Diabetes mellitus and dementia

Navigating the intersection: Diabetes and Alzheimer's intertwined relationship

Alzheimer's disease (AD) and Diabetes mellitus (DM) exhibit comparable pathophysiological pathways. Genetic abnormalities in APP, PS-1, and PS-2 are linked to AD, with diagnostic aid from CSF and blood biomarkers. Insulin dysfunction, termed "type 3 diabetes mellitus" in AD, involves altered insulin signalling and neuronal shrinkage. Insulin influences beta-amyloid metabolism, exacerbating neurotoxicity in AD and amyloid production in DM. Both disorders display impaired glucose transporter expression, hastening cognitive decline. Mitochondrial dysfunction and Toll-like receptor 4-mediated inflammation worsen neurodegeneration in both diseases. ApoE4 raises disease risk, especially when coupled with dyslipidemia common in DM. Targeting shared pathways like insulin-degrading enzyme activation and HSP60 holds promise for therapeutic intervention. Recognizing these interconnected mechanisms underscores the imperative for developing tailored treatments addressing the overlapping pathophysiology of AD and DM, offering potential avenues for more effective management of both conditions.

General anesthesia is not associated with dementia in older adults with osteoarthritis for hip/knee replacements, a national population-based nested case-control study

BACKGROUND

Dementia is a prevalent neurological condition, yet the relationship between dementia and general anesthesia remains uncertain. The study aimed to explore the association between general anesthesia and dementia using a nationwide population-based database.

METHODS

The study extracted data from Taiwan's national health insurance, which encompassed the records of one million insured residents. A total of 59,817 patients aged 65 years and above, diagnosed with osteoarthritis between 2002 and 2010, were included. Among these patients, 3277 individuals with an initial diagnosis of dementia between 2004 and 2013 were matched with non-dementia patients based on age, gender, and the date of osteoarthritis diagnosis. Following a 1:2 random matching, the case group included 2171 patients with dementia, while the control group consisted of 4342 patients without dementia. The data was analyzed using conditional and unconditional logistic regressions.

RESULTS

No significant differences in the odds of dementia were found between individuals exposed to general and regional anesthesia during hip/knee replacement surgeries (OR = 1.11; 95%CI: 0.73-1.70), after adjusting for age, sex, and co-morbidities. Similarly, there were no significant differences in the odds of dementia based on different durations of anesthesia exposure (General: <2 h: OR = 0.91, 95%CI = 0.43-1.92; 2-4 h: OR = 1.21, 95%CI = 0.82-1.79; >4 h: OR = 0.39, 95%CI = 0.15-1.01; compared to no exposure. Regional: <2 h: OR = 1.18, 95%CI = 0.85-1.62; 2-4 h: OR = 0.9, 95%CI = 0.64-1.27; >4 h: OR = 0.55, 95%CI = 0.15-1.96; compared to no exposure). Likewise, no significant differences were observed in the odds of dementia based on the number of replacement surgeries (twice: OR = 0.74, 95%CI = 0.44-1.23, compared to once).

CONCLUSION

Neither general anesthesia nor regional anesthesia in hip/knee surgery was associated with dementia. Different numbers and durations of anesthesia exposure showed no significant differences in the odds for dementia.

The individual and combined impacts of pre-existing diabetes and dementia on ischemic stroke outcomes: a registry-based cohort study

BACKGROUND

Individually, diabetes mellitus and dementia are associated with poorer outcomes after stroke. However, the combined impact of these pre-existing factors on acute ischemic stroke (AIS) outcomes has not been examined.

METHODS

All consecutive patients with AIS admitted to Norfolk and Norwich University Hospitals between 2003 and 2016 (catchment population ~ 900,000) were divided into four groups: those with neither diabetes nor dementia (reference), with diabetes without dementia, with dementia without diabetes, and with both co-morbidities. In-hospital mortality, length of hospital stay (LoS), and disability outcomes were analysed using logistic regressions. Post-discharge mortality and recurrence were assessed using Cox regressions. Additionally, interaction terms were added to the models for the short-term outcomes and long-term mortality to test for synergistic effects of diabetes and dementia. Models were adjusted for age, sex, Oxfordshire Community Stroke Project classification, comorbidities, hematological and biochemical measures, and antithrombotic medications.

RESULTS

The cohort was 10,812 patients with 52% females and a median age of 80. The median follow-up was 3.8 years for stroke recurrence and 5.5 years for mortality. No significant differences between the four groups existed for in-hospital mortality and post-stroke disability. Patients with dementia had significantly longer LoS (OR 2.25 [95% CI: 1.34-3.77] and 1.31 [1.02-1.68] with and without diabetes, respectively). Patients with both comorbidities had the highest risk of stroke recurrence (HR 2.06 [1.12-3.77]), followed by those with only dementia (1.59 [1.15-2.20]) and only diabetes (1.25 [1.06-1.49]). Similarly, the patient group with both diabetes and dementia had the highest long-term mortality risk (1.76 [1.33-2.37]). The hazard ratios for patients with only dementia and only diabetes were 1.71 [1.46-2.01] and 1.19 [1.08-1.32], respectively. No significant interactions were seen between diabetes and dementia with regards to their effects on the outcomes.

CONCLUSION

Individual and cumulative impacts of the two conditions on long-term mortality and stroke recurrence were notable. However, no synergistic impact of the two comorbidities were seen on the stroke outcomes tested in our study. Therefore, tailoring the management of stroke patients based on additional requirements associated with each pre-existing condition will be more impactful towards improving outcomes.

The clinical features and potential mechanisms of cognitive disorders in peripheral autoimmune and inflammatory diseases

According to a study from World Health Organization's Global Burden of Disease, mental and neurological disorders have accounted for 13% of global diseases in recent years and are on the rise. Neuropsychiatric conditions or neuroinflammatory disorders are linked by the presence of an exaggerated immune response both peripherally and in the central nervous system (CNS). Cognitive dysfunction (CD) encompasses a complex group of diseases and has frequently been described in the field of autoimmune diseases, especially in multiple non-CNS-related autoimmune diseases. Recent studies have provided various hypotheses regarding the occurrence of cognitive impairment in autoimmune diseases, including that abnormally activated immune cells can disrupt the integrity of the blood-brain barrier (BBB) to trigger a central neuroinflammatory response. When the BBB is intact, autoantibodies and pro-inflammatory molecules in peripheral circulation can enter the brain to activate microglia, inducing CNS inflammation and CD. However, the mechanisms explaining the association between the immune system and neural function and their contribution to diseases are uncertain. In this review, we used clinical statistics to illustrate the correlation between CD and autoimmune diseases that do not directly affect the CNS, summarized the clinical features and mechanisms by which autoimmune diseases trigger cognitive impairment, and explored existing knowledge regarding the link between CD and autoimmune diseases from the perspective of the field of neuroimmunology.

Dementia risk in patients with heart disease and depression

The high prevalence of Alzheimer's disease and dementia is a growing concern for healthcare systems and patients.

Objective

The primary objective of our study was to assess the association of depression and heart disease on the risk of dementias like Alzheimer's disease or vascular dementia in patients.

Methods

This retrospective study used electronic health records data that was provided by the HealthVerity™ Marketplace. The characteristics of the patient population were recorded and the risk of dementia was examined using adjusted logistic regression models.

Results

The analysis included 49,735 participants and revealed that patients who have heart disease or depression had a higher risk of dementia. Patients who had both heart disease and depression were over three times more likely to have dementia and Alzheimer's disease, and over five times more likely to have vascular dementia compared to patients who only have a diagnosis of heart disease. Depression was associated with a fourfold increase in the risk of dementia. Participants with a diagnosis of most types of heart disease as well as depression had increased risk for developing dementia.

Conclusion

This study revealed that patients with both heart disease and depression had increased odds of having dementia as well as vascular dementia and Alzheimer's disease. These findings may serve to support policies and healthcare decision-making to increase preventive measures for dementia and Alzheimer's disease among patients with both depression and heart disease.

Function and therapeutic value of astrocytes in diabetic cognitive impairment

Diabetic cognitive impairment (DCI) is a complex complication of diabetes in the central nervous system, and its pathological mechanism is still being explored. Astrocytes are abundant glial cells in central nervous system that perform diverse functions in health and disease. Accumulating excellent research has identified astrocyte dysfunction in many neurodegenerative diseases (such as Alzheimer's disease, aging and Parkinson's disease), and summarized and discussed its pathological mechanisms and potential therapeutic value. However, the contribution of astrocytes to DCI has been largely overlooked. In this review, we first systematically summarized the effects and mechanisms of diabetes on brain astrocytes, and found that the diabetic environment (such as hyperglycemia, advanced glycation end products and cerebral insulin resistance) mediated brain reactive astrogliosis, which was specifically reflected in the changes of cell morphology and the remodeling of signature molecules. Secondly, we emphasized the contribution and potential targets of reactive astrogliosis to DCI, and found that reactive astrogliosis-induced increased blood-brain barrier permeability, glymphatic system dysfunction, neuroinflammation, abnormal cell communication and cholesterol metabolism dysregulation worsened cognitive function. In addition, we summarized effective strategies for treating DCI by targeting astrocytes. Finally, we discuss the application of new techniques in astrocytes, including single-cell transcriptome, in situ sequencing, and prospected new functions, new subsets and new targets of astrocytes in DCI.

Distinct cerebral small vessel disease impairment in early- and late-onset Alzheimer's disease

OBJECTIVE

This study investigated cerebral small vessel disease (CSVD) damage patterns in early-onset and late-onset Alzheimer's disease (EOAD and LOAD) and their effects on cognitive function.

METHODS

This study included 93 participants, 45 AD patients (14 EOAD and 31 LOAD), and 48 normal controls (13 YNC and 35 ONC) from the ADNI database. All participants had diffusion tensor imaging data; some had amyloid PET and plasma p-tau181 data. The study used peak width of skeletonized mean diffusivity (PSMD) to measure CSVD severity and compared PSMD between patients and age-matched controls. The effect of age on the relationship between PSMD and cognition was also examined. The study also repeated the analysis in amyloid-positive AD patients and amyloid-negative controls in another independent database (31 EOAD and 38 LOAD), and the merged database.

RESULTS

EOAD and LOAD showed similar cognitive function and disease severity. PSMD was validated as a reliable correlate of cognitive function. In the ADNI database, PSMD was significantly higher for LOAD and showed a tendency to increase for EOAD; in the independent and merged databases, PSMD was significantly higher for both LOAD and EOAD. The impact of PSMD on cognitive function was notably greater in the younger group (YNC and EOAD) than in the older group (ONC and LOAD), as supported by the ADNI and merged databases.

INTERPRETATION

EOAD has less CSVD burden than LOAD, but has a greater impact on cognition. Proactive cerebrovascular prevention strategies may have potential clinical value for younger older adults with cognitive decline.

Antioxidant evaluation and computational prediction of prospective drug-like compounds from polyphenolic-rich extract of Hibiscus cannabinus L. seed as antidiabetic and neuroprotective targets: assessment through in vitro and in silico studies

BACKGROUND

Reports have implicated diabetes mellitus (DM) and Alzheimer's disease (AD) as some of the global persistent health challenges with no lasting solutions, despite of significant inputs of modern-day pharmaceutical firms. This study therefore, aimed to appraise the in vitro antioxidant potential, enzymes inhibitory activities, and as well carry out in silico study on bioactive compounds from polyphenolic-rich extract of Hibiscus cannabinus seed (PEHc).

METHODS

In vitro antioxidant assays were performed on PEHc using standard methods while the identification of phytoconstituents was carried out with high performance liquid chromatography (HPLC). For the in silico molecular docking using Schrodinger's Grid-based ligand docking with energetics software, seven target proteins were retrieved from the database ( https://www.rcsb.org/ ).

RESULTS

HPLC technique identified twelve chemical compounds in PEHc, while antioxidant quantification revealed higher total phenolic contents (243.5 ± 0.71 mg GAE/g) than total flavonoid contents (54.06 ± 0.09 mg QE/g) with a significant (p < 0.05) inhibition of ABTS (IC₅₀ = 218.30 ± 0.87 µg/ml) and 1, 1-diphenyl-2-picrylhydrazyl free radicals (IC₅₀ = 227.79 ± 0.74 µg/ml). In a similar manner, the extract demonstrated a significant (p < 0.05) inhibitory activity against α-amylase (IC₅₀ = 256.88 ± 6.15 µg/ml) and α-glucosidase (IC₅₀ = 183.19 ± 0.23 µg/ml) as well as acetylcholinesterase (IC₅₀ = 262.95 ± 1.47 µg/ml) and butyrylcholinesterase (IC₅₀ = 189.97 ± 0.82 µg/ml), respectively. Furthermore, In silico study showed that hibiscetin (a lead) revealed a very strong binding affinity energies for DPP-4, (PDB ID: 1RWQ) and α-amylase (PDB ID: 1SMD), gamma-tocopherol ( for peptide-1 receptor; PDB ID: 3C59, AChE; PDB ID: 4EY7 and BChE; PDB ID: 7B04), cianidanol for α-glucosidase; PDB ID: 7KBJ and kaempferol for Poly [ADP-ribose] polymerase 1 (PARP-1); PDB ID: 6BHV, respectively. More so, ADMET scores revealed drug-like potentials of the lead compounds identified in PEHc.

CONCLUSION

As a result, the findings of this study point to potential drug-able compounds in PEHc that could be useful for the management of DM and AD.

Sporadic Use of Antibiotics in Older Adults and the Risk of Dementia: A Nested Case-Control Study Based on German Health Claims Data

BACKGROUND

Antibiotics for systemic use may increase the risk of neurodegeneration, yet antibiotic therapy may be able to halt or mitigate an episode of neurodegenerative decline.

OBJECTIVE

To investigate the association of sporadic use of antibiotics and subsequent dementia risk (including Alzheimer's disease).

METHODS

We used data from the largest public health insurance fund in Germany, the Allgemeine Ortskrankenkasse (AOK). Each of the 35,072 dementia cases aged 60 years and older with a new dementia diagnosis during the observation period from 2006 to 2018 was matched with two control-patients by age, sex, and time since 2006. We ran conditional logistic regression models for dementia risk in terms of odds ratios (OR) as a function of antibiotic use for the entire antibiotic group and for each antibiotic subgroup. We controlled for comorbidities, need for long-term care, hospitalizations, and nursing home placement.

RESULTS

Antibiotic use was positively associated with dementia (OR = 1.18, 95% confidence interval (95% CI):1.14-1.22), which became negative after adjustment for comorbidities, at least one diagnosis of bacterial infection or disease, and covariates (OR = 0.93, 95% CI:0.90-0.96). Subgroups of antibiotics were also negatively associated with dementia after controlling for covariates: tetracyclines (OR = 0.94, 95% CI:0.90-0.98), beta-lactam antibacterials, penicillins (OR = 0.93, 95% CI:0.90-0.97), other beta-lactam antibacterials (OR = 0.92, 95% CI:0.88-0.95), macrolides, lincosamides, and streptogramins (OR = 0.88, 95% CI:0.85-0.92), and quinolone antibacterials (OR = 0.96, 95% CI:0.92-0.99).

CONCLUSION

Our results suggest that there was a decreased likelihood of dementia for preceding antibiotic use. The benefits of antibiotics in reducing inflammation and thus the risk of dementia need to be carefully weighed against the increase in antibiotic resistance.

Prevalence of Cognitive Decline in Type 2 Diabetes Mellitus Patients: A Real-World Cross-Sectional Study in Mysuru, India

The goal of this research is to study the prevalence of cognitive impairment in diabetes mellitus (DM) patients and establish the necessity of detecting and treating it early in these patients. A cross-sectional study was conducted at a tertiary care hospital in Mysuru for 4 months examined diabetic patients (test) and nondiabetic subjects (control) for cognitive decline using the Montreal Cognitive Assessment (MoCA) tool. Cognitive functions such as visuospatial/executive function, naming, attention, language, abstraction, delayed recall, and orientation were assessed in both groups. The diabetic group showed a significantly lower total MoCA score than the non-diabetic group (18.99 ± 0.48 and 26.21 ± 0.46, respectively; p < 0.001). Assessment of scores in diabetic patients demonstrated the significant influence of age demographics on cognitive impairment (p-value < 0.001). Furthermore, a higher proportion of diabetic patients displayed cognitive impairment despite a higher score in a single subdomain, making it evident that diabetes is diverse and multifactorial in origin, where oxidative stress and inflammatory responses play a predominant role. This study suggested that the local T2DM population residing in Mysuru (India) has a high prevalence of cognitive impairment, evident from poor performance in almost all cognitive domains assessed by MoCA. Future studies could examine the generalizability of cognitive function findings in diabetic patients across diverse geographic regions and ethnic groups, as well as investigate interventions such as lifestyle modifications and medication to prevent or delay cognitive decline in those with diabetes.

Regional high iron deposition on quantitative susceptibility mapping correlates with cognitive decline in type 2 diabetes mellitus

Objective

To quantitatively evaluate the iron deposition and volume changes in deep gray nuclei according to threshold-method of quantitative susceptibility mapping (QSM) acquired by strategically acquired gradient echo (STAGE) sequence, and to analyze the correlation between the magnetic susceptibility values (MSV) and cognitive scores in type 2 diabetes mellitus (T2DM) patients.

Methods

Twenty-nine patients with T2DM and 24 healthy controls (HC) matched by age and gender were recruited in this prospective study. QSM images were used to evaluate whole-structural volumes (V_wh), regional magnetic susceptibility values (MSV_RII), and volumes (V_RII) in high-iron regions in nine gray nuclei. All QSM data were compared between groups. Receiver operating characteristic (ROC) analysis was used to assess the discriminating ability between groups. The predictive model from single and combined QSM parameters was also established using logistic regression analysis. The correlation between MSV_RII and cognitive scores was further analyzed. Multiple comparisons of all statistical values were corrected by false discovery rate (FDR). A statistically significant P-value was set at 0.05.

Results

Compared with HC group, the MSV_RII of all gray matter nuclei in T2DM were increased by 5.1-14.8%, with significant differences found in bilateral head of caudate nucleus (HCN), right putamen (PUT), right globus pallidus (GP), and left dentate nucleus (DN) (P < 0.05). The V_wh of most gray nucleus in T2DM group were decreased by 1.5-16.9% except bilateral subthalamic nucleus (STN). Significant differences were found in bilateral HCN, bilateral red nucleus (RN), and bilateral substantia nigra (SN) (P < 0.05). V_RII was increased in bilateral GP, bilateral PUT (P < 0.05). V_RII/V_wh was also increased in bilateral GP, bilateral PUT, bilateral SN, left HCN and right STN (P < 0.05). Compared with the single QSM parameter, the combined parameter showed the largest area under curve (AUC) of 0.86, with a sensitivity of 87.5% and specificity of 75.9%. The MSV_RII in the right GP was strongly associated with List A Long-delay free recall (List A LDFR) scores (r = -0.590, P = 0.009).

Conclusion

In T2DM patients, excessive and heterogeneous iron deposition as well as volume loss occurs in deep gray nuclei. The MSV in high iron regions can better evaluate the distribution of iron, which is related to the decline of cognitive function.

Malignant Brain Aging: The Formidable Link Between Dysregulated Signaling Through Mechanistic Target of Rapamycin Pathways and Alzheimer's Disease (Type 3 Diabetes)

Malignant brain aging corresponds to accelerated age-related declines in brain functions eventually derailing the self-sustaining forces that govern independent vitality. Malignant brain aging establishes the path toward dementing neurodegeneration, including Alzheimer's disease (AD). The full spectrum of AD includes progressive dysfunction of neurons, oligodendrocytes, astrocytes, microglia, and the microvascular systems, and is mechanistically driven by insulin and insulin-like growth factor (IGF) deficiencies and resistances with accompanying deficits in energy balance, increased cellular stress, inflammation, and impaired perfusion, mimicking the core features of diabetes mellitus. The underlying pathophysiological derangements result in mitochondrial dysfunction, abnormal protein aggregation, increased oxidative and endoplasmic reticulum stress, aberrant autophagy, and abnormal post-translational modification of proteins, all of which are signature features of both AD and dysregulated insulin/IGF-1-mechanistic target of rapamycin (mTOR) signaling. This article connects the dots from benign to malignant aging to neurodegeneration by reviewing the salient pathologies associated with initially adaptive and later dysfunctional mTOR signaling in the brain. Effective therapeutic and preventive measures must be two-pronged and designed to 1) address complex and shifting impairments in mTOR signaling through the re-purpose of effective anti-diabetes therapeutics that target the brain, and 2) minimize the impact of extrinsic mediators of benign to malignant aging transitions, e.g., inflammatory states, obesity, systemic insulin resistance diseases, and repeated bouts of general anesthesia, by minimizing exposures or implementing neuroprotective measures.

Olive- and Coconut-Oil-Enriched Diets Decreased Secondary Bile Acids and Regulated Metabolic and Transcriptomic Markers of Brain Injury in the Frontal Cortexes of NAFLD Pigs

The objective of this study was to investigate the effect of dietary fatty acid (FA) saturation and carbon chain length on brain bile acid (BA) metabolism and neuronal number in a pig model of pediatric NAFLD. Thirty 20-day-old Iberian pigs, pair-housed in pens, were randomly assigned to receive one of three hypercaloric diets for 10 weeks: (1) lard-enriched (LAR; n = 5 pens), (2) olive-oil-enriched (OLI, n = 5), and (3) coconut-oil-enriched (COC; n = 5). Pig behavior and activity were analyzed throughout the study. All animals were euthanized on week 10 and frontal cortex (FC) samples were collected for immunohistochemistry, metabolomic, and transcriptomic analyses. Data were analyzed by multivariate and univariate statistics. No differences were observed in relative brain weight, neuronal number, or cognitive functioning between diets. Pig activity and FC levels of neuroprotective secondary BAs and betaine decreased in the COC and OLI groups compared with LAR, and paralleled the severity of NAFLD. In addition, OLI-fed pigs showed downregulation of genes involved in neurotransmission, synaptic transmission, and nervous tissue development. Similarly, COC-fed pigs showed upregulation of neurogenesis and myelin repair genes, which caused the accumulation of medium-chain acylcarnitines in brain tissue. In conclusion, our results indicate that secondary BA levels in the FCs of NAFLD pigs are affected by dietary FA composition and are associated with metabolic and transcriptomic markers of brain injury. Dietary interventions that aim to replace saturated FAs by medium-chain or monounsaturated FAs in high-fat hypercaloric diets may have a negative effect on brain health in NAFLD patients.

HMGB1 signaling pathway in diabetes-related dementia: Blood-brain barrier breakdown, brain insulin resistance, and Aβ accumulation

Diabetes contributes to the onset of various diseases, including cancer and cardiovascular and neurodegenerative diseases. Recent studies have highlighted the similarities and relationship between diabetes and dementia as an important issue for treating diabetes-related cognitive deficits. Diabetes-related dementia exhibits several features, including blood-brain barrier disruption, brain insulin resistance, and Aβ over-accumulation. High-mobility group box1 (HMGB1) is a protein known to regulate gene transcription and cellular mechanisms by binding to DNA or chromatin via receptor for advanced glycation end-products (RAGE) and toll-like receptor 4 (TLR4). Recent studies have demonstrated that the interplay between HMGB1, RAGE, and TLR4 can impact both neuropathology and diabetic alterations. Herein, we review the recent research regarding the roles of HMGB1-RAGE-TLR4 axis in diabetes-related dementia from several perspectives and emphasize the importance of the influence of HMGB1 in diabetes-related dementia.

Targeting hypercoagulation to alleviate Alzheimer's disease progression in metabolic syndrome

INTRODUCTION

Metabolic Syndrome (MetS) constitutes an important risk factor for Alzheimer's disease (AD); however, the mechanism linking these two disorders has not been completely elucidated. Hence, hypercoagulation may account for the missing hallmark connecting MetS and AD. The present review proposes how hemostatic imbalance triggered in MetS advances in the context of AD. MetS causes interruption of insulin signaling and inflammation, inciting insulin resistance in the brain. Subsequently, neuroinflammation and brain endothelial dysfunction are prompted that further intensify the exorbitant infiltration of circulating lipids and platelet aggregation, thereby causing hypercoagulable state, impairing fibrinolysis and eventually inducing prothrombic state in the brain leading to neurodegeneration.

OBJECTIVE

This study aims to understand the role of hypercoagulation in triggering the progression of neurodegeneration in MetS. It also offers a few interventions to prevent the progression of AD in MetS targeting hypercoagulation.

METHODS

Literature studies based on MetS related neurodegeneration, the impact of coagulation on aggravating obesity and AD via the mechanisms of BBB disruption, neuroinflammation, and hypofibrinolysis.

CONCLUSION

The present paper proposes the hypothesis that hypercoagulation might amplify MetS associated insulin resistance, neuroinflammation, BBB disruption, and amyloid beta accumulation which eventually leads to AD.

The mechanism of Girdin in degenerative brain disease caused by high glucose stimulation

Girdin, as an actin-binding protein, plays a major role in maintaining the stability of the actin skeleton structure and affects the growth, development, and migration of neurons. This study discusses the mechanism of Girdin in brain degeneration caused by high glucose stimulation. We examined the expression of Girdin in diabetic patients. The positive expression rate of Girdin in the diabetic group was 17.2% (5/29), which was obviously lower than the positive expression rate of 83.3% (20/24) in the non-diabetic group. We examined the expression of Girdin and its signaling pathway-related proteins Akt and STAT3 in hippocampal neurons induced by high glucose. The results showed that, in contrast to the control group (glucose concentration = 25 mmol/L), the expression of Girdin in the high-glucose group (glucose concentration = 225 mmol/L) was reduced (P < 0.05); the phosphorylation levels of Akt and STAT3 related to Girdin signaling pathway were also reduced (P < 0.05). Under high-glucose stimulation, the structure of neurons is abnormal, such as the reduction or disappearance of dendritic spines, and the number of neurons is reduced. In addition, Girdin and Akt were less expressed in neurons and synapses, especially the most obvious reduction in synaptic terminals. The activity of Girdin and its signaling pathway-related proteins Akt and STAT3 decreased in neurons under high glucose stimulation, indicating that the mechanism of Girdin in brain degeneration caused by high glucose stimulation was closely related to the Akt and STAT3 pathways.

GRAPHIC ABSTRACT

The mechanism of Girdin in degenerative brain disease caused by high glucose stimulation. This article discusses the mechanism of Girdin in brain degeneration induced by high glucose stimulation. The expression of Girdin in the diabetic group was significantly lower than that in the non-diabetic group. The expression of Girdin and its signaling pathway-related proteins Akt and STAT3 in hippocampal neurons was significantly reduced under high glucose stimulation. Under high glucose stimulation, the structure of neurons is abnormal and the number decreases; synapses become shorter. It indicates that the mechanism of brain degeneration caused by high glucose stimulation by Girdin is closely related to the Akt and STAT3 pathways.

Molecular and Biochemical Pathways Encompassing Diabetes Mellitus and Dementia

Diabetes mellitus is a major metabolic disorder that has now emerged as an epidemic, and it affects the brain through an array of pathways. Diabetes mellitus patients can develop pathological changes in the brain, which eventually take the shape of mild cognitive impairment progressing to Alzheimer's Disease. A number of preclinical and clinical studies demonstrate this fact, and it comes out to be those molecular pathways such as amyloidogenesis, oxidative stress, inflammation, and impaired insulin signaling are identical in diabetes mellitus and dementia. However, the critical player involved in the vicious cycle of diabetes mellitus and dementia is insulin, whose signaling, when impaired in diabetes mellitus (both type 1 and 2), leads to a decline in cognition, although other pathways are also essential contributors. Moreover, it is not only that diabetes mellitus patients indicate cognitive decline at a later stage; many Alzheimer's Disease patients also reflect symptoms of diabetes mellitus, thus creating a vicious cycle inculcating a web of complex molecular mechanisms and hence categorizing Alzheimer's Disease as 'brain diabetes'. Thus, it is practical to suggest that anti-diabetic drugs are beneficial in Alzheimer's Disease; but only smaller trials, not the larger ones, have showcased positive outcomes mainly because of the late onset of therapy. Therefore, it is extremely important to develop more of such molecules that target insulin in dementia patients along with such methods that diagnose impaired insulin signaling and the associated cognitive decline so that early therapy may be initiated and the progression of the disease be prevented.

Neuroprotective effects of novel compound Tozan on cognition, neurogenesis and apoptosis in diabetes

Background

Cognitive impairment is a serious complication of diabetes that manifests as an impairment of spatial memory and learning ability. Its pathogenesis is unclear, and effective therapeutic drugs are very limited. Our group designed and synthesized a novel compound named 3-p-tolyl-9H-xanthen-9-one (Tozan). In this study, we sought to investigate the effects and mechanism of Tozan on diabetic cognitive impairment.

Methods

Methylglyoxal (MG)-induced SH-SY5Y cells and streptozotocin (STZ)-induced type 1 diabetic mice were treated with Tozan. Methyl thiazolul tetrazolium (MTT) and lactate dehydrogenase (LDH) were used to test cytotoxicity. Morris water maze (MWM) and Y-maze tests were used to evaluate cognitive function. Immunofluorescence and western blot analyses were used to evaluate neurogenesis, apoptosis, and signal transduction pathway-related proteins. In addition, Lentivirus (LV)-estrogen receptor beta (ERβ)-ribonucleic acid interference (RNAi) was used to knockdown the ERβ gene in SH-SY5Y cells.

Results

We found that Tozan ameliorated MG-induced cytotoxicity in SH-SY5Y cells, improved cognitive dysfunction in STZ-induced type 1 diabetic mice, increased neurogenesis, and prevented apoptotic responses in vitro and in vivo. Importantly, Tozan (2, 4, and 8 mg/kg) mediated phosphatidylinositol-3-kinase and protein kinase B cAMP-response element binding protein (PI3K/Akt-CREB) signaling by activating membrane ERβ, and a high dose of Tozan (8 mg/kg) mediated CREB signaling by activating nuclear ERβ in the hippocampus. Notably, Tozan did not have an anti-apoptosis and regeneration protective role in ERβ gene knockdown cells.

Conclusions

Our study demonstrates Tozan’s contributions to and role in cognition, neurogenesis, and apoptosis in diabetes, and lays an experimental foundation for the development of new anti-diabetic cognitive impairment drugs.

Association of Alzheimer's Disease and Insulin Resistance in King Abdulaziz Medical City, Jeddah

Background Alzheimer's disease (AD) and insulin resistance (IR) are common in the elderly. IR reduces the ability of insulin to work effectively on target tissues. This results in hyperglycemia, increased triglyceride levels, decreased high-density lipoprotein (HDL) levels, elevated blood pressure, and central obesity, a condition known as metabolic syndrome (MetS). MetS eventually affects cognition, but its relationship with AD is unclear. Therefore, we studied the association between AD and IR and the relation between AD and diabetic patients treated with insulin. Methods This was a record-based retrospective cohort study using data from King Abdulaziz Medical City, Jeddah, Ministry of National Guards-Health Affairs. for all patients with dementia and AD, from 2009 to 2018. We examined 354 patient files. The triglyceride-glucose (TyG) index was used for the assessment of IR. Results There was no significant association between patients' demographic data, glycated hemoglobin, and co-morbidities and developing AD. Statistical models showed that, after adjustment for age, patients with IR had a significantly higher likelihood of AD (adjusted OR = 1.4; 95% CI: 1.01-2.33). After multivariate adjustment, patients with IR still had a 20% higher probability of developing AD than others (adjusted OR = 1.2; 95% CI: 1.0-3.1). Conclusion These results suggest that AD is associated with IR. Moreover, the association may be confounded by many patient-related factors.

Bridging Scales in Alzheimer's Disease: Biological Framework for Brain Simulation With The Virtual Brain

Despite the acceleration of knowledge and data accumulation in neuroscience over the last years, the highly prevalent neurodegenerative disease of AD remains a growing problem. Alzheimer's Disease (AD) is the most common cause of dementia and represents the most prevalent neurodegenerative disease. For AD, disease-modifying treatments are presently lacking, and the understanding of disease mechanisms continues to be incomplete. In the present review, we discuss candidate contributing factors leading to AD, and evaluate novel computational brain simulation methods to further disentangle their potential roles. We first present an overview of existing computational models for AD that aim to provide a mechanistic understanding of the disease. Next, we outline the potential to link molecular aspects of neurodegeneration in AD with large-scale brain network modeling using The Virtual Brain (www.thevirtualbrain.org), an open-source, multiscale, whole-brain simulation neuroinformatics platform. Finally, we discuss how this methodological approach may contribute to the understanding, improved diagnostics, and treatment optimization of AD.

Structural elucidation of three novel oligosaccharides from Kunlun Chrysanthemum flower tea and their bioactivities

Coreopsis tinctoria is commonly called Kunlun Chrysanthemum and a plateau plant with tremendous commercial value in functional tea and medicinal applications. In folk medicine, Kunlun Chrysanthemum flower is often used as an adjunctive therapy for diabetes and Alzheimer's disease. To further explore the chemicals responsible for the health benefits of Kunlun Chrysanthemum flowers, three homogeneous oligosaccharides, CT70-1A, CT70-1B and CT70-2 were isolated, and their detailed structures were determined from chemical and spectral analyses. The three oligosaccharides were composed of glucose, mannose, galactose, and arabinose in different ratios. They showed dose-dependent α-amylase and α-glucosidase inhibitory effects. In addition, they showed NO production inhibitory activities in BV2 cells, with IC₅₀ values of 0.23, 0.24 and 0.27 mM, respectively. Taken together, these results suggested that Kunlun Chrysanthemum oligosaccharides might ameliorate hyperglycemia and neuroinflammation, which could prevent the development of diseases such as type 2 diabetes and Alzheimer's disease. This study provides chemical and bioactive perspectives that support the consumption of Kunlun Chrysanthemum flower tea for health benefits.

Neurodegeneration in juvenile Iberian pigs with diet-induced nonalcoholic fatty liver disease

The objective of this study was to investigate whether juvenile Iberian pigs with diet-induced nonalcoholic fatty liver disease (NAFLD), cholestasis, and gut dysbiosis would develop histological and metabolic markers of neurodegeneration in the frontal cortex (FC) and whether supplementing probiotics would influence the response to the diet. Twenty-eight juvenile Iberian pigs were fed for 10 wk either a control (CON) or high-fructose high-fat (HFF) diet with or without a commercial probiotic mixture. Compared with CON, HFF-fed pigs had a decreased number of neurons and an increase in reactive astrocytes in FC tissue. There was also a decrease in one-carbon metabolites choline and betaine and a marked accumulation of bile acids, cholesteryl esters, and polyol pathway intermediates in FC of HFF-fed pigs, which were associated with markers of neurodegeneration and accentuated with the severity of NAFLD. Betaine depletion in FC tissue was negatively correlated with choline-derived phospholipids in colon content, whereas primary conjugated bile acids in FC were associated with cholestasis. Plasma kynurenine-to-tryptophan quotient, as a marker of indoleamine 2,3-dioxygenase activity, and intestinal dysbiosis were also correlated with neuronal loss and astrogliosis. Recognition memory test and FC levels of amyloid-β and phosphorylated Tau did not differ between diets, whereas probiotics increased amyloid-β and memory loss in HFF-fed pigs. In conclusion, our results show evidence of neurodegeneration in FC of juvenile Iberian pigs and establish a novel pediatric model to investigate the role of gut-liver-brain axis in diet-induced NAFLD.

Evaluating blood-brain barrier permeability in a rat model of type 2 diabetes

Background

This is an exploratory study using a novel imaging modality, quantitative ultrashort time-to-echo, contrast enhanced (QUTE-CE) magnetic resonance imaging to evaluate the permeability of the blood–brain barrier in a rat model of type 2 diabetes with the presumption that small vessel disease is a contributing factor to neuropathology in diabetes.

Methods

The BBZDR/Wor rat, a model of type 2 diabetes, and age-matched controls were studied for changes in blood–brain barrier permeability. QUTE-CE, a quantitative vascular biomarker, generated angiographic images with over 500,000 voxels that were registered to a 3D MRI rat brain atlas providing site-specific information on blood–brain barrier permeability in 173 different brain areas.

Results

In this model of diabetes, without the support of insulin treatment, there was global capillary pathology with over 84% of the brain showing a significant increase in blood–brain barrier permeability over wild-type controls. Areas of the cerebellum and midbrain dopaminergic system were not significantly affected.

Conclusion

Small vessel disease as assessed by permeability in the blood–brain barrier in type 2 diabetes is pervasive and includes much of the brain. The increase in blood–brain barrier permeability is a likely contributing factor to diabetic encephalopathy and dementia.

Extending Arms of Insulin Resistance from Diabetes to Alzheimer's Disease: Identification of Potential Therapeutic Targets

BACKGROUND & OBJECTIVE

Type 3 diabetes (T3D) is chronic insulin resistant state of brain which shares pathology with sporadic Alzheimer's disease (sAD). Insulin signaling is a highly conserved pathway in the living systems that orchestrate cell growth, repair, maintenance, energy homeostasis and reproduction. Although insulin is primarily studied as a key molecule in diabetes mellitus, its role has recently been implicated in the development of Alzheimer's disease (AD). Severe complications in brain of diabetic patients and metabolically compromised status is evident in brain of AD patients. Underlying shared pathology of two disorders draws a trajectory from peripheral insulin resistance to insulin unresponsiveness in the central nervous system (CNS). As insulin has a pivotal role in AD, it is not an overreach to address diabetic condition in AD brain as T3D. Insulin signaling is indispensable to nervous system and it is vital for neuronal growth, repair, and maintenance of chemical milieu at synapses. Downstream mediators of insulin signaling pathway work as a regulatory hub for aggregation and clearance of unfolded proteins like Aβ and tau.

CONCLUSION

In this review, we discuss the regulatory roles of insulin as a pivotal molecule in brain with the understanding of defective insulin signaling as a key pathological mechanism in sAD. This article also highlights ongoing trials of targeting insulin signaling as a therapeutic manifestation to treat diabetic condition in brain.

Using Multistate Observational Studies to Determine Role of Hypertension and Diabetes as Risk Factors for Dementia

BACKGROUND

Evidence suggests that modifiable risk factors which can be targeted by prevention are vascular diseases, such as diabetes, midlife hypertension (HTN), midlife obesity, midlife cholesterol, mid- and late-life depression as well as lifestyle factors such as smoking, physical inactivity, and poor diet.

METHODS

A comprehensive search of the National Library of Medicine's PubMed database and Google Scholar was conducted. A combinations of medical subject headings and free text words that included search terms related to the exposure (e.g., prevalence, HTN, raised BP, high BP, diabetes, high blood sugar, DM, India, state), were combined with search terms related to the outcomes (e.g., prevalence, disease burden, estimate, dementia, India). The filters included were English for the language category and humans for the study category.

RESULTS

The PubMed search initially identified 269 references, and a total of 204 abstracts were screened by inclusion criteria. Full-text assessment of 136 articles on prevalence of dementia resulted in 20 relevant articles from which the different regions of the country were identified. Based on the search conducted according to the regions; 287abstracts of the prevalence of HTN and 577 on the prevalence of diabetes mellitus were screened. There were 43 full-text articles on the prevalence of HTN and diabetes from the regions where the prevalence of dementia was available. Of these potentially relevant articles were 14 in number.

CONCLUSION

Despite the uncertainty in the role, the data analysis, therefore, points to a role in the prevention of HTN and diabetes to prevent dementia.

Thymol polymeric nanoparticle synthesis and its effects on the toxicity of high glucose on OEC cells: involvement of growth factors and integrin-linked kinase

Background

Nowadays, the drug delivery system is important in the treatment of diseases.

Purpose

A polymeric nanoparticle modified by oleic acid (NPMO) as a Thymol (Thy) drug release system was synthesized from Thymbra spicata and its neurotrophic and angiogenic effects on rat’s olfactory ensheathing cells (OECs) in normal (NG) and high glucose (HG) conditions were studied.

Methods

The NPMO was characterized by using different spectroscopy methods, such as infrared, HNMR, CNMR, gel permeation chromatography, dynamic light scattering, and atomic force microscopy. Load and releasing were investigated by HPLC. The toxicity against OECs diet-induced by MTT assay. ROS and generation of nitric oxide (NO) were evaluated using dichloro-dihydro-fluorescein and Griess method, respectively. The expression of protein integrin-linked kinase (ILK), vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) were evaluated by Western blotting.

Results

ThyNPMO is desirable for transferring drug as a carrier. The amount of Thy and extract (E) loaded on NPMO estimated at 43±2.5% and 41±1.8%, respectively. Then, 65% and 63% of the drug load were released, respectively. Thy, ThyNPMO, E, and ENPMO prevented HG-induced OECs cell death (EC50 33±1.5, 22±0.9, 35±1.8, and 25±1.1 μM, respectively). Incubation with Thy, ThyNPMO, E ,and ENPMO at high concentrations increased cell death with LC50 105±3.5, 82±2.8, 109±4.3, and 86±3.4 μM, respectively in HG states.

Conclusion

OECs were protected by ThyNPMO and ENPMO in protective concentrations by reducing the amount of ROS and NO, maintaining ILK, reducing VEGF, and increasing BDNF and NGF. The mentioned mechanisms were totally reversed at high concentrations.

Rhizoma Coptidis for Alzheimer's Disease and Vascular Dementia: A Literature Review

BACKGROUND

Alzheimer's disease (AD) and vascular dementia (VaD) are major types of dementia, both of which cause heavy economic burdens for families and society. However, no currently available medicines can control dementia progression. Rhizoma coptidis, a Chinese herbal medicine, has been used for >2000 years and is now gaining attention as a potential treatment for AD and VaD.

METHODS

We reviewed the mechanisms of the active ingredients of Rhizoma coptidis and Rhizoma coptidis-containing Chinese herbal compounds in the treatment of AD and VaD. We focused on studies on ameliorating the risk factors and the pathological changes of these diseases.

RESULTS

The Rhizoma coptidis active ingredients include berberine, palmatine, coptisine, epiberberine, jatrorrhizine and protopine. The most widely studied ingredient is berberine, which has extensive therapeutic effects on the risk factors and pathogenesis of dementia. It can control blood glucose and lipid levels, regulate blood pressure, ameliorate atherosclerosis, inhibit cholinesterase activity, Aβ generation, and tau hyperphosphorylation, decrease neuroinflammation and oxidative stress and alleviate cognitive impairment. Other ingredients (such as jatrorrhizine, coptisine, epiberberine and palmatine) also regulate blood lipids and blood pressure; however, there are relatively few studies on them. Rhizoma coptidis-containing Chinese herbal compounds like Huanglian-Jie-Du-Tang, Huanglian Wendan Decoction, Banxia Xiexin Decoction and Huannao Yicong Formula have anti-inflammatory and antioxidant stress activities, regulate insulin signaling, inhibit γ-secretase activity, neuronal apoptosis, tau hyperphosphorylation, and Aβ deposition, and promote neural stem cell differentiation, thereby improving cognitive function.

CONCLUSION

The "One-Molecule, One-Target" paradigm has suffered heavy setbacks, but a "multitarget- directed ligands" strategy may be viable. Rhizoma coptidis active ingredients and Rhizoma coptidiscontaining Chinese herbal compounds have multi-aspect therapeutic effects on AD and VaD.

Review of the Effect of Natural Compounds and Extracts on Neurodegeneration in Animal Models of Diabetes Mellitus

Diabetes mellitus is a chronic metabolic disease with a high prevalence in the Western population. It is characterized by pancreas failure to produce insulin, which involves high blood glucose levels. The two main forms of diabetes are type 1 and type 2 diabetes, which correspond with >85% of the cases. Diabetes shows several associated alterations including vascular dysfunction, neuropathies as well as central complications. Brain alterations in diabetes are widely studied; however, the mechanisms implicated have not been completely elucidated. Diabetic brain shows a wide profile of micro and macrostructural changes, such as neurovascular deterioration or neuroinflammation leading to neurodegeneration and progressive cognition dysfunction. Natural compounds (single isolated compounds and/or natural extracts) have been widely assessed in metabolic disorders and many of them have also shown antioxidant, antiinflamatory and neuroprotective properties at central level. This work reviews natural compounds with brain neuroprotective activities, taking into account several therapeutic targets: Inflammation and oxidative stress, vascular damage, neuronal loss or cognitive impairment. Altogether, a wide range of natural extracts and compounds contribute to limit neurodegeneration and cognitive dysfunction under diabetic state. Therefore, they could broaden therapeutic alternatives to reduce or slow down complications associated with diabetes at central level.

Cross-disease analysis of Alzheimer's disease and type-2 Diabetes highlights the role of autophagy in the pathophysiology of two highly comorbid diseases

Evidence is accumulating that the main chronic diseases of aging Alzheimer's disease (AD) and type-2 diabetes mellitus (T2DM) share common pathophysiological mechanisms. This study aimed at applying systems biology approaches to increase the knowledge of the shared molecular pathways underpinnings of AD and T2DM. We analysed transcriptomic data of post-mortem AD and T2DM human brains to obtain disease signatures of AD and T2DM and combined them with protein-protein interaction information to construct two disease-specific networks. The overlapping AD/T2DM network proteins were then used to extract the most representative Gene Ontology biological process terms. The expression of genes identified as relevant was studied in two AD models, 3xTg-AD and ApoE3/ApoE4 targeted replacement mice. The present transcriptomic data analysis revealed a principal role for autophagy in the molecular basis of both AD and T2DM. Our experimental validation in mouse AD models confirmed the role of autophagy-related genes. Among modulated genes, Cyclin-Dependent Kinase Inhibitor 1B, Autophagy Related 16-Like 2, and insulin were highlighted. In conclusion, the present investigation revealed autophagy as the central dys-regulated pathway in highly co-morbid diseases such as AD and T2DM allowing the identification of specific genes potentially involved in disease pathophysiology which could become novel targets for therapeutic intervention.

Association between the Vicious Cycle of Diabetes-Associated Complications and Glycemic Control among the Elderly: A Systematic Review

Background and objectives: Improved quality of life (QoL) and life expectancy of elderly diabetic patients revolves around optimal glycemic control. Inadequate glycemic control may lead to the development of diabetes-associated complications (DAC), which not only complicate the disease, but also affect morbidity and mortality. Based on the available literature, the aim was to elucidate the vicious cycle underpinning the relationship between diabetes complications and glycemic control. Materials and Methods: A comprehensive literature search was performed to find eligible studies published between 1 January 2000 and 22 September 2018 pertaining to diabetes complications and glycemic control. Results: Initially, 261 studies were retrieved. Out of these, 67 were duplicates and therefore were excluded. From the 194 remaining articles, 85 were removed based on irrelevant titles and/or abstracts. Subsequently, the texts of 109 articles were read in full and 71 studies were removed at this stage for failing to provide relevant information. Finally, 38 articles were selected for this review. Depression, impaired cognition, poor physical functioning, frailty, malnutrition, chronic pain, and poor self-care behavior were identified as the major diabetes-associated complications that were associated with poor glycemic control in elderly diabetic patients. Conclusions: This paper proposes that diabetes-associated complications are interrelated, and that impaired glycemic control aggravates diabetes complications; as a result, patient’s self-care abilities are compromised. A schema is generated to reflect a synthesis of the literature found through the systematic review process. This not only affects patients’ therapeutic goals, but may also hamper their health-related quality of life (HRQoL) and financial status.

MicroRNA and Diabetic Complications: A Clinical Perspective

SIGNIFICANCE

The rising global prevalence of diabetes and its debilitating complications give rise to significant disability and premature mortality. Due to the silent nature of diabetes and its vascular complications, and limitations in current methods for detection, there is a need for novel biomarkers for early detection and prognosis. Recent Advances: Metabolic memory and epigenetic factors are important in the pathogenesis of diabetic complications and interact with genetic variants, metabolic factors, and clinical risk factors. Micro(mi)RNAs interact with epigenetic mechanisms and pleiotropically mediate the effects of hyperglycemia on the vasculature. Utilizing mature profiling techniques and platforms, an increasing number of miRNA signatures and interaction networks have been identified for diabetes and its related cardiorenal complications. As a result, these short, single-stranded molecules are emerging as potential diagnostic and predictive tools in human studies, and may function as disease biomarkers, as well as treatment targets.

CRITICAL ISSUES

However, there is complex interaction between the genome and epigenome. The regulation of miRNAs may differ across species and tissues. Most profiling studies to date lack validation, often requiring large, well-characterized cohorts and reliable normalization strategies. Furthermore, the incremental benefits of miRNAs as biomarkers, beyond prediction provided by traditional risk factors, are critical issues to consider, yet often neglected in published studies.

FUTURE DIRECTIONS

All in all, the future for miRNA-based diagnostics and therapeutics for diabetic complications appears promising. Improved understanding of the complex mechanisms underlying miRNA dysregulation, and more well-designed studies utilizing prospective samples would facilitate the translation to clinical use.

ERα and/or ERβ activation ameliorates cognitive impairment, neurogenesis and apoptosis in type 2 diabetes mellitus mice

Estrogen receptors (ERs) are thought to be associated with the onset and progression of neurodegenerative injuries and diseases, but the relationship and mechanisms underlying between ERs and cognition in type 2 diabetes remain elusive. In the current study, we investigated the effects of ERα and ERβ on the cognition, neurogenesis and apoptosis in high-fat diet and streptozocin-induced diabetic mice. We found that ERα and/or ERβ activation using their agonists (0.5 mg/kg E2, PPT or DPN) ameliorate memory impairment in the Morris water maze and Y-maze tests, increase hippocampal neurogenesis and prevent hippocampal apoptotic responses. Importantly, treatment with the pharmacologic ERs agonists caused significant increases in the membrane ERα and ERβ expression and subsequent PI3K/Akt, CREB and BDNF activation in the hippocampus of type 2 diabetes mellitus mice. Our data indicate that ERα and ERβ are involved in the cognitive impairment in type 2 diabetes, and that activated ERs, such as application of ERs agonists, could be a novel and promising strategy for the treatment of diabetic cognitive impairment.

Activation of ERα and/or ERβ ameliorates cognitive impairment and apoptosis in streptozotocin-induced diabetic mice

Estrogen receptors (ERs) are thought to be associated with the onset and progression of neurodegenerative injuries and diseases, but the relationship and mechanisms underlying between ERs and cognition in type 1 diabetes remain elusive. In the current study, we investigated the effects of ERα and ERβ on the memory impairment and apoptosis in streptozotocin-induced diabetic mice. We found that ERα and/or ERβ activation using their agonists (0.5 mg/kg E2, PPT or DPN) ameliorate memory impairment in the Morris water maze (MWM) and Y-maze tests and suppress apoptosis as evidenced by decreased caspase-3 activity and increased ratio of Bcl-2/Bax. Importantly, treatment with the pharmacologic ERs agonists caused significant increases in the membrane ERα and ERβ expression and subsequent PI3K/Akt, CREB and BDNF activation in the hippocampus of diabetic mice. Our data indicate that ERα and ERβ are involved in the cognitive impairment of type 1 diabetes and that activation of ERs via administration of ERs agonists could be a novel and promising strategy for the treatment of diabetic cognitive impairment.

The Effect of Agomelatine Treatment on Diabetes-Induced Cognitive Impairments in Rats: Concomitant Alterations in the Hippocampal Neuron Numbers

Researches that are related to the central nervous system complications of diabetes have indicated higher incidence of cognitive disorders in patients. Since the variety of nootropic drugs used in clinics is limited and none of them consistently improves the outcomes, new and effective drug alternatives are needed for the treatment of diabetes-induced cognitive disorders. Based on the nootropic potential of agomelatine, the promising efficacy of this drug on cognitive impairments of diabetic rats was investigated in the current study. Experimental diabetes model was induced by streptozotocin. After development of diabetes-related cognitive impairments in rats, agomelatine (40 and 80 mg/kg) was administrated orally for two weeks. Cognitive performance was assessed by Morris water-maze and passive avoidance tests. Then, the total numbers of neurons in both dentate gyrus and Cornu Ammonis (CA) 1–3 subfields of the hippocampus were estimated by the optical fractionator method. Agomelatine treatment induced notable enhancement in the learning and memory performance of diabetic rats. Moreover, it reversed the neuronal loss in the hippocampal subregions of diabetic animals. Obtained results suggest that agomelatine has a significant potential for the treatment of diabetes-induced cognitive impairments. However, therapeutic efficacy of this drug in diabetic patients suffering from cognitive dysfunctions needs to be confirmed by further clinical trials.

New views and possibilities of antidiabetic drugs in treating and/or preventing mild cognitive impairment and Alzheimer's Disease

Mounting evidence suggests that diabetes mellitus (DM) is associated with mild cognitive impairment (MCI), vascular dementia and Alzheimer's disease (AD). Biological, clinical and epidemiological data support a close link between DM and AD. Increasingly, studies have found that several antidiabetic agents can promote neurogenesis, and clinically ameliorate cognitive and memory impairments in different clinical settings. Data has shown that these antidiabetic drugs positively affect mitochondrial and synaptic function, neuroinflammation, and brain metabolism. Evidence to date strongly suggests that these antidiabetic drugs could be developed as disease-modifying therapies for MCI and AD in patients with and without diabetes.

Factors associated with type 2 diabetes in patients with vascular dementia: a population-based cross-sectional study

BACKGROUND

Incidence of dementia is growing rapidly and affects many people worldwide. Type 2 diabetes mellitus (DM) might link cognitive decline and dementia, but the reasons for this association remain unclear. Our study explored the factors associated with type 2 DM in patients with dementia.

METHODS

Patients (n = 40,404) with vascular dementia were identified in Taiwan's 1997 to 2008 National Health Insurance Research Database and divided into a DM group and non-DM group. Eleven comorbidities were identified and categorized into four groups: cardiovascular and cerebrovascular diseases, digestive system diseases, renal and metabolic system diseases, and cancer. The associations of these factors with type 2 DM were explored through multivaraible logistic regression.

RESULTS

Of the patients with dementia, 22.5% had DM. Associated with a higher likelihood of DM in this population were female sex (adjusted odds ratio [OR]: 1.44, 95% confidence interval [CI]: 1.36-1.52), young age (range of adjusted OR: 0.55-1.13), low income (range of adjusted OR: 1.09-1.18), and renal and metabolic system diseases (OR: 2.81, 95% CI: 2.64-2.98).

CONCLUSIONS

The findings of this study suggest that clinicians should encourage patients with dementia to receive regular glucose impairment screening if they are female, have low socioeconomic status, or have renal or metabolic diseases.

Blood-Brain Barrier Disruption Induced Cognitive Impairment Is Associated With Increase of Inflammatory Cytokine

Patients with diabetes suffer the higher risk of dementia and the underlying pathological mechanism of cognitive dysfunction in diabetes is not fully understood. In this study, we explore whether the cognitive impairment in the diabetic rat is associated with increased blood brain barrier (BBB) permeability and the change of the inflammatory cytokine. Experimental diabetic rats were induced by single intraperitoneal injection of streptozotocin (STZ). Cognitive function was evaluated by Morris water maze in the normal and the diabetic rats, respectively. The spatial acquisition trials were conducted over five consecutive days and the probe test was performed on day 6, followed by working memory test on the next 4 days. Escape latency was recorded in the acquisition trials and working memory test; time spent in the target quadrant and the number of crossing the former platform were recorded in the probe test. BBB permeability was assessed by measuring the extravasation of IgG. The image of occludin and claudin-5 staining by a confocal microscope were acquired to measure the gap in the tight junction. Cytokines TNF-α, IL-1β and IL-6 mRNA expression were further examined by Real-time PCR. The time spent in the target quadrant within 30 s decreased in the 8-week STZ rats compared to that of the normal rats (p < 0.05), while no difference was seen in the performance of working memory between the diabetic and normal rats. IgG leakage significantly increased in the brain parenchyma of the 8-week STZ rats compared to the normal rats (p < 0.05). The immunostaining of occludin and claudin-5 suggested the gap in the tight junction increased in the 8-week STZ rats compared to the normal rats (p < 0.05). Moreover, TNF-α and IL-6 mRNA also increased in the brain of 8-week STZ rats compared to the normal rats (p < 0.05). These results suggested that loss of BBB integrity might contribute to progressive impairment of cognitive in the diabetic rats. The increase of TNF-α and IL-6 expression might trigger the disruption of BBB in the brain, which eventually caused cognitive impairment in the 8-week STZ rats.

High glucose upregulates myosin light chain kinase to induce microfilament cytoskeleton rearrangement in hippocampal neurons

Chronic hyperglycemia leads to myosin light chain kinase (MLCK) upregulation and induces neuronal damage. However, the underlying molecular mechanism of neuronal damage in hyperglycemia has not yet been fully elucidated. In the present study, hippocampal neuronal cells were cultured and treated with a high glucose concentration (45 mmol/l). The results demonstrated that high glucose induced shrinking of the synapses, nuclear shape irregularity and microfilament damage. Filamentous actin (F‑actin) filaments were rearranged, cell apoptosis rate was increased and the protein expression of MLCK and phosphorylated (p)‑MLC was upregulated. The MLCK inhibitor ML‑7 largely reversed the alterations in the microfilament cytoskeleton, inhibited F‑actin depolymerization, reduced apoptosis and downregulated MLCK and p‑MLC protein expression. Overall, these results indicated that high glucose upregulated MLCK to promote F‑actin depolymerization, which induced microfilament cytoskeleton rearrangement in hippocampal neuronal cells.

TrkB signalling pathway mediates the protective effects of exercise in the diabetic rat retina

Diabetic retinopathy is a leading cause of vision loss. Treatment options for early retinopathy are sparse. Exercise protects dying photoreceptors in models of retinal degeneration, thereby preserving vision. We tested the protective effects of exercise on retinal and cognitive deficits in a type 1 diabetes model and determined whether the TrkB pathway mediates this effect. Hyperglycaemia was induced in Long Evans rats via streptozotocin injection (STZ; 100 mg/kg). Following confirmed hyperglycaemia, both control and diabetic rats underwent treadmill exercise for 30 min, 5 days/week at 0 m/min (inactive groups) or 15 m/min (active groups) for 8 weeks. A TrkB receptor antagonist (ANA-12), or vehicle, was injected 2.5 h before exercise training. We measured spatial frequency and contrast sensitivity using optokinetic tracking biweekly post-STZ; retinal function using electroretinography at 4 and 8 weeks; and cognitive function and exploratory behaviour using Y-maze at 8 weeks. Retinal neurotrophin-4 was measured using ELISA. Compared with non-diabetic controls, diabetic rats showed significantly reduced spatial frequency and contrast sensitivity, delayed electroretinogram oscillatory potential and flicker implicit times and reduced cognitive function and exploratory behaviour. Exercise interventions significantly delayed the appearance of all deficits, except for exploratory behaviour. Treatment with ANA-12 significantly reduced this protection, suggesting a TrkB-mediated mechanism. Despite this, no changes in retinal neurotrohin-4 were observed with diabetes or exercise. Exercise protected against early visual and cognitive dysfunction in diabetic rats, suggesting that exercise interventions started after hyperglycaemia diagnosis may be a beneficial treatment. The translational potential is high, given that exercise treatment is non-invasive, patient controlled and inexpensive.

Cognitive deficits and Alzheimer-like neuropathological impairments during adolescence in a rat model of type 2 diabetes mellitus

Numerous studies have shown that many patients who suffer from type 2 diabetes mellitus exhibit cognitive dysfunction and neuronal synaptic impairments. Therefore, growing evidence suggests that type 2 diabetes mellitus has a close relationship with occurrence and progression of neurodegeneration and neural impairment in Alzheimer's disease. However, the relationship between metabolic disorders caused by type 2 diabetes mellitus and neurodegeneration and neural impairments in Alzheimer's disease is still not fully determined. Thus, in this study, we replicated a type 2 diabetic animal model by subcutaneous injection of newborn Sprague-Dawley rats with monosodium glutamate during the neonatal period. At 3 months old, the Barnes maze assay was performed to evaluate spatial memory function. Microelectrodes were used to measure electrophysiological function in the hippocampal CA1 region. Western blot assay was used to determine expression levels of glutamate ionotropic receptor NMDA type subunit 2A (GluN2A) and GluN2B in the hippocampus. Enzyme-linked immunosorbent assay was used to determine levels of interleukin-1β, tumor necrosis factor α, and interleukin-6 in the hippocampus and cerebral cortex, as well as hippocampal amyloid beta (Aβ)_1–40 and Aβ_1–42 levels. Our results showed that in the rat model of type 2 diabetes mellitus caused by monosodium glutamate exposure during the neonatal period, latency was prolonged and the number of errors increased in the Barnes maze. Further, latency was increased and time in the escape platform quadrant shortened. Number of times crossing the platform was also reduced in the Morris water maze. After high frequency stimulation of the hippocampus, synaptic transmission was inhibited, expression of GluN2A and GluN2B were decreased in the hippocampus, expression of interleukin 1β, interleukin 6, and tumor necrosis factor α was increased in the hippocampus and cortex, and levels of Aβ_1–40 and Aβ_1–42 were increased in the hippocampus. These findings confirm that type 2 diabetes mellitus induced by neonatal monosodium glutamate exposure results in Alzheimer-like neuropathological changes and further causes cognitive deficits and neurodegeneration in young adulthood.

Alzheimer's disease and metabolic syndrome: A link from oxidative stress and inflammation to neurodegeneration

Alzheimer's disease (AD) is the most common cause of dementia and one of the most important causes of morbidity and mortality among the aging population. AD diagnosis is made post-mortem, and the two pathologic hallmarks, particularly evident in the end stages of the illness, are amyloid plaques and neurofibrillary tangles. Currently, there is no curative treatment for AD. Additionally, there is a strong relation between oxidative stress, metabolic syndrome, and AD. The high levels of circulating lipids and glucose imbalances amplify lipid peroxidation that gradually diminishes the antioxidant systems, causing high levels of oxidative metabolism that affects cell structure, leading to neuronal damage. Accumulating evidence suggests that AD is closely related to a dysfunction of both insulin signaling and glucose metabolism in the brain, leading to an insulin-resistant brain state. Four drugs are currently used for this pathology: Three FDA-approved cholinesterase inhibitors and one NMDA receptor antagonist. However, wide varieties of antioxidants are promissory to delay or prevent the symptoms of AD and may help in treating the disease. Therefore, therapeutic efforts to achieve attenuation of oxidative stress could be beneficial in AD treatment, attenuating Aβ-induced neurotoxicity and improve neurological outcomes in AD. The term inflammaging characterizes a widely accepted paradigm that aging is accompanied by a low-grade chronic up-regulation of certain pro-inflammatory responses in the absence of overt infection, and is a highly significant risk factor for both morbidity and mortality in the elderly.

Erythropoietin ameliorates diabetes-associated cognitive dysfunction in vitro and in vivo

Several studies indicate that erythropoietin (EPO) has remarkable neuroprotective effects in various central nervous system disorders, while little is known about the effects of EPO in diabetes-associated cognitive dysfunction. Therefore, the present study aimed to investigate whether EPO ameliorates diabetes-associated cognitive dysfunction in vivo and in vitro. We investigated the protective effects of EPO on high-glucose (HG)-induced PC12 cell death and oxidative stress. The effects of EPO (300 U/kg administered three times a week for 4 weeks) on diabetes-associated cognitive decline were investigated in diabetic rats. EPO significantly increased cell viability, increased the activity of superoxide dismutase, decreased the production of malondialdehyde and reactive oxygen species, and decreased the apoptosis rate. Additionally, LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, abolished the protective effects of EPO in HG-treated PC12 cells. In diabetic rats, EPO prevented deficits in spatial learning and memory in the Morris water maze test. The results of real-time PCR and Western blotting showed that EPO upregulated EPO receptor, PI3K, and phosphorylated Akt2 relative to unphosphorylated Akt2 (p-Akt2/Akt2) and downregulated glycogen synthase kinase-3β (GSK-3β). These studies demonstrate that EPO is an effective neuroprotective agent in the context of diabetes-associated cognitive dysfunction and show that this effect involves the PI3K/Akt/GSK-3β pathway.

Blood Brain Barrier Injury in Diabetes: Unrecognized Effects on Brain and Cognition

Diabetes mellitus (DM) is a disorder due to the inability properly to metabolize glucose associated with dysregulation of metabolic pathways of lipids and proteins resulting in structural and functional changes of various organ systems. DM has detrimental effects on the vasculature, resulting in the development of various cardiovascular diseases and stemming from microvascular injury. The blood brain barrier (BBB) is a highly specialized structure protecting the unique microenvironment of the brain. Endothelial cells, connected by junctional complexes and expressing numerous transporters, constitute the main cell type in the BBB. Other components, including pericytes, basement membrane, astrocytes and perivascular macrophages, join endothelial cells to form the neurovascular unit (NVU) and contribute to the proper function and integrity of the BBB. The role of the BBB in the pathogenesis of diabetic encephalopathy and other diabetes-related complications in the central nervous system is apparent. However, the mechanisms, timing and consequences of BBB injury in diabetes are not well understood. The importance of further studies related to barrier dysfunction in diabetes is dictated by its potential involvement in the cognitive demise associated with DM. This review summarizes the impact of DM on BBB/NVU integrity and function leading to neurological and cognitive complications.