairment (MCI) and dementia in the racially and ethnically diverse community-based Northern Manhattan Study cohort and examine sociodemographic, vascular risk factor, and brain imaging correlates.

METHODS

Cases of MCI and dementia were adjudicated by a team of neuropsychologists and neurologists and prevalence was estimated across race/ethnic groups. Ordinal proportional odds models were used to estimate race/ethnic differences in the prevalence of MCI or dementia adjusting for sociodemographic variables (model 1), model 1 plus potentially modifiable vascular risk factors (model 2), and model 1 plus structural imaging markers of brain integrity (model 3).

RESULTS

There were 989 participants with cognitive outcome determinations (mean age 69±9 years; 68% Hispanic, 16% Black, 14% White; 62% women; mean (±SD) follow-up five (±0.6) years). Hispanic and Black participants had greater likelihood of MCI (20%) and dementia (5%) than White participants accounting for age and education differences. Hispanic participants had greater odds of MCI or dementia than both White and Black participants adjusting for sociodemographic variables, vascular risk factors, and brain imaging factors. White matter hyperintensity burden was significantly associated with greater odds of MCI or dementia (OR = 1.3, 1.1 to 1.6), but there was no significant interaction by race/ethnicity.

CONCLUSION

In this diverse community-based cohort, cross-sectional data revealed significant race/ethnic disparities in the prevalence of MCI and dementia. Longer follow-up and incidence data are needed to further clarify these relationships.

Characterization of the Meal-Stimulated Incretin Response and Relationship With Structural Brain Outcomes in Aging and Alzheimer's Disease

BACKGROUND

Individuals with Alzheimer's Disease (AD) are often characterized by systemic markers of insulin resistance; however, the broader effects of AD on other relevant metabolic hormones, such as incretins that affect insulin secretion and food intake, remains less clear.

METHODS

Here, we leveraged a physiologically relevant meal tolerance test to assess diagnostic differences in these metabolic responses in cognitively healthy older adults (CH; n = 32) and AD (n = 23) participants. All individuals also underwent a comprehensive clinical examination, cognitive evaluation, and structural magnetic resonance imaging.

RESULTS

The meal-stimulated response of glucose, insulin, and peptide tyrosine tyrosine (PYY) was significantly greater in individuals with AD as compared to CH. Voxel-based morphometry revealed negative relationships between brain volume and the meal-stimulated response of insulin, C-Peptide, and glucose-dependent insulinotropic polypeptide (GIP) in primarily parietal brain regions.

CONCLUSION

Our findings are consistent with prior work that shows differences in metabolic regulation in AD and relationships with cognition and brain structure.

Diabetes-Associated Dementia Risk and Competing Risk of Death in the Three-City Study

Diabetes is associated with a higher dementia and mortality risk. However, few studies have accounted for death when estimating the association between diabetes and dementia. We estimated absolute and relative risks of all-cause dementia according to diabetes exposure status in older adults while accounting for competing risk of death using illness-death models. Effect modification by specific characteristics (age, gender, education, cardiovascular risk factors, body mass index, cardiovascular history, depressive symptomatology, impaired renal function, and APOEɛ4 genotype) was also investigated. We analyzed the Three-City study data, a French population-based cohort of adults aged 65 years and above who were followed up for 12 years from 1999-2001. Among 8,328 participants selected in the analytical sample (median age, 73.3 years; 60.3% women), 809 (9.3%) presented with diabetes at baseline. Over a median follow-up period of 8.3 years, 836 participants developed incident dementia. Baseline diabetes was associated with a higher risk of dementia: hazard ratio, 1.79 [95% confidence interval, 1.46-2.19]. No effect modification was shown. Diabetes was associated with a higher 12-year absolute risk of dementia and a lower dementia-free life expectancy (e.g., 14.5% [11.2-18.1] versus 8.7% [7.6-10.2], and 13.4 [12.7-14.1] years versus 16.5 [16.0-17.1] years, respectively, for a 70-year-old woman with the highest level of education). These findings support the potential impact of preventing diabetes on reducing dementia risk in older adults, with a 2-3-year higher dementia-free life expectancy for individuals without diabetes, and inform the design of future interventional trials.

Clusterin as a Potential Biomarker of Obesity-Related Alzheimer's Disease Risk

Over 35% of the adult US population is obese. In turn, excess adiposity increases the risk of multiple complications including type 2 diabetes (T2D), insulin resistance, and cardiovascular disease; yet, obesity also independently heightens risk of Alzheimer's Disease (AD), even after adjusting for other important confounding risk factors including blood pressure, sociodemographics, cholesterol levels, smoking status, and Apolipoprotein E (ApoE) genotype. Among patients over the age of 65 with dementia, 37% have coexisting diabetes, and an estimated 7.3% of cases of AD are directly attributable to midlife obesity. Clusterin, also known as apolipoprotein J (ApoJ), is a multifunctional glycoprotein that acts as a molecular chaperone, assisting folding of secreted proteins. Clusterin has been implicated in several physiological and pathological states, including AD, metabolic disease, and cardiovascular disease. Despite long-standing interest in elucidating clusterin's relationship with amyloid beta (Aβ) aggregation/clearance and toxicity, significant knowledge gaps still exist. Altered clusterin expression and protein levels have been linked with cognitive and memory function, disrupted central nervous system lipid flux, as well as pathogenic brain structure; and its role in cardiometabolic disease suggests that it may be a link between insulin resistance, dyslipidemia, and AD. Here, we briefly highlight clusterin's relevance to AD by presenting existing evidence linking clusterin to AD and cardiometabolic disease, and discussing its potential utility as a biomarker for AD in the presence of obesity-related metabolic disease.

Heat therapy: possible benefits for cognitive function and the aging brain

Alzheimer's disease (AD) is the most common neurodegenerative disease, yet there are no disease-modifying treatments available and there is no cure. It is becoming apparent that metabolic and vascular conditions such as type 2 diabetes (T2D) and hypertension promote the development and accumulation of Alzheimer's disease-related dementia pathologies. To this end, aerobic exercise, which is a common lifestyle intervention for both metabolic disease and hypertension, is shown to improve brain health during both healthy aging and dementia. However, noncompliance or other barriers to exercise response are common in exercise treatment paradigms. In addition, reduced intracellular proteostasis and mitochondrial function could contribute to the etiology of AD. Specifically, compromised chaperone systems [i.e., heat shock protein (HSP) systems] can contribute to protein aggregates (i.e., β-amyloid plaques and neurofibrillary tangles) and reduced mitochondrial quality control (i.e., mitophagy). Therefore, novel therapies that target whole body metabolism, the vasculature, and chaperone systems (like HSPs) are needed to effectively treat AD. This review focuses on the role of heat therapy in the treatment and prevention of AD. Heat therapy has been independently shown to reduce whole body insulin resistance, improve vascular function, activate interorgan cross talk via endocytic vesicles, and activate HSPs to improve mitochondrial function and proteostasis in a variety of tissues. Thus, heat therapy could offer immense clinical benefit to patients suffering from AD. Importantly, future studies in patients are needed to determine the safety and efficacy of heat therapy in preventing AD.

Anemia and incidence of dementia in patients with new-onset type 2 diabetes: a nationwide population-based cohort study

INTRODUCTION

This study aimed to examine the association between anemia and the incidence of dementia in patients with new-onset type 2 diabetes.

RESEARCH DESIGN AND METHODS

This study used the Korean National Health Insurance Service-Health Screening Cohort and included 32 590 participants aged ≥40 years who were diagnosed with new-onset type 2 diabetes between 2004 and 2007 and followed up until 2013. Anemia was defined according to the criteria provided by the WHO, hemoglobin <120 g/L for women and <130 g/L for men, and was measured from after diagnosis date of type 2 diabetes to 2007. Dementia was defined by the Classification of Diseases 10th revision code as primary diagnosis and was measured from after hemoglobin measurement to 2013. We calculated the adjusted HR (AHR) and 95% CI to assess the risk of dementia using multivariable Cox proportional hazards regression models.

RESULTS

We identified 1682 patients who developed dementia within a 7.5-year follow-up. Among patients with type 2 diabetes, patients with anemia were associated with an increased risk of dementia than those without anemia (AHR, 1.21; 95% CI 1.06 to 1.39). Patients with mild (AHR, 1.18; 95% CI 1.03 to 1.38) and moderate (AHR, 1.39; 95% CI 1.06 to 1.83) anemia were associated with an increased risk of dementia than those without anemia among patients with type 2 diabetes. Men (AHR, 1.47; 95% CI 1.16 to 1.83) and middle-aged adults (AHR, 1.31; 95% CI 1.03 to 1.75) with anemia were associated with an increased risk of dementia than their counterparts without anemia among patients with type 2 diabetes.

CONCLUSIONS

Our findings suggest that anemia is significantly associated with an increased risk of dementia among patients with newly diagnosed type 2 diabetes.

Enhancement of Amyloid β1-43 Production in the Lens Epithelium of Japanese Type 2 Diabetic Patients

We investigated whether the accumulation of amyloid β-protein (Aβ) is enhanced in the lenses of diabetic patients. Lens epithelium samples were collected from Japanese patients during cataract surgery, and the Aβ levels and gene expression of Aβ-producing and -degrading enzymes in the samples were measured by ELISA and real-time RT-PCR, respectively. The Aβ_1–43 levels in lenses of non-diabetic patients were low (0.11 pmol/g protein), while the levels in lenses of diabetic patients were significantly (6-fold) higher. Moreover, the Aβ_1–43/total-Aβ ratio in the lenses of diabetic patients was also significantly higher than non-diabetic patients (p < 0.05). In addition, the mRNA levels for Aβ-producing enzymes were also enhanced in the lenses of diabetic patients. In contrast to the results for Aβ-producing enzymes, the mRNAs for the Aβ-degrading enzymes in the lenses of diabetic patients were significantly lower than in non-diabetic patients (p < 0.05). Furthermore, Aβ_1–43/total-Aβ ratio in lenses was found to increase with plasma glucose level. In conclusion, these results suggest that high glucose levels cause both an increase in Aβ production and a decrease in Aβ degradation, and these changes lead to the enhancement in Aβ_1–43 accumulation in the lenses of diabetic patients. These findings are useful for developing therapies for diabetic cataracts and for developing anti-cataract drugs.

Does hyperglycemia downregulate glucose transporters in the brain?

Diabetes is a metabolic condition associated with hyperglycemia manifested by the elevation of blood glucose levels occurring when the pancreas decreases or stops the production of insulin, in case of insulin resistance or both. The current literature supports that insulin resistance may be responsible for the memory decline associated with diabetes. Glucose transporters (GLUTs) are a family of proteins involved in glucose transport across biological membranes. GLUT-1 and GLUT-3 are involved in glucose delivery to the brain. Evidence suggests that both transporters are downregulated in chronic peripheral hyperglycemia. Here we show the mechanisms of glucose transport and its influence on cognitive function, including a hypothesis of how peripheral hyperglycemia related genes network interactions may lead to glucose transporters downregulation and its possible consequences.

Bis(ethylmaltolato)oxidovanadium(iv) inhibited the pathogenesis of Alzheimer's disease in triple transgenic model mice

Vanadium compounds have been reported to mimic the anti-diabetes effects of insulin on rodent models, but their effects on Alzheimer's disease (AD) have rarely been explored. In this paper, 9-month-old triple transgenic AD model mice (3×Tg-AD) received bis(ethylmaltolato)oxidovanadium(iv) (BEOV) at doses of 0.2 mmol L^-1 (68.4 μg mL^-1) and 1.0 mmol L^-1 (342 μg mL^-1) for 3 months. BEOV at both doses was found to improve contextual memory and spatial learning in AD mice. It also improved glucose metabolism and protected neuronal synapses in the AD brain, as evidenced respectively by ¹⁸F-labeled fluoro-deoxyglucose positron emission tomography (¹⁸F-FDG-PET) scanning and by transmission electron microscopy. Inhibitory effects of BEOV on β-amyloid (Aβ) plaques and neuronal impairment in the cortex and hippocampus of fluorescent AD mice were visualized three-dimensionally by applying optical clearing technology to brain slices before confocal laser scanning microscopy. Western blot analysis semi-quantitatively revealed the altered levels of Aβ₄₂ in the brains of wildtype, AD, and AD treated with 0.2 and 1.0 mmol L^-1 BEOV mice (70.3%, 100%, 83.2% and 56.8% in the hippocampus; 82.4%, 100%, 66.9% and 42% in the cortex, respectively). The mechanism study showed that BEOV increased the expression of peroxisome proliferator-activated receptor γ (PPARγ) (140%, 100%, 142% and 160% in the hippocampus; 167%, 100%, 124% and 133% in the cortex) to inactivate the JAK2/STAT3/SOCS-1 pathway and to block the amyloidogenesis cascade, thus attenuating Aβ-induced insulin resistance in AD models. BEOV also reduced protein tyrosine phosphatase 1B (PTP1B) expression (74.8%, 100%, 76.5% and 53.8% in the hippocampus; 71.8%, 100%, 94.2% and 81.8% in cortex) to promote insulin sensitivity and to stimulate the PI3K/Akt/GSK3β pathway, subsequently reducing tau hyperphosphorylation (phosphorylated tau396 levels were 51.1%, 100%, 56.1% and 50.2% in the hippocampus; 22.2%, 100%, 36.1%, and 24% in the cortex). Our results suggested that BEOV reduced the pathological hallmarks of AD by targeting the pathways of PPARγ and PTP1B in 3×Tg AD mice.

The Effect of Type 2 Diabetes Mellitus on Neuropsychological Symptoms in Chinese Early Alzheimer's Disease Population

OBJECTIVE

To explore the effect of Type 2 diabetes mellitus (T2DM) on the development of neuropsychiatric symptoms (NPS) in early Alzheimer's disease (AD).

METHODS

From September 2017 to March 2019, a cross-sectional study was conducted on the clinical data of 158 early AD patients over 65 years old in the Department of Neurology of Daping Hospital. All early stage of AD patients were divided into early stage of AD with NPS group and early stage of AD without NPS group according to the presence or absence of NPS. Clinical data of age, sex, body mass index (BMI), smoking and alcohol consumption, history of hypertension, hyperlipidemia, white matter leisure (WML) and T2DM, MMSE, CDR and NPI-Q scores were collected. Multivariate logistic regression analyses were performed to examine the relationship between T2DM and NPS in early AD.

RESULTS

Compared with the early stage of AD group without NPS, the early stage of AD group with NPS was older, the proportion of women was higher, the proportion of T2DM, hypertension, hyperlipidemia and WML was higher, and the MMSE score was lower (P< 0.05). T2DM was an independent risk factor for NPS in early stage of AD patients (OR 3.48, 95% CI 2.91-3.84). The incidence of T2DM in AD patients with depression, anxiety, nighttime behavioral disturbances, and appetite disturbances was significantly higher than in AD patients without these symptoms. T2DM was an independent risk factor of depression (OR 2.04, 95% CI 1.71-2.38), anxiety (OR 1.69, 95% CI 1.38-1.97), nighttime behavioral disturbances (OR 1.95, 95% CI 1.75-2.13) and appetite disturbances (OR 1.62, 95% CI 1.33-1.94) in early AD patients.

CONCLUSION

T2DM was an important independent risk factor for NPS in early AD, which promotes the occurrence of depression, anxiety, nighttime behavioral disturbances and appetite disturbances in early AD.

O-GlcNAcylation as a Therapeutic Target for Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia and the number of elderly patients suffering from AD has been steadily increasing. Despite worldwide efforts to cope with this disease, little progress has been achieved with regard to identification of effective therapeutics. Thus, active research focusing on identification of new therapeutic targets of AD is ongoing. Among the new targets, post-translational modifications which modify the properties of mature proteins have gained attention. O-GlcNAcylation, a type of PTM that attaches O-linked β-N-acetylglucosamine (O-GlcNAc) to a protein, is being sought as a new target to treat AD pathologies. O-GlcNAcylation has been known to modify the two important components of AD pathological hallmarks, amyloid precursor protein, and tau protein. In addition, elevating O-GlcNAcylation levels in AD animal models has been shown to be effective in alleviating AD-associated pathology. Although studies investigating the precise mechanism of reversal of AD pathologies by targeting O-GlcNAcylation are not yet complete, it is clearly important to examine O-GlcNAcylation regulation as a target of AD therapeutics. This review highlights the mechanisms of O-GlcNAcylation and its role as a potential therapeutic target under physiological and pathological AD conditions.

Role of the Glyoxalase System in Alzheimer's Disease

Alzheimer's disease (AD) is an insidious and progressive neurodegenerative disease. The main pathological features of AD are the formation of amyloid-β deposits in the anterior cerebral cortex and hippocampus as well as the formation of intracellular neurofibrillary tangles. Thus far, accumulating evidence shows that glycation is closely related to AD. As a final product resulting from the crosslinking of a reducing sugar or other reactive carbonyls and a protein, the advanced glycation end products have been found to be associated with the formation of amyloid-β and neurofibrillary tangles in AD. As a saccharification inhibitor, the glyoxalase system and its substrate methylglyoxal (MG) were certified to be associated with AD onset and development. As an active substance of AGEs, MG could cause direct or indirect damage to nerve cells and tissues. MG is converted to D-lactic acid after decomposition by the glyoxalase system. Under normal circumstances, MG metabolism is in a dynamic equilibrium, whereas MG accumulates in cells in the case of aging or pathological states. Studies have shown that increasing glyoxalase activity and reducing the MG level can inhibit the generation of oxidative stress and AGEs, thereby alleviating the symptoms and signs of AD to some extent. This paper focuses on the relevant mechanisms of action of the glyoxalase system and MG in the pathogenesis of AD, as well as the potential of inhibiting the production of advanced glycation end products in the treatment of AD.

The Association Between Diabetes and Cognitive Function in Later Life

Introduction:

Although diabetes through several possible mechanisms such as increased microvascular pathology and inefficiency of glucose utilization during cognitive tasks can be associated with cognitive impairment, there is inconclusive evidence that shows elderly diabetic patients under therapy have higher cognitive function compared to their non-diabetics counterparts. The present study was conducted to elucidate the association between diabetes and cognitive function in later life.

Methods:

Data for this study, consisting of 2202 older adults aged 60 years and above, were taken from a population-based survey entitled “Identifying Psychosocial and Identifying Economic Risk Factor of Cognitive Impairment among Elderly. Data analysis was conducted using the IBM SPSS Version 23.0.

Results:

The mean of MMSE was found to be 22.67 (SD = 4.93). The overall prevalence of self-reported diabetes was found to be 23.6% (CI95%: 21.8% - 25.4%). The result of independent t-test showed diabetic subjects had a higher mean score of MMSE (M = 23.05, SD =4 .55) than their counterparts without diabetes (M = 22.55, SD = 5.04) (t = -2.13 p<.05). The results of multiple linear regression analysis showed that diabetes was not significantly associated with cognitive function, after controlling the possible confounding factors.

Conclusions:

The findings from the current study revealed that diabetes is not associated with cognitive decline. This study supports the findings that long-term treatment of diabetes may reduce the risk of cognitive decline. This finding may provide new opportunities for the prevention and management of cognitive decline.

BMI, Weight Change, and Dementia Risk in Patients With New-Onset Type 2 Diabetes: A Nationwide Cohort Study

OBJECTIVE

This study examined the association between baseline BMI, percentage weight change, and the risk of dementia in patients newly diagnosed with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Using the South Korean National Health Insurance Service-National Health Screening Cohort database, we identified 167,876 subjects aged ≥40 years diagnosed with new-onset type 2 diabetes between 2007 and 2012. Their weight changes were monitored for ∼2 years after diagnosis, with follow-up assessments occurring for an average of 3.5 years. The hazard ratios (HRs) and Bonferroni-adjusted 95% CIs of all-cause dementia, Alzheimer disease (AD), and vascular dementia were estimated using multivariable Cox proportional hazards regression models.

RESULTS

We identified 2,563 incident dementia cases during follow-up. Baseline BMI among patients with new-onset type 2 diabetes was inversely associated with the risk of all-cause dementia and AD, independent of confounding variables (P for trend <0.001). The percentage weight change during the 2 years after a diagnosis of type 2 diabetes showed significant U-shaped associations with the risk of all-cause dementia development (P < 0.001); the HRs of the disease increased significantly when weight loss or gain was >10% (1.34 [95% CI 1.11-1.63] and 1.38 [1.08-1.76], respectively). Additionally, weight loss >10% was associated with an increased risk of AD (HR 1.26 [95% CI 1.01-1.59]).

CONCLUSIONS

A lower baseline BMI was associated with increased risks of all-cause dementia and AD in patients with new-onset type 2 diabetes. Weight loss or weight gain after the diagnosis of diabetes was associated with an increased risk of all-cause dementia. Weight loss was associated with an increased risk of AD.

Sweet Mitochondria: A Shortcut to Alzheimer's Disease

A growing body of evidence supports a clear association between Alzheimer's disease and diabetes and several mechanistic links have been revealed. This paper is mainly devoted to the discussion of the role of diabetes-associated mitochondrial defects in the pathogenesis of Alzheimer's disease. The research experience and views of the author on this subject will be highlighted.

Exercise-Induced Modulation of Neuroinflammation in Models of Alzheimer's Disease

 Alzheimer's disease (AD), a progressive, neurodegenerative condition characterised by accumulation of toxic βeta-amyloid (Aβ) plaques, is one of the leading causes of dementia globally. The cognitive impairment that is a hallmark of AD may be caused by inflammation in the brain triggered and maintained by the presence of Aβ protein, ultimately leading to neuronal dysfunction and loss. Since there is a significant inflammatory component to AD, it is postulated that anti-inflammatory strategies may be of prophylactic or therapeutic benefit in AD. One such strategy is that of regular physical activity, which has been shown in epidemiological studies to be protective against various forms of dementia including AD. Exercise induces an anti-inflammatory environment in peripheral organs and also increases expression of anti-inflammatory molecules within the brain. Here we review the evidence, mainly from animal models of AD, supporting the hypothesis that exercise can reduce or slow the cellular and cognitive impairments associated with AD by modulating neuroinflammation.

Inflammation as a central mechanism in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is characterized by cognitive decline and the presence of two core pathologies, amyloid β plaques and neurofibrillary tangles. Over the last decade, the presence of a sustained immune response in the brain has emerged as a third core pathology in AD. The sustained activation of the brain's resident macrophages (microglia) and other immune cells has been demonstrated to exacerbate both amyloid and tau pathology and may serve as a link in the pathogenesis of the disorder. In the following review, we provide an overview of inflammation in AD and a detailed coverage of a number of microglia-related signaling mechanisms that have been implicated in AD. Additional information on microglia signaling and a number of cytokines in AD are also reviewed. We also review the potential connection of risk factors for AD and how they may be related to inflammatory mechanisms.

Cognitive Impairment and Glycemic Control in Elderly Patients Under Health-Care Case Management

We aim to test whether the association between glucose control and cognitive function still holds true in elderly patients with diabetes mellitus (DM) and Alzheimer disease (AD) under health-care case management. We enrolled 100 patients with DM (mean age: 74.6 years; male: 49%) and 102 patients with AD (mean age: 77.9 years; male: 41.2%) consecutively from the Diabetes Shared Care Program and the memory clinic. These patients were followed up every 3 months with scheduled examinations. Most patients with AD were at early stage and DM was a common comorbidity (n = 42). In the DM group, there were 76 patients with subjective cognitive decline and 19 patients with mild cognitive impairment, but none sought further consultation. After adjusting for age, sex, education, and comorbidity, higher levels of glycated hemoglobin (HbA_1C) were not associated with lower Mini-Mental State Examination (MMSE) scores in the DM group (coefficient: 0.03; 95% confidence interval [CI]: -0.44 to 0.50) and lower MMSE scores were not associated with higher HbA_1C in the AD group either (coefficient: -0.05; 95% CI: -0.11 to 0.01). When additionally accounting for the variability of HbA_1C in the DM group, higher standard deviation of HbA_1C was associated with poor clock drawing test scores, but not MMSE. The coexistence of AD-DM was common, but the association between hyperglycemia and cognitive impairment was not seen in patients under regular health monitoring.

The rs1277306 Variant of the REST Gene Confers Susceptibility to Cognitive Aging in an Elderly Taiwanese Population

BACKGROUND/AIMS

There is growing evidence that the RE1-silencing transcription factor (REST) gene may contribute to cognitive aging and Alzheimer diseases. In this replication study, we reassessed whether single nucleotide polymorphisms (SNPs) within the REST gene are linked with cognitive aging independently and/or through complex interactions in an older Taiwanese population.

METHODS

A total of 634 Taiwanese subjects aged over 60 years from the Taiwan Biobank were analyzed. Mini-Mental State Examination (MMSE) scores were performed for all subjects to weigh cognitive functions.

RESULTS

Our data showed that the REST rs1277306 SNP was significantly associated with cognitive aging among all subjects (p = 0.0052). Furthermore, the association remained significant for individuals without APOE ε4 allele (p = 0.0092), but not for individuals with at least 1 APOE ε4 allele. This association remained significant after Bonferroni correction. Additionally, we found the interactions between the rs1713985 and rs1277306 SNPs on cognitive aging (p = 0.016). However, the 3-marker haplotype derived from the rs1713985, rs3796529, and rs7680734 SNPs in the REST gene demonstrated no association with cognitive aging.

CONCLUSION

Our study indicates that the REST gene may contribute to susceptibility to cognitive aging independently as well as through SNP-SNP and APOE-REST interactions.

Polymorphisms Within RYR3 Gene Are Associated With Risk and Age at Onset of Hypertension, Diabetes, and Alzheimer's Disease

BACKGROUND

Hypertension affects 33% of Americans while type 2 diabetes and Alzheimer's disease (AD) affect 10% of Americans, respectively. Ryanodine receptor 3 gene (RYR3) codes for the RYR which functions to release stored endoplasmic reticulum calcium ions (Ca2+) to increase intracellular Ca2+ concentration. Increasing studies demonstrate that altered levels of intracellular Ca2+ affect cardiac contraction, insulin secretion, and neurodegeneration. In this study, we investigated associations of the RYR3 genetic variants with hypertension, AD, and diabetes.

METHODS

Family data sets were used to explore association of RYR3 polymorphisms with risk and age at onset (AAO) of hypertension, diabetes, and AD.

RESULTS

Family-based association tests using generalized estimating equations (FBAT-GEE) showed several unique or shared disease-1 associated variants in the RYR3 gene. Three single nuclear polymorphisms (SNPs; rs2033610, rs2596164, and rs2278317) are significantly associated with risk for hypertension, diabetes, and AD. Two SNPs (rs4780174 and rs7498093) are significantly associated with AAO of the 3 diseases.

CONCLUSIONS

RYR3 variants are associated with hypertension, diabetes, and AD. Replication of these results of this gene in these 3 complex traits may help to better understand the genetic basis of calcium-signaling gene, RYR3 in association with risk and AAO of these diseases.

Alzheimer's Disease and Type 2 Diabetes: A Critical Assessment of the Shared Pathological Traits

Alzheimer's disease (AD) and Type 2 Diabetes Mellitus (T2DM) are two of the most prevalent diseases in the elderly population worldwide. A growing body of epidemiological studies suggest that people with T2DM are at a higher risk of developing AD. Likewise, AD brains are less capable of glucose uptake from the surroundings resembling a condition of brain insulin resistance. Pathologically AD is characterized by extracellular plaques of Aβ and intracellular neurofibrillary tangles of hyperphosphorylated tau. T2DM, on the other hand is a metabolic disorder characterized by hyperglycemia and insulin resistance. In this review we have discussed how Insulin resistance in T2DM directly exacerbates Aβ and tau pathologies and elucidated the pathophysiological traits of synaptic dysfunction, inflammation, and autophagic impairments that are common to both diseases and indirectly impact Aβ and tau functions in the neurons. Elucidation of the underlying pathways that connect these two diseases will be immensely valuable for designing novel drug targets for Alzheimer's disease.

The serum metabolomics signature of type 2 diabetes is obscured in Alzheimer's disease

There is evidence for systemic metabolic impairment in Alzheimer's disease (AD), and type 2 diabetes (T2D) increases AD risk. Although studies analyzing blood metabolomics signatures have shown differences between cognitively healthy (CH) and AD subjects, these signatures have not been compared with individuals with T2D. We utilized untargeted analysis platforms (primary metabolism and complex lipids) to characterize the serum metabolome of 126 overnight-fasted elderly subjects classified into four groups based upon AD status (CH or AD) and T2D status [nondiabetic (ND) or T2D]. Cognitive diagnosis groups were a priori weighted equally with T2D subjects. We hypothesized that AD subjects would display a metabolic profile similar to cognitively normal elderly individuals with T2D. However, partial least squares-discriminant analysis (PLS-DA) modeling resulted in poor classification across the four groups (<50% classification accuracy of test subjects). Binary classification of AD vs. CH was poor, but binary classification of T2D vs. ND was good, providing >79.5% and >76.9% classification accuracy for held-out samples using primary metabolism and complex lipids, respectively. When modeling was limited to CH subjects, T2D discrimination improved for the primary metabolism platform (>89.5%) and remained accurate for complex lipids (>73% accuracy). Greater abundances of glucose, fatty acids (C20:2), and phosphatidylcholines and lower abundances of glycine, maleimide, octanol, and tryptophan, cholesterol esters, phosphatidylcholines, and sphingomyelins were identified in CH subjects with T2D relative to those without T2D. In contrast, T2D was not accurately discriminated within AD subjects. Results herein suggest that AD may obscure the typical metabolic phenotype of T2D.

Diabetes is Not Associated with Alzheimer's Disease Neuropathology

BACKGROUND

Previous evidence linking diabetes to Alzheimer's disease (AD) neuropathology is mixed and scant data are available from low- and middle-income countries.

OBJECTIVE

To investigate the association between diabetes and AD neuropathology in a large autopsy study of older Brazilian adults.

METHODS

In this cross-sectional study, diabetes was defined by diagnosis during life or use of antidiabetic medication. A standardized neuropathological examination was performed using immunohistochemistry. The associations of diabetes with Consortium to Establish and Registry for Alzheimer Disease (CERAD) scores for neuritic plaques and Braak-Braak (BB) scores for neurofibrillary tangles were investigated using multivariable ordinal logistic regression. We investigated effect modification of education, race, and APOE on these associations.

RESULTS

Among 1,037 subjects (mean age = 74.4±11.5 y; mean education = 4.0±3.7 y; 48% male, 61% White), diabetes was present in 279 subjects. Diabetes was not associated with BB (OR = 1.12, 95% CI = 0.81-1.54, p = 0.48) or with CERAD (OR = 0.97, 95% CI = 0.68-1.38, p = 0.86) scores on analyses adjusted for sociodemographic and clinical variables. We observed effect modification by the APOE allele ɛ4 on the association between diabetes mellitus and BB scores.

CONCLUSION

No evidence of an association between diabetes and AD neuropathology was found in a large sample of Brazilians; however, certain subgroups, such as APOE allele ɛ4 carriers, had higher odds of accumulation of neurofibrillary tangles.

Prion protein modulates glucose homeostasis by altering intracellular iron

The prion protein (PrP^C), a mainly neuronal protein, is known to modulate glucose homeostasis in mouse models. We explored the underlying mechanism in mouse models and the human pancreatic β-cell line 1.1B4. We report expression of PrP^C on mouse pancreatic β-cells, where it promoted uptake of iron through divalent-metal-transporters. Accordingly, pancreatic iron stores in PrP knockout mice (PrP^-/-) were significantly lower than wild type (PrP^+/+) controls. Silencing of PrP^C in 1.1B4 cells resulted in significant depletion of intracellular (IC) iron, and remarkably, upregulation of glucose transporter GLUT2 and insulin. Iron overloading, on the other hand, resulted in downregulation of GLUT2 and insulin in a PrP^C-dependent manner. Similar observations were noted in the brain, liver, and neuroretina of iron overloaded PrP^+/+ but not PrP^-/- mice, indicating PrP^C-mediated modulation of insulin and glucose homeostasis through iron. Peripheral challenge with glucose and insulin revealed blunting of the response in iron-overloaded PrP^+/+ relative to PrP^-/- mice, suggesting that PrP^C-mediated modulation of IC iron influences both secretion and sensitivity of peripheral organs to insulin. These observations have implications for Alzheimer's disease and diabetic retinopathy, known complications of type-2-diabetes associated with brain and ocular iron-dyshomeostasis.

The Role of microRNAs in Alzheimer's Disease and Their Therapeutic Potentials

MicroRNAs (miRNAs) are short, endogenous, non-coding RNAs that post-transcriptionally regulate gene expression by base pairing with mRNA targets. Altered miRNA expression profiles have been observed in several diseases, including neurodegeneration. Multiple studies have reported altered expressions of miRNAs in the brains of individuals with Alzheimer’s disease (AD) as compared to those of healthy elderly adults. Some of the miRNAs found to be dysregulated in AD have been reported to correlate with neuropathological changes, including plaque and tangle accumulation, as well as altered expressions of species that are known to be involved in AD pathology. To examine the potentially pathogenic functions of several dysregulated miRNAs in AD, we review the current literature with a focus on the activities of ten miRNAs in biological pathways involved in AD pathogenesis. Comprehensive understandings of the expression profiles and activities of these miRNAs will illuminate their roles as potential therapeutic targets in AD brain and may lead to the discovery of breakthrough treatment strategies for AD.

An Update on Type 2 Diabetes Mellitus as a Risk Factor for Dementia

With the rapidly expanding evidence on brain structural and functional changes in type 2 diabetes mellitus (T2DM) patients, there is an increasing need to update our understanding on how T2DM associates with dementia as well as the underlying pathophysiological mechanisms. A literature search of T2DM and dementia or cognition impairments was carried out in electronic databases Medline, EMBASE, and Google Scholar. In this review, the chosen evidence was limited to human subject studies only, and data on either type 1 diabetes mellitus (T1DM) or non-classified diabetes were excluded. T2DM is a risk factor for both vascular dementia (VaD) and Alzheimer's disease (AD), although AD pathological marker studies have not provided sufficient evidence. T2DM interacts additively or synergistically with many factors, including old age, hypertension, total cholesterol, and APOEɛ4 carrier status for impaired cognition functions seen in patients with T2DM. In addition, comorbid T2DM can worsen the clinical presentations of patients with either AD or VaD. In summary, T2DM increases the risk for AD through different mechanisms for VaD although some mechanisms may overlap. Tau-related neurofibrillary tangles instead of amyloid-β plaques are more likely to be the pathological biomarkers for T2DM-related dementia. Degeneration of neurons in the brain, impaired regional blood supply/metabolism, and genetic predisposition are all involved in T2DM-associated dementia or cognitive impairments.

Medical Comorbidity in Alzheimer's Disease: A Nested Case-Control Study

BACKGROUND

Little is known about the distribution of medical comorbidities in Alzheimer's disease (AD).

OBJECTIVE

We aimed to describe the comorbidity pattern of AD in a nested case-control study.

METHODS

Incident AD cases were identified by International Classification of Diseases codes in a random sample of 2 million individuals in Taiwan National Health Insurance program during 2001-2011. We further restricted cases to those treated with AD drugs of approved reimbursement. We sampled a set of age- and sex-matched control subjects (2:1 ratio) and employed conditional logistic regression to estimate the associations between pre-specified 14 comorbidities and AD. The clusters of multiple chronic diseases were then identified by exploratory factor analysis.

RESULTS

A total of 2,618 AD cases were identified during 2001-2011 with a mean age of 76.1 years and female preponderance (59%). The most common 5 comorbidities in AD were hypertension (55.1%), osteoarthritis (38.2%), depression (32.3%), diabetes mellitus (DM) (25.7%), and cerebrovascular disease (CVD) (22.7%). After adjusting for age and sex, DM, osteoporosis, depression, and CVD were significantly associated with AD. The number of comorbidity was 3-fold greater in the AD group. The cluster of hypertension, DM, and hyperlipidemia was the most common combination in old age, whereas the cluster osteoarthritis and osteoporosis was the only multimorbidity pattern significantly associated with AD.

CONCLUSION

Multimorbidity is common in AD. Depression, CVD, osteoporosis, and DM are associated with incident AD, supporting that their co-existence is a typical feature of AD at old age. Comorbidity care should be integrated into current management for patients with AD.

Epidemiology of estrogen and dementia in women with Down syndrome

Several lines of investigation have shown a protective role for estrogen in Alzheimer's disease through a number of biological actions. This review examines studies of the role of estrogen-related factors in age at onset and risk for Alzheimer's disease in women with Down syndrome, a population at high risk for early onset of dementia. The studies are consistent in showing that early age at menopause and that low levels of endogenous bioavailable estradiol in postmenopausal women with Down syndrome are associated with earlier age at onset and overall risk for dementia. Polymorphisms in genes associated with estrogen receptor activity and in genes for estrogen biosynthesis affecting endogenous estrogen are related to age at onset and cumulative incidence of dementia, and may serve as biomarkers of risk. To date, no clinical trials of estrogen or hormone replacement therapy (ERT/HRT) have been published for women with Down syndrome. While findings from clinical trials of ERT or HRT for dementia have generally been negative among women in the neurotypical population, the short interval between menopause and onset of cognitive decline, together with a more positive balance between potential benefits and risks, suggests an opportunity to evaluate the efficacy of ERT/HRT for delaying or preventing dementia in this high risk population, although questions concerning the optimal formulation and timing of the hormone therapy are not yet resolved.