Diabetes as a risk factor for dementia and mild cognitive impairment: a meta-analysis of longitudinal studies

Amyloid growth and membrane damage: Current themes and emerging perspectives from theory and experiments on Aβ and hIAPP

Alzheimer's Disease (AD) and Type 2 diabetes mellitus (T2DM) are two incurable diseases both hallmarked by an abnormal deposition of the amyloidogenic peptides Aβ and Islet Amyloid Polypeptide (IAPP) in affected tissues. Epidemiological data demonstrate that patients suffering from diabetes are at high risk of developing AD, thus making the search for factors common to the two pathologies of special interest for the design of new therapies. Accumulating evidence suggests that the toxic properties of both Aβ or IAPP are ascribable to their ability to damage the cell membrane. However, the molecular details describing Aβ or IAPP interaction with membranes are poorly understood. This review focuses on biophysical and in silico studies addressing these topics. Effects of calcium, cholesterol and membrane lipid composition in driving aberrant Aβ or IAPP interaction with the membrane will be specifically considered. The cross correlation of all these factors appears to be a key issue not only to shed light in the countless and often controversial reports relative to this area but also to gain valuable insights into the central events leading to membrane damage caused by amyloidogenic peptides. This article is part of a Special Issue entitled: Protein Aggregation and Misfolding at the Cell Membrane Interface edited by Ayyalusamy Ramamoorthy.

Poor cognitive ageing: Vulnerabilities, mechanisms and the impact of nutritional interventions

BACKGROUND

Ageing is a highly complex process marked by a temporal cascade of events, which promote alterations in the normal functioning of an individual organism. The triggers of normal brain ageing are not well understood, even less so the factors which initiate and steer the neuronal degeneration, which underpin disorders such as dementia. A wealth of data on how nutrients and diets may support cognitive function and preserve brain health are available, yet the molecular mechanisms underlying their biological action in both normal ageing, age-related cognitive decline, and in the development of neurodegenerative disorders have not been clearly elucidated.

OBJECTIVES

This review aims to summarise the current state of knowledge of vulnerabilities that predispose towards dysfunctional brain ageing, highlight potential protective mechanisms, and discuss dietary interventions that may be used as therapies. A special focus of this paper is on the impact of nutrition on neuroprotection and the underlying molecular mechanisms, and this focus reflects the discussions held during the 2nd workshop 'Nutrition for the Ageing Brain: Functional Aspects and Mechanisms' in Copenhagen in June 2016. The present review is the most recent in a series produced by the Nutrition and Mental Performance Task Force under the auspice of the International Life Sciences Institute Europe (ILSI Europe).

CONCLUSION

Coupling studies of cognitive ageing with studies investigating the effect of nutrition and dietary interventions as strategies targeting specific mechanisms, such as neurogenesis, protein clearance, inflammation, and non-coding and microRNAs is of high value. Future research on the impact of nutrition on cognitive ageing will need to adopt a longitudinal approach and multimodal nutritional interventions will likely need to be imposed in early-life to observe significant impact in older age.

Anesthesia and Alzheimer disease – Current perceptions

Background and objectives

It has been speculated that the use of anesthetic agents may be a risk factor for the development of Alzheimer disease. The objective of this review is to describe and discuss pre-clinical and clinical data related to anesthesia and this disease.

Content

Alzheimer disease affects about 5% of the population over 65 years old, with age being the main risk factor and being associated with a high morbidity. Current evidence questions a possible association between anesthesia, surgery, and long-term cognitive effects, including Alzheimer disease. Although data from some animal studies suggest an association between anesthesia and neurotoxicity, this link remains inconclusive in humans. We performed a review of the literature in which we selected scientific articles in the PubMed database, published between 2005 and 2016 (one article from 1998 due to its historical relevance), in English, which address the possible relationship between anesthesia and Alzheimer disease. 49 articles were selected.

Conclusion

The possible relationship between anesthetic agents, cognitive dysfunction, and Alzheimer disease remains to be clarified. Prospective cohort studies or randomized clinical trials for a better understanding of this association will be required.

Midlife insulin resistance, APOE genotype, and late-life brain amyloid accumulation

Objective

To examine whether midlife insulin resistance is an independent risk factor for brain amyloid accumulation in vivo after 15 years, and whether this risk is modulated by APOE ε4 genotype.

Methods

This observational study examined 60 elderly volunteers without dementia (mean age at baseline 55.4 and at follow-up 70.9 years, 55.5% women) from the Finnish population-based, nationwide Health2000 study with [¹¹C]Pittsburgh compound B–PET imaging in 2014–2016. The participants were recruited according to their homeostatic model assessment of insulin resistance (HOMA-IR) values in the year 2000, and their APOE ε4 genotype. The exposure group (IR+, n = 30) consisted of individuals with HOMA-IR >2.17 at baseline (highest tertile of the Health2000 study population), and the control group (IR−, n = 30) consisted of individuals with HOMA-IR <1.25 at baseline (lowest tertile). The groups were enriched for APOE ε4 carriers, resulting in 50% (n = 15) APOE ε4 carriers in both groups. Analyses were performed with multivariate logistic and linear regression.

Results

An amyloid-positive PET scan was found in 33.3% of the IR− group and 60.0% of the IR+ group (odds ratio 3.0, 95% confidence interval 1.1–8.9, p = 0.04). The increased risk was seen in carriers and noncarriers of APOE ε4 genotype. Higher midlife, but not late-life continuous HOMA-IR was associated with a greater brain amyloid burden at follow-up after multivariate adjustments for other cognitive and metabolic risk factors (β = 0.11, 95% confidence interval 0.002–0.22, p = 0.04).

Conclusions

These results indicate that midlife insulin resistance is an independent risk factor for brain amyloid accumulation in elderly individuals without dementia.

Risk Factors for Mild Cognitive Impairment in German Primary Care Practices

BACKGROUND

Mild cognitive impairment (MCI) is a common mental disorder affecting around 16% of elderly people without dementia. MCI is considered an intermediate state between normal cognition and dementia.

OBJECTIVE

To analyze risk factors for the development of MCI in German primary care practices.

METHODS

In total, 3,604 MCI patients and 3,604 controls without MCI were included between January 2010 and December 2015. Several disorders potentially associated with MCI were determined. Multivariate logistic regression models were fitted with MCI as a dependent variable and other disorders as potential predictors.

RESULTS

The mean age was 75.2 years and 45.3% of patients were men. MCI development was found to be associated with 12 disorders: intracranial injury, anxiety disorder, depression, mental and behavioral disorders due to alcohol use, stroke, hyperlipidemia, obesity, hypertension, Parkinson's disease, sleep disorder, coronary heart disease, and diabetes with odds ratios ranging from 1.13 (diabetes) to 2.27 (intracranial injury).

CONCLUSION

Intracranial injury, anxiety, and depression showed the strongest association with MCI. Further analyses are needed to gain a better understanding of the MCI risk factors.

Plasma Amyloid-β Peptides in Type 2 Diabetes: A Matched Case-Control Study

BACKGROUND

Plasma amyloid-β (Aβ) levels have rarely been investigated in type 2 diabetes despite its known associations with Alzheimer's disease.

OBJECTIVE

To compare blood plasma Aβ concentrations (Aβ40 and Aβ42) in cognitively normal individuals with and without type 2 diabetes.

METHODS

Plasma Aβ40 and Aβ42 were measured in 194 participants with diabetes recruited from the community-based Fremantle Diabetes Study Phase II cohort (mean age 71 years, 59% males) and 194 age-, sex-, and APOEɛ4 allele-matched, control subjects without diabetes from the Australian Imaging, Biomarkers and Lifestyle Study using a multiplex microsphere-based immunoassay.

RESULTS

Plasma Aβ40 and Aβ42 were normally distributed in the controls but were bimodal in the participants with diabetes. Median Aβ40 and Aβ42 concentrations were significantly lower in those with type 2 diabetes (Aβ40 median [inter-quartile range]: 125.0 [52.6-148.3] versus 149.3 [134.0-165.6] pg/mL; Aβ42: 26.9 [14.5-38.3] versus 33.6 [28.0-38.9] pg/mL, both p < 0.001) while the ratio Aβ42:Aβ40 was significantly higher (0.26 [0.23-0.32] versus 0.22 [0.19-0.25], p < 0.001). After adjustment, participants with diabetes and plasma Aβ40 levels in the low peak of the bimodal distribution were significantly more likely to have normal to high estimated glomerular filtration rates (odds ratio (95% CI): 2.40 (1.20-4.80), p = 0.013) although the group with diabetes had lower renal function overall.

CONCLUSION

Type 2 diabetes is associated with altered plasma concentrations of Aβ peptides and is an important source of variation that needs to be taken into account when considering plasma Aβ peptides as biomarkers for Alzheimer's disease.

Association between residual teeth number in later life and incidence of dementia: A systematic review and meta-analysis

Background

It has been suggested that tooth loss in later life might increase dementia incidence. The objective of this analysis is to systematically review the current evidence on the relationship between the number of remaining teeth and dementia occurrence in later life.

Methods

A search of multiple databases of scientific literature was conducted with relevant parameters for articles published up to March 25th, 2017. Multiple cohort studies that reported the incidence of dementia and residual teeth in later life were found with observation periods ranging from 2.4 to 32 years. Random-effects pooled odds ratios (OR) and 95% confidence intervals (CI) were estimated to examine whether high residual tooth number in later life was associated with a decreased risk of dementia. Heterogeneity was measured by I². The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used to assess the overall quality of evidence.

Results

The literature search initially yielded 419 articles and 11 studies (aged 52 to 75 at study enrollment, n = 28,894) were finally included for analysis. Compared to the low residual teeth number group, the high residual teeth number group was associated with a decreased risk of dementia by approximately 50% (pooled OR = 0.483; 95% CI 0.315 to 0.740; p < 0.001; I² = 92.421%). The overall quality of evidence, however, was rated as very low.

Conclusion

Despite limited scientific strength, the current meta-analysis reported that a higher number of residual teeth was associated with having a lower risk of dementia occurrence in later life.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0729-z) contains supplementary material, which is available to authorized users.

Diabetes Care and Dementia Among Older Adults: A Nationwide 3-Year Longitudinal Study

OBJECTIVES

To compare diabetes monitoring and the incidence of acute diabetic complications between patients with and without incident Alzheimer's Disease and Related Syndromes (ADRS).

DESIGN

Longitudinal observational study from 2010 to 2014.

SETTING

Data from the French national health system database.

PARTICIPANTS

The France-Démence cohort: individuals aged 65 years or older suffering from incident ADRS, based on long-term disease registry, hospitalization for dementia, or antidementia drug delivery. They were matched (1:1) to a pair free of ADRS on age, sex, residence area, and insurance scheme. This study included France-Démence population with known diabetes for at least 2 years.

MEASUREMENTS

Data related to diabetes control and complications: biological monitoring such as glycated hemoglobin A_1c (HbA_1c, ≥1/y, ≥2/y), lipid profile, microalbuminuria; eye examination; hospitalization for diabetes-related complications such as coma with ketoacidosis; and hospitalization for hypoglycemia were studied between the year prior to ADRS identification (Y_-1) and the 2 following years (Y₀; Y₁). Incidences between the 2 groups (ADRS/non-ADRS) were compared using age-standardized incidence ratios (SIR).

RESULTS

The studied population included 87,816 individuals. HbA1c determination was less frequent in ADRS group, no matter the study period and the minimal annual threshold used. Respectively, 82.6% and 88.5% of ADRS and non-ADRS group had at least 1 HbA_1c testing during Y_-1 [SIR = 0.94, 95% confidence interval (CI) 0.93-0.95], 73.4% and 89.0% during Y₀ (SIR = 0.83, 95% CI 0.82-0.84), and 75.4% and 89.3% during Y₁ (SIR = 0.85, 95% CI 0.83‒0.86). Subjects with ADRS were also consistently more hospitalized than non-ADRS peers. The gap was maximal in the year following the diagnosis, as observed for hospitalizations for any cause related to diabetes (SIR Y_-1: 2.04, Y₀: 3.14, Y₁: 1.67), diabetes mellitus with coma (SIR Y_-1: 3.84, Y₀: 9.30, Y₁: 3.06), and hypoglycemia (SIR Y_-1: 4.20, Y₀: 5.25, Y₁: 2.27).

CONCLUSIONS

Incident ADRS is associated with a less frequent diabetes monitoring and an increased risk of diabetes complications compared with older people without ADRS. Our study questions healthcare quality offered to participants with ADRS in comorbidity control. Further investigations are required to explain the mechanisms underlying our results and to propose actions to improve care of patients with ADRS.

Non-estrogenic Xanthohumol Derivatives Mitigate Insulin Resistance and Cognitive Impairment in High-Fat Diet-induced Obese Mice

Xanthohumol (XN), a prenylated flavonoid from hops, improves dysfunctional glucose and lipid metabolism in animal models of metabolic syndrome (MetS). However, its metabolic transformation into the estrogenic metabolite, 8-prenylnaringenin (8-PN), poses a potential health concern for its use in humans. To address this concern, we evaluated two hydrogenated derivatives, α,β-dihydro-XN (DXN) and tetrahydro-XN (TXN), which showed negligible affinity for estrogen receptors α and β, and which cannot be metabolically converted into 8-PN. We compared their effects to those of XN by feeding C57BL/6J mice a high-fat diet (HFD) containing XN, DXN, or TXN for 13 weeks. DXN and TXN were present at higher concentrations than XN in plasma, liver and muscle. Mice administered XN, DXN or TXN showed improvements of impaired glucose tolerance compared to the controls. DXN and TXN treatment resulted in a decrease of HOMA-IR and plasma leptin. C2C12 embryonic muscle cells treated with DXN or TXN exhibited higher rates of uncoupled mitochondrial respiration compared to XN and the control. Finally, XN, DXN, or TXN treatment ameliorated HFD-induced deficits in spatial learning and memory. Taken together, DXN and TXN could ameliorate the neurocognitive-metabolic impairments associated with HFD-induced obesity without risk of liver injury and adverse estrogenic effects.

Hippocampal atrophy, asymmetry, and cognition in type 2 diabetes mellitus

INTRODUCTION

Type 2 diabetes mellitus is associated with global and hippocampal atrophy and cognitive deficits, and some studies suggest that the right hippocampus may display greater vulnerability than the left.

METHODS

Hippocampal volumes, the hippocampal asymmetry index, and cognitive functioning were assessed in 120 nondemented adults with long duration type 2 diabetes.

RESULTS

The majority of the sample displayed left greater than right hippocampal asymmetry (which is the reverse of the expected direction seen with normal aging). After adjustment for age, sex, and IQ, right (but not left) hippocampal volumes were negatively associated with memory, executive function, and semantic fluency. These associations were stronger with the hippocampal asymmetry index and remained significant for memory and executive function after additional adjustment for global brain atrophy.

CONCLUSIONS

We conclude that asymmetric hippocampal atrophy may occur in type 2 diabetes, with greater atrophy occurring in the right than the left hippocampus, and that this may contribute to cognitive impairment in this disorder. These cross-sectional associations require further verification but may provide clues into the pathogenesis of cognitive disorders in type 2 diabetes.

Mild cognitive impairment and progression to dementia in people with diabetes, prediabetes and metabolic syndrome: a systematic review and meta-analysis

PURPOSE

We aimed to quantify the relative risk of progression from mild cognitive impairment (MCI) to dementia in people with and without diabetes, and with and without the MetS (MetS); and to identify potential modifiers of the risk of progression from MCI to dementia in people with diabetes or MetS.

METHODS

We searched Medline, Embase, PsycINFO, PsycArticles and Web of Science from inception through to 20th March 2018. Where possible, the results from three or more studies were pooled in a meta-analysis, while other findings have been described narratively.

RESULTS

We included 15 articles reporting 12 studies (6865 participants). The overall unadjusted pooled odds ratio for the progression of MCI to dementia in people with diabetes/MetS was 1.67 (95% CI 1.27-2.19); the pooled odds ratio for progression in diabetes + MCI was 1.53 (95% CI 1.20-1.97) and in people with MetS + MCI was 2.95 (95% CI 1.23-7.05). There was moderate heterogeneity in the included studies (I² < 60%). In diabetes, a longer duration of diabetes and the presence of retinopathy were associated with an increased risk of progression, while the use of statins and oral hypoglycaemic agents reduced the risk. Having multiple cardiovascular risk factors was a significant risk factor for progression from MCI to dementia in people with MetS.

CONCLUSIONS

Diabetes and MetS were both associated with an increased incidence of dementia when co-existing with MCI. Intensive cardiovascular risk reduction and lifestyle changes for patients presenting with MCI and diabetes, prediabetes or MetS may be important in reducing incidence of dementia in this high risk population.

Predicting cognitive function of the Malaysian elderly: a structural equation modelling approach

OBJECTIVES

The aim of this study was to identify the predictors of elderly's cognitive function based on biopsychosocial and cognitive reserve perspectives.

METHOD

The study included 2322 community-dwelling elderly in Malaysia, randomly selected through a multi-stage proportional cluster random sampling from Peninsular Malaysia. The elderly were surveyed on socio-demographic information, biomarkers, psychosocial status, disability, and cognitive function. A biopsychosocial model of cognitive function was developed to test variables' predictive power on cognitive function. Statistical analyses were performed using SPSS (version 15.0) in conjunction with Analysis of Moment Structures Graphics (AMOS 7.0).

RESULTS

The estimated theoretical model fitted the data well. Psychosocial stress and metabolic syndrome (MetS) negatively predicted cognitive function and psychosocial stress appeared as a main predictor. Socio-demographic characteristics, except gender, also had significant effects on cognitive function. However, disability failed to predict cognitive function.

CONCLUSION

Several factors together may predict cognitive function in the Malaysian elderly population, and the variance accounted for it is large enough to be considered substantial. Key factor associated with the elderly's cognitive function seems to be psychosocial well-being. Thus, psychosocial well-being should be included in the elderly assessment, apart from medical conditions, both in clinical and community setting.

Neuropsychological Criteria for Mild Cognitive Impairment in the Framingham Heart Study's Old-Old

BACKGROUND/AIMS

Mild cognitive impairment (MCI) lacks a "gold standard" operational definition. The Jak/Bondi actuarial neuropsychological criteria for MCI are associated with improved diagnostic stability and prediction of progression to dementia compared to conventional MCI diagnostic approaches, although its utility in diagnosing MCI in old-old individuals (age 75+) is unknown. Therefore, we investigated the applicability of neuropsychological MCI criteria among old-old from the Framingham Heart Study.

METHODS

A total of 347 adults (ages 79-102) were classified as cognitively normal or MCI via Jak/Bondi and conventional Petersen/Winblad criteria, which differ on cutoffs for cognitive impairment and number of impaired scores required for a diagnosis. Cox models examined MCI status in predicting risk of progression to dementia.

RESULTS

MCI diagnosed by both the Jak/Bondi and Petersen/Winblad criteria was associated with incident dementia; however, when both criteria were included in the regression model together, only the Jak/Bondi criteria remained statistically significant. At follow-up, the Jak/Bondi criteria had a lower MCI-to-normal reversion rate than the Petersen/Winblad criteria.

CONCLUSIONS

Our findings are consistent with previous research on the Jak/Bondi criteria and support the use of a comprehensive neuropsychological diagnostic approach for MCI among old-old individuals.

Serum adiponectin levels are associated with worse cognitive function in postmenopausal women

INTRODUCTION

Adiponectin may be a biomarker of cognitive impairment stage, and its clinical progression. In this study we aimed to evaluate the relationship between serum adiponectin levels and cognitive performances in menopausal women, and whether serum adiponectin levels may be differently associated with cognitive performances as compared to overweight/obese subjects.

METHODS

We enrolled 188 post-menopausal women, divided into two groups: obese/overweight group (n = 96) and normal weight group (n = 92). After a clinical examination, and laboratory measurements, we assessed cognitive functions by Montreal Cognitive Assessment test (MoCA).

RESULTS

A significant and greater decrease in executive/visuo-spatial and in attention functions occurred in obese/overweight group as compared to normal weight group (p< 0.001). A significant positive relationship between serum adiponectin levels, and MoCA Global cognitive function was found. MoCA executive, and MoCA attention functions significantly and positively correlated with serum adiponectin levels. BMI, WHR, and serum adiponectin levels were independently associated with MoCA Global cognitive function, but only serum adiponectin levels were independently associated with MoCA attention.

CONCLUSION

A significant positive association may exist between serum adiponectin levels, and better cognitive function in postmenopausal status. The major determinant of attentional capacity was just serum adiponectin levels, and dosage of serum adiponectin levels may be early serum marker of cognitive decline. Therefore, serum adiponectin level has to be used, as early biomarker, to detect cognitive decline, and to support an early prevention.

Comorbidity of chronic kidney disease, diabetes and lower glycated hemoglobin predicts support/care-need certification in community-dwelling older adults

AIM

Chronic kidney disease (CKD), diabetes and lower glycated hemoglobin (HbA_1c ) range in diabetes patients are associated with higher mortality. We investigated whether these conditions were associated with the risk of loss of independence in community-dwelling older adults.

METHODS

We analyzed 1078 older adults with no history of support/care-need certification in Long-Term Care Insurance aged 65-94 years. Associations of baseline CKD, diabetes, and lower HbA_1c range of <6.0% in the diabetes patients, at baseline health checkup with risk of later certification and/or death for 5 years were estimated using the Cox proportional hazards regression model.

RESULTS

The prevalence of both CKD and diabetes in the total population increased with age, due to a net increase in the coexistence of CKD and diabetes. The prevalence of the lower HbA_1c range also increased with age in participants with the coexistence. During 5 years, 135 certifications and 53 deaths occurred. After adjustment, patients with comorbidity of the triad of CKD, diabetes and the lower HbA_1c range had significantly higher hazard ratios (HR) for certification (HR 3.52, 95% confidence interval [CI] 1.91-6.48, P < 0.001) and for death (HR 3.79, 95% CI 1.46-9.85, P = 0.006) compared with those without CKD and diabetes. The harmful impact of the lower HbA_1c range on later certification compared with higher HbA_1c range of ≥6.0% was maintained in diabetes patients with use of antidiabetic agents and CKD (HR 2.40, 95% CI 1.06-6.45, P = 0.036).

CONCLUSIONS

Excessive HbA_1c reduction might cause discontinuance of disability-free survival in community-dwelling older diabetes patients with CKD. Geriatr Gerontol Int 2018; 18: 521-529.

Biomarkers for cognitive decline in patients with diabetes mellitus: evidence from clinical studies

Diabetes mellitus is considered as an important factor for cognitive decline and dementia in recent years. However, cognitive impairment in diabetic patients is often underestimated and kept undiagnosed, leading to thousands of diabetic patients suffering from worsening memory. Available reviews in this field were limited and not comprehensive enough. Thus, the present review aimed to summarize all available clinical studies on diabetic patients with cognitive decline, and to find valuable biomarkers that might be applied as diagnostic and therapeutic targets of cognitive impairment in diabetes. The biomarkers or risk factors of cognitive decline in diabetic patients could be classified into the following three aspects: serum molecules or relevant complications, functional or metabolic changes by neuroimaging tools, and genetic variants. Specifically, factors related to poor glucose metabolism, insulin resistance, inflammation, comorbid depression, micro-/macrovascular complications, adipokines, neurotrophic molecules and Tau protein presented significant changes in diabetic patients with cognitive decline. Besides, neuroimaging platform could provide more clues on the structural, functional and metabolic changes during the cognitive decline progression of diabetic patients. Genetic factors related to cognitive decline showed inconsistency based on the limited studies. Future studies might apply above biomarkers as diagnostic and treatment targets in a large population, and regulation of these parameters might shed light on a more valuable, sensitive and specific strategy for the diagnosis and treatment of cognitive decline in diabetic patients.

Diabetic Microvascular Disease: An Endocrine Society Scientific Statement

Both type 1 and type 2 diabetes adversely affect the microvasculature in multiple organs. Our understanding of the genesis of this injury and of potential interventions to prevent, limit, or reverse injury/dysfunction is continuously evolving. This statement reviews biochemical/cellular pathways involved in facilitating and abrogating microvascular injury. The statement summarizes the types of injury/dysfunction that occur in the three classical diabetes microvascular target tissues, the eye, the kidney, and the peripheral nervous system; the statement also reviews information on the effects of diabetes and insulin resistance on the microvasculature of skin, brain, adipose tissue, and cardiac and skeletal muscle. Despite extensive and intensive research, it is disappointing that microvascular complications of diabetes continue to compromise the quantity and quality of life for patients with diabetes. Hopefully, by understanding and building on current research findings, we will discover new approaches for prevention and treatment that will be effective for future generations.

Correlation study of Framingham risk score and vascular dementia: An observational study

Vascular dementia (VaD) is one of the most common forms of dementia, and second only to Alzheimer's disease. The purpose of this study was to evaluate the potential diagnostic value of Framingham risk score (FRS) in VaD by investigating the relationship among cardiovascular risks, FRS, and VaD.Data were collected from patients (n = 130) at Tongji Hospital in Wuhan, China. They were divided into 2 groups, including the control group (n = 70) and the VaD group (n = 60). Statistical methods including t-test, logistic regression model, multiple linear regression model, and receiver-operating characteristic (ROC) curve were adopted for the assessment.A significant difference (all P < .05) was observed in systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure, total cholesterol (TC), homosysteine (HCY), glycosylated hemoglobin A1c (HbA1c), FRS, and cerebral white matter lesions (WMLs) between the 2 groups, even after adjusting for age (both P < .05). Age [odds ratio (OR) = 1.20; P = .002], FRS (OR = 1.55; P = .006), and WMLs (OR = 10.17; P = .011) were independent prognostic factors for VaD. The area under the ROC curve (AUC) of FRS for VaD diagnosis prediction was 0.830 (95% confidence interval, 95% CI: 0.730∼ 0.929). There was a significant difference in the AUC between WMLs and WMLs combined with FRS (0.788 (95% CI: 0.667 ∼ 0.880) versus 0.863 (95% CI: 0.754 ∼ 0.936, P = .049). Age, HbA1c, and FRS were negatively correlated with the mini-mental state examination (MMSE) scores (all P < .05) in the VaD group. Moreover, multiple stepwise linear regression analysis showed that the age and FRS were independent predictors of MMSE scores.FRS has a moderate predictive value for the VaD diagnosis, and also increases the risk of cognitive decline.

High Hemoglobin A1c and Diabetes Predict Memory Decline in the Health and Retirement Study

BACKGROUND

Type 2 diabetes (T2D) is an established risk factor for dementia, but evidence for T2D and memory decline is less consistent. Understanding how T2D and blood glucose relate to memory decline is crucial to elucidating the mechanisms linking T2D and dementia.

MATERIALS AND METHODS

For 8888 Health and Retirement Study participants aged 50+, glycosylated hemoglobin (HbA1c) was measured in either 2006 or 2008 and physician's diagnosis of diabetes was self-reported in the same year. Composite memory (z scored) was assessed biennially through 2012 using immediate and delayed word list recall or the Informant Questionnaire for Cognitive Decline. Marginal mean regression models for repeated outcomes were specified to predict memory decline as a function of diabetes or HbA1c, using age as the timescale and adjusting for health and social confounders.

RESULTS

Diabetes was associated with a 10% faster rate of memory decline [β=-0.04 per decade; 95% confidence interval (CI), -0.06 to -0.01). A 1 U increase in HbA1c corresponded with a 0.05 SD decrease in memory score per decade (95% CI, -0.08 to -0.03). Even among individuals with HbA1c<6.5% (threshold for diabetes), higher HbA1c was associated with memory decline (β=-0.05 per decade; 95% CI, -0.08 to -0.03).

DISCUSSION

Diabetes accelerated memory loss and higher HbA1c predicted memory decline even in nondiabetics.

Practical considerations for managing patients with diabetes and dementia

Diabetes and dementia appear to be linked epidemiologically and share a common pathogenetic mechanism. The development of dementia in older people with diabetes will have a significant impact on diabetes self-care and will increase the risk of hypoglycaemia and frailty which ultimately lead to disability and poor outcome. Areas covered: We performed a Medline and Embase search from 1997 to present on relevant dementia and diabetes studies published in English language. Expert commentary: Older people with comorbid diabetes and dementia are functionally heterogeneous and interventions should be proportionate to patients 'functional capacity. Metabolic targets can be tightened in fit persons and relaxed when cognitive abilities continue to decline and overall function deteriorates. A holistic multidisciplinary team approach that involves patients, their carers and integrated primary and secondary care services at one point of care that focuses on improving function and maintaining quality of life is needed.

Insulin Resistance and Alzheimer's Disease: Bioenergetic Linkages

Metabolic dysfunction is a well-established feature of Alzheimer's disease (AD), evidenced by brain glucose hypometabolism that can be observed potentially decades prior to the development of AD symptoms. Furthermore, there is mounting support for an association between metabolic disease and the development of AD and related dementias. Individuals with insulin resistance, type 2 diabetes mellitus (T2D), hyperlipidemia, obesity, or other metabolic disease may have increased risk for the development of AD and similar conditions, such as vascular dementia. This association may in part be due to the systemic mitochondrial dysfunction that is common to these pathologies. Accumulating evidence suggests that mitochondrial dysfunction is a significant feature of AD and may play a fundamental role in its pathogenesis. In fact, aging itself presents a unique challenge due to inherent mitochondrial dysfunction and prevalence of chronic metabolic disease. Despite the progress made in understanding the pathogenesis of AD and in the development of potential therapies, at present we remain without a disease-modifying treatment. In this review, we will discuss insulin resistance as a contributing factor to the pathogenesis of AD, as well as the metabolic and bioenergetic disruptions linking insulin resistance and AD. We will also focus on potential neuroimaging tools for the study of the metabolic dysfunction commonly seen in AD with hopes of developing therapeutic and preventative targets.

Physical activity and cohabitation status moderate the link between diabetes mellitus and cognitive performance in a community-dwelling elderly population in Germany

AIMS/HYPOTHESIS

The increasing number of people with dementia and cognitive impairments makes it essential to detect and prevent modifiable risk factors of dementia. This study focuses on type 2 diabetes mellitus, especially on undiagnosed cases and their increased risk of cognitive impairment. Furthermore, the potential of physical activity and social integration to moderate the relation between diabetes and cognitive impairment is assessed.

METHODS

We used cross-sectional data from 1299 participants of the Berlin Aging Study II (BASE-II) aged between 60 to 84 years and performed logistic regression models to analyze the association of diabetes status, physical activity, and cohabitation status with poor cognitive performance. Cognitive performance was measured with the Consortium to Establish a Registry for Alzheimer's Disease (CERAD)-Plus test battery.

RESULTS

Undiagnosed diabetes (odds ratio (OR) = 2.12, p = 0.031), physical inactivity (OR = 1.43, p = 0.008) and non-cohabiting (OR = 1.58, p = 0.002) were associated with an increased likelihood of poor cognitive performance. The highest odds were observed in participants who suffered from undiagnosed or insulin-dependent diabetes and, in addition, were inactive (undiagnosed diabetes: OR = 3.44, p = 0.003; insulin-dependent diabetes: OR = 6.19, p = 0.019) or lived alone (undiagnosed diabetes: OR = 4.46, p = 0.006; insulin-dependent diabetes: OR = 6.46 p = 0.052). Physical activity and cohabiting appeared to be beneficial.

CONCLUSIONS/INTERPRETATION

Physical activity and cohabitation status moderate the link between diabetes mellitus and cognitive performance. Special attention should be paid to undiagnosed and insulin-dependent diabetes cases, which have a particularly high risk of poor cognitive performance.

Mild cognitive impairment in type 2 diabetes mellitus and related risk factors: a review

Type 2 diabetes mellitus (T2DM) is a global epidemic disease and has become a significant health problem. Many studies have raised concern about the mild cognitive impairment (MCI) with T2DM and even the Alzheimer’s disease patients with T2DM. The incidence of MCI is higher in individuals with T2DM than those without diabetes. Cognitive changes might affect everyday activities depending on the work and situation. Although the exact pathophysiology of MCI in T2DM is unclear, many studies suggest that the alterations in pathoglycemia, diabetic complications, related end products, and physical/psychological status are significant risk factors. In this article, we systematically overview the studies to illustrate the related risk factors of cognitive impairment in patients with T2DM. Further high quality studies and treatment need to be initiated and it will become incumbent on clinicians to identify and cure the earliest signs of clinical impairment.

Insulin Resistance is Associated with Increased Levels of Cerebrospinal Fluid Biomarkers of Alzheimer's Disease and Reduced Memory Function in At-Risk Healthy Middle-Aged Adults

BACKGROUND

Type 2 diabetes is associated with an increased risk for Alzheimer's disease (AD). Regulation of normal insulin function may be important in reducing the prevalence of dementia due to AD, particularly in individuals who harbor genetic risk for or have a parental family history of AD. The relationship between insulin resistance (IR) and AD pathology remains poorly understood, particularly in midlife prior to the onset of clinical metabolic disease or cognitive decline.

OBJECTIVE

We examined associations between IR as indexed by HOMA-IR, cerebrospinal fluid (CSF) biomarkers of AD pathology, and memory in middle-aged adults enriched for AD. We postulated that higher HOMA-IR and APOEɛ4 carriage would be associated with greater CSF AD pathology and poor memory performance.

METHODS

Cognitively asymptomatic middle-aged adults (N = 70, mean age = 57.7 years) from the Wisconsin Alzheimer's Disease Research Center with a parental family history of dementia due to AD underwent lumbar puncture, blood draw, and neuropsychological testing. CSF AD biomarkers including soluble amyloid-β protein precursor β (sAβPPβ), amyloid-β42 (Aβ42), and phosphorylated tau (P-tau181) were examined with respect to HOMA-IR and APOEɛ4 status. Delayed memory performance was examined with respect to HOMA-IR, CSF AD biomarkers, and APOEɛ4 status.

RESULTS

Higher HOMA-IR was associated with higher sAβPPβ and Aβ42 . APOEɛ4 carriers had significantly higher levels of sAβPPα, sAβPPβ, and P-tau181/Aβ42 compared to noncarriers. The concurrent presence of higher HOMA-IR and CSF AD pathology predicted worse delayed memory performance.

CONCLUSION

Overall, the findings suggest that IR and APOEɛ4 are contributing factors to the development of AD pathology in midlife, and provide support for targeting insulin function as a potentially modifiable risk factor for AD.

Feasibility of a multi-modal exercise program on cognition in older adults with Type 2 diabetes - a pilot randomised controlled trial

BACKGROUND

Type 2 Diabetes (T2D) is associated with increased risk of dementia. We aimed to determine the feasibility of a randomised controlled trial (RCT) examining the efficacy of exercise on cognition and brain structure in people with T2D.

METHODS

A 6-month pilot parallel RCT of a progressive aerobic- and resistance-training program versus a gentle movement control group in people with T2D aged 50-75 years (n = 50) at the University of Tasmania, Australia. Assessors were blinded to group allocation. Brain volume (total, white matter, hippocampus), cortical thickness and white matter microstructure (fractional anisotrophy and mean diffusivity) were measured using magnetic resonance imaging, and cognition using a battery of neuropsychological tests. Study design was assessed by any changes (during the pilot or recommended) to the protocol, recruitment by numbers screened and time to enrol 50 participants; randomisation by similarity of characteristics in groups at baseline, adherence by exercise class attendance; safety by number and description of adverse events and retention by numbers withdrawn.

RESULTS

The mean age of participants was 66.2 (SD 4.9) years and 48% were women. There were no changes to the design during the study. A total of 114 people were screened for eligibility, with 50 participants with T2D enrolled over 8 months. Forty-seven participants (94%) completed the study (23 of 24 controls; 24 of 26 in the intervention group). Baseline characteristics were reasonably balanced between groups. Exercise class attendance was 79% for the intervention and 75% for the control group. There were 6 serious adverse events assessed as not or unlikely to be due to the intervention. Effect sizes for each outcome variable are provided.

CONCLUSION

This study supports the feasibility of a large scale RCT to test the benefits of multi-modal exercise to prevent cognitive decline in people with T2D. Design changes to the future trial are provided.

TRIAL REGISTRATION

ANZCTR 12614000222640 ; Registered 3/3/2014; First participant enrolled 26/6/2014, study screening commenced 1/9/2014; Australian and New Zealand Clinical Trial Registry.

Cognitive performance of older adults in a specialized diabetes clinic

BACKGROUND

Diabetes mellitus is a risk factor for cognitive changes, but assessment for cognitive disorders in this population is performed infrequently. The present study examined the frequency of cognitive disorders and patterns of deficit in patients enrolled in a specialized clinic for diabetes.

METHODS

A cross-sectional study was conducted to assess cognition in Mount Sinai Diabetes Center patients. Thirty eligible subjects aged ≥50 years were assessed and compared with non-diabetic cognitively normal control subjects, as well as non-diabetic subjects with mild cognitive impairment (MCI). The main outcome(s) and measure(s) were obtained through cognitive assessment and diagnosis using the Alzheimer's Disease Centers' uniform data set.

RESULTS

Forty percent of subjects were newly diagnosed with a cognitive disorder: 10% were diagnosed with dementia and 30% with MCI. Diabetic subjects performed worse on the Mini-Mental State Examination (27.2 vs 28.4; P = 0.0132), list generation (9.5 vs 12.2; P = 0.0190), Trail Making Test, Parts A (70.1 vs 43.0; P < 0.0001) and B (197.2 vs 123.6; P < 0.0001), and the Digit Symbol test (12.7 vs 40.1; P < 0.0001) than cognitively normal individuals. Compared with subjects with MCI (amnestic type), diabetic subjects performed better on tasks of immediate and delayed recall (11.2 vs 7.3 [P = 0.0048] and 8.4 vs. 4.1 [P = 0.0003], respectively).

CONCLUSIONS

Undiagnosed cognitive disorders are common and underappreciated in patients being treated in a specialized diabetes clinic. It may be important to make cognitive assessment a standard part of patient assessments.

Brain functional alterations in Type 2 Diabetes - A systematic review of fMRI studies

Type 2 Diabetes (T2DM) is emerging as a major global health issue. T2DM can adversely affect cognition and increase dementia risk. This systematic review aimed to examine the functional brain changes that may underlie cognitive dysfunction in adults with T2DM. Studies were restricted to those which used functional magnetic resonance imaging (fMRI). Nineteen independent studies were identified, mostly comprised of middle aged or older adults. Resting-state studies demonstrated that compared to controls, connectivity of the Default Mode Network (DMN) was reduced and the majority of task-based studies identified reduced activation in T2DM patients in regions relevant to task performance. Abnormalities of low frequency spontaneous brain activity were observed, particularly in visual regions. As most studies demonstrated that alterations in fMRI were related to poorer neuropsychological task performance, these results indicate that functional brain abnormalities in T2DM have consequences for cognition.

The relationship between obesity and cognitive health and decline

The relationship between obesity and cognitive impairment is important given the globally ageing population in whom cognitive decline and neurodegenerative disorders will carry grave individual, societal and financial burdens. This review examines the evidence for the link between obesity and cognitive function in terms of both the immediate effects on cognitive performance, and effects on the trajectory of cognitive ageing and likelihood of dementia. In mid-life, there is a strong association between obesity and impaired cognitive function. Anthropometric measures of obesity are also associated with reduced neural integrity (e.g. grey and white matter atrophy). Increasing age coupled with the negative metabolic consequences of obesity (e.g. type 2 diabetes mellitus) are likely to significantly contribute to cognitive decline and incidence of dementia. Stress is identified as a potential risk factor promoting abdominal obesity and contributing to impaired cognitive function. However, the potentially protective effects of obesity against cognitive decline in older age require further examination. Finally, surgical and whole diet interventions, which address obesity may improve cognitive capacity and confer some protection against later cognitive decline. In conclusion, obesity and its comorbidities are associated with impaired cognitive performance, accelerated cognitive decline and neurodegenerative pathologies such as dementia in later life. Interventions targeting mid-life obesity may prove beneficial in reducing the cognitive risks associated with obesity.

Factors Associated with Mild Cognitive Impairment among Elderly Filipinos with Type 2 Diabetes Mellitus

Objectives

This study aims to identify factors associated with mild cognitive impairment (MCI) among elderly Filipinos with Type 2 diabetes mellitus.

Methodology

This is an analytic cross-sectional study involving 133 elderly (≥60 years old) with Type 2 diabetes mellitus consecutively sampled from the General Medicine and Diabetes Clinics of the Philippine General Hospital. Eligible subjects were interviewed to gather demographic and clinical data. Body mass index, waist-hip ratio and mean blood pressure were computed. HBA1c, lipid profile, creatinine and urine proteinuria were tested or recorded if done recently. Dilated fundus examination via indirect ophthalmoscopy and 10-gram monofilament test were performed to detect retinopathy and neuropathy. The Montreal Cognitive Assessment-Philippines tool was administered to detect patients with probable MCI using a cutoff score of ≤21. Multivariate logistic regression analysis was performed to determine the associated factors.

Results

Using MoCA-P tool, MCI has a rate of 45% among elderly Filipino diabetics. Having more than 12 years of education is significantly associated with lower odds of MCI. (OR 0.38 CI 0.18, 0.80, p value 0.010).

Conclusion

The rate of MCI among Filipino elderly diabetics is high. Higher education is associated with lower odds of having MCI. Case-control or prospective cohort studies involving larger sample and non-diabetic population are recommended.

Longitudinal association between diabetes and cognitive decline: The National Health and Aging Trends Study

Type II diabetes mellitus (DM) is associated with increased risk of dementia; however, few studies have examined the longitudinal association between DM and cognitive outcomes in large nationally representative cohorts. We investigated these associations in 7605 participants enrolled in the National Health and Aging Trends Study, a nationally representative prospective study of Medicare beneficiaries ≥65, from 2011 to 2015. Participants or proxy respondents reported DM and dementia diagnosis, and participants completed immediate and delayed recall word list learning tests and the Clock Drawing Test. In multivariable-adjusted generalized linear mixed models, baseline DM diagnosis was associated with decline on immediate and delayed word recall and the Clock Drawing Test. In Cox proportional hazards models, DM also predicted incident dementia in older age groups at baseline. These findings further support the notion that DM is associated with cognitive outcomes, suggesting that treatment and prevention of DM may reduce the risk of these outcomes. However, more studies are needed to better understand whether DM treatments affect this relationship.

Visit-to-Visit Variations in Fasting Plasma Glucose and HbA1c Associated With an Increased Risk of Alzheimer Disease: Taiwan Diabetes Study

OBJECTIVE

The relationship between glycemic variability and the incidence of Alzheimer disease (AD) in patients with type 2 diabetes mellitus (T2DM) is unclear. The aim of this study was to examine visit-to-visit variations in fasting plasma glucose (FPG) and glycated hemoglobin (HbA_1c) represented by the coefficient of variation (CV) and to determine whether they were independently associated with AD, irrespective of HbA_1c and other traditional risk factors in such patients.

RESEARCH DESIGN AND METHODS

Patients with T2DM enrolled in the National Diabetes Care Management Program, age ≥60 years, and without diagnosis of AD (n = 16,706) were included in the study. Potential risk factors were analyzed using extended Cox proportional hazards regression models for competing risk of mortality on AD incidence.

RESULTS

During a median follow-up of 8.88 years, 831 incident cases of AD were identified, with a crude incidence rate of 3.5/1,000 person-years. After adjustment for sociodemographic factors, lifestyle behaviors, diabetes-related variables, FPG and HbA_1c, drug-related variables, and comorbidities, both FPG CV and HbA_1c CV were found to be significant predictors of AD, with corresponding hazard ratios of 1.27 (95% CI 1.06-1.52) for the third tertile in FPG CV and 1.32 (95% CI 1.11-1.58) for the third tertile in HbA_1c CV.

CONCLUSIONS

FPG CV and HbA_1c CV are independently associated with AD. The associations between glycemic variability and AD demonstrated in this study suggest a linked pathophysiological mechanism, which is worthy of further investigation. Further research is required to confirm our results and to evaluate whether FPG CV and HbA_1c CV can be valuable therapeutic targets for patients with T2DM at risk.

Reduction of Cognitive Decline in Patients with or at High Risk for Diabetes

PURPOSE OF REVIEW

The incidence of Alzheimer's disease and related disorders is expected to triple by 2050. People with type 2 diabetes and prediabetes have a higher risk of cognitive dysfunction, including Alzheimer's disease and vascular dementia. Controversy remains about when and how to prevent and treat cognitive dysfunction in people with or at high risk of diabetes.

RECENT FINDINGS

In our review of ongoing clinical trials, we have found that there has been an increase in the number of studies assessing the efficacy of pharmacological and non-pharmacological approaches to prevent or slow down cognitive impairment among people with or at high risk of diabetes.

SUMMARY

Despite the considerable risk of cognitive impairment in people with diabetes and prediabetes, there is not enough evidence to support a specific treatment to prevent or slow mild cognitive impairment, or progression to Alzheimer's disease or related disorders. Several ongoing trials are attempting to identify the usefulness of several compounds, as well as lifestyle changes including exercise and diet. Direct mechanisms linking diabetes to cognitive decline have not been elucidated.

An association of cognitive impairment with diabetes and retinopathy in end stage renal disease patients under peritoneal dialysis

Background

Diabetes and retinopathy have been considered as risk factors of cognitive impairment (CI) in previous studies. We investigated both of these two factors and their relationship with global and specific cognitive functions in end stage renal disease patients under peritoneal dialysis (PD).

Methods

In this multicenter cross-sectional study, 424 clinically stable patients were enrolled from 5 PD units, who performed PD for at least three months and completed fundoscopy examination if they had diabetes. Global cognitive function was measured using the Modified Mini-Mental State Examination (3MS), Trail-Making Test forms A and B for executive function, and subtests of the Battery for the Assessment of Neuropsychological Status for immediate and delayed memory, visuospatial skills, and language ability.

Results

PD Patients with DM and Retinopathy had significantly higher prevalence of CI, executive dysfunction, impaired immediate memory and visuospatial skill, compared with patients in non-DM group. By multivariate logistic regression analyses, DM and retinopathy rather than DM only were significantly associated with increased risk for CI, executive dysfunction, impaired immediate memory and visuospatial skill, odds ratios(ORs) and 95% confidence intervals were 2.09[1.11,3.92], 2.89[1.55,5.37], 2.16 [1.15,4.06] and 2.37[1.32,4.22], respectively (all P < 0.05).

Conclusions

Diabetic PD patients with retinopathy were at two times risk for overall cognitive impairment, executive dysfunction, impaired immediate memory and visuospatial skill as compared to non-diabetic PD patients.

Diabetes Mellitus is Associated with More Severe Brain Spontaneous Activity Impairment and Gray Matter Loss in Patients with Cirrhosis

Recent studies showed many cirrhosis patients may have diabetes mellitus (DM), however, the effect of DM on brain in cirrhotic patients is unclear. This study included 34 cirrhosis patients (17 with DM, 17 without DM) and 17 age-, sex-matched healthy controls. MRI examination and neuropsychological tests were performed. Fractional amplitude of low-frequency fluctuation (fALFF) and voxel-based morphometry algorithms were used to obtain fALFF values and gray matter volume, which were compared and correlated with clinical variables. In cirrhosis patients with and without DM, fALFF values were decreased in the left postcentral gyrus, right precentral gyrus, left supramarginal gyrus, bilateral lingual gyri and occipital lobe, while increased in the left orbital frontal gyrus. Gray matter volume was decreased in bilateral caudates and putamen, while increased in bilateral thalami. Compared with non-DM cirrhosis patients, DM cirrhosis patients showed decreased fALFF values in bilateral caudates and decreased gray matter volume in bilateral thalami. The blood glucose levels of cirrhosis patients showed negative correlations with fALFF values in bilateral caudates and gray matter volume in bilateral thalami. In conclusion, DM aggravates brain damage in cirrhosis patients. Thus, it is important to pay more attention to the management of DM in cirrhotic patients.

The role of melatonin in the onset and progression of type 3 diabetes

Alzheimer’s disease (AD) is defined by the excessive accumulation of toxic peptides, such as beta amyloid (Aβ) plaques and intracellular neurofibrillary tangles (NFT). The risk factors associated with AD include genetic mutations, aging, insulin resistance, and oxidative stress. To date, several studies that have demonstrated an association between AD and diabetes have revealed that the common risk factors include insulin resistance, sleep disturbances, blood brain barrier (BBB) disruption, and altered glucose homeostasis. Many researchers have discovered that there are mechanisms common to both diabetes and AD. AD that results from insulin resistance in the brain is termed “type 3 diabetes”. Melatonin synthesized by the pineal gland is known to contribute to circadian rhythms, insulin resistance, protection of the BBB, and cell survival mechanisms. Here, we review the relationship between melatonin and type 3 diabetes, and suggest that melatonin might regulate the risk factors for type 3 diabetes. We suggest that melatonin is crucial for attenuating the onset of type 3 diabetes by intervening in Aβ accumulation, insulin resistance, glucose metabolism, and BBB permeability.

ATP Maintenance via Two Types of ATP Regulators Mitigates Pathological Phenotypes in Mouse Models of Parkinson's Disease

Parkinson's disease is assumed to be caused by mitochondrial dysfunction in the affected dopaminergic neurons in the brain. We have recently created small chemicals, KUSs (Kyoto University Substances), which can reduce cellular ATP consumption. By contrast, agonistic ligands of ERRs (estrogen receptor-related receptors) are expected to raise cellular ATP levels via enhancing ATP production. Here, we show that esculetin functions as an ERR agonist, and its addition to culture media enhances glycolysis and mitochondrial respiration, leading to elevated cellular ATP levels. Subsequently, we show the neuroprotective efficacies of KUSs, esculetin, and GSK4716 (an ERRγ agonist) against cell death in Parkinson's disease models. In the surviving neurons, ATP levels and expression levels of α-synuclein and CHOP (an ER stress-mediated cell death executor) were all rectified. We propose that maintenance of ATP levels, by inhibiting ATP consumption or enhancing ATP production, or both, would be a promising therapeutic strategy for Parkinson's disease.

Weaker Functional Connectivity Strength in Patients with Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is related to cognitive impairments and increased risk for dementia. Neuroimaging studies have demonstrated T2DM-related brain structural and functional changes which are partly associated to the cognitive decline. However, few studies focused on the early neuroimaging findingsin T2DM patients. In this study, a data-driven whole-brain resting state functional connectivity strength (rsFCS) methodwas used to evaluate resting functional changes in 53 T2DM patients compared with 55 matched healthy controls (HCs), and to detect the associations between the rsFCSchanges and cognitive functions in T2DM patients. The T2DM patients exhibited weaker long-range rsFCS in the right insula and weaker short-range rsFCS in the right supramarginalgyrus (SG) compared with the HCs. Additionally, seed-based functional connectivity (FC) analysis revealed weaker FC between the right insula and the bilateral superior parietal lobule (SPL), and between the right SG and the bilateral supplementary motor area (SMA)/right SPL in T2DM patientscompared with the HCs. In T2DM patients, negative correlation was found between the long-range rsFCS in the right insula and HbA1c levels; and the FC between the right SG and the bilateral SMA negatively correlated with TMT-A scores. Our results indicated that the rsFCS alteration occurredbefore obvious cognitive deficits in T2DM patients, which might be helpful for understanding the neuromechanism of cognitive declines in T2DM patients.

Brain function and structure and risk for incident diabetes: The Atherosclerosis Risk in Communities Study

INTRODUCTION

Diabetes is prospectively associated with cognitive decline. Whether lower cognitive function and worse brain structure are prospectively associated with incident diabetes is unclear.

METHODS

We analyzed data for 10,133 individuals with cognitive function testing (1990-1992) and 1212 individuals with brain magnetic resonance imaging (1993-1994) from the Atherosclerosis Risk in Communities cohort. We estimated hazard ratios for incident diabetes through 2014 after adjustment for traditional diabetes risk factors and cohort attrition.

RESULTS

Higher level of baseline cognitive function was associated with lower risk for diabetes (per 1 standard deviation, hazard ratio = 0.94; 95% confidence interval = 0.90, 0.98). This association did not persist after accounting for baseline glucose level, case ascertainment methods, and cohort attrition. No association was observed between any brain magnetic resonance imaging measure and incident diabetes.

DISCUSSION

This is one of the first studies to prospectively evaluate the association between both cognitive function and brain structure and the incidence of diabetes.

Effect of the treatment of Type 2 diabetes mellitus on the development of cognitive impairment and dementia

BACKGROUND

Prevention of cognitive impairment and dementia is an important public health goal. Epidemiological evidence shows a relationship between cognitive impairment and Type 2 diabetes mellitus. The risk of dementia increases with duration of disease. This updated systematic review investigated the effect on cognitive function of the type of treatment and level of metabolic control in people with Type 2 diabetes.

OBJECTIVES

To assess the effects of different strategies for managing Type 2 diabetes mellitus on cognitive function and the incidence of dementia.

SEARCH METHODS

We searched ALOIS (the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG)), the Cochrane Library, MEDLINE, Embase, PsycINFO, CINAHL and LILACS on 15 October 2016. ALOIS contains records from all major health care databases, (CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS), as well as from many trials' registers and grey literature sources.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) which compared two or more different treatments for Type 2 diabetes mellitus and in which cognitive function was measured at baseline and after treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the quality of the included RCTs. We pooled data for comparable trials and estimated the effects of treatment by using risk ratios (RRs) and mean differences (MDs), according to the nature of the outcome. We assessed the quality of the evidence using GRADE methods.

MAIN RESULTS

We identified seven eligible studies but only four provided data we could include in efficacy analyses. Two of these studies compared intensive versus standard glycaemic control and two compared different pharmacological treatments. All studies were at unclear risk of bias in at least two domains and one large study was at high risk of performance and detection bias.(a) Two studies with 13,934 participants at high cardiovascular risk provided efficacy data on intensive versus standard glycaemic control. A third study with 1791 participants provided additional data on hypoglycaemic episodes and mortality. There is probably no difference between treatment groups in the number of participants who decline by at least 3 points on the Mini-Mental State Examination (MMSE) over five years (RR 0.98, 95% CI 0.88 to 1.08; 1 study; n = 11,140; moderate-quality evidence); and there may also be little or no difference in the incidence of dementia (RR 1.27, 95% CI 0.87 to 1.85; 1 study; n = 11,140; low-quality evidence). From another study, there was probably little or no difference in MMSE score after 40 months (MD -0.01, 95% CI -0.18 to 0.16; 1 study; n = 2794; moderate quality evidence). Participants exposed to the intensive glycaemic control strategy probably experience more episodes of severe hypoglycaemia than those who have standard treatment (RR 2.18, 95% CI 1.52 to 3.14; 2 studies; n = 12,827; moderate-quality evidence). The evidence from these trials suggests that the intensity of glycaemic control may have little or no effect on all-cause mortality (RR 0.99, 95% CI 0.87 to 1.13; 3 studies; n = 15,888; low-quality evidence).(b) One study with 156 participants compared glibenclamide (glyburide) with repaglinide. There may be a small advantage of glibenclamide on global cognitive function measured with the MMSE after 12 months (MD -0.90, 95% CI -1.68 to -0.12; low-quality evidence). No data were reported on the incidence of dementia, hypoglycaemic events or all-cause mortality.(c) One study with 145 participants compared rosiglitazone plus metformin to glibenclamide (glyburide) plus metformin over 24 weeks. It reported only on cognitive subdomains and not on global cognitive function, incidence of MCI or dementia, hypoglycaemic events or all causes of mortality.

AUTHORS' CONCLUSIONS

We found no good evidence that any specific treatment or treatment strategy for Type 2 diabetes can prevent or delay cognitive impairment. The best available evidence related to the comparison of intensive with standard glycaemic control strategies. Here there was moderate-quality evidence that the strategies do not differ in their effect on global cognitive functioning over 40 to 60 months.

The impact of obesity on neurodegenerative diseases

Neurodegenerative diseases are a growing health concern. The increasing incidences of these disorders have a great impact on the patients' quality of life. Although the mechanisms of neurodegenerative diseases are still far from being clarified, several studies look for new discoveries about their pathophysiology and prevention. Furthermore, evidence has shown a strong correlation between obesity and the development of Alzheimer's disease (AD) and Parkinson's disease (PD). Metabolic changes caused by overweight are related to damage to the central nervous system (CNS), which can lead to neural death, either by apoptosis or cell necrosis, as well as alter the synaptic plasticity of the neuron. This review aims to show the association between neurodegenerative diseases, focusing on AD and PD, and metabolic alterations.

Insulin Resistance Predicts Cognitive Decline: An 11-Year Follow-up of a Nationally Representative Adult Population Sample

OBJECTIVE

The aim of this study was to examine whether insulin resistance, assessed by HOMA of insulin resistance (HOMA-IR), is an independent predictor of cognitive decline.

RESEARCH DESIGN AND METHODS

The roles of HOMA-IR, fasting insulin and glucose, HbA_1c, and hs-CRP as predictors of cognitive performance and its change were evaluated in the Finnish nationwide, population-based Health 2000 Health Examination Survey and its 11-year follow-up, the Health 2011 study (n = 3,695, mean age at baseline 49.3 years, 55.5% women). Categorical verbal fluency, word-list learning, and word-list delayed recall were used as measures of cognitive function. Multivariate linear regression analysis was performed and adjusted for previously reported risk factors for cognitive decline.

RESULTS

Higher baseline HOMA-IR and fasting insulin levels were independent predictors of poorer verbal fluency performance (P = 0.0002 for both) and of a greater decline in verbal fluency during the follow-up time (P = 0.004 for both). Baseline HOMA-IR and insulin did not predict word-list learning or word-list delayed recall scores. There were no interactions between HOMA-IR and apolipoprotein E ε4 (APOEε4) genotype, hs-CRP, or type 2 diabetes on the cognitive tests. Fasting glucose and hs-CRP levels at baseline were not associated with cognitive functioning.

CONCLUSIONS

Our results show that higher serum fasting insulin and insulin resistance predict poorer verbal fluency and a steeper decline in verbal fluency during 11 years in a representative sample of an adult population. Prevention and treatment of insulin resistance might help reduce cognitive decline later in life.