Glucose intolerance, hyperinsulinaemia and cognitive function in a general population of elderly men

Impact of blood glucose on cognitive function in insulin resistance: novel insights from ambulatory assessment

BACKGROUND/OBJECTIVES

Insulin resistance (IR)-related disorders and cognitive impairment lead to reduced quality of life and cause a significant strain on individuals and the public health system. Thus, we investigated the effects of insulin resistance (IR), and blood glucose fluctuations on cognitive function under laboratory and free-living conditions, using ecological momentary assessment (EMA).

SUBJECTS/METHODS

Baseline assessments included neuropsychological tests and blood analysis. Individuals were classified as either insulin-sensitive (<2) or insulin-resistant (≥2), based on their Homeostatic Model Assessment (HOMA-IR) values. Continuous glucose monitoring (CGM) using a percutaneous sensor was performed for 1 week. Using multiple linear regression, we examined the effects of HOMA-IR and CGM metrics on cognitive domains. Working memory (WM) performance, which was assessed using EMA, 4 times a day for 3 consecutive days, was matched to short-term pre-task CGM metrics. Multilevel analysis was used to map the within-day associations of HOMA-IR, short-term CGM metrics, and WM.

RESULTS

Analyses included 110 individuals (mean age 48.7 ± 14.3 years, 59% female, n = 53 insulin-resistant). IR was associated with lower global cognitive function (b = -0.267, P = 0.027), and WM (b = -0.316; P = 0.029), but not with executive function (b = -0.216; P = 0.154) during baseline. EMA showed that higher HOMA-IR was associated with lower within-day WM performance (β = -0.20, 95% CI -0.40 to -0.00). CGM metrics were not associated with cognitive performance.

CONCLUSIONS

The results confirm the association between IR and decrements in global cognitive functioning and WM, while no effects of CGM metrics were observed, making IR a crucial time point for intervention. Targeting underlying mechanisms (e.g., inflammation) in addition to glycemia could be promising to minimize adverse cognitive effects. Registered under https://drks.de/register/de identifier no. DRKS00022774.

Diabetes and cognitive decline: Challenges and future direction

There is growing evidence that diabetes can induce cognitive decline and dementia. It is a slow, progressive cognitive decline that can occur in any age group, but is seen more frequently in older individuals. Symptoms related to cognitive decline are worsened by chronic metabolic syndrome. Animal models are frequently utilized to elucidate the mechanisms of cognitive decline in diabetes and to assess potential drugs for therapy and prevention. This review addresses the common factors and pathophysiology involved in diabetes-related cognitive decline and outlines the various animal models used to study this condition.

Neuroimaging and clinical characteristics of cognitive migration in community-dwelling older adults

BACKGROUND

Multiple neuroimaging and clinical biomarkers have been identified to predict cognitive decline and clinical progression to mild cognitive impairment (MCI) or dementia. However, early biomarkers associated with transition to and reversion from cognitive impairment (cognitive migration) require further understanding. We investigated the impacts of baseline neuroimaging and clinical biomarkers on cognitive migration in a community-dwelling older cohort.

METHODS

We studied 391 participants from the Wake Forest Alzheimer's Disease Research Center Clinical Core cohort who underwent neuropsychological assessment and magnetic resonance imaging (MRI). At baseline, each participant was categorized to a functional/cognitive state using global Clinical Dementia Rating (CDR) score: CDR = 0 indicates normal cognitive function; CDR = 0.5 is minimal cognitive impairment. The primary outcome was cognitive migration status determined by CDR change between baseline and follow-up (mean difference = 13.9 months): CDR-0 Stables (no migration; maintained CDR = 0), CDR-0.5 Stables (no migration; maintained CDR = 0.5), Migrants- (negative migration; CDR 0 to CDR 0.5), and Reverters+ (positive migration; CDR 0.5 to CDR 0). Baseline T1-weighted MRI was analyzed for gray matter (GM) volume using voxel-based morphometry (VBM). For VBM, we used a two-sample t-test controlling for age, sex, education years and intracranial volume for group comparisons: CDR-0 Stables vs CDR-0.5 Stables, CDR-0 Stables vs Migrants-, CDR-0.5 Stables vs Reverters+ and Migrants- vs Reverters+ (thresholded at k = 30 voxels, p <.01 uncorrected). Oral Glucose Tolerance Testing (OGTT-2h) assessed blood glucose 120-minute post challenge. Multinomial logistic regression estimated average predicted probabilities of cognitive migration status using OGTT-2h and age range (55-65, 65-75 and 75+) as predictors.

RESULTS

VBM analyses revealed lower GM volume in inferior and middle temporal gyri, hippocampus, parahippocampal gyrus, and superior and inferior frontal regions in Migrants- and CDR-0.5 Stables. Predicted probabilities indicated that individuals aged 55-65 with normal OGTT-2h levels were more likely to have better cognitive migration status (e.g., CDR-0 Stables or Reverters+) than those aged 75+ with high OGTT-2h.

CONCLUSIONS

Lower GM volumes and high OGTT-2h glucose levels may predict worse cognitive migration status in early stages of disease. The opposite is true for better cognitive migration. Validating these biomarkers may guide clinical diagnosis and treatments.

Cardiometabolic multimorbidity, genetic risk, and dementia: a prospective cohort study

Background

Individual cardiometabolic disorders and genetic factors are associated with an increased dementia risk; however, the relationship between dementia and cardiometabolic multimorbidity is unclear. We investigated whether cardiometabolic multimorbidity increases the risk of dementia, regardless of genetic risk, and examined for associated brain structural changes.

Methods

We examined health and genetic data from 203 038 UK Biobank participants of European ancestry, aged 60 years or older without dementia at baseline assessment (2006-10) and followed up until March 31, 2021, in England and Scotland and Feb 28, 2018, in Wales, as well as brain structural data in a nested imaging subsample of 12 236 participants. A cardiometabolic multimorbidity index comprising stroke, diabetes, and myocardial infarction (one point for each), and a polygenic risk score for dementia (with low, intermediate, and high risk groups) were calculated for each participant. The main outcome measures were incident all-cause dementia and brain structural metrics.

Findings

The dementia risk associated with high cardiometabolic multimorbidity was three times greater than that associated with high genetic risk (hazard ratio [HR] 5·55, 95% CI 3·39-9·08, p<0·0001, and 1·68, 1·53-1·84, p<0·0001, respectively). Participants with both a high genetic risk and a cardiometabolic multimorbidity index of two or greater had an increased risk of developing dementia (HR 5·74, 95% CI 4·26-7·74, p<0·0001), compared with those with a low genetic risk and no cardiometabolic conditions. Crucially, we found no interaction between cardiometabolic multimorbidity and polygenic risk (p=0·18). Cardiometabolic multimorbidity was independently associated with more extensive, widespread brain structural changes including lower hippocampal volume (F2, 12 110 = 10·70; p<0·0001) and total grey matter volume (F2, 12 236 = 55·65; p<0·0001).

Interpretation

Cardiometabolic multimorbidity was independently associated with the risk of dementia and extensive brain imaging differences to a greater extent than was genetic risk. Targeting cardiometabolic multimorbidity might help to reduce the risk of dementia, regardless of genetic risk.

Funding

Wellcome Trust, Alzheimer's Research UK, Alan Turing Institute/Engineering and Physical Sciences Research Council, the National Institute for Health Research Applied Research Collaboration South West Peninsula, National Health and Medical Research Council, JP Moulton Foundation, and National Institute on Aging/National Institutes of Health.

The Association between HbA1c Levels, Olfactory Memory and Cognition in Normal, Pre-Diabetic and Diabetic Persons

BACKGROUND AND AIM

Recent data have shown that olfactory dysfunction is strongly related to Alzheimer's Disease (AD) that is often preceded by olfactory deficits suggesting that olfactory dysfunction might represent an early indicator of future cognitive in prediabetes.

METHODS

We have applied to a group of normal (n=15), prediabetic (n=16) and type 2 diabetic outpatients (n=15) olfactory testing, 1.5-T MRI scanner and detailed cognitive evaluation including the standard Mini-Mental State Examination (MMSE) form, Short Blessed Test (SBT), Letter Fluency Test (LFT) and the category fluency test with animal, Fruit and Vegetable Naming (CFT).

RESULTS

We have shown that Odour Threshold (OT), Discrimination (OD), and Identification (OI) scores and most cognitive test results were significantly different in the prediabetes and diabetes group compared to those in the control group. OD and OT were significantly different between the prediabetes and diabetes group, although the cognitive test results were only significantly different in the prediabetes and diabetes group compared to those in the control group. In evaluating the association between OI, OT, OD scores and specific cognitive tests, we have found, that impaired olfactory identification was the only parameter that correlated significantly with the SBT both in the pre-diabetes and diabetes group. Although spot glucose values were only correlated with OT, HbA1c levels were correlated with OT, OD, and OI, as well as results of the letter fluency test suggesting that HbA1c levels rather than the spot glucose values play a critical role in specific cognitive dysfunction.

CONCLUSION

To the best of our knowledge, this is the first prospective study to demonstrate a strong association between olfactory dysfunction and specific memory impairment in a population with prediabetes and diabetes suggesting that impaired olfactory identification might play an important role as a specific predictor of memory decline.

A Pilot Study of Diabetes Mellitus Classification from rs-fMRI Data Using Convolutional Neural Networks

Background. As a chronic progressive disease, diabetes mellitus (DM) has a high incidence worldwide, and it impacts on cognitive and learning abilities in the lifetime even in the early stage, may degenerate memory in middle age, and perhaps increases the risk of Alzheimer’s disease. Method. In this work, we propose a convolutional neural network (CNN) based classification method to help classify diabetes by distinguishing the brains with abnormal functions from the normal ones on resting-state functional magnetic resonance imaging (rs-fMRI). The proposed classification model is based on the Inception-v4-Residual convolutional neural network architecture. In our workflow, the original rs-fMRI data are first mapped to generate amplitude of low-frequency fluctuation (ALFF) images and then fed into the CNN model to get the classification result to indicate the potential existence of DM. Result. We validate our method on a realistic clinical rs-fMRI dataset, and the achieved average accuracy is $89.95$ % in fivefold cross-validation. Our model achieves a 0.8690 AUC with 77.50% and 77.51% sensitivity and specificity using our local dataset, respectively. Conclusion. It has the potential to become a novel clinical preliminary screening tool that provides help for the classification of different categories based on functional brain alteration caused by diabetes, benefiting from its accuracy and robustness, as well as efficiency and patient friendliness.

Clinical Features of Geriatric Syndromes in Older Koreans with Diabetes Mellitus

BACKGROUND

This study explored the prevalence and clinical characteristics of geriatric syndromes among Korean older adults with diabetes mellitus (DM).

METHODS

We used data from the 2017 National Survey of Older Koreans to analyze the classic geriatric syndromes of polypharmacy, urinary incontinence, falls, cognitive impairment, and functional impairment according to the presence of DM.

RESULTS

Among 10,299 participants aged 65 years or older, 2,395 had DM. The prevalence of polypharmacy was 64.1% in the DM group and 31.6% in the non-DM group (p<0.001). One or more falls per year occurred in 18.7% of participants with DM compared with 14.9% of those without DM (p<0.001). The prevalence of urinary incontinence was significantly higher in the DM group (3.8%) than in the non-DM group (2.5%) (p=0.001). The prevalence of cognitive impairment was 17.7% in the DM group versus 14.9% in the non-DM group (p=0.001). Functional impairment occurred in 32.2% of participants in the DM group compared with 26.8% of participants in the non-DM group (p<0.001). Finally, the number of geriatric syndromes was significantly associated with cardiovascular disease (CVD) and chronic kidney disease (CKD) in patients with DM.

CONCLUSION

The results of this study showed a higher prevalence of geriatric syndromes among older Korean adults with DM. In addition, the coexistence of multiple geriatric syndromes was associated with CVD and CKD among patients with DM. These findings support the current guidelines for older adults with DM that recommend assessment for geriatric syndromes.

Effect of Crataegus extract supplementation on diabetes induced memory deficits and serum biochemical parameters in male rats

This study was undertaken to investigate the Crataegus extract (CE) eff ;ects on diabetes-induced memory deficit in passive avoidance learning (PAL), blood glucose, and lipid profile panel. Male Wistar rats were divided into five groups: Control (CTRL); Diabetic (DM); and Diabetic animals treated with three doses of CE (100, 300 and 1000 mg/kg) (DM + CE). Streptozotocin (STZ)-induced diabetic rats (50 mg/kg, ip) were orally administrated with CE once a day for 2 weeks. After 2 weeks, PAL task was used to evaluate the passive avoidance learning and memory. At the end of experiment, the level of plasma glucose, triglycerides (TG), cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) were determined. Our results showed that the step-through latency (STLr) in diabetic animals was less than the control group (P = 0.0009). Crataegus (300 mg) increased STLr in diabetic animals (P = 0.0418). Diabetic animals spent more time in the dark compartment (TDC) (P = 0.0009). Crataegus (300 and 1000 mg) decreased TDC in diabetic animals (P = 0.0175). Crataegus (100 and 300 mg) decreased blood glucose in diabetic animals (P < 0.001). TG and Cholesterol concentration increased in diabetic animals in comparison with control (P < 0.05). CE (100 and 300 mg) reduced the cholesterol concentration in diabetic animals (P < 0.001). There was no significant difference in the case of LDL among the experimental groups (P > 0.05). CE (1000 mg) increased HDL in diabetic animals (P < 0.05). Our findings demonstrated that CE had the hypolipidemic and hypoglycemic effects and lead to memory improvement in STZ-induced diabetes.

Glycaemic Control for People with Type 2 Diabetes Mellitus in Bangladesh - An urgent need for optimization of management plan

AIMS

The objective of this study was to identify the determinants of glycaemic control among people with type 2 diabetes mellitus in Bangladesh. A cross-sectional study was carried out during March to September 2017, and 1253 adult patients with type 2 diabetes mellitus were recruited from six hospitals. Data were collected from patients via face-to-face interview, and their medical records were reviewed. Multiple logistic regression analysis was performed. Among the participants, 53.2% were male. Mean (±SD) age was 54.1 (±12.1) years and mean (±SD) duration of diabetes was 9.9 (±7.2) years. About 82% participants had inadequate glycaemic control (HbA1c ≥ 7%) and 54.7% had very poor control (HbA1c ≥ 9%). Low education level, rural residence, unhealthy eating habits, insulin use, infrequent follow up check-ups and history of coronary artery diseases found associated with inadequate and very poor controls. Being female and smokeless tobacco consumer appeared to be associated with inadequate control however cognitive impairment was associated with very poor control only. Prevalence of inadequate glycaemic level was very high in Bangladesh. Having understood relatable lifestyle modification factors, demographics and co-morbidities among people with type 2 diabetes, health care providers in conjunction with patients should work together to address the glycaemic control.

Pathological and cognitive changes in patients with type 2 diabetes mellitus and comorbid MCI and protective hypoglycemic therapies: a narrative review

Type 2 diabetes mellitus (T2DM) is becoming a significant health issue worldwide. Many studies support the hypothesis that patients with T2DM have a higher-than-expected incidence of mild cognitive impairment (MCI) than individuals without diabetes. Based on the results from recent studies, MCI might be associated with the effects of T2DM on glucose metabolism and brain atrophy. As a narrative review, we will illuminate pathological and cognitive changes in patients with T2DM and comorbid MCI and protective hypoglycemic therapies. The early abnormal signs of cognition must be elucidated, and extensive investigations are needed to develop improved therapies for use in the clinic.

Pathophysiological Mechanisms Linking Type 2 Diabetes and Dementia: Review of Evidence from Clinical, Translational and Epidemiological Research

BACKGROUND

Type 2 diabetes represents an increasing health burden world-wide and its prevalence in particularly higher in elderly population. Consistent epidemiological evidence suggests an increased risk of dementia associated to type 2 diabetes; the mechanisms underlying these associations, however, remain unclear.

OBJECTIVE

The study aims to review epidemiological, clinical and pre-clinical data that weigh on pathophysiological links, mechanisms of disease and associations between type 2 diabetes and dementia to identify areas of opportunity for future research.

METHODS

We searched the following electronic bibliographic databases: PUBMED, EMBASE, SCIELO, MEDLINE and OVID for clinical, translational and epidemiological research literature that summarize diabetes-related risk factors for dementia, metabolic and neurological changes associated to T2D, evidence of therapeutic approaches in type 2 diabetes and its pathophysiological implications for dementia.

RESULTS

Type 2 diabetes mellitus increases risk for all-cause dementia, vascular dementia and Alzheimer's disease. The most evaluated mechanisms linking both disorders in pre-clinical studies include an increase in neuronal insulin resistance, impaired insulin signaling, pro-inflammatory state, mitochondrial dysfunction and vascular damage which increase deposition of β-amyloid, tau proteins and GSK3β, leading to an earlier onset of dementia in individuals with impairment in the glucose metabolism. Neuroimaging and neuropathology evidence linking cerebrovascular lesions, neurodegeneration and particularly small-vessel disease in the onset of dementia is consistent with the increased risk of incident dementia in type 2 diabetes, but consistent evidence of AD-related pathology is scarce. Epidemiological data shows increased risk of dementia related to hypoglycemic episodes, glycemic control, metabolic syndrome, insulin resistance and genetic predisposition, but the evidence is not consistent and statistical analysis might be affected by inconsistent covariate controlling. Therapeutic approaches for T2D have shown inconsistent result in relation to dementia prevention and delay of cognitive decline; lifestyle intervention, particularly physical activity, is a promising alternative to ameliorate the impact of disability and frailty on T2D-related dementia.

CONCLUSION

Vascular disease, inflammation and impaired brain insulin signaling might occur in T2D and contribute to dementia risk. Evidence from epidemiological studies has not consistently reported associations that could integrate a unified mechanism of disease in humans. Evaluation of the effect of antidiabetic medications and non-pharmacological interventions in dementia prevention in type 2 diabetes is promising but has thus far offered inconsistent results.

Impact of glycemic status on longitudinal cognitive performance in men with and without HIV infection

OBJECTIVES

To determine the relationship between glycemic status and cognitive performance in men living with HIV (MLWH) and without HIV infection.

DESIGN

A prospective HIV/AIDS cohort study in four US cities between 1999 and 2016.

METHODS

Glycemic status was categorized as normal glucose, impaired fasting glucose, controlled diabetes mellitus and uncontrolled diabetes mellitus at each semiannual visit. Cognitive performance was evaluated using nine neuropsychological tests which measure attention, constructional ability, verbal learning, executive functioning, memory and psychomotor speed. Linear mixed models were used to assess the association between glycemic status and cognition.

RESULTS

Overall, 900 MLWH and 1149 men without HIV were included. MLWH had significantly more person-visits with impaired fasting glucose (52.1 vs. 47.9%) and controlled diabetes mellitus (58.2 vs. 41.8%) than men without HIV (P < 0.05). Compared with men with normal glucose, men with diabetes mellitus had significantly poorer performance on psychomotor speed, executive function and verbal learning (all P < 0.05). There was no difference in cognition by HIV serostatus. The largest effect was observed in individuals with uncontrolled diabetes mellitus throughout the study period, equivalent to 16.5 and 13.4 years of aging on psychomotor speed and executive function, respectively, the effect of which remained significant after adjusting for HIV-related risk factors. Lower CD4+ nadir was also associated with worse cognitive performance.

CONCLUSION

Abnormalities in glucose metabolism were more common among MLWH than men without HIV and were related to impaired cognitive performance. Metabolic status, along with advanced age and previous immunosuppression, may be important predictors of cognition in the modern antiretroviral therapy era.

Occipital blood-brain barrier permeability is an independent predictor of visual outcome in type 2 diabetes, irrespective of the retinal barrier: A longitudinal study

Blood-brain barrier (BBB) permeability in type 2 diabetic patients has been previously shown to be altered in certain brain regions such as the basal ganglia and the hippocampus. Because of the histological and functional similarities between the BBB) and the blood-retinal barrier (BRB), we aimed to investigate how the permeability of both barriers predicts visual outcome. We included 2 control groups (acute unilateral stroke patients, n = 9; type 2 diabetics without BRB leakage n = 10) and a case study group of type 2 diabetics with established BRB leakage (n = 17). We evaluated sex, age, disease duration, metabolic impairment, retinopathy grade and BBB permeability as predictors of visual acuity at baseline, 12  and 24 months in the type 2 diabetics without BRB leakage group and the case study group. We have also explored differences in BBB permeability in the occipital lobe and frontal lobe in the 3 different groups. K^trans (volume transfer coefficient) and V_p (fractional plasma volume) were estimated. The BBB permeability parameter V_p was higher in the case study group compared to the unaffected hemisphere of the stroke patient control group, suggesting vascular dynamics were changed in the occipital lobe of type 2 diabetics with established BRB leakage. These patients showed a significant correlation between glycated hemoglobin (HbA1C) levels and occipital and frontal K^trans . We report for the first time that occipital BBB permeability is an independent predictor of visual acuity at baseline, as well as at 12 and 24 months, in type 2 diabetics with established BRB leakage. Our results suggest that occipital BBB permeability might be an independent biomarker for visual impairment in patients with established BRB leakage.

Cognitive Function Is Impaired in Patients with Recently Diagnosed Type 2 Diabetes, but Not Type 1 Diabetes

OBJECTIVE

To test whether cognitive function is impaired in early states of diabetes and to identify possible risk factors for cognitive impairment.

METHODS

A cross-sectional analysis within the German Diabetes Study included patients with type 1 or type 2 diabetes within the first year after diagnosis or five years after study inclusion and metabolically healthy individuals. Participants underwent comprehensive metabolic phenotyping and testing of different domains of cognitive function. Linear regression models were used to compare cognition test outcomes and to test associations between cognitive function and possible influencing factors within the groups.

RESULTS

In participants with recently diagnosed diabetes, verbal memory was poorer in patients with type 2 diabetes (P = 0.029), but not in type 1 diabetes (P = 0.156), when compared to healthy individuals. Five years after diagnosis, type 2 diabetes patients also showed lower verbal memory than those with type 1 diabetes (P = 0.012). In addition to crystallized intelligence, a higher body mass index among individuals with recently diagnosed type 2 diabetes and male sex among individuals with recently diagnosed type 1 diabetes were associated with impaired verbal memory (all P < 0.05).

CONCLUSION

Verbal memory is impaired in individuals with recently diagnosed type 2 diabetes and likely associated with higher body mass. This trial is registered with the trial registration number NCT01055093.

Computerized cognitive training for older diabetic adults at risk of dementia: Study protocol for a randomized controlled trial

Introduction

Older adults with type 2 diabetes are at high risk of cognitive decline and dementia and form an important target group for dementia risk reduction studies. Despite evidence that computerized cognitive training (CCT) may benefit cognitive performance in cognitively healthy older adults and those with mild cognitive impairment, whether CCT may benefit cognitive performance or improve disease self-management in older diabetic adults has not been studied to date. In addition, whether adaptive difficulty levels and tailoring of interventions to individuals' cognitive profile are superior to generic training remains to be established.

Methods

Ninety community-dwelling older (age ≥ 65) diabetic adults are recruited and randomized into a tailored and adaptive computerized cognitive training condition or to a generic, nontailored, or adaptive CCT condition. Both groups complete an 8-week training program using the commercially available CogniFit program. The intervention is augmented by a range of behavior-change techniques, and participants in each condition are further randomized into a global or cognition-specific phone-based self-efficacy (SE) condition, or a no-SE condition. The primary outcome is global cognitive performance immediately after the intervention. Secondary outcomes include diabetes self-management, meta-memory, mood, and SE.

Discussion

This pilot study is the first trial evaluating the potential benefits of home-based tailored and adaptive CCT in relation to cognitive and disease self-management in older diabetic adults. Methodological strengths of this trial include the double-blind design, the clear identification of the proposed active ingredients of the intervention, and the use of evidence-based behavior-change techniques. Results from this study will indicate whether CCT has the potential to lower the risk of diabetes-related cognitive decline. The outcomes of the trial will also advance our understanding of essential intervention parameters required to improve or maintain cognitive function and enhance disease self-management in this at-risk group.

Neuropsychological profiles of vascular disease and risk of dementia: implications for defining vascular cognitive impairment no dementia (VCI-ND)

Background

vascular cognitive impairment no dementia (VCI-ND) defines a preclinical phase of cognitive decline associated with vascular disorders. The neuropsychological profile of VCI-ND may vary according to different vascular conditions.

Objective

to determine the neuropsychological profile of individuals with no dementia and vascular disorders, including hypertension, peripheral vascular disease (PVD), coronary heart disease (CHD), diabetes and stroke. Risk of 2-year incident dementia in individuals with disease and cognitive impairment was also tested.

Methods

participants were from the Cognitive Function and Ageing Study. At baseline, 13,004 individuals aged ≥65 years were enrolled into the study. Individuals were grouped by baseline disorder status (present, absent) for each condition. Cognitive performance was assessed using the Mini Mental State Examination (MMSE) and the Cambridge Cognitive Examination (CAMCOG). Dementia was assessed at 2 years.

Results

in the cross-sectional analysis, hypertension, PVD and CHD were not associated with cognitive impairment. Stroke was associated with impaired global (MMSE) and CAMCOG sub-scale (including memory and non-memory) scores. Diabetes was associated with impairments in global cognitive function (MMSE) and abstract thinking. In the longitudinal analysis, cognitive impairments were associated with incident dementia in all groups.

Conclusion

the neuropsychological profile in individuals with vascular disorders depends on the specific condition investigated. In all conditions cognitive impairment is a risk factor for dementia. A better understanding of which cognitive domains are affected in different disease groups could help improve operationalisation of the neuropsychological criteria for VCI-ND and could also aid with the development of dementia risk prediction models in persons with vascular disease.

Connexin channel and its role in diabetic retinopathy

Diabetic retinopathy is the leading cause of blindness in the working age population. Unfortunately, there is no cure for this devastating ocular complication. The early stage of diabetic retinopathy is characterized by the loss of various cell types in the retina, namely endothelial cells and pericytes. As the disease progresses, vascular leakage, a clinical hallmark of diabetic retinopathy, becomes evident and may eventually lead to diabetic macular edema, the most common cause of vision loss in diabetic retinopathy. Substantial evidence indicates that the disruption of connexin-mediated cellular communication plays a critical role in the pathogenesis of diabetic retinopathy. Yet, it is unclear how altered communication via connexin channel mediated cell-to-cell and cell-to-extracellular microenvironment is linked to the development of diabetic retinopathy. Recent observations suggest the possibility that connexin hemichannels may play a role in the pathogenesis of diabetic retinopathy by allowing communication between cells and the microenvironment. Interestingly, recent studies suggest that connexin channels may be involved in regulating retinal vascular permeability. These cellular events are coordinated at least in part via connexin-mediated intercellular communication and the maintenance of retinal vascular homeostasis. This review highlights the effect of high glucose and diabetic condition on connexin channels and their impact on the development of diabetic retinopathy.

Diabetic brain or retina? Visual psychophysical performance in diabetic patients in relation to GABA levels in occipital cortex

Visual impairment is one of the most feared complications of Type 2 Diabetes Mellitus. Here, we aimed to investigate the role of occipital cortex γ-aminobutyric acid (GABA) as a predictor of visual performance in type 2 diabetes. 18 type 2 diabetes patients were included in a longitudinal prospective one-year study, as well as 22 healthy age-matched controls. We collected demographic data, HbA1C and used a novel set of visual psychophysical tests addressing color, achromatic luminance and speed discrimination in both groups. Psychophysical tests underwent dimension reduction with principle component analysis into three synthetic variables: speed, achromatic luminance and color discrimination. A MEGA-PRESS magnetic resonance brain spectroscopy sequence was used to measure occipital GABA levels in the type 2 diabetes group. Retinopathy grading and retinal microaneurysms counting were performed in the type 2 diabetes group for single-armed correlations. Speed discrimination thresholds were significantly higher in the type 2 diabetes group in both visits; mean difference (95% confidence interval), [0.86 (0.32-1.40) in the first visit, 0.74 (0.04-1.44) in the second visit]. GABA from the occipital cortex predicted speed and achromatic luminance discrimination thresholds within the same visit (r = 0.54 and 0.52; p = 0.02 and 0.03, respectively) in type 2 diabetes group. GABA from the occipital cortex also predicted speed discrimination thresholds one year later (r = 0.52; p = 0.03) in the type 2 diabetes group. Our results suggest that speed discrimination is impaired in type 2 diabetes and that occipital cortical GABA is a novel predictor of visual psychophysical performance independently from retinopathy grade, metabolic control or disease duration in the early stages of the disease.

A four-day Western-style dietary intervention causes reductions in hippocampal-dependent learning and memory and interoceptive sensitivity

In animals, a Western style diet-high in saturated fat and added sugar-causes impairments in hippocampal-dependent learning and memory (HDLM) and perception of internal bodily state (interoception). In humans, while there is correlational support for a link between Western-style diet, HDLM, and interoception, there is as yet no causal data. Here, healthy individuals were randomly assigned to consume either a breakfast high in saturated fat and added sugar (Experimental condition) or a healthier breakfast (Control condition), over four consecutive days. Tests of HDLM, interoception and biological measures were administered before and after breakfast on the days one and four, and participants completed food diaries before and during the study. At the end of the study, the Experimental condition showed significant reductions in HDLM and reduced interoceptive sensitivity to hunger and fullness, relative to the Control condition. The Experimental condition also showed a markedly different blood glucose and triglyceride responses to their breakfast, relative to Controls, with larger changes in blood glucose across breakfast being associated with greater reductions in HDLM. The Experimental condition compensated for their energy-dense breakfast by reducing carbohydrate intake, while saturated fat intake remained consistently higher than Controls. This is the first experimental study in humans to demonstrate that a Western-style diet impacts HDLM following a relatively short exposure-just as in animals. The link between diet-induced HDLM changes and blood glucose suggests one pathway by which diet impacts HDLM in humans.

Diabetes and neurodegeneration in the brain

Although an association between diabetes mellitus (DM) and cognitive dysfunction has been recognized for a century, it is often not considered as a complication of DM and remains under-recognized. Cognitive dysfunction, usually present as mild cognitive impairment, can occur with either type 1 or type 2 DM. Both forms of DM contribute to accelerated cerebral atrophy and to the presence of heightened white matter abnormalities. These effects are noted most at the two extremes of life, in childhood and in the advanced years. The cognitive spheres most affected include attention and executive function, processing speed, perception, and memory. Although DM is unlikely to lead to frank dementia, its ability to exacerbate existing neurodegenerative processes, such as Alzheimer disease, will impact tremendously upon our society in the upcoming decades as our population ages. This chapter describes the clinical impact of DM upon the brain, along with discussion of the potential therapeutic avenues to be discovered in the coming decades. We need to prepare for better preventative and therapeutic management of this cerebral neurodegenerative condition.

Does Intensive Glucose Control Prevent Cognitive Decline in Diabetes? A Meta-Analysis

Diabetes mellitus is associated with cognitive decline and impaired performance in cognitive function tests among type 1 and type 2 diabetics. Even though the use of tight glucose control has been limited by a reported higher mortality, few reports have assessed the impact of treatment intensity on cognitive function. We conducted a meta-analysis to evaluate if an intensive glucose control in diabetes improves cognitive function, in comparison to standard therapy. We included 7 studies that included type 1 or type 2 diabetics and used standardized tests to evaluate various cognitive function domains. Standardized mean differences (SMDs) were calculated for each domain. We found that type 1 diabetics get no cognitive benefit from a tight glucose control, whereas type 2 diabetics get some benefit on processing speed and executive domains but had worse performances in the memory and attention domains, along with a higher incidence of mortality when using intensive glucose control regimes.

Sitagliptin versus mitiglinide switched from mealtime dosing of a rapid-acting insulin analog in patients with type 2 diabetes: a randomized, parallel-group study

PURPOSE

We determined the feasibility of substituting sitagliptin or mitiglinide for bolus insulin injection therapy in patients with type 2 diabetes.

METHODS

60 patients with type 2 diabetes were enrolled and randomized to switch from mealtime dosing of a rapid-acting insulin analog to either sitagliptin or mitiglinide for 16 weeks.

RESULTS

Body weight, body mass index, and waist circumference decreased significantly in both groups at the end of the study. Mitiglinide significantly increased fasting plasma glucose (FPG) levels at the end of the study from 146.5±36.3 to 168.0±38.8 mg/dL, whereas sitagliptin did not affect FPG. Glycated hemoglobin (HbA1c) and 1,5-anhydroglucitol increased significantly in both groups. The C peptide immunoreactivity (CPR) responses after arginine were diminished in both groups. γ-GTP and triglycerides increased, and high-density lipoprotein cholesterol and adiponectin decreased, in the sitagliptin group, but not in the mitiglinide group. Mean Diabetes Treatment Satisfaction Questionnaire scores improved significantly in both groups. Patients whose mean total daily doses of rapid-acting insulin analog were 16.6 and 17.8 units were switched to sitagliptin and mitiglinide, respectively, without a change in the HbA1c level. Total insulin doses/body weight predicted changes in HbA1c only in the sitagliptin group, but not in the mitiglinide group. Use of >0.27 IU/kg of a rapid-acting insulin analog predicted an increase in HbA1c after switching to sitagliptin. The CPR index (CPI) was also a predictor for a change in HbA1c in the sitagliptin group, but not in the mitiglinide group; patients with a CPI<1.4 developed a worse HbA1c after switching to sitagliptin.

CONCLUSIONS

Sitagliptin may predominantly act on FPG, whereas mitiglinide may act on postprandial plasma glucose to achieve glycemic control after switching from a bolus insulin regimen. Additional therapy to sitagliptin or mitiglinide is clearly required to obtain equivalent glycemic control in patients using a higher dose of insulin.

TRIAL REGISTRATION NUMBER

(UMIN 000007051).

Glucose regulation, cognition, and brain MRI in type 2 diabetes: a systematic review

Type 2 diabetes is associated with cognitive dysfunction and structural brain changes. Abnormalities in glucose regulation are involved in several complications related to type 2 diabetes, but their role in these cerebral complications is unclear. We systematically reviewed studies of the association between glucose regulation (glycaemia, hypoglycaemic events, insulin concentration, insulin resistance, and glucose-lowering treatment) and cognitive function and brain abnormalities on MRI in people with type 2 diabetes. The 86 papers included showed that glycaemia, particularly high HbA1c concentration and glucose variability, are negatively associated with cognitive function in people with type 2 diabetes without dementia. However, the strength of this association is weak, and HbA1c generally accounted for less than 10% of the variance in cognition. Importantly, few studies have measured long-term cerebral outcomes, such as dementia and structural brain changes on MRI, and the effect of glucose-lowering treatment on these outcomes. More randomised controlled trials are needed to establish the effect of glucose-lowering treatment on long-term cognitive function in people with type 2 diabetes.

Metabolic syndrome is associated with poor memory and executive performance in elderly community residents: the PROOF study

OBJECTIVE

Aging is associated with a loss of cognitive performance and an increasing occurrence of cardiovascular events. Moreover, cardiovascular risk factors are linked to cognitive impairment and dementia. Whereas individual components of metabolic syndrome (Met S) have been reported to be linked to cognitive decline and dementia, there are very few studies on Met S as a whole. The present study aims to assess the relationship between Met S and its components and cognitive functioning in a cohort of elderly non-demented community residents.

DESIGN

Population-based cohort study (PROOF study). Cross-sectional analysis.

PARTICIPANTS

Dementia-free community-dwellers aged 65.

MEASURES

The PROOF participants underwent an extensive neuropsychological battery at baseline. Summary cognitive measures including memory, attention, and executive performance were created by converting the individual test results to Z scores and computing the average scores within each domain. Each of the three cognitive scores was individually compared between groups as a function of Met S. The cognitive scores and the covariates which were significant in univariate analyses were then included in logistic regression models.

RESULTS

A significant association was observed between the presence of metabolic syndrome, poor memory, and executive function even after adjusting for confounding factors (memory: odds ratio: 1.77, p = 0.008; executive functions: odds ratio: 1.91, p = 0.002).

CONCLUSIONS

Our study showed that in a sample of elderly community dwellers, Met S was associated with poor memory and executive performance. These results underline the importance of detecting and managing metabolic syndrome components to prevent cognitive impairment and dementia.

Role of dietary and endogenous antioxidants in diabetes

Diabetes affects different people of all ages, race, and sex. This is a condition characterized by a state of chronic hyperglycaemia that leads to an increase of intracellular oxidative stress linked to the overproduction of free radicals. In the present review, we focus our attention on the molecular mechanisms leading to oxidative stress-mediates complications with particular regard to central nervous system (CNS). Furthermore, the present review reports the effects of different kind of antioxidants with enzymatic and nonenzymatic action that may significantly decrease the intracellular free radicals' overproduction and prevents the hyperglycaemia-mediated complications.

Coupling physical exercise with dietary glucose supplement for treating cognitive impairment in schizophrenia: a theoretical model and future directions

AIMS

Metabolic dysregulation may disrupt the complex neuroprotective mechanisms essential for brain health. Recent studies have pointed out the possible aetiological role of metabolic dysregulation in the onset of schizophrenia and the associated cognitive impairment. In this paper, we aimed to generate a theoretical model of how a combination of physical exercise and dietary glucose supplement may help to alleviate cognitive impairment in schizophrenia.

METHODS

Literature on metabolic dysregulation, especially insulin resistance, in relation to the onset of schizophrenia and the associated cognitive impairment is reviewed. The cognitive enhancement effects of physical exercise and dietary glucose supplement are then summarised. Finally, we propose a theoretical model based on the concerted effects of physical exercise and glucose supplement.

RESULTS

In general, the joint action of physical exercise and dietary glucose supplement could up-regulate glucose and insulin transport into the brain, as well as augmenting the release of insulin growth factor-1 and brain-derived neurotrophic factor. Physical exercise and glucose supplement could enhance energy supply and neuroplasticity in brain, subsequently leading to potential cognitive enhancement in schizophrenia. However, glucose supplement is not suitable for patients with abnormal metabolic profile.

CONCLUSIONS

The combination of physical exercise and glucose supplement has potential therapeutic values in treating cognitive impairment in schizophrenia. Further research is necessary to investigate the optimal patterns of exercise and doses of glucose for treating cognitive impairment in schizophrenia.

Dietary glycaemic load associated with cognitive performance in elderly subjects

PURPOSE

Ageing is associated with loss of cognitive function and an increased risk of dementia which is expected to place growing demands on health and long-term care providers. Among multiple causative factors, evidence suggests that cognitive impairment in older subjects may be influenced by diet. The objective of this study was to examine the association between dietary patterns, dietary glycaemic load (GL) and cognition in older Irish adults.

METHODS

Community-dwelling subjects (n 208; 94 males and 114 females; aged 64-93 years) were analysed. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Cognitive capacity was tested using the Mini-Mental State Examination (MMSE). The data were clustered to derive patterns of dietary intake. Multivariable-adjusted logistic and Poisson regression models were used to examine the relationship between dietary GL and MMSE score.

RESULTS

Elderly subjects consuming 'prudent' dietary patterns (high in fruit, vegetables, fish, low-fat dairy and salad dressings and low in red meat and white bread) had higher MMSE scores (better cognitive function) than those consuming 'Western' dietary pattern (high in red meat and white bread and low in fruit and vegetables; P < 0.05). Logistic and Poisson regression analyses both indicated that the MMSE score was inversely associated with the GL of the diet (P < 0.05) even after adjusting for age, gender, diabetes, hypertension, healthy food diversity, nutritional status, residential property price, cardiovascular medications and energy intake.

CONCLUSION

In this community-dwelling elderly Irish cohort, consumption of a high glycaemic diet is associated with poorer cognitive performance as assessed by the MMSE.

Serum 25-hydroxyvitamin D is associated with cognitive executive function in Dutch prefrail and frail elderly: a cross-sectional study exploring the associations of 25-hydroxyvitamin D with glucose metabolism, cognitive performance and depression

OBJECTIVES

The primary objective was to explore the possible association of serum 25-hydroxyvitamin D (25[OH]D) and vitamin D intake with markers of glucose metabolism, depression, and cognitive performance. In addition, we examined to what extent the associations between vitamin D and cognitive performance were modified or mediated by fasting plasma glucose (FPG) levels.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study using data of 127 frail or prefrail Dutch elderly, aged 65 years or older. Frailty was defined according to the criteria of Fried and colleagues. A participant was classified prefrail when 1 to 2 criteria were met; frailty was classified as the presence of 3 or more criteria.

MEASUREMENTS

Associations of 25(OH)D and vitamin D intake with markers of glucose metabolism and domain-specific cognitive performance were examined by multivariable regression analyses. The possible association of vitamin D with depression and global cognitive performance was explored by Poisson regression.

RESULTS

No associations were observed for 25(OH)D with FPG, fasting plasma insulin (FPI), Homeostasis Model Assessment-estimated Insulin Resistance (HOMA-IR), or depression. In contrast, serum 25(OH)D was positively associated with executive functioning (β 0.007, P = .01) and tended to be associated with information-processing speed (β 0.006, P = .06). FPG did not modify or mediate these associations. Vitamin D intake was not associated with cognitive performance, glucose metabolism, or depression.

CONCLUSION

This cross-sectional study suggests an association of serum 25(OH)D with domain-specific cognitive performance, in particular executive functioning and possibly information-processing speed, but not with FPG, FPI, HOMA-IR, or depression. Whether these associations are causal is yet to be demonstrated.

Hippocampal calcium dysregulation at the nexus of diabetes and brain aging

Recently it has become clear that conditions of insulin resistance/metabolic syndrome, obesity and diabetes, are linked with moderate cognitive impairment in normal aging and elevated risk of Alzheimer's disease. It appears that a common feature of these conditions is impaired insulin signaling, affecting the brain as well as peripheral target tissues. A number of studies have documented that insulin directly affects brain processes and that reduced insulin signaling results in impaired learning and memory. Several studies have also shown that diabetes induces Ca(2+) dysregulation in neurons. Because brain aging is associated with substantial Ca(2+) dyshomeostasis, it has been proposed that impaired insulin signaling exacerbates or accelerates aging-related Ca(2+) dyshomeostasis. However, there have been few studies examining insulin interactions with Ca(2+) regulation in aging animals. We have been testing predictions of the Ca(2+) dysregulation/diabetes/brain aging hypothesis and have found that insulin and insulin-sensitizers (thiazolidinediones) target several hippocampal Ca(2+)-related processes affected by aging. The drugs appear able to reduce the age-dependent increase in Ca(2+) transients and the Ca(2+) -sensitive afterhyperpolarization. Thus, while additional testing is needed, the results to date are consistent with the view that strategies that enhance insulin signaling can counteract the effect of aging on Ca(2+) dysregulation.

Vascular cognitive impairment

PURPOSE OF REVIEW

Clinically apparent and subclinical forms of vascular disease including stroke are important causes of cognitive dysfunction. In this review, we will describe the current nomenclature for vascular cognitive impairment (VCI) from the histopathological and clinical perspectives to raise awareness among practitioners about the interaction between conventional and novel vascular risk factors and VCI, with an emphasis on the prevention and risk factor modification.

RECENT FINDINGS

There is substantial evidence from observational studies and clinical trials that conventional risk factors such as hypertension, diabetes, dyslipidemia, smoking, and atrial fibrillation play a role in the development of VCI. Additional novel risk factors such as the metabolic syndrome have been associated with cognitive dysfunction as well. Targeting these risk factors will minimize the burden of VCI in our aging population.

SUMMARY

The concept of VCI has evolved to describe a continuum of cognitive disorders in which vascular brain injury plays a role, ranging from mild cognitive impairment to dementia. Future research is needed to clarify the role of risk factor modification in limiting vascular brain injury to prevent VCI and progression to dementia.

Insulin and sex interactions in older adults with mild cognitive impairment

Alzheimer's disease (AD) and other dementias are likely preceded by a protracted preclinical state. Thus, identification of biomarkers that signal potential points of intervention during this prodromal phase (during which patients are largely able to compensate for their cognitive deficits) is of paramount importance. Insulin is a pancreatic hormone with potent central nervous system effects, and insulin dysregulation has been implicated in the pathogenesis of both AD and vascular dementia. The aim of the current study was to determine whether circulating insulin differs as a function of mild cognitive impairment (MCI) diagnosis, and whether this relationship is mediated by sex and apolipoprotein E (APOE) genotype. A sample of 549 nondemented participants aged 65 and over from the Adult Changes in Thought community-based cohort underwent cognitive testing and blood draw to determine fasting levels of plasma insulin. Subjects were categorized as having normal cognitive functioning, amnestic MCI, or nonamnestic MCI. Results showed that the relationship between insulin and diagnostic category is moderated by sex, such that men with nonamnestic or amnestic MCI have higher fasting plasma insulin than cognitively normal men, while women with amnestic MCI have lower fasting plasma insulin than cognitively normal women. Exploratory analyses suggest that APOE ε4 genotype may further influence the relationship between sex and insulin. Future research will help determine whether insulin dysregulation results in differential effects on vascular function and AD pathology as a function of sex and/or APOE genotype.

Continuous glucose monitoring and cognitive performance in type 2 diabetes

BACKGROUND

Type 2 diabetes is associated with reductions in cognitive function that are associated with glycated hemoglobin (HbA1c) levels, but there is no information on whether cognition is related to postmeal glucose spikes. We explored the relationship of cognition to glucose levels measured by a continuous glucose monitoring system (CGMS) both before and after a weight loss diet.

SUBJECTS AND METHODS

Forty-four white subjects with type 2 diabetes (59.0 ± 6.2 years old; body mass index, 32.8 ± 4.2 kg/m(2); HbA1c, 6.9 ± 1.0%) completed an 8-week energy-restricted (approximately 6-7 MJ, 30% deficit) diet. Cognitive functioning (short-term memory, working memory, speed of processing [inspection time], psychomotor speed, and executive function) was assessed during four practice sessions, baseline, and Week 8. Parallel glucose levels were attained using the CGMS in 27 subjects. Outcomes were assessed by fasting blood glucose (FBG), postprandial peak glucose (G(max)), time spent >12 mmol/L (T > 12), and 24-h area under the glucose curve (AUC(24)).

RESULTS

Despite a fall in FBG of 0.65 mmol/L after 8 weeks, digits backward results correlated with FBG at both Week 0 and Week 8 (r = -0.43, P < 0.01 and r = -0.32, P < 0.01, respectively). Digits forward results correlated with FBG (r = -0.39, P < 0.01), G(max) (r = -0.46, P < 0.05), and AUC(24) (r = -0.50, P < 0.01) at Week 0 and FBG (r = -0.59, P < 0.001), G(max) (r = 0.37, P = 0.01), AUC(24) (r = -0.41, P < 0.01), and percentage weight loss (r = 0.31, P < 0.01) at Week 8. Cognitive function was not altered by weight loss, gender, baseline lipid levels, or premorbid intelligence levels (National Adult Reading Test).

CONCLUSIONS

FBG, G(max,) and AUC(24) were related to cognitive function and an energy-restricted diet for 8 weeks did not alter this relationship.

Impact of postprandial glycaemia on health and prevention of disease

Postprandial glucose, together with related hyperinsulinemia and lipidaemia, has been implicated in the development of chronic metabolic diseases like obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). In this review, available evidence is discussed on postprandial glucose in relation to body weight control, the development of oxidative stress, T2DM, and CVD and in maintaining optimal exercise and cognitive performance. There is mechanistic evidence linking postprandial glycaemia or glycaemic variability to the development of these conditions or in the impairment in cognitive and exercise performance. Nevertheless, postprandial glycaemia is interrelated with many other (risk) factors as well as to fasting glucose. In many studies, meal-related glycaemic response is not sufficiently characterized, or the methodology with respect to the description of food or meal composition, or the duration of the measurement of postprandial glycaemia is limited. It is evident that more randomized controlled dietary intervention trials using effective low vs. high glucose response diets are necessary in order to draw more definite conclusions on the role of postprandial glycaemia in relation to health and disease. Also of importance is the evaluation of the potential role of the time course of postprandial glycaemia.

Diabetes, impaired fasting glucose, and cognitive decline in a population of elderly community residents

BACKGROUND AND AIMS

Diabetes and impaired fasting glucose, as well as cognitive impairment, are common in the elderly. Although several cross-sectional studies have demonstrated the influence of diabetes on cognitive impairment, only a few longitudinal studies have assessed the relationship between diabetes, impaired fasting glucose and cognitive decline in non-demented elderly community dwellers, by means of extensive neuropsychological batteries. The present study assesses the relationship between baseline diabetes, impaired fasting glucose (IFG) and 2- year evolution of memory, attention and executive performance in a sample of non-demented elderly subjects.

METHODS

DESIGN

Population-based cohort study [(PROgnostic indicator OF cardiovascular and cerebrovascular events (PROOF)].

PARTICIPANTS

One hundred and sixty-three community dwellers aged 65 years without dementia at recruitment.

MAIN OUTCOME MEASURES

Memory, attention and executive performance.

RESULTS

A significant association was observed between baseline diabetes mellitus and a higher 2-year decline in the Trial Making Test B and Stroop test exploring attention and executive function. This effect remained significant after adjusting for age, gender, education, anxiety and depressive symptoms, as well as other cardiovascular risk factors (F=2.41; p=0.007). Instead, no relationship was observed between IFG and cognitive decline.

CONCLUSIONS

Our study showed that, in a sample of elderly non-demented community dwellers, diabetes mellitus (but not IFG) is associated with a higher decline in selective attention and executive functioning. These results emphasize the importance of detecting and man- aging diabetes and impaired fasting glucose, in order to prevent cognitive impairment and dementia.

Associations of 25-hydroxyvitamin D with fasting glucose, fasting insulin, dementia and depression in European elderly: the SENECA study

Purpose

The classical consequence of vitamin D deficiency is osteomalacia, but recent insights into the function of vitamin D suggest that it may play a role in other body systems as well. The objective of this study was to examine the association between 25-hydroxyvitamin D (25(OH)D) and markers of glucose metabolism (n = 593), global cognitive functioning (n = 116) and depression (n = 118) in European elderly participating in the SENECA study. Moreover, we wanted to explore whether the observed associations of 25(OH)D with depression and global cognitive performance were mediated by fasting plasma glucose (FPG) levels.

Methods

Cross-sectional associations between 25(OH)D and FPG, fasting plasma insulin (FPI) and homeostatic model assessment-insulin resistance (HOMA-IR), a marker of insulin resistance, were estimated from multiple regression analyses. Associations of 25(OH)D with global cognitive functioning (Mini Mental State Examination) and depression (Geriatric Depression Scale) were examined using Poisson regression.

Results

An inverse association was observed between 25(OH)D and FPG (β-0.001), indicating a 1 % decrease in FPG per 10 nmol/L increase in 25(OH)D, but after full adjustment for demographic factors, lifestyle factors and calcium intake, this association was not statistically significant (P = 0.07). Although participants with intermediate and high serum 25(OH)D levels showed a tendency towards a lower depression score after adjustment for demographic and lifestyle factors, RR and 95 % CI: 0.73 (0.51–1.04) and 0.76 (0.52–1.11), respectively, these findings were not statistically significant.

Conclusion

An inverse association of 25(OH)D with depression and FPG was observed, but this association was not statistically significant. There was no association between 25(OH)D with FPI and HOMA-IR or with global cognitive functioning. More studies are needed to further explore the possible role of vitamin D in the various body systems.

Does mild cognitive impairment affect the occurrence of radiographic knee osteoarthritis? A 3-year follow-up in the ROAD study

OBJECTIVE

To determine whether mild cognitive impairment (MCI) increases the risk of occurrence or progression of radiographic knee osteoarthritis (KOA) in a general population.

DESIGN

Population-based cohort study.

SETTING

Residents in mountain and seaside areas of Wakayama Prefecture, Japan.

PARTICIPANTS

1690 participants (596 men, 1094 women; mean age 65.2 years old) were enrolled from the large-scale cohort for the Research on Osteoarthritis (OA)/osteoporosis Against Disability (ROAD) study initiated in 2005 to investigate epidemiological features of OA in Japan. Of these, 1384 individuals (81.9%; 466 men, 918 women) completed the second survey including knee radiography 3 years later.

PRIMARY OUTCOME MEASURES

Radiographic KOA was defined as Kellgren-Lawrence (KL) grade ≥ 2 using paired x-ray films. Incidence of KOA during follow-up defined on radiographs as KL grade ≥2, progression of KOA defined as a higher KL grade (either knee) at follow-up compared with baseline. MCI defined as a summary mini-mental state examination (MMSE) score ≤23. Associations between MCI and incidence or progression of KOA were analysed.

RESULTS

The annual cumulative incidence of KOA was 3.3%; for progression of OA it was 8.0%. On logistic regression analysis adjusted for age, gender, regional differences, body mass index, grip strength (worse side), smoking, alcohol consumption, regular exercise and history of knee injury, baseline MMSE summary score was significantly associated with the incidence of KOA (+1 MMSE score; OR 0.83, p=0.010). Baseline MCI was also significantly associated with the incidence of KOA (vs non-occurrence of KOA; OR 4.90, p=0.027). There was no significant association between MMSE scores, the presence of MCI and progression of KOA (+1 MMSE score; OR 0.96, p=0.232; vs non-progression of KOA; OR 1.38, p=0.416).

CONCLUSIONS

MCI significantly increases the risk of incident radiographic KOA, but not the progression of KOA.

Does caring for a spouse with dementia promote cognitive decline? A hypothesis and proposed mechanisms

OBJECTIVE

To discuss why spouse caregivers (CGs) of people with dementia may be at higher risk for cognitive problems and decline than demographically similar people not caring for a spouse with dementia (noncaregivers; NCGs).

DESIGN

Literature review.

SETTING

Community.

PARTICIPANTS

Older adults caring for a family member (primarily spouses) with dementia.

MEASUREMENTS

Cognitive, psychosocial, physiological, and behavioral.

RESULTS

This article reports a review of the literature examining relationships between CG status and cognitive problems in the context of a theoretical model of chronic stress. The model suggests that spouse CGs may be at higher risk of cognitive impairment or dementia than NCG spouses in response to several mediators, including psychosocial (e.g., depression, loneliness, social isolation, sleep problems), behavioral (e.g., exercise, diet), and physiological (e.g., metabolic syndrome and inflammation) variables.

CONCLUSION

This research has important implications because it considers modifiable risk factors for dementia that, if unchecked, may compromise the lives of CGs and their ability to function. It is hoped that an understanding of such stress-mediator-cognitive processes will help clinicians, researchers, policy-makers, and stakeholders mitigate what may be characterized as an "ironic tragedy"-dementia in both members of the caregiving dyad-if left unchecked.

Neurocognitive impairment and comorbid depression in patients of diabetes mellitus

This study was conducted to find out the association of diabetes mellitus with cognitive functioning and depressive features. We included 50 diabetic and 30 control subjects who were screened on the basis of various inclusion and exclusion criteria. Then, a history of variables under study was taken and respective laboratory investigations were noted. First, the Becks Depression Inventory (BDI) was administrated to the patients. The cognitive function was then assessed using the digit span test, stroop Test, controlled oral word association test, visual target cancellation test, digit symbol substitution test, and visuospatial working memory matrix. The composite score on all tests was used to make cognitive index. The data was compiled and appropriate statistical methods were used. We found that 48% of elderly diabetic patients showed cognitive impairment. Poor metabolic control (hyperglycemia) was associated significantly and negatively with cognitive index in diabetic patients. Hyperglycemia was significantly and negatively correlated with immediate memory and attention, verbal memory, psychomotor functioning (DSST), and visuospatial memory. In conclusion, genesis of cognitive deficits in diabetic patients is complex. However, it appears from the study that such deficits do exist and may be associated with chronically poorly controlled diabetes.

Glucagon-like peptide-1, diabetes, and cognitive decline: possible pathophysiological links and therapeutic opportunities

Metabolic and neurodegenerative disorders have a growing prevalence in Western countries. Available epidemiologic and neurobiological evidences support the existence of a pathophysiological link between these conditions. Glucagon-like peptide 1 (GLP-1), whose activity is reduced in insulin resistance, has been implicated in central nervous system function, including cognition, synaptic plasticity, and neurogenesis. We review the experimental researches suggesting that GLP-1 dysfunction might be a mediating factor between Type 2 diabetes mellitus (T2DM) and neurodegeneration. Drug treatments enhancing GLP-1 activity hold out hope for treatment and prevention of Alzheimer's disease (AD) and cognitive decline.

Diabetes and cognitive impairment: how to evaluate the cognitive status?

AIM

Patients with diabetes have shown lower performance in tests of cognitive function especially those testing memory, executive functions, and psychomotor efficiency. They also have an elevated risk of both vascular dementia and Alzheimer's disease. Cognitive impairment may have consequence on treatment compliance.

METHODS AND RESULTS

This article provides indication for holding an interview, and reports a few screening bedside tests to detect a cognitive impairment. Some neuropsychological tests useful for characterizing the cognitive profile of a patient are described, as well as the main cognitive profiles expected in patients with diabetes and cognitive decline.

CONCLUSION

A systematic assessment of cognition with a rapid interview and screening tests in patients with diabetes, especially the oldest, with a long history of diabetes, co-morbidities, or with unexplained poor metabolic control would be a good clinical practice. Patients with cognitive decline may be referred to memory clinics for identifying the cause of the decline and contribute to provide appropriate medical and medicosocial management.

Hypoglycaemia and dementia in diabetic patients

Diabetes and dementia, which have a complex relationship between them, are undergoing extensive growth in their fields. The occurrence of hypoglycaemia, the potential severity of which has just been pointed out in some recent studies, must be included in these relationships. In fact, diabetes is the cause of decline in cognitive functions and most certainly is involved in the occurrence of vascular dementia. The brain, which is highly dependent on glucose for its metabolism, is particularly vulnerable to hypoglycaemia in children and the elderly. Animal studies and pathoanatomical observations confirm the clinical impression of the reality of genuine post-hypoglycaemic encephalopathy. The impact of mild hypoglycaemia however is being debated. Lastly, the existence of dementia promotes the occurrence of hypoglycaemia due to disorders related to eating habits or poor treatment management. This hypoglycaemic risk however must not constitute a pretext for exaggerated laxity in achieving the blood glucose objectives.

White blood cell count and psychomotor cognitive performance in the elderly

BACKGROUND

White blood cell (WBC) count is associated with many inflammatory diseases such as cardiovascular disease, diabetes and hypertension. Research on the relationship of WBC count and cognition in the elderly is relatively sparse. This study examined the association between WBC count and cognitive performance in older adults.

METHODS

Data from the National Health and Nutrition Examination Survey (1999-2002) containing 1670 older adults were analysed. Every subject completed a household interview, examination of digit symbol substitution test (DSST) scores, WBC count measurement and a questionnaire regarding personal health. WBC count was restricted to the normal range and divided into quartiles, using a multiple hierarchical regression model to estimate the relationship between WBC counts and DSST scores. Quartile-based analysis with an extended-model approach was used for further covariates adjustment. Trends test examining the associations across increasing quartiles of WBC counts and DSST scores were also conducted.

RESULTS

In the multiple hierarchical regression model, the β coefficient, representing the change of DSST scores for each 1000 cells uL(-1) increase in WBC count, was -0·097 (R(2) = 0·343, P < 0·001). After additional competent covariates adjustment, the negative correlation remained (all P < 0·001). In quartile-based multiple linear regression, the negative trends between DSST scores and WBC count quartiles in the stratified comparison with extended-model approach were all statistically significant (P for trends <0·001).

CONCLUSIONS

Higher WBC counts, even within the normal range, were associated with poor psychomotor cognitive performance in the elderly.

Western diet consumption and cognitive impairment: links to hippocampal dysfunction and obesity

Intake of saturated fats and simple carbohydrates, two of the primary components of a modern Western diet, is linked with the development of obesity and Alzheimer's Disease. The present paper summarizes research showing that Western diet intake is associated with cognitive impairment, with a specific emphasis on learning and memory functions that are dependent on the integrity of the hippocampus. The paper then considers evidence that saturated fat and simple carbohydrate intake is correlated with neurobiological changes in the hippocampus that may be related to the ability of these dietary components to impair cognitive function. Finally, a model is described proposing that Western diet consumption contributes to the development of excessive food intake and obesity, in part, by interfering with a type of hippocampal-dependent memory inhibition that is critical in the ability of animals to refrain from responding to environmental cues associated with food, and ultimately from consuming energy intake in excess of that driven solely by caloric need.

Neurovascular coupling in cognitive impairment associated with diabetes mellitus

Although it is feared that diabetes-induced cognitive decline will become a major clinical problem worldwide in the future, the detailed pathological mechanism is not well known. Because patients with diabetes have various complications of vascular disease, with not only macrovascular but also microvascular disorders, vascular disorders in the brain are considered to be one of the mechanisms in diabetes-induced cognitive impairment. Indeed, disruption of the blood-brain barrier (BBB) has been observed in some diabetic patients and experimental diabetes models. Moreover, white matter lesions, part of the evidence of BBB dysfunction, are reported to be observed more frequently in patients with diabetes. Animal studies demonstrate that diabetes enhances BBB permeability through a decrease in the level of tight junction proteins and an increase in matrix metalloproteinase activity. However, there are several reports indicating that BBB disruption does not occur with diabetes. Therefore, the association of BBB breakdown with diabetes-induced cognitive impairment is not conclusive. Recently, neuronal diseases involving dementia have been induced experimentally through dysfunction of neurovascular coupling, which involves blood vessels, astrocytes and neutrons. Diabetes-induced cognitive decline may be induced via disruption of neurovascular coupling, with not only vascular disorder but also impairment of astrocytic trafficking. Here, the relation between vascular disorder and cognitive impairment in diabetes is discussed.

R D Lawrence Lecture 2010. The brain as a target organ in Type 2 diabetes: exploring the links with cognitive impairment and dementia

Type 2 diabetes is associated with cognitive impairment and dementia, but the precise underlying mechanisms remain unresolved. Very high blood glucose concentrations are associated with mood changes and poor memory function, possibly by causing alterations in cerebral blood flow or osmotic changes in neurones, and correction of acute hyperglycaemia appears beneficial. Chronic hyperglycaemia may cause structural changes in the brain, such as cerebral microvascular disease, and there are strong associations between the presence of retinal microvascular abnormalities and cognitive function. Functional insulin deficiency in the brain may also be a factor, but trials with rosiglitazone in people with diabetes and other trials in people with Alzheimer's disease have shown no specific benefit of insulin sensitization. There is an association between hypoglycaemia and cognitive impairment in people with Type 2 diabetes; part of that association may simply be a consequence of the fact that people with cognitive impairment find it more difficult to manage their diabetes and so are more prone to hypoglycaemia. The potential for hypoglycaemia to cause harm to the brain has been debated for many years, and the issue remains unresolved. An ongoing prospective study of risk factors for cognitive impairment in people with Type 2 diabetes (Edinburgh Type 2 Diabetes Study) should improve our understanding of the aetiology of cognitive impairment and inform the design of future intervention trials.

Primary care for diabetes mellitus: perspective from older patients

BACKGROUND

Care of diabetes mellitus in the elderly requires an additional perspective to take into account impaired cognitive function, physical function, low level of education, and difficulty making lifestyle changes. Existing services tend to be driven by the views of tertiary and secondary care staff, rather than those of primary care staff and elderly patients. This study aimed to explore the attitudes and preferences of elderly patients with diabetes mellitus towards primary care (clinical care and community program).

METHOD

Elderly patients with diabetes mellitus aged 60 years or above were recruited from governmental diabetes mellitus clinics and diabetes mellitus specific community centers. Three focus group discussions of 14 diabetic elderly patients were conducted and their perspectives on the new service model were assessed. Participants were interviewed according to an open-ended discussion guide which includes the following items: comments on existing clinic follow up and community program, motivation for joining the community program, and suggestions on further clinical services and community service program development.

RESULTS

Incapability of the current health service to address their special needs was a common concern in three focus group discussions. The majority highlighted the benefits of the new service program, that is, self-care knowledge and skill, attitudes to living with diabetes mellitus, and supportive network. Key facilitators included experiential learning, a group discussion platform, and goal setting with patients.

CONCLUSIONS

This study is the first qualitative study to explore the views of elderly diabetic patients' on their self-care needs. Elderly people with diabetes mellitus in this study identified bad experiences of clinical follow-up; benefit from the community program; and recommendations for the future development of primary care. Study findings revealed a number of discrepancies between elderly diabetic patients' needs and existing health services in Hong Kong. The study findings provide health practitioners, researchers and educators with an additional perspective on the provision of quality of care for elderly diabetic patients in the community.