Early Cognitive Deficits in Type 2 Diabetes: A Population-Based Study

Jiao-tai-wan and its effective component-coptisine alleviate cognitive impairment in db/db mice through the JAK2/STAT3 signaling pathway

BACKGROUND

Cognitive impairment (CI) is now well-accepted as a complication and comorbidity of diabetes mellitus (DM), becoming a serious medical and social problem. Jiao-tai-wan (JTW), one of noted traditional Chinese medicine (TCM), showed dual therapeutic effects on DM and CI. Nevertheless, the potential mechanism is unclear.

PURPOSE

This study sought to investigate the mechanism how JTW protected against DM and CI and screen the active component in JTW.

METHODS

Db/db mice were used as mouse models. Mice were treated by gavage with 0.9 % saline (0.1 mL/10g/d), low dose of JTW (2.4 g/kg/d) or high dose of JTW (4.8 g/kg/d) for 8 weeks separately. To access the effects of JTW, the levels of OGTT, HOMA-IR, blood lipids, inflammatory cytokines in serum and hippocampus were measured, behavioral tests were conducted, and histopathological changes were observed. The mechanism exploration was performed via network pharmacology, RT-qPCR, western blot, and immunofluorescence staining (IF). The impact and mechanism of coptisine in vitro were investigated using BV2 cells induced by LPS as cellular models. In vitro experiments were conducted in two parts. The first part comprised four groups: Control group, LPS group, LPS+LCOP group and LPS+HCOP group. The second part consisted of four groups: Control group, LPS group, LPS+HCOP group, and LPS+ Fed group. The western blot and RT-qPCR methods were used to examine the changes in biomarkers of the JAK2/STAT3 signaling pathways in BV2 cells.

RESULTS

The results demonstrated that JTW could improve OGTT and HOMA-IR, reduce the serum levels of LDL-C, HDL-C, TG, and TC, restore neuronal dysfunction and synaptic plasticity, and decrease the deposition of Aβ in the hippocampus. The findings from ELISA, IF, and RT-qPCR revealed that JTW could alleviate microglial activation and inflammatory status in vivo and coptisine could play the same role in vitro. Moreover, the changes of the JAK2/STAT3 signaling pathway in LPS-induced BV2 cells or hippocampus of db/db mice were distinctly reversed by coptisine or JTW, respectively.

CONCLUSION

Our study suggested that JTW and its effective component coptisine could alleviate diabetes mellitus-related cognitive impairment, closely linked to the JAK2/STAT3 signaling pathway.

The effects of a six-month exercise intervention on white matter microstructure in older adults at risk for diabetes

Older adults with prediabetes or obesity (i.e., those at risk for diabetes) exhibit impaired structural brain networks. Given findings that resistance training (RT) can combat brain impairments in many populations, this study aimed to test the effects of this type of exercise on white matter microstructure in older adults at risk for diabetes. Seventeen community-dwelling older adults (mean age 67.8 ± 5.7, 52.9 % female) with prediabetes or obesity were randomly allocated to thrice weekly RT or balance and tone training (BAT; control group) for six months. Diffusion weighted imaging via a 3T scanner was used to assess changes in white matter parameters -fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) - over time. Participants in the RT group showed no significant changes in FA but had increased MD and RD in various regions related to cognitive function including the cingulate gyrus. Participants in the control group had both increased and decreased FA depending on the specific white matter tracts; increased FA was seen in areas related to motor coordination such as the middle cerebellar peduncle. The control group also exhibited decreased MD and RD in areas responsible for motor function (e.g., left anterior limb of the internal capsule). We conclude that both resistance and balance exercises result in changes in white matter microstructure albeit in divergent tracts that may be linked to the specific exercises performed.

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

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

Change in cardiovascular health and rate of cognitive decline in older adults: a 15-year population-based study

BACKGROUND

Previous research on associations between cardiovascular health, measured at a single timepoint, and rate of age-related cognitive decline shows divergent findings dependent on the participants' age and the health metric studied. The aim of this study was to add to the knowledge in this field by investigating whether change in cardiovascular health, assessed with Life's Simple 7 (LS7) score, is associated with rate of cognitive change in young-old and old-old adults.

METHODS

The study included 1022 participants aged ≥ 60 years from the Swedish National Study on Aging and Care-Kungsholmen (SNAC-K), who underwent repeated neuropsychological testing (episodic memory, semantic memory, verbal fluency, and perceptual speed) across up to 15 years. LS7, composed of seven cardiovascular health metrics (smoking, diet, physical activity, body mass index, plasma glucose, total serum cholesterol, and blood pressure), was assessed at baseline and at the 6-year follow-up. Change in LS7 was calculated as the difference between baseline and 6 years (range - 5 to 8 points) and categorised into worse (-5 to -2 points), stable (-1 to 1 points), and improved (2 to 8 points). Change in cognitive performance as a function of LS7 change categories was estimated using linear mixed-effects models.

RESULTS

Participants were classified as stable (67.1%), improved (21.0%), or worse (11.8%) according to changes in LS7 score. Both the worse and improved categories were associated with faster cognitive decline. Age-stratified analyses revealed that worsening of LS7 was clearly associated with faster cognitive decline in the old-old (≥ 78 years), whereas improvement tended be associated with faster cognitive decline in the young-old (< 78 years) group.

CONCLUSIONS

Change in cardiovascular health in old age may lead to accelerated cognitive decline, particularly in late senescence. These results suggest that it is important to monitor and maintain cardiovascular health status in very old adults.

Metabolic Disturbance of High-Saturated Fatty Acid Diet in Cognitive Preservation

Aging continues to be the main cause of the development of Alzheimer's, although it has been described that certain chronic inflammatory pathologies can negatively influence the progress of dementia, including obesity and hyperlipidemia. In this sense, previous studies have shown a relationship between low-density lipoprotein receptor (LDLR) and the amyloid-beta (Aβ) binding activity, one of the main neuropathological features of Alzheimer's disease (AD). LDLR is involved in several processes, including lipid transport, regulation of inflammatory response and lipid metabolism. From this perspective, LDLR^-/- mice are a widely accepted animal model for the study of pathologies associated with alterations in lipid metabolism, such as familial hypercholesterolemia, cardiovascular diseases, metabolic syndrome, or early cognitive decline. In this context, we induced hyperlipidemia in LDLR^-/- mice after feeding with a high-saturated fatty acid diet (HFD) for 44 weeks. LDLR^-/--HFD mice exhibited obesity, hypertriglyceridemia, higher glucose levels, and early hepatic steatosis. In addition, HFD increased plasmatic APOE and ubiquitin 60S levels. These proteins are related to neuronal integrity and health maintenance. In agreement, we detected mild cognitive dysfunctions in mice fed with HFD, whereas LDLR^-/--HFD mice showed a more severe and evident affectation. Our data suggest central nervous system dysfunction is associated with a well-established metabolic syndrome. As a late consequence, metabolic syndrome boots many behavioral and pathological alterations recognized in dementia, supporting that the control of metabolic parameters could improve cognitive preservation and prognosis.

Altered Functional Connectivity Density in Type 2 Diabetes Mellitus with and without Mild Cognitive Impairment

Although disturbed functional connectivity is known to be a factor influencing cognitive impairment, the neuropathological mechanisms underlying the cognitive impairment caused by type 2 diabetes mellitus (T2DM) remain unclear. To characterize the neural mechanisms underlying T2DM-related brain damage, we explored the altered functional architecture patterns in different cognitive states in T2DM patients. Thirty-seven T2DM patients with normal cognitive function (DMCN), 40 T2DM patients with mild cognitive impairment (MCI) (DMCI), and 40 healthy controls underwent neuropsychological assessments and resting-state functional MRI examinations. Functional connectivity density (FCD) analysis was performed, and the relationship between abnormal FCD and clinical/cognitive variables was assessed. The regions showing abnormal FCD in T2DM patients were mainly located in the temporal lobe and cerebellum, but the abnormal functional architecture was more extensive in DMCI patients. Moreover, in comparison with the DMCN group, DMCI patients showed reduced long-range FCD in the left superior temporal gyrus (STG), which was correlated with the Rey auditory verbal learning test score in all T2DM patients. Thus, DMCI patients show functional architecture abnormalities in more brain regions involved in higher-level cognitive function (executive function and auditory memory function), and the left STG may be involved in the neuropathology of auditory memory in T2DM patients. These findings provide some new insights into understanding the neural mechanisms underlying T2DM-related cognitive impairment.

"Adjust Zang and arouse spirit" electroacupuncture ameliorates cognitive impairment by reducing endoplasmic reticulum stress in db/db mice

Introduction

Diabetic cognitive impairment (DCI) is a chronic complication of the central nervous system (CNS) caused by diabetes that affects learning and memory capacities over time. Recently, acupuncture has been shown to improve cognitive impairment in streptozotocin-induced diabetic rats. However, the effects of electroacupuncture on DCI and its underlying mechanism have not yet been elucidated in detail.

Methods

In this study, we used db/db mice as DCI animal models which showed low cognitive, learning and memory functions. Electroacupuncture significantly ameliorated DCI, which is reflected by better spatial learning and memory function using behavioral tests. The db/db mice with cognitive impairment were randomly divided into a model group (Mod) and an electroacupuncture treatment group (Acup), while db/m mice were used as a normal control group (Con). First, the mice were subjected to behavioural tests using the Morris water maze (MWM), and body weight, blood glucose, insulin, triglycerides (TG) and total cholesterol (TC) were observed; HE, Nissl, and TUNEL staining were used to observe the morphological changes and neuronal apoptosis in the mice hippocampus; Finally, Western blot and rt-PCR were applied to detect the essential proteins and mRNA of ERS and insulin signalling pathway, as well as the expression levels of Tau and Aβ.

Results

Electroacupuncture significantly ameliorated DCI, which is reflected by better spatial learning and memory function using behavioral tests. Moreover, electroacupuncture attenuated diabetes-induced morphological structure change, neuronal apoptosis in the hippocampus of db/db mice. Our results revealed that electroacupuncture could regulate the expression levels of Tau and Aβ by improving hippocampal ERS levels in db/db mice, inhibiting JNK activation, attenuating IRS1 serine phosphorylation, and restoring normal transduction of the insulin signaling pathway.

Discussion

In summary, ERS and insulin signaling pathway paly causal roles in DCI development. Electroacupuncture can significantly alleviate the pathogenesis of DCI, improve mice's learning and memory ability, and improve cognitive dysfunction. This study adds to our understanding of the effect of acupuncture on DCI and opens the door to further research on DCI.

Causal Structural Covariance Network Suggesting Structural Alterations Progression in Type 2 Diabetes Patients

Background and Purpose

According to reports, type 2 diabetes (T2D) is a progressive disease. However, no known research has examined the progressive brain structural changes associated with T2D. The purpose of this study was to determine whether T2D patients exhibit progressive brain structural alterations and, if so, how the alterations progress.

Materials and Methods

Structural magnetic resonance imaging scans were collected for 81 T2D patients and 48 sex-and age-matched healthy controls (HCs). Voxel-based morphometry (VBM) and causal structural covariance network (CaSCN) analyses were applied to investigate gray matter volume (GMV) alterations and the likely chronological processes underlying them in T2D. Two sample t-tests were performed to compare group differences, and the differences were corrected using Gaussian random field (GRF) correction (voxel-level p < 0.001, cluster-level p < 0.01).

Results

Our findings demonstrated that GMV alterations progressed in T2D patients as disease duration increased. In the early stages of the disease, the right temporal pole of T2D patients had GMV atrophy. As the diseases duration prolonged, the limbic system, cerebellum, subcortical structures, parietal cortex, frontal cortex, and occipital cortex progressively exhibited GMV alterations. The patients also exhibited a GMV alterations sequence exerting from the right temporal pole to the limbic-cerebellum-striatal-cortical network areas.

Conclusion

Our results indicate that the progressive GMV alterations of T2D patients manifested a limbic-cerebellum-striatal-cortical sequence. These findings may contribute to a better understanding of the progression and an improvement of current diagnosis and intervention strategies for T2D.

Hypothyroidism and Diabetes-Related Dementia: Focused on Neuronal Dysfunction, Insulin Resistance, and Dyslipidemia

The incidence of dementia is steadily increasing worldwide. The risk factors for dementia are diverse, and include genetic background, environmental factors, sex differences, and vascular abnormalities. Among the subtypes of dementia, diabetes-related dementia is emerging as a complex type of dementia related to metabolic imbalance, due to the increase in the number of patients with metabolic syndrome and dementia worldwide. Thyroid hormones are considered metabolic regulatory hormones and affect various diseases, such as liver failure, obesity, and dementia. Thyroid dysregulation affects various cellular mechanisms and is linked to multiple disease pathologies. In particular, hypothyroidism is considered a critical cause for various neurological problems-such as metabolic disease, depressive symptoms, and dementia-in the central nervous system. Recent studies have demonstrated the relationship between hypothyroidism and brain insulin resistance and dyslipidemia, leading to diabetes-related dementia. Therefore, we reviewed the relationship between hypothyroidism and diabetes-related dementia, with a focus on major features of diabetes-related dementia such as insulin resistance, neuronal dysfunction, and dyslipidemia.

Toward the Decipherment of Molecular Interactions in the Diabetic Brain

Diabetes mellitus (DM) has been associated with cognitive complications in the brain resulting from acute and chronic metabolic disturbances happening peripherally and centrally. Numerous studies have reported on the morphological, electrophysiological, biochemical, and cognitive changes in the brains of diabetic individuals. The detailed pathophysiological mechanisms implicated in the development of the diabetic cognitive phenotype remain unclear due to intricate molecular changes evolving over time and space. This review provides an insight into recent advances in understanding molecular events in the diabetic brain, focusing on cerebral glucose and insulin uptake, insulin action in the brain, and the role of the brain in the regulation of glucose homeostasis. Fully competent mitochondria are essential for energy metabolism and proper brain function; hence, the potential contribution of mitochondria to the DM-induced impairment of the brain is also discussed.

Cerebral small vessel disease, cardiovascular risk factors, and future walking speed in old age: a population-based cohort study

Background

The purpose of this study was to examine the associations between combined and individual cerebral small vessel disease (cSVD) markers on future walking speed over 9 years; and to explore whether these associations varied by the presence of cardiovascular risk factors (CRFs).

Methods

This population-based cohort study included 331 adults, aged ≥60 years, without limitation in walking speed (≥0.8 m/s). At baseline, cSVD markers, including white matter hyperintensities (WMH), lacunes, and perivascular spaces (PVS), were assessed on magnetic resonance imaging. The modifiable CRFs (physical inactivity, heavy alcohol consumption, smoking, hypertension, high total cholesterol, diabetes, and overweight/obese) were combined into a score. The association between baseline cSVD markers and the decline in walking speed was examined using linear mixed-effects models, whereas Cox proportional hazards models were used to estimate the association with walking speed limitation (defined as < 0.8 m/s) over the follow-up.

Results

Over the follow-up period, 76 (23.0%) persons developed walking speed limitation. Participants in the highest tertile of the combined cSVD marker score had a hazard ratio (HR) of 3.78 (95% confidence interval [CI] 1.70-8.45) for walking speed limitation compared with people in the lowest score tertile, even after adjusting for socio-demographics, CRFs, cognitive function, and chronic conditions. When investigating the cSVD markers individually, having the highest burden of WMH was associated with a significantly faster decline in walking speed (β coefficient − 0.020; 95% CI -0.035-0.004) and a greater HR of walking speed limitation (HR 2.78; 95% CI 1.31-5.89) compared with having the lowest WMH burden. Similar results were obtained for the highest tertile of PVS (HR 2.13; 95% CI 1.04-4.36). Lacunes were associated with walking speed limitation, but only in men. Having ≥4 CRFs and high WMH volume simultaneously, showed a greater risk of walking speed limitation compared with having ≥4 CRFs and low WMH burden. CRFs did not modify the associations between lacunes or PVS and walking speed.

Conclusions

Combined cSVD markers strongly predict walking speed limitation in healthy older adults, independent of cognitive function, with WMH and PVS being the strongest contributors. Improving cardiovascular health may help to mitigate the negative effects of WMH on future walking speed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02529-6.

Loneliness, Not Social Support, Is Associated with Cognitive Decline and Dementia Across Two Longitudinal Population-Based Cohorts

Background:

Poor social health is likely associated with cognitive decline and risk of dementia; however, studies show inconsistent results. Additionally, few studies separate social health components or control for mental health.

Objective:

To investigate whether loneliness and social support are independently associated with cognitive decline and risk of dementia, and whether depressive symptoms confound the association.

Methods:

We included 4,514 participants from the population-based Rotterdam Study (RS; aged 71±7SD years) followed up to 14 years (median 10.8, interquartile range 7.4–11.6), and 2,112 participants from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K; aged 72±10SD years) followed up to 10 years (mean 5.9±1.6SD). At baseline, participants were free of major depression and scored on the Mini-Mental State Examination (MMSE) ≥26 for RS and ≥25 for SNAC-K. We investigated loneliness, perceived social support, and structural social support (specifically marital status and number of children). In both cohorts, dementia was diagnosed and cognitive function was repeatedly assessed with MMSE and a global cognitive factor (g-factor).

Results:

Loneliness was prospectively associated with a decline in the MMSE in both cohorts. Consistently, persons who were lonely had an increased risk of developing dementia (RS: HR 1.34, 95%CI 1.08–1.67; SNAC-K: HR 2.16, 95%CI 1.12–4.17). Adjustment for depressive symptoms and exclusion of the first 5 years of follow-up did not alter results. Neither perceived or structural social support was associated with cognitive decline or dementia risk.

Conclusion:

Loneliness, not social support, predicted cognitive decline and incident dementia independently of depressive symptoms.

The Relationship Between Cardiovascular Health and Rate of Cognitive Decline in Young-Old and Old-Old Adults: A Population-Based Study

Background:

Modifiable vascular risk factors have been associated with late-life cognitive impairment. The Life Simple 7 (LS7) score comprises seven cardiovascular health metrics: smoking, diet, physical activity, body mass index, plasma glucose, total serum cholesterol, and blood pressure.

Objective:

To investigate the association between individual and composite LS7 metrics and rate of cognitive decline, and potential differences in these associations between young-old and old-old individuals.

Methods:

This cohort study included 1,950 participants aged≥60 years (M = 70.7 years) from the Swedish National Study on Aging and Care-Kungsholmen (SNAC-K), who underwent repeated neuropsychological testing (episodic and semantic memory, verbal fluency, processing speed, global cognition) across 12 years. The LS7 score was assessed at baseline and categorized as poor, intermediate, or optimal. Level and change in cognitive performance as a function of LS7 categories were estimated using linear mixed-effects models.

Results:

Having an optimal LS7 total score was associated with better performance (expressed in standard deviation units) at baseline for perceptual speed (β= 0.21, 95%CI 0.12–0.29), verbal fluency (β= 0.08, 0.00–0.16), and global cognition (β= 0.06, 0.00–0.12) compared to the poor group. Age-stratified analyses revealed associations for cognitive level and change only in the young-old (< 78 years) group. For the specific metrics, diverging patterns were observed for young-old and old-old individuals.

Conclusion:

Meeting the LS7 criteria for ideal cardiovascular health in younger old age is associated with slower rate of cognitive decline. However, the LS7 criteria may have a different meaning for cognitive function in very old adults.

Classification of type 2 diabetes mellitus with or without cognitive impairment from healthy controls using high-order functional connectivity

Type 2 diabetes mellitus (T2DM) is associated with cognitive impairment and may progress to dementia. However, the brain functional mechanism of T2DM-related dementia is still less understood. Recent resting-state functional magnetic resonance imaging functional connectivity (FC) studies have proved its potential value in the study of T2DM with cognitive impairment (T2DM-CI). However, they mainly used a mass-univariate statistical analysis that was not suitable to reveal the altered FC "pattern" in T2DM-CI, due to lower sensitivity. In this study, we proposed to use high-order FC to reveal the abnormal connectomics pattern in T2DM-CI with a multivariate, machine learning-based strategy. We also investigated whether such patterns were different between T2DM-CI and T2DM without cognitive impairment (T2DM-noCI) to better understand T2DM-induced cognitive impairment, on 23 T2DM-CI and 27 T2DM-noCI patients, as well as 50 healthy controls (HCs). We first built the large-scale high-order brain networks based on temporal synchronization of the dynamic FC time series among multiple brain region pairs and then used this information to classify the T2DM-CI (as well as T2DM-noCI) from the matched HC based on support vector machine. Our model achieved an accuracy of 79.17% in T2DM-CI versus HC differentiation, but only 59.62% in T2DM-noCI versus HC classification. We found abnormal high-order FC patterns in T2DM-CI compared to HC, which was different from that in T2DM-noCI. Our study indicates that there could be widespread connectivity alterations underlying the T2DM-induced cognitive impairment. The results help to better understand the changes in the central neural system due to T2DM.

The Gaze Fixation Assessed by Microperimetry: A Useful Tool for the Monitoring of the Cognitive Function in Patients with Type 2 Diabetes

Current guidelines recommend annual screening for cognitive impairment in patients > 65 years with type 2 diabetes (T2D). The most used tool is the mini-mental state evaluation (MMSE). Retinal microperimetry is useful for detecting cognitive impairment in these patients, but there is no information regarding its usefulness as a monitoring tool. We aimed to explore the role of retinal microperimetry in the annual follow-up of the cognitive function of patients with T2D older than 65 years. Materials and Methods: Prospective observational study, comprising patients > 65 years with T2D, attended at our center between March–October 2019. A complete neuropsychological evaluation assessed the baseline cognitive status (mild cognitive impairment, MCI, or normal, NC). Retinal microperimetry (sensitivity, gaze fixation) and MMSE were performed at baseline and after 12 months. Results: Fifty-nine patients with MCI and 22 NC were identified. A significant decline in the MMSE score was observed after 12 months in the MCI group (25.74 ± 0.9 vs. 24.71 ± 1.4; p = 0.001). While no significant changes in retinal sensitivity were seen, all gaze-fixation parameters worsened at 12 months and significantly correlated with a decrease in the MMSE scores. Conclusion: Retinal microperimetry is useful for the monitoring of cognitive decline in patients > 65 years with T2D. Gaze fixation seems a more sensitive parameter for follow-up after 12 months than retinal sensitivity.

Metabolic syndrome is associated with poor cognition: a population-based study of 70-year-olds without dementia

Background

Individual conditions of metabolic syndrome (MetS) have been related to dementia; however, their combined impact on the preclinical stage is unknown. We investigated the associations between MetS and domain-specific cognitive function as well as the role of sociodemographic, cardiovascular, and genetic factors.

Methods

Within the Gothenburg H70 Birth Cohort Study-Birth cohort 1944, 1131 dementia-free participants (aged 70 years) were examined during 2014–2016. MetS (central obesity plus at least 2 factors [reduced HDL-cholesterol, elevated triglycerides, blood pressure, or blood glucose]) was identified according to the International Diabetes Federation criteria. Five cognitive domains (memory, attention/perceptual speed, executive function, verbal fluency, visuospatial abilities) were generated after z-standardizing raw scores from 10 neuropsychological tests. Education, heart disease, claudication (indicating peripheral atherosclerosis), and apolipoprotein genotype were ascertained by trained staff. Data were analyzed with linear regression models.

Results

Overall, 618 participants (55%) had MetS. In multiadjusted linear regressions, MetS was related to poorer performance in attention/perceptual speed (β −0.14 [95% CI −0.25, −0.02]), executive function (β −0.12 [95% CI −0.23, −0.01]), and verbal fluency (β −0.19 [95% CI −0.30, −0.08]). These associations were present only among individuals who did not carry any APOE-ε4 allele or were highly educated. However, among those with MetS, high education was related to better cognitive performance. MetS together with comorbid heart disease or claudication was associated with even worse cognitive performance than each alone.

Conclusions

MetS is associated with poor attention/perceptual speed, executive function, and verbal fluency performance. Education, apolipoprotein E-ε4 allele, and comorbid cardiovascular disease influenced the observed associations.

Diabetic patients are deficient in intentional visuospatial learning and show different learning-related patterns of theta and gamma EEG activity

Introduction: We hypothesized that diabetic patients without mild cognitive impairment would present deficiencies in visuospatial incidental/intentional memory processing and alterations in the underlying EEG alpha, theta and gamma patterns.Methods: Non-diabetic, diabetic-controlled, and diabetic-uncontrolled patients underwent a visuospatial incidental-intentional memory test under simultaneous recording of temporal, parietal, and frontal EEG. The test required patients to solve a maze, with eight objects irrelevant to the task, embedded in it, after an interference instruction, participants were asked to recall the positions of the objects (incidental test). Finally, the participants were explicitly told to study the object positions, and then were asked to recall the objects again (intentional test). Power from baseline, incidental learning, incidental memory, and intentional learning conditions was obtained in alpha, theta, and low-gamma bands. Comparisons were made across groups and conditions for each band, with age, sex, and years from the diagnosis as covariates (ANCOVA with blocking).Results: Diabetic patients showed spared incidental but deficient intentional visuospatial learning. Uncontrolled patients showed a more profound intentional learning deficit as they scored similar numbers of correct positions under incidental and intentional conditions; whereas, non-diabetic and diabetic-controlled patients increased their number after the intentional study. Non-diabetic participants showed increased power during intentional learning compared with the baseline condition in frontal theta, frontoparietal gamma (Fp2 and P4) and frontal alpha (F4) bands; whereas in diabetic patients the power increased in the theta band, in T5 (uncontrolled) and T5 and F7 (controlled).Conclusions: Diabetic patients without mild cognitive impairment show deficient intentional visuospatial learning which was worse in uncontrolled patients. Theta and gamma power increased in healthy participants during intentional learning principally in frontal areas. These EEG power changes were absent in diabetic patients. The reduced accuracy of diabetic patients in intentional visuospatial learning was associated with different EEG learning-related patterns.

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.

Feasibility of a 26-Week Exercise Program to Improve Brain Health in Older Adults at Risk for Type 2 Diabetes: A Pilot Study

OBJECTIVES

Older adults at risk for type 2 diabetes (i.e. overweight individuals or those with prediabetes) experience accelerated cognitive and brain deficits. Aerobic training is known to improve these deficits, but the effects of resistance training are relatively unknown. Before conducting a large-scale, randomized, controlled trial to assess the effects of resistance training, we first conducted a pilot feasibility study to examine recruitment, attendance and retention rates in this population.

METHODS

Program participants (aged 60 to 80 years, mean age 68.7±5.7 years, 50% females) at risk for type 2 diabetes (body mass index of ≥25 or fasting blood glucose of 6.1 to <7 mmol/L) underwent 26 weeks of thrice-weekly progressive resistance training (n=13) or balance-and-tone exercises (control group, n=11). Recruitment, attendance and retention rates were recorded, and study feedback from program participants and research assistants was collected via questionnaires.

RESULTS

We recruited 72 older adults (total number enrolled = 24) over 17 months. Program retention and attendance were 95.8% and 84.4%, respectively. Program participants and research assistants expressed a high level of study enjoyment, and suggestions on how to improve study procedures were provided.

CONCLUSIONS

Based on our findings, a large-scale study in this at-risk group of older adults is feasible, and key strategies to improving future trials were identified.

The Relation of Diabetes to Memory Function

PURPOSE OF REVIEW

Research has consistently shown that type 2 diabetes (T2D) is associated with increased risk of all-cause dementia. Because one of the most common clinical presentations of early stage dementia is memory impairment, we examined the relationship of T2D with memory function, using the recently published scientific literature.

RECENT FINDINGS

We conducted a structured review to identify studies of "T2D and memory" published since 2015. After review of the 129 articles retrieved, we identified 14 studies meeting the inclusion and exclusion criteria. Among the eight studies with a single assessment of memory function in time (mostly cross-sectional), six found an association of T2D with lower memory function, but mostly in select subgroups of persons. Separately, six studies included repeated measures of memory (longitudinal design). Four out of six longitudinal studies found that T2D was related with a faster decline in memory, while two did not. Among the four studies showing a relation with memory decline, two had sample sizes of 9000-10,000 persons. Further, three longitudinal studies controlled for hypertension and stroke as covariates, and results suggested that common vascular risk factors and diseases do not account for the relation. While mechanistic studies clearly support a role for cerebrovascular disease in the relation of T2D with cognition, emerging data suggest that insulin resistance in the brain itself may also play a role. Most, but not all, recently published studies suggest that T2D is associated with a lower level and faster decline in memory function. This association does not appear to be fully accounted for by common vascular processes. More research will clarify the mechanisms linking T2D to memory and dementia.

Validation and psychometric properties of the self-efficacy for Appropriate Medication Use Scale in elderly Chinese patients

Background Self-efficacy for appropriate medication use is an important construct when evaluating the optimal use of medications. However, no instrument that assesses this construct in elderly Chinese patients has been shown to have valid psychometric properties. Objective To investigate the psychometric properties of the Chinese version of the self-efficacy for Appropriate Medication Use Scale in elderly patients with type 2 diabetes. Setting Geriatric patients were recruited from the endocrinology department of a tertiary hospital in Shanghai, China. Method Self-efficacy was assessed by the Chinese version of the Self-Efficacy for Appropriate Medication Use Scale in subjects who were at least 65 years old. Exploratory and confirmatory factor analyses were used to develop a psychometrically sound model of the scale. Main outcome measures Internal and test-retest reliability; convergent and discriminant validity of the scale; model fit indices of the factor model. Results The two-factor model of the self-efficacy for Appropriate Medication Use Scale was not suitable for elderly patients with respect to both item factor loadings and model fit indices. Conceptually overlapping scale items emerged when the scale was used in these patients. The final model developed appeared to achieve an ideal model fit and presented acceptable convergent and discriminant validity. Conclusions This study presented a Chinese version of the self-efficacy for Appropriate Medication Use Scale with psychometrically sound properties that will enable pharmacists, nurses and physicians to prospectively evaluate the impact of medication self-efficacy on a variety of health outcomes in elderly patients with type 2 diabetes.

Targeting cognitive function: Development of a cognitive training intervention for diabetes

AIM

The aim of this project was to develop and demonstrate the feasibility of a comprehensive cognitive training intervention to build self-efficacy for implementation of cognitive strategies in people with diabetes.

BACKGROUND

People with diabetes are at greater risk than the general population for developing cognitive dysfunction. Some attention has been paid to the effect of cognitive impairments on diabetes self-management, but even when cognitive problems have been identified, few interventions have been tailored for those with diabetes.

METHODS

The intervention combines in-person classes and home-based online computer training. Development, in 2017, included (a) adaptation of prior established, tested interventions; (b) interviews with stakeholders; and (c) integration of course content.

RESULTS

Information provided by the stakeholders was used to modify an existing intervention to meet the needs of people with diabetes so that feasibility testing could occur. Despite initial difficulty with recruitment, the intervention was found to be feasible, and nineteen participants found it to be acceptable.

CONCLUSION

This comprehensive cognitive training intervention targeting type 2 diabetes and cognitive dysfunction demonstrates that existing interventions can be adapted for use with people with diabetes.

The relation of poor mastication with cognition and dementia risk: a population-based longitudinal study

We investigated the effect of poor masticatory ability on cognitive trajectories and dementia risk in older adults. 544 cognitively intact adults aged ≥50 were followed for up to 22 years. Cognitive domains (verbal, spatial/fluid, memory, and perceptual speed) were assessed at baseline and follow-ups. Dementia was ascertained according to standard criteria. Masticatory ability was assessed using the Eichner Index and categorized according to the number of posterior occlusal zones: A (all four), B (3-1), and C (none).

At baseline, 147 (27.0%) participants were in Eichner category A, 169 (31.1%) in B and 228 (41.9%) in C. After the age of 65, participants in Eichner category B and C showed an accelerated decline in spatial/fluid abilities (β: -0.16, 95% CI: -0.30 to -0.03) and (β: -0.15, 95% CI: -0.28 to -0.02), respectively. Over the follow-up, 52 incident dementia cases were identified. Eichner categories B or C were not associated with an increased risk of dementia, compared to category A (Hazard Ratio [HR]: 0.83, 95% CI: 0.39 to 1.76 and HR: 0.63, 95% CI: 0.30 to 1.29, respectively).

Poor masticatory ability is associated with an accelerated cognitive decline in fluid/spatial abilities, however it was not related to a higher risk of dementia.

Interaction between APOE genotype and diabetes in cognitive decline

INTRODUCTION

Although diabetes and apolipoprotein E (apoE) are both significant risk factors for dementia, including Alzheimer's disease, it remains to be clarified how they are related to each other in contributing to the risk of dementia.

METHODS

By reviewing the National Alzheimer's Coordinating Center (NACC) clinical records, we investigated whether diabetes affects cognitive decline depending on APOE genotype and their potential relationships with neuropathology.

RESULTS

A significant interaction between diabetes and APOE genotype exists, where diabetes affected cognitive decline in APOE3 carriers and APOE2 carriers, but not APOE4 carriers. Moreover, the presence of vascular pathology was increased by diabetes in APOE3 carriers, while APOE4 carriers nearly reached plateau levels irrespective of diabetes.

DISCUSSION

Diabetes accelerates cognitive decline, in part, through accelerating vascular impairment in non-APOE ε4 carriers, but such effects are negligible in APOE4 carriers, who themselves are already vulnerable to vascular impairment.

Leisure activity and social integration mitigate the risk of dementia related to cardiometabolic diseases: A population-based longitudinal study

INTRODUCTION

The effect of comorbid cardiometabolic diseases (CMDs), including diabetes, heart diseases, and stroke, on dementia remains unclear.

METHODS

A cohort of 2648 dementia-free adults aged ≥60 years was followed up for 12 years. An active lifestyle was defined in accordance with the engagement in leisure activities and/or a social network. Cox models were used in data analysis.

RESULTS

The multiadjusted hazard ratio (HR, 95% confidence interval) of dementia was 1.41 (1.07-1.86) for one, 2.38 (1.58-3.59) for two, and 4.76 (2.04-11.13) for three CMDs. In joint exposure analysis, the HR of dementia was 3.36 (2.14-5.30) for participants with CMDs plus an inactive lifestyle and 1.32 (0.95-1.84) for those with CMDs plus an active lifestyle (reference: no CMDs plus active lifestyle). An active lifestyle delayed dementia onset by 3.50 years in people with CMDs.

DISCUSSION

CMDs, especially when comorbid, are associated with increased dementia risk; however, leisure activities and social integration mitigate this risk.

Cognitive, Genetic, Brain Volume, and Diffusion Tensor Imaging Markers as Early Indicators of Dementia

BACKGROUND

Although associated with dementia and cognitive impairment, microstructural white matter integrity is a rarely used marker of preclinical dementia.

OBJECTIVE

We aimed to evaluate the individual and combined effects of multiple markers, with special focus on microstructural white matter integrity, in detecting individuals with increased dementia risk.

METHODS

A dementia-free subsample (n = 212, mean age = 71.33 years) included in the population-based Swedish National Study on Aging and Care (SNAC-K) underwent magnetic resonance imaging (T1-weighted, fluid-attenuated inversion recovery, diffusion tensor imaging), neuropsychological testing (perceptual speed, episodic memory, semantic memory, letter and category fluency), and genotyping (APOE). Incident dementia was assessed during six years of follow-up.

RESULTS

A global model (global cognition, APOE, total brain tissue volume: AUC = 0.920) rendered the highest predictive value for future dementia. Of the models based on specific markers, white matter integrity of the forceps major tract was included in the most predictive model, in combination with perceptual speed and hippocampal volume (AUC = 0.911).

CONCLUSION

Assessment of microstructural white matter integrity may improve the early detection of dementia, although the added benefit in this study was relatively small.

EEG spectral power abnormalities and their relationship with cognitive dysfunction in patients with Alzheimer's disease and type 2 diabetes

Rhythmic neural activity has been proposed to play a fundamental role in cognition. Both healthy and pathological aging are characterized by frequency-specific changes in oscillatory activity. However, the cognitive relevance of these changes across the spectrum from normal to pathological aging remains unknown. We examined electroencephalography (EEG) correlates of cognitive function in healthy aging and 2 of the most prominent and debilitating age-related disorders: type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD). Relative to healthy controls (HC), patients with AD were impaired on nearly every cognitive measure, whereas patients with T2DM performed worse mainly on learning and memory tests. A continuum of alterations in resting-state EEG was associated with pathological aging, generally characterized by reduced alpha (α) and beta (β) power (AD < T2DM < HC) and increased delta (δ) and theta (θ) power (AD > T2DM > HC), with some variations across different brain regions. There were also reductions in the frequency and power density of the posterior dominant rhythm in AD. The ratio of (α + β)/(δ + θ) was specifically associated with cognitive function in a domain- and diagnosis-specific manner. The results thus captured both similarities and differences in the pathophysiology of cerebral oscillations in T2DM and AD. Overall, pathological brain aging is marked by a shift in oscillatory power from higher to lower frequencies, which can be captured by a single cognitively relevant measure of the ratio of (α + β) over (δ + θ) power.

Retinal Microperimetry: A Useful Tool for Detecting Insulin Resistance-Related Cognitive Impairment in Morbid Obesity

Background: There is clear association between type 2 diabetes (T2D) and cognitive decline. Retinal microperimetry is a useful tool for detecting cognitive impairment in T2D. Morbid obesity (MO) has been associated with cognitive impairment. Insulin resistance (IR) seems a major determinant, but the data are unclear. The aim of this study was to evaluate the cognitive impairment in MO as well as the utility of retinal microperimetry in identifying these alterations. Methods: In total, 50 consecutive patients with MO were matched by age and gender with 30 healthy controls. All patients underwent cognitive evaluation (Montreal Cognitive Assessment Test-MoCA) and retinal microperimetry, using MAIA microperimeter 3rd generation. Retinal sensitivity and gaze fixation parameters were used for the evaluation of the analysis. Results: MO patients showed a significantly lower neurocognitive performance than the controls: MoCA score 24.94 ± 2.74 vs. 28.95 ± 1.05, p < 0.001. Cognitive function inversely correlated with the HOMA-IR (r = −0.402, p = 0.007). The AUROC for cognitive impairment using microperimetry was 0.807, CI 95% (0.592–0.947), p = 0.017. Conclusions: (1) Systemic insulin resistance is a major underlying mechanism accounting for the higher prevalence of cognitive impairment detected in young MO subjects. (2) Retinal microperimetry is a useful tool for identifying MO patients with cognitive impairment.

Feasibility of a 6-month pilot randomised controlled trial of resistance training on cognition and brain health in Canadian older adults at-risk for diabetes: study protocol

INTRODUCTION

Type 2 diabetes (T2D) is associated with cognitive deficits and increased risk of dementia, and thus individuals at high risk for T2D (ie, those who are overweight or prediabetic) are also at greater risk for cognitive decline. Aerobic exercise is known to preserve and improve cognitive function, but the effects of resistance training (RT) are much less known in older adults. Moreover, research on the effects of RT on cognition and brain health (structure and function) in older adults at-risk for diabetes is limited. To address this question, a 6-month RT intervention is needed. Importantly, before conducting a full-scale randomised controlled trial (RCT), we are conducting a feasibility pilot study to assess potential recruitment rates, adherence and retention in this specific population.

METHODS AND ANALYSIS

We are conducting a 6-month, thrice-weekly RT RCT. Participants (aged 60-80; sedentary; fasting plasma glucose of 6.1-7.0 mmol/L or body mass index ≥25) are randomised into one of two groups: (1) RT or (2) balance and tone (control). Based on other exercise trials using a similar population, we will consider our trial feasible if we have adherence and retention at 70%. Recruitment rate will be measured as time it takes to enrol 20 participants. To assess behavioural and MRI data, we will report descriptive statistics and estimation using a 95% CI.

ETHICS AND DISSEMINATION

Our study has received ethics approval from the Health Sciences Research Ethics Board at Western University. As this is a small pilot study, data will only be made available to other researchers on request. Results from this study will be disseminated via academic publication.

TRIAL REGISTRATION NUMBER

NCT03254381.

Factors Associated with Cognitive and Functional Performance in Indigenous Older Adults of Nariño, Colombia

INTRODUCTION

Ethnicity in Latin America is a factor of poverty and social exclusion. Like in developed countries, demographic, medical, psychosocial, global cognitive, and functional variables interact in a complex relationship on the elderly population. Such interaction should be considered to determine cognitive and functional performance using screening tests. The aim of this study was to evaluate the demographic, medical, and psychosocial factors affecting global cognitive performance as well as functional activities.

METHODS

The study was conducted in a Colombian elderly indigenous population which included a sample of 518 adults. This research employed a structural model of latent factors to assess the effects of demographic, medical, and psychosocial factors on cognitive and functional performance. The model was estimated by least squares and used a maximum-likelihood procedure, and it was determined RMSEA, TLI, and CFI to assess the model's goodness of fit. The categorical variables used in the model were as follows: (1) demographics, (2) psychosocial factors, (3) medical condition, (4) global cognition, and (5) functional factors.

RESULTS

Demographics, in addition to medical and psychosocial factors, were related to global cognition and functional factors (RMSEA = 0.051, CI 90% 0.045-0.057, CFI = 0.901, and TLI = 0.881).

CONCLUSION

These results provide strong evidence about the complex relationships among demographics, medical conditions, and psychosocial factors and their influence on global cognition and functional performance in Colombian indigenous elderly population.

Insulin resistance: Genetic associations with depression and cognition in population based cohorts

Insulin resistance, broadly defined as the reduced ability of insulin to exert its biological action, has been associated with depression and cognitive dysfunction in observational studies. However, it is unclear whether these associations are causal and whether they might be underpinned by other shared factors. To address this knowledge gap, we capitalized on the stability of genetic biomarkers through the lifetime, and on their unidirectional relationship with depression and cognition. Specifically, we determined the association between quantitative measures of cognitive function and depression and genetic instruments of insulin resistance traits in two large-scale population samples, the Generation Scotland: Scottish Family Health Study (GS: SFHS; N = 19,994) and in the UK Biobank (N = 331,374). In the GS:SFHS, the polygenic risk score (PRS) for fasting insulin was associated with verbal intelligence and depression while the PRS for the homeostasis model assessment of insulin resistance was associated with verbal intelligence. Despite this overlap in genetic architecture, Mendelian randomization analyses in the GS:SFHS and in the UK Biobank samples did not yield evidence for causal associations from insulin resistance traits to either depression or cognition. These findings may be due to weak genetic instruments, limited cognitive measures and insufficient power but they may also indicate the need to identify other biological mechanisms that may mediate the relationship from insulin resistance to depression and cognition.

Participating in Mental, Social, and Physical Leisure Activities and Having a Rich Social Network Reduce the Incidence of Diabetes-Related Dementia in a Cohort of Swedish Older Adults

OBJECTIVE

The effect of a healthy lifestyle on diabetes-related dementia remains unknown. We examined whether an active lifestyle and rich social network may counteract the increased risk of dementia in people with diabetes.

RESEARCH DESIGN AND METHODS

Dementia-free older adults from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K) (n = 2,650) were followed up for 10 years. Diabetes was ascertained on the basis of medical history, medication use, medical records, or glycated hemoglobin (HbA_1c) ≥6.5% and prediabetes as HbA_1c between 5.7 and 6.5%. Dementia was diagnosed by specialists following standard criteria. An active lifestyle was defined as a moderate to high (vs. low) level of engagement in leisure activities or a rich social network (having moderate to rich [vs. poor] social connections and support). Hazard ratios (HRs) of dementia risk were derived from Cox regression models.

RESULTS

There were 246 incident dementia cases during follow-up. Those with diabetes (n = 243), but not those with prediabetes (n = 921), had greater risk of dementia (adjusted HR 2.0 [95% CI 1.4-2.9]) than diabetes-free participants. Participants with diabetes but low level of engagement in leisure activities (HR 4.2 [95% CI 2.2-8.2]) or a poor social network (HR 3.4 [95% CI 1.9-6.1]) had greater dementia risk than diabetes-free participants with moderate to high levels of leisure activity engagement or a moderate to rich social network. In participants with diabetes, an active lifestyle (high level of engagement in leisure activities or a rich social network) was associated with less of a raised risk (HR 1.9 [95% CI 1.1-3.4]).

CONCLUSIONS

An active and socially integrated lifestyle may significantly counteract the detrimental effect of diabetes on dementia risk.

Usefulness of Eye Fixation Assessment for Identifying Type 2 Diabetic Subjects at Risk of Dementia

Type 2 diabetic (T2D) subjects have a significantly higher risk of developing mild cognitive impairment (MCI) and dementia than age-matched non-diabetic individuals. However, the accurate evaluation of cognitive status is based on complex neuropsychological tests, which makes their incorporation into the current standard of care for the T2D population infeasible. Given that the ability to maintain visual gaze on a single location (fixation) is hampered in Alzheimer’s disease (AD), the aim of the present study was: (1) To assess whether the evaluation of gaze fixation during fundus-driven microperimetry correlated with cognitive status in T2D subjects; (2) to examine whether the addition of fixational parameters to the assessment of retinal sensitivity increased the predictive value of retinal microperimetry in identifying T2D subjects with MCI. For this purpose, fixation parameters and retinal sensitivity were compared in three age-matched groups of T2D subjects: normocognitive (n = 34), MCI (n = 33), and AD (n = 33). Our results showed that fixation is significantly more unstable in MCI subjects than normocognitive subjects, and even more altered in those affected by AD (ANOVA; p < 0.01). Moreover, adding fixation parameters to retinal sensitivity significantly increases the predictive value in identifying those subjects with MCI: ROC (Receiver Operating Characteristic) Area 0.68 with retinal sensitivity alone vs. ROC Area 0.86 when parameters of fixation are added to retinal sensitivity (p < 0.01). In conclusion, our results suggest that fixational eye movement parameters assessed by fundus-microperimetry represent a new tool for identifying T2D subjects at risk of dementia.

Cardiovascular Risk Factors and the Risk of Disability in Older Adults: Variation by Age and Functional Status

OBJECTIVES

We aimed to quantify the increased risk of disability associated with cardiovascular risk factors among older adults, and to verify whether this risk may vary by age and functional status.

DESIGN

Longitudinal population-based cohort study.

SETTING

Urban area of Stockholm, Sweden.

PARTICIPANTS

Community-dwelling and institutionalized adults ≥60 years in the Swedish National study on Aging and Care in Kungsholmen free of cardiovascular diseases and disability (n = 1756) at baseline (2001-2004).

MEASURES

Incident disability in activities of daily living (ADL) was ascertained over 9 years. Cardiovascular risk factors (physical inactivity, alcohol consumption, smoking, high blood pressure, diabetes, high body mass index, high levels of total cholesterol, and high C-reactive protein) and walking speed were assessed at baseline. Data were analyzed using Cox proportional hazards models, stratifying by younger-old (age 60-72 years) and older-old (≥78 years).

RESULTS

During the follow-up, 23 and 148 persons developed ADL-disability among the younger- and older-old, respectively. In the younger-old, the adjusted hazard ratio (HR) of developing ADL-disability was 4.10 (95% confidence interval [CI] 1.22-13.76) for physical inactivity and 5.61 (95% CI 1.17-26.82) for diabetes. In the older-old, physical inactivity was associated with incident ADL-disability (HR 1.99, 95% CI 1.36-2.93), and there was a significant interaction between physical inactivity and walking speed limitation (<0.8 m/s), showing a 6-fold higher risk of ADL-disability in those who were both physically inactive and had walking speed limitation than being active with no limitation, accounting for a population-attributable risk of 42.7%.

CONCLUSIONS/IMPLICATIONS

Interventions targeting cardiovascular risk factors may be more important for the younger-old in decreasing the risk of disability, whereas improving physical function and maintaining physical activity may be more beneficial for the older-old.

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

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

Midlife Metabolic Profile and the Risk of Late-Life Cognitive Decline

Among metabolic syndrome components, the effects of higher plasma glucose levels on cognitive decline (CD) have been considered in few studies. We evaluated the associations among midlife glycemia, total cholesterol, high-density lipoprotein cholesterol, triglycerides, midlife insulin resistance [homeostasis model assessment for insulin resistance (HOMA-index)], and CD in the older subjects of the population-based MICOL Study (Castellana Grotte, Italy) at baseline (M1) and at follow-ups seven (M2) and twenty years later (M3). At M1, a dementia risk score and a composite cardiovascular risk score for dementia were calculated. For 797 subjects out of 833, we obtained a Mini-Mental State Examination (MMSE) score at M3, subdividing these subjects in three cognitive functioning subgroups: normal cognition, mild CD, and moderate-severe CD. Mean fasting glycemia at baseline was significantly higher in moderate-severe CD subgroup (114.6±71.4 mg/dl) than in the normal cognition subgroup (101.2±20.6). Adjusting for gender, age, and other metabolic components, higher fasting glycemia values both at M1 [odds ratio (OR) = 1.31; 95% confidence interval (CI): 1.08-1.59] and M2 (OR = 1.26; 95% CI: 1.01-1.57) were associated with an increased risk of moderate-severe CD. Mean HOMA index value was significantly higher in the moderate-severe CD subgroup (5.7±9.4) compared to the normal cognition subgroup (2.9±1.4) at M1. The dementia risk probability (MMSE < 24) increased moving through higher categories of the dementia risk score and decreased as long as the cardiovascular score increased. The present findings highlighted the indication to control blood glucose levels, regardless of a diagnosis of diabetes mellitus, as early as midlife for prevention of late-life dementia.

Cognitive Trajectories of Older Adults With Prediabetes and Diabetes: A Population-Based Cohort Study

Background

Diabetes has been linked to dementia risk; however, the cognitive trajectories in older adults with diabetes remain unclear. We aimed to investigate the effect of prediabetes and diabetes on cognitive trajectories among cognitively intact older adults in a long-term follow-up study.

Methods

Within the Swedish Adoption/Twin Study of Aging, 793 cognitively intact older adults aged ≥50 were identified at baseline and followed for up to 23 years. Based on standardized scores from 11 cognitive tests, administered at baseline and up to seven follow-ups, four cognitive domains (verbal abilities, spatial/fluid, memory, perceptual speed) were identified by principal-component analysis. Prediabetes was defined according to blood glucose levels in diabetes-free participants. Diabetes was ascertained based on self-report, hypoglycemic medication use and blood glucose levels. Data were analyzed with linear mixed-effect models adjusting for potential confounders.

Results

At baseline, 68 participants (8.6%) had prediabetes and 45 (5.7%) had diabetes. Compared to diabetes-free individuals, people with diabetes had a steeper decline over time in perceptual speed and verbal abilities. The annual declines in these domains were greater than the annual decline in memory. Prediabetes was associated with lower performance in memory in middle-age, but also associated with a less steep memory decline over the follow-up.

Conclusions

Diabetes is associated with a faster decline in perceptual speed and verbal abilities, while prediabetes is associated with lower memory performance in middle-age. However, the detrimental effects of hyperglycemia seem to not affect memory over time.

Retinal Microperimetry: A New Tool for Identifying Patients With Type 2 Diabetes at Risk for Developing Alzheimer Disease

Type 2 diabetes is associated with a high risk of cognitive impairment and dementia. Therefore, strategies are needed to identify patients who are at risk for dementia. Given that the retina is a brain-derived tissue, it may provide a noninvasive way to examine brain pathology. The aims of this study were to evaluate whether retinal sensitivity 1) correlates with the specific parameters of brain imaging related to cognitive impairment and 2) discriminates patients with diabetes with mild cognitive impairment (MCI) from those with normal cognition and those with Alzheimer disease (AD). For this purpose, a prospective, nested case-control study was performed and included 35 patients with type 2 diabetes without cognitive impairment, 35 with MCI, and 35 with AD. Retinal sensitivity was assessed by Macular Integrity Assessment microperimetry, and a neuropsychological evaluation was performed. Brain neurodegeneration was assessed by MRI and fludeoxyglucose-18 positron emission tomography (¹⁸FDG-PET). A significant correlation was found between retinal sensitivity and the MRI and ¹⁸FDG-PET parameters related to brain neurodegeneration. Retinal sensitivity was related to cognitive status (normocognitive > MCI > AD; P < 0.0001). Our results suggest that retinal sensitivity assessed by microperimetry is related to brain neurodegeneration and could be a useful biomarker for identifying patients with type 2 diabetes who are at risk for developing AD.

Cardiovascular Risk Burden and Future Risk of Walking Speed Limitation in Older Adults

OBJECTIVES

To explore the association between cardiovascular risk factor (CRF) burden and limitation in walking speed, balance, and chair stand and to verify whether these associations vary according to age and cognitive status.

DESIGN

Longitudinal population-based study.

SETTING

Urban area of Stockholm, Sweden.

PARTICIPANTS

Individuals aged 60 and older who participated in the Swedish National Study on Aging and Care in Kungsholmen and were free of limitations in walking speed (n = 1,441), balance (n = 1,154), or chair stands (n = 1,496) at baseline (2001-04).

MEASUREMENTS

At baseline, data on demographic characteristics, CRFs, other lifestyle factors, C-reactive protein, and cognitive function were collected. CRF burden was measured using the Framingham general cardiovascular risk score (FRS). Limitations in walking speed (<0.8 m/s), balance (<5 seconds), and chair stand (inability to rise 5 times) were determined at 3-, 6-, and 9-year follow-up. Data were analyzed using Cox proportional hazards models stratified according to age (<78, ≥78).

RESULTS

During follow-up, 326 persons developed limitations in walking speed, 303 in balance, and 374 in chair stands. An association between the FRS and walking speed limitation was evident only in adults younger than 78 (for each 1-point increase in FRS: hazard ratio (HR) = 1.09, 95% confidence interval (CI) = 1.02-1.17) after controlling for potential confounders including cognitive function (correspondingly, in adults aged ≥78: HR = 0.98, 95% CI = 0.92-1.03). Also, higher FRS was significantly associated with faster decline in walking speed (P < .001).

CONCLUSION

A higher FRS is associated with greater risk of subsequent development of walking speed limitation in adults younger than 78, independent of cognitive function. Interventions targeting multiple CRFs in younger-old people may help in maintaining mobility function.

Association of plasma ghrelin levels and ghrelin rs4684677 polymorphism with mild cognitive impairment in type 2 diabetic patients

BACKGROUND AND AIMS

People with insulin resistance and type 2 diabetes mellitus (T2DM) are at increased risks of cognitive impairment. We aimed to investigate the association of plasma ghrelin levels and ghrelin rs4684677 polymorphism with mild cognitive impairment (MCI) in T2DM patients.

RESULTS

In addition to elevated glycosylated hemoglobin (HbA1c), fasting blood glucose (FBG) and homeostasis model assessment of insulin resistance (HOMA-IR), T2DM patients with MCI had decreased plasma ghrelin levels compared with their healthy-cognition subjects (all p < 0.05). Further logistic regression analysis showed that ghrelin level was one of independent factors for MCI in T2DM patients (p < 0.05). Moreover, partial correlation analysis demonstrated that ghrelin levels were positively associated with the scores of Montreal Cognitive Assessment (r = 0.196, p = 0.041) and Auditory Verbal Learning Test-delayed recall (r = 0.197, p = 0.040) after adjustment for HbA1c, FBG and HOMA-IR, wherein the latter represented episodic memory functions. No significant differences were found for the distributions of genotype and allele of ghrelin rs4684677 polymorphism between MCI and control group.

MATERIALS AND METHODS

A total of 218 T2DM patients, with 112 patients who satisfied the MCI diagnostic criteria and 106 who exhibited healthy cognition, were enrolled in this study. Demographic characteristics, clinical variables and cognitive performances were extensively assessed. Plasma ghrelin levels and ghrelin rs4684677 polymorphism were also determined.

CONCLUSIONS

Our results suggest that decreased ghrelin levels are associated with MCI, especially with episodic memory dysfunction in T2DM populations.

Thinking About Cognitive Function: Perceptions of Cognitive Changes in People With Type 2 Diabetes

Purpose The purpose of this study is 2-fold: (1) to explore how people with diabetes view diabetes-related cognitive problems and (2) to examine participants' ideas on a cognitive rehabilitation intervention to adapt it for persons diagnosed with type 2 diabetes (T2DM). Methods A qualitative descriptive study based on narrative interviews was conducted with adults (n = 10) with T2DM. The interview data were analyzed using content analysis. Results The interviews reflected 4 major themes: search for advice regarding cognitive complaints, cognitive symptoms, impact of perceived cognitive dysfunction on diabetes self-management, and maintenance of cognitive health. Specific areas of interest for an intervention included the following: understanding how cognitive function relates to diabetes, dealing with cognitive barriers to self-management, and learning how to incorporate a "brain healthy" lifestyle into daily activities. Conclusions Findings showed that perceived cognitive impairment impacted self-management and suggested that cognitive rehabilitation interventions have potential utility for people with T2DM. Existing successful interventions can be tailored to meet the needs of those whose diabetes self-management is impacted by cognitive problems.

The diabetic brain and cognition

The prevalence of both Alzheimer's disease (AD) and vascular dementia (VaD) is increasing with the aging of the population. Studies from the last several years have shown that people with diabetes have an increased risk for dementia and cognitive impairment. Therefore, the authors of this consensus review tried to elaborate on the role of diabetes, especially diabetes type 2 (T2DM) in both AD and VaD. Based on the clinical and experimental work of scientists from 18 countries participating in the International Congress on Vascular Disorders and on literature search using PUBMED, it can be concluded that T2DM is a risk factor for both, AD and VaD, based on a pathology of glucose utilization. This pathology is the consequence of a disturbance of insulin-related mechanisms leading to brain insulin resistance. Although the underlying pathological mechanisms for AD and VaD are different in many aspects, the contribution of T2DM and insulin resistant brain state (IRBS) to cerebrovascular disturbances in both disorders cannot be neglected. Therefore, early diagnosis of metabolic parameters including those relevant for T2DM is required. Moreover, it is possible that therapeutic options utilized today for diabetes treatment may also have an effect on the risk for dementia. T2DM/IRBS contribute to pathological processes in AD and VaD.

Antihypertensive agents do not prevent blood-brain barrier dysfunction and cognitive deficits in dietary-induced obese mice

BACKGROUND

While vascular risk factors including Western-styled diet and obesity are reported to induce cognitive decline and increase dementia risk, recent reports consistently suggest that compromised integrity of cerebrovascular blood-brain barrier (BBB) may have an important role in neurodegeneration and cognitive deficits. A number of studies report that elevated blood pressure increases the permeability of BBB.

METHODS

In this study, we investigated the effects of antihypertensive agents, candesartan or ursodeoxycholic acid (UDCA), on BBB dysfunction and cognitive decline in wild-type mice maintained on high fat and fructose (HFF) diet for 24 weeks.

RESULTS

In HFF-fed mice, significantly increased body weight with elevated blood pressure, plasma insulin and glucose compared with mice fed with low-fat control chow was observed. Concomitantly, significant disruption of BBB and cognitive decline were evident in the HFF-fed obese mice. Hypertension was completely prevented by the coprovision of candesartan or UDCA in mice maintained on HFF diet, while only candesartan significantly reduced the body weight compared with HFF-fed mice. Nevertheless, BBB dysfunction and cognitive decline remained unaffected by candesartan or UDCA.

CONCLUSIONS

These data conclusively indicate that modulation of blood pressure and/or body weight may not be directly associated with BBB dysfunction and cognitive deficits in Western diet-induced obese mice, and hence antihypertensive agents may not be effective in preventing BBB disruption and cognitive decline. The findings may provide important mechanistical insights to obesity-associated cognitive decline and its therapy.

Apolipoprotein E4, Gender, Body Mass Index, Inflammation, Insulin Resistance, and Air Pollution Interactions: Recipe for Alzheimer's Disease Development in Mexico City Young Females

Given the epidemiological trends of increasing Alzheimer's disease (AD) and growing evidence that exposure and lifestyle factors contribute to AD risk and pathogenesis, attention should be paid to variables such as air pollution, in order to reduce rates of cognitive decline and dementia. Exposure to fine particulate matter (PM2.5) and ozone (O3) above the US EPA standards is associated with AD risk. Mexico City children experienced pre- and postnatal high exposures to PM2.5, O3, combustion-derived iron-rich nanoparticles, metals, polycyclic aromatic hydrocarbons, and endotoxins. Exposures are associated with early brain gene imbalance in oxidative stress, inflammation, innate and adaptive immune responses, along with epigenetic changes, accumulation of misfolded proteins, cognitive deficits, and brain structural and metabolic changes. The Apolipoprotein E (APOE) 4 allele, the most prevalent genetic risk for AD, plays a key role in the response to air pollution in young girls. APOE 4 heterozygous females with >75% to <94% BMI percentiles are at the highest risk of severe cognitive deficits (1.5-2 SD from average IQ). This review focused on the relationships between gender, BMI, systemic and neural inflammation, insulin resistance, hyperleptinemia, dyslipidemia, vascular risk factors, and central nervous system involvement in APOE4 urbanites exposed to PM2.5 and magnetite combustion-derived iron-rich nanoparticles that can reach the brain. APOE4 young female heterozygous carriers constitute a high-risk group for a fatal disease: AD. Multidisciplinary intervention strategies could be critical for prevention or amelioration of cognitive deficits and long-term AD progression in young individuals at high risk.