Effect of diabetes on brain structure: the action to control cardiovascular risk in diabetes MR imaging baseline data

Reporting of Participant Demographics in Clinical Trials Published in General Radiology Journals

OBJECTIVES

The reporting of research participant demographics provides insights into study generalizability. Our study aimed to determine the frequency at which participant age, sex/gender, race/ethnicity, and socioeconomic status (SES) are reported and used for subgroup analyses in radiology randomized controlled trials (RCTs) and their secondary analyses; as well as the study characteristics associated with, and the classification systems used for demographics reporting.

METHODS

RCTs and their secondary analyses published in 8 leading radiology journals between 2013 and 2021 were included. Associations between study characteristics and demographic reporting were tested with the chi-square goodness of fit test for categorical variables, Wilcoxon-Mann-Whitney test for impact factor, and logistic regression for publication year.

RESULTS

Among 432 included articles, 89.4% (386) reported age, 90.3% (390) sex/gender, 5.6% (24) race/ethnicity, and 3.0% (13) SES. Among articles that reported these demographics and were not specific to a subgroup, results were analyzed by age in 14.2% (55/386), sex/gender in 19.4% (66/340), race/ethnicity in 13.6% (3/22), and SES in 46.2% (6/13). Journal, impact factor, and last author continent were predictors of race/ethnicity and SES reporting. Funding was associated with race/ethnicity reporting. No study reported sex and gender separately, or documented transgender, nonbinary gender spectrum or intersex participants. A single category for race/ethnicity was used in 37.5% (9/24) of studies, consisting of either "White" or "Caucasian."

CONCLUSION

The reporting of participant demographics in radiology trials is variable and not always representative of the population diversity. Editorial guidelines on the reporting and analysis of participant demographics could help standardize practices.

Region-specific hippocampal atrophy is correlated with poor glycemic control in type 2 diabetes: a cross-sectional study

To examine the association between prediabetes/type 2 diabetes mellitus (T2DM) and hippocampal subfields and to investigate the effects of glycemic control (HbA1c and FBG)/diabetes duration on the volume of hippocampal subfields in T2DM patients. This cross-sectional study included 268 participants from Tianjin Union Medical Center between August 2019 and July 2022. The participants were divided into three groups: T2DM, prediabetes and no diabetes. All participants underwent brain MRI examination on a 3T MRI scanner. FreeSurfer was performed to segment hippocampus automatically based on T1 MPRAGE images. The relationships between glycemic status/glycemic control/diabetes duration and hippocampal subfield volumes were estimated by multiple linear regression analysis/generalized additive modeling (GAM). Among all participants, 76 (28.36%) had prediabetes, and 96 (35.82%) had T2DM. In multi-adjusted linear regression models, those with prediabetes had a significantly lower volume of bilateral parasubiculum (βright = -5.540; βleft = -6.497). Those with diabetes had lower volume of parasubiculum (βleft = -7.868), presubiculum-head (βleft = -6.244) and fimbria (βleft = -7.187). We did not find relationship between diabetes duration and hippocampal subfield volumes. In stratified analysis, long duration with high FBG related with lower volume of right fimbria (βright = -15.583). Long duration with high HbA1c related with lower volume of presubiculum-head (βright = -19.693), subiculum-head (βright = -28.303), subiculum-body (βleft = -38.599), CA1-head (βright = -62.300, βleft = -47.922), CA1-body (βright = -19.043), CA4-body (βright = -14.392), GC-ML-DG-head (βright = -20.521), GC-ML-DG-body (βright = -16.293, βleft = -12.799), molecular_layer_HP-head (βright = -44.202, βleft = -26.071) and molecular_layer_HP-body, (βright = -31.368), hippocampal_tail (βleft = -80.073). Prediabetes related with lower bilateral parasubiculum volume, and T2DM related with lower left parasubiculum, presubiculum-head and fimbria. T2DM with chronic poor glycemic control had lower volume in multiple hippocampal subregions.

The longitudinal impact of type 2 diabetes on brain gyrification

Type 2 diabetes has an effect on brain structure, including cortical gyrification. The significance of these changes is better understood if assessed over time. However, there is a lack of studies assessing longitudinally the effect of this disease with complex aethology in gyrification. While changes in this feature have been associated mainly with genetic legacy, our study allowed to shed light on the effect of the variation of glycaemic profile over time in gyrification in this metabolic disease. In this longitudinal study, we analysed brain anatomical magnetic resonance images of 15 participants with type 2 diabetes and 13 healthy control participants to investigate the impact of this metabolic disease on the gyrification index over a 7-year period. We observed a significant interaction between time and group in six regions, four of which (left precentral gyrus, left gyrus rectus, left subcentral gyrus and sulci and right inferior temporal gyrus) showed an increase in gyrification in type 2 diabetes and a decrease in the control group and the two others (left pericallosal sulcus and right inferior frontal sulcus) the opposite pattern. The variation of the gyrification was correlated with the variation of the glycaemic profile. Following the interaction, the simple main effect of time in each group separately has shown that in the group with diabetes, there were more regions susceptible to alterations of gyrification. In sum, our results raise credit for the possibility that glycaemic control also might influence gyrification in type 2 diabetes.

Brain and Cognition Signature Fingerprinting Vascular Health in Diabetic Individuals: An International Multi-Cohort Study

OBJECTIVE

To evaluate the correlation between cognitive signatures and the risk of diabetic vascular complications and mortality, based on a multicountry prospective study.

METHODS

The participants comprised 27,773 diabetics from the UK Biobank (UKB) and 1307 diabetics from the Guangzhou Diabetic Eye Study (GDES) cohort. The exposures were brain volume and cognitive screening tests for UKB participants, whilst the global cognitive score (GCS) measuring orientation to time and attention, episodic memory, and visuospatial abilities were determined for GDES participants. The outcomes for the UKB group were mortality, as well as macrovascular (myocardial infarction [MI] and stroke), microvascular (end-stage renal disease [ESRD], and diabetic retinopathy [DR]) events. The outcomes for the GDES group were retinal and renal microvascular damage.

RESULTS

In the UKB group, a 1-SD reduction in brain gray matter volume was associated with 34%-77% higher risks of incident MI, ESRD, and DR. The presence of impaired memory was associated with 18%-73% higher risk of mortality and ESRD; impaired reaction was associated with 1.2-1.7-fold higher risks of mortality, stroke, ESRD, and DR. In the GDES group, the lowest GCS tertile exhibited 1.4-2.2-fold higher risk of developing referable DR and a twofold faster decline in renal function and retinal capillary density compared with the highest tertile. Restricting data analysis to individuals aged less than 65 years produced consistent results.

CONCLUSION

Cognitive decline significantly elevates the risk of diabetic vascular complications and is correlated with retinal and renal microcirculation damage. Cognitive screening tests are strongly recommended as routine tools for management of diabetes.

Sugar-Sweetened Coffee Intake and Blood Glucose Management in Korean Patients with Diabetes Mellitus

One of the most frequently consumed beverages by Korean adults is 3-in-1 coffee (mixed coffee) with sugar and creamer. Hence, understanding the effect of sugar-sweetened coffee (SSC) consumption on blood sugar levels in patients with diabetes mellitus (DM) is important. This study was conducted using the Korea National Health and Nutrition Examination Survey data from 2008 to 2020. In total, 5671 patients with DM were included in the analysis. Coffee consumption patterns were assessed using a 24 h recall. Fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) levels were used to evaluate whether patients reached the glycemic control targets defined by the Korean Diabetes Association. In total, 46.57% of patients with DM included in this analysis consumed SSC. Patients who frequently consumed SSC had significantly higher FBG and HbA1c levels than those who did not (both p for trend <0.01). In a multivariate logistic regression model, the odds ratios of not achieving the target FBG and HbA1c levels were 1.24 (95% confidence interval [CI]: 1.03−1.48, p for trend = 0.01) and 1.29 (95% CI: 1.05−1.58, p for trend = 0.009), respectively. Frequent consumption of SSC can cause difficulty in FBG and HbA1c management in patients with DM.

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.

Obstructive sleep apnea and white matter hyperintensities: correlation or causation?

Obstructive sleep apnea (apnea) is thought to cause small vessel ischemic episodes in the brain from hypoxic events, postulated as white matter hyperintensities (hyperintensities) identified on MRI which are implicated in cognitive decline. This study sought to evaluate these correlations. A retrospective evaluation of adults who underwent polysomnography (4/1/2016 to 4/30/2017) and a brain MRI prior to apnea diagnosis or within a year post-diagnosis was completed. MRI visual evaluation of hyperintensities using Fazekas scores were collected blind to clinical data. Collated clinical/MRI data were stratified and analyzed using chi-square, fishers t-tests, ANOVA/ANCOVA and linear regression. Stratification by apnea category revealed no significant differences in any variables including hyperintensity measures (Fazekas p=0.1584; periventricular p=0.3238; deep p=0.4618; deep total p=0.1770). Stratification by Fazekas category, periventricular and deep hyperintensities revealed increasing prevalence with age (p=0.0001); however, apnea categories were not significantly associated (Fazekas p=0.1479; periventricular p=0.3188; deep p=0.4503), nor were any individual apnea indicators. Continuous apnea measurements werre not associated with any hyperintensity factor; total deep hyperintensities were not associated with any apnea factors. Continuous BMI was not found to be associated with any apnea or hyperintensity factors. Only hypertension was noted to be associated with Fazekas (p=0.0045), deep (p=0.0010) and total deep (p=0.0021) hyperintensities; however, hypertension was not associated with apnea category (p=0.3038) or any associated factors. These data suggest apneas alone from OSA are insufficient to cause WMH, but other factors appear to contribute to the complex development of small vessel ischemic injury associated with age and cognitive decline.

Brain Structural Alterations, Diabetes Biomarkers, and Cognitive Performance in Older Adults With Dysglycemia

Despite the high risk of dementia in older adults with type 2 diabetes, the neuroanatomical correlates of cognitive dysfunction that are particularly affected by diabetes are not well characterized. This study is aimed to examine the structural brain alterations in dysglycemic older adults. Using voxel-based morphometric and tract-based spatial statistics, we examined changes in gray matter volume, white matter volume, and microstructural integrity in older adults with prediabetes and diabetes. We also assessed the correlation of these structural changes with diabetes biomarkers and cognitive performance. A total of 74 non-demented older adults (normal, n = 14; prediabetes, n = 37; and diabetes, n = 23) participated in this study and underwent structural and diffusion magnetic resonance imaging (MRI) scans and neuropsychological tests. Subjects with diabetes showed reduced volume of cerebellar gray matter and frontal white matter and diffuse white matter dysintegrity, while those with prediabetes only showed reduced volume of insular gray matter. Atrophic changes in the cerebellum and frontal lobe and frontal white matter dysintegrity were correlated with chronic hyperglycemia and insulin resistance and worse performance in verbal memory recognition and executive function tests. Our findings suggest that chronic hyperglycemia and insulin resistance may alter brain structures forming the fronto-cerebellar network, which may cause cognitive dysfunction in older adults.

A novel morphometric signature of brain alterations in type 2 diabetes: Patterns of changed cortical gyrification

Type 2 diabetes is a chronic disease that creates atrophic signatures in the brain, including decreases of total and regional volume of grey matter, white matter and cortical thickness. However, there is a lack of studies assessing cortical gyrification in type 2 diabetes. Changes in this emerging feature have been associated mainly with genetic legacy, but environmental factors may also play a role. Here, we investigated alterations of the gyrification index and classical morphometric measures in type 2 diabetes, a late acquired disease with complex aetiology with both underlying genetic and more preponderant environmental factors. In this cross-sectional study, we analysed brain anatomical magnetic resonance images of 86 participants with type 2 diabetes and 40 healthy control participants, to investigate structural alterations in type 2 diabetes, including whole-brain volumetric measures, local alterations of grey matter volume, cortical thickness and the gyrification index. We found concordant significant decrements in total and regional grey matter volume, and cortical thickness. Surprisingly, the cortical gyrification index was found to be mainly increased and mainly located in cortical sensory areas in type 2 diabetes. Moreover, alterations in gyrification correlated with clinical data, suggesting an influence of metabolic profile in alterations of gyrification in type 2 diabetes. Further studies should address causal influences of genetic and/or environmental factors in patterns of cortical gyrification in type 2 diabetes.

ESO Guideline on covert cerebral small vessel disease

'Covert' cerebral small vessel disease (ccSVD) is common on neuroimaging in persons without overt neurological manifestations, and increases the risk of future stroke, cognitive impairment, dependency, and death. These European Stroke Organisation (ESO) guidelines provide evidence-based recommendations to assist with clinical decisions about management of ccSVD, specifically white matter hyperintensities and lacunes, to prevent adverse clinical outcomes. The guidelines were developed according to ESO standard operating procedures and Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. We prioritised the clinical outcomes of stroke, cognitive decline or dementia, dependency, death, mobility and mood disorders, and interventions of blood pressure lowering, antiplatelet drugs, lipid lowering, lifestyle modifications, glucose lowering and conventional treatments for dementia. We systematically reviewed the literature, assessed the evidence, formulated evidence-based recommendations where feasible, and expert consensus statements. We found little direct evidence, mostly of low quality. We recommend patients with ccSVD and hypertension to have their blood pressure well controlled; lower blood pressure targets may reduce ccSVD progression. We do not recommend antiplatelet drugs such as aspirin in ccSVD. We found little evidence on lipid lowering in ccSVD. Smoking cessation is a health priority. We recommend regular exercise which may benefit cognition, and a healthy diet, good sleep habits, avoiding obesity and stress for general health reasons. In ccSVD, we found no evidence for glucose control in the absence of diabetes or for conventional Alzheimer dementia treatments. Randomised controlled trials with clinical endpoints are a priority for ccSVD.

Common Brain Structural Alterations Associated with Cardiovascular Disease Risk Factors and Alzheimer's Dementia: Future Directions and Implications

Recent reports suggest declines in the age-specific risk of Alzheimer's dementia in higher income Western countries. At the same time, investigators believe that worldwide trends of increasing mid-life modifiable risk factors [e.g., cardiovascular disease (CVD) risk factors] coupled with the growth of the world's oldest age groups may nonetheless lead to an increase in Alzheimer's dementia. Thus, understanding the overlap in neuroanatomical profiles associated with CVD risk factors and AD may offer more relevant targets for investigating ways to reduce the growing dementia epidemic than current targets specific to isolated AD-related neuropathology. We hypothesized that a core group of common brain structural alterations exist between CVD risk factors and Alzheimer's dementia. Two co-authors conducted independent literature reviews in PubMed using search terms for CVD risk factor burden (separate searches for 'cardiovascular disease risk factors', 'hypertension', and 'Type 2 diabetes') and 'aging' or 'Alzheimer's dementia' with either 'grey matter volumes' or 'white matter'. Of studies that reported regionally localized results, we found support for our hypothesis, determining 23 regions commonly associated with both CVD risk factors and Alzheimer's dementia. Within this context, we outline future directions for research as well as larger cerebrovascular implications for these commonalities. Overall, this review supports previous as well as more recent calls for the consideration that both vascular and neurodegenerative factors contribute to the pathogenesis of dementia.

Cardiovascular Risk Factors and White Matter Hyperintensities: Difference in Susceptibility in South Asians Compared With Europeans

Background

Cardiovascular risk factors vary between ethnicities but little is known about their differential effects on white matter hyperintensities (WMH), an indicator of brain aging and burden of cerebrovascular disease.

Methods and Results

Brain magnetic resonance imaging scans from 213 people of South Asian and 256 of European ethnicity (total=469) were analyzed for global and regional WMH load. Associations with cardiovascular risk factors and a composite cardiovascular risk score (National Cholesterol Education Programme Adult Treatment Panel III) were compared by ethnicity, diabetes mellitus, smoking, and hypertension status. Distributional patterns of WMH were similar by ethnicity but the vulnerability to specific risk factors differed. Associations between WMH and age or National Cholesterol Education Programme Adult Treatment Panel III scores were stronger in South Asians compared with Europeans. For instance, a year of age led to an excess of 3.8% (confidence interval=[0.2, 7.6]; P=0.04) of WMH load in frontal regions in South Asians compared with Europeans. In the diabetic subgroup, South Asians had more WMH than Europeans (+63.3%, confidence interval=[14.1, 133.9]; P=0.007), particularly in the deeper regions (+102% confidence interval=[24, 329]; P=0.004). In the population as a whole, diabetes mellitus was not, or only weakly, related to an increase in WMH volume (12.4%, confidence interval=[−10.7, 41.3]; P=0.32), and diabetes mellitus duration was a positive predictor of frontal periventricular WMH load in Europeans but not in South Asians. In turn, diastolic blood pressure was positively associated with WMH volumes in South Asians but not in Europeans. Hypertension was not associated with WMH load (P=0.9).

Conclusions

Distribution patterns of WMH are similar in South Asians and Europeans but older age and higher cardiovascular risk are associated with more WMH in South Asians.

Cognitive Dysfunction in Persons with Type 2 Diabetes Mellitus: A Concept Analysis

Although cognitive dysfunction is related to type 2 diabetes mellitus (T2DM), the concept has not yet been well defined. The purpose of this study was to define the concept of cognitive dysfunction in persons with T2DM and examine its defining attributes, antecedents, and consequences. Literature was retrieved from 2008 to 2018 by systematically searching the PubMed, CINAHL, and PsycINFO databases. Based on 37 included studies, three defining attributes were identified: cognitive dysfunction is a recognized or unrecognized symptom, is characterized by a subtle decline in one or more cognitive domains, and is accompanied by pronounced structural changes observed in brain imaging. One major antecedent was diabetes-related or diabetes-specific pathological changes. Consequences included interference with diabetes self-management, nonadherence to recommended self-management behaviors, and a higher risk of having hypoglycemic events. The concept analysis provides a theoretical foundation that can be used to guide evaluations and interventions related to cognitive dysfunction in individuals with T2DM.

Sugar in mind: Untangling a sweet and sour relationship beyond type 2 diabetes

It is widely recognised that type 2 diabetes (T2D) represents a major disease burden but it is only recently that its role in neurodegeneration has attracted more attention. This research has shown that T2D is associated with impaired cerebral health, cognitive decline and dementia. However, the impact on the brain of progressive metabolic changes associated with the pre-clinical development of the disease is less clear. The aim of this review is to comprehensively summarise how the emergence of risk factors and co-morbid conditions linked to the development of T2D impact cerebral health. Particular attention is directed at characterising how normal but elevated blood glucose levels in individuals without T2D contribute to neurodegenerative processes, and how the main risk factors for T2D including obesity, physical activity and diet modulate these effects. Where available, evidence from the animal and human literature is contrasted, and sex differences in risk and outcomes are highlighted.

Age Modulates the Association of Caffeine Intake With Cognition and With Gray Matter in Elderly Diabetics

BACKGROUND

The association between caffeine and cognitive performance has not been tested in older individuals with type 2 diabetes (T2D). Its association with brain volume in T2D has been tested only in animals.

METHODS

We examined the association of caffeine with cognitive function and brain volume in a sample of elderly diabetics participating in the Israel Diabetes and Cognitive Decline Study (n = 638) and the moderating effect of age on this association. In a subsample (n = 185) with magnetic resonance imaging, we also examined these associations with gray and white matter volumes (GM/WM).

RESULTS

Using linear regression adjusting for cognition-related covariates, we found that higher caffeine intake was associated with better function in overall cognition (p = .018), attention/working memory (p = .002), executive functioning (p = .047), and semantic categorization (p = .026). Interaction analyses of caffeine intake with age were significant for semantic categorization (p = .025), and approached significance for overall cognition (p = .066). This association was driven by the older group (above-median) for whom the association of caffeine intake with semantic categorization (p = .001), attention/working memory (p = .007), executive functioning (p = .005), and overall cognition (p = .002) were significant. In the magnetic resonance imaging subsample, there was an interaction (p = .034) of caffeine intake with age for GM volume; in the older group, higher caffeine intake was associated with greater GM volume (β = .198, p = .033).

CONCLUSIONS

Caffeine intake may have a beneficial role in cognitive functioning of elderly adults with T2D, which may be moderated by age. Greater GM volume may be a mechanism underlying the association of higher caffeine intake with better cognitive function.

Effects of Diabetes on Motor Recovery after Cerebral Infarct: A Diffusion Tensor Imaging Study

PURPOSE

Little is known about the effects of diabetes on motor recovery after cerebral infarct. To address this, we recruited patients with corona radiata infarct and controlled for the integrity of the corticospinal tract (CST) determined using diffusion tensor tractography (DTT).

METHODS

One hundred patients were recruited, and DTT was performed within 7-30 days of infarct onset. Based on the DTT findings (DTT+: CST was preserved around the infarct, DTT-: CST was interrupted by the infarct) and the presence (DM+) or absence (DM-) of diabetes, patients were divided into, DTT+/DM- (36 patients), DTT+/DM+ (19 patients), DTT-/DM- (32 patients), and DTT-/DM+ (13 patients) groups. Six months after cerebral infarct, motor function on the affected side was evaluated for each patient using the upper Motricity Index (MI), lower MI, modified Brunnstrom classification (MBC), and the functional ambulation category (FAC).

RESULTS

In the patients with a DTT+ finding, no motor function scores were significantly different between the DTT+/DM- and DTT+/DM+ groups at six-month evaluation. However, in patients with DTT- finding, all motor function scores at the six-month evaluation were significantly higher in the DTT-/DM- group than in the DTT-/DM+ group.

CONCLUSION

When the CST is interrupted by a corona radiata infarct, recovery of motor function in patients with diabetes is more impaired than those without diabetes.

Prediabetes Is Associated With Structural Brain Abnormalities: The Maastricht Study

OBJECTIVE

Structural brain abnormalities are key risk factors for brain diseases, such as dementia, stroke, and depression, in type 2 diabetes. It is unknown whether structural brain abnormalities already occur in prediabetes. Therefore, we investigated whether both prediabetes and type 2 diabetes are associated with lacunar infarcts (LIs), white matter hyperintensities (WMHs), cerebral microbleeds (CMBs), and brain atrophy.

RESEARCH DESIGN AND METHODS

We used data from 2,228 participants (1,373 with normal glucose metabolism [NGM], 347 with prediabetes, and 508 with type 2 diabetes (oversampled); mean age 59.2 ± 8.2 years; 48.3% women) of the Maastricht Study, a population-based cohort study. Diabetes status was determined with an oral glucose tolerance test. Brain imaging was performed with 3 Tesla MRI. Results were analyzed with multivariable logistic and linear regression analyses.

RESULTS

Prediabetes and type 2 diabetes were associated with the presence of LIs (odds ratio 1.61 [95% CI 0.98-2.63] and 1.67 [1.04-2.68], respectively; P _trend = 0.027), larger WMH (β 0.07 log10-transformed mL [log-mL] [95% CI 0.00-0.15] and 0.21 log-mL [0.14-0.28], respectively; P _trend <0.001), and smaller white matter volumes (β -4.0 mL [-7.3 to -0.6] and -7.2 mL [-10.4 to -4.0], respectively; P _trend <0.001) compared with NGM. Prediabetes was not associated with gray matter volumes or the presence of CMBs.

CONCLUSIONS

Prediabetes is associated with structural brain abnormalities, with further deterioration in type 2 diabetes. These results indicate that, in middle-aged populations, structural brain abnormalities already occur in prediabetes, which may suggest that the treatment of early dysglycemia may contribute to the prevention of brain diseases.

Region-specific susceptibility change in cognitively impaired patients with diabetes mellitus

Emerging evidence suggests that diabetes mellitus (DM) is associated with iron and calcium metabolism. However, few studies have investigated the presence of DM in cognitively impaired patients and its effect on brain iron and calcium accumulation. Therefore, we assessed the effects of DM on cognitively impaired patients using quantitative susceptibility mapping (QSM). From June 2012 to Feb 2014, 92 eligible cognitively impaired patients underwent 3T magnetic resonance imaging (MRI). There were 46 patients with DM (DM+) and 46 aged matched patients without DM (DM-). QSM was obtained from gradient echo data and analyzed by drawing regions of interest around relevant anatomical structures. Clinical factors and vascular pathology were also evaluated. Measurement differences between DM+ and DM- patients were assessed by t tests. A multiple regression analysis was performed to identify independent predictors of magnetic susceptibility. DM+ patients showed lower susceptibility values, indicative of lower brain iron content, than DM- patients, which was significant in the hippocampus (4.80 ± 8.31 ppb versus 0.22 ± 10.60 ppb, p = 0.024) and pulvinar of the thalamus (36.30 ± 19.88 ppb versus 45.90 ± 20.02 ppb, p = 0.023). On multiple regression analysis, microbleed number was a predictor of susceptibility change in the hippocampus (F = 4.291, beta = 0.236, p = 0.042) and DM was a predictor of susceptibility change in the pulvinar of the thalamus (F = 4.900, beta = - 0.251, p = 0.030). In cognitively impaired patients, presence of DM was associated with lower susceptibility change in the pulvinar of the thalamus and hippocampus. This suggests that there may be region-specific alterations of calcium deposition in cognitively impaired subjects with DM.

Postprandial Hyperglycemia Is Associated With White Matter Hyperintensity and Brain Atrophy in Older Patients With Type 2 Diabetes Mellitus

Type 2 diabetes mellitus is associated with neurodegeneration and cerebrovascular disease. However, the precise mechanism underlying the effects of glucose management on brain abnormalities is not fully understood. The differential impacts of glucose alteration on brain changes in patients with and without cognitive impairment are also unclear. This cross-sectional study included 57 older type 2 diabetes patients with a diagnosis of Alzheimer's disease (AD) or normal cognition (NC). We examined the effects of hypoglycemia, postprandial hyperglycemia and glucose fluctuations on regional white matter hyperintensity (WMH) and brain atrophy among these patients. In a multiple regression analysis, postprandial hyperglycemia was independently associated with frontal WMH in the AD patients. In addition, postprandial hyperglycemia was significantly associated with brain atrophy, regardless of the presence of cognitive decline. Altogether, our findings indicate that postprandial hyperglycemia is associated with WMH in AD patients but not NC patients, which suggests that AD patients are more susceptible to postprandial hyperglycemia associated with WMH.

Prediabetes is associated with lower brain gray matter volume in the general population. The Study of Health in Pomerania (SHIP)

BACKGROUND AND AIMS

We investigated the associations of fasting (FG) and 2-h postload (2HG) plasma glucose from oral glucose tolerance test (OGTT) with gray (GMV) and white (WMV) matter volume.

METHODS AND RESULTS

We analyzed data from 1330 subjects without known diabetes mellitus, aged 21 to 81, from the second cohort (SHIP-Trend-0) of the population-based Study of Health in Pomerania (SHIP). Following the OGTT, individuals were classified in five groups (according to the American Diabetes Association criteria): normal glucose tolerance (NGT), isolated impaired fasting glucose (i-IFG), isolated impaired glucose tolerance (i-IGT), combined IFG and IGT (IFG + IGT) and unknown type 2 diabetes mellitus (UDM). GMV and WMV were determined by magnetic resonance imaging. FG, 2HG and OGTT groups were associated with GMV and WMV by linear regression models adjusted for confounders. FG and 2HG were inversely associated with GMV. The adjusted mean GMV, when compared with the NGT group (584 ml [95% CI: 581 to 587]), was significantly lower in the groups i-IFG (578 ml [95% CI: 573 to 582]; p = 0.035) and UDM (562 ml [95% CI: 551 to 573]; p < 0.001), but not different in the i-IGT (586 ml [95% CI: 576 to 596]; p = 0.688) and IFG + IGT (579 ml [95% CI: 571 to 586]; p = 0.209) groups. There were no associations of FG, 2HG and OGTT parameters with WMV.

CONCLUSION

Our findings suggest that elevated FG levels, even within the prediabetic range, might already have some harmful effects on GMV.

Diabetes, Prediabetes, and Brain Volumes and Subclinical Cerebrovascular Disease on MRI: The Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS)

OBJECTIVE

To examine the associations of prediabetes, diabetes, and diabetes severity (as assessed by HbA_1c and diabetes duration) with brain volumes and vascular pathology on brain MRI and to assess whether the associations of diabetes with brain volumes are mediated by brain vascular pathology.

RESEARCH DESIGN AND METHODS

Cross-sectional study of 1,713 participants in the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS) (mean age 75 years, 60% female, 27% black, 30% prediabetes, and 35% diabetes) who underwent 3T brain MRI scans in 2011-2013. Participants were categorized by diabetes-HbA_1c status as without diabetes (<5.7% [reference]), with prediabetes (5.7 to <6.5%), and with diabetes ([defined as prior diagnosis or HbA_1c ≥6.5%] <7.0% vs. ≥7.0%), with further stratification by diabetes duration (<10 vs. ≥10 years).

RESULTS

In adjusted analyses, compared with participants without diabetes and HbA_1c <5.7%, participants with prediabetes and those with diabetes and HbA_1c <7.0% did not have significantly different brain volumes or vascular pathology (all P > 0.05), but those with diabetes and HbA_1c ≥7.0% had smaller total brain volume (β -0.20 SDs, 95% CI -0.31, -0.09), smaller regional brain volumes (including frontal, temporal, occipital, and parietal lobes; deep gray matter; Alzheimer disease signature region; and hippocampus [all P < 0.05]), and increased burden of white matter hyperintensities (WMH) (P = 0.016). Among participants with diabetes, those with HbA_1c ≥7.0% had smaller total and regional brain volumes and an increased burden of WMH (all P < 0.05) compared with those with HbA_1c <7.0%. Similarly, participants with longer duration of diabetes (≥10 years) had smaller brain volumes and higher burden of lacunes (all P < 0.05) than those with a diabetes duration <10 years. We found no evidence for mediation by WMH in associations of diabetes with smaller brain volumes by structural equation models (all P > 0.05).

CONCLUSIONS

More-severe diabetes (defined by higher HbA_1c and longer disease duration) but not prediabetes or less-severe diabetes was associated with smaller brain volumes and an increased burden of brain vascular pathology. No evidence was found that associations of diabetes with smaller brain volumes are mediated by brain vascular pathology, suggesting that other mechanisms may be responsible for these associations.

Brain structure and verbal function across adulthood while controlling for cerebrovascular risks

The development and decline of brain structure and function throughout adulthood is a complex issue, with cognitive aging trajectories influenced by a host of factors including cerebrovascular risk. Neuroimaging studies of age-related cognitive decline typically reveal a linear decrease in gray matter (GM) volume/density in frontal regions across adulthood. However, white matter (WM) tracts mature later than GM, particularly in regions necessary for executive functions and memory. Therefore, it was predicted that a middle-aged group (MC: 35-45 years) would perform best on a verbal working memory task and reveal greater regional WM integrity, compared with both young (YC: 18-25 years) and elder groups (EC: 60+ years). Diffusion tensor imaging (DTI) and magnetoencephalography (MEG) were obtained from 80 healthy participants. Objective measures of cerebrovascular risk and cognition were also obtained. As predicted, MC revealed best verbal working memory accuracy overall indicating some maturation of brain function between YC and MC. However, contrary to the prediction fractional anisotropy values (FA), a measure of WM integrity, were not greater in MC (i.e., there were no significant differences in FA between YC and MC but both groups showed greater FA than EC). An overall multivariate model for MEG ROIs showed greater peak amplitudes for MC and YC, compared with EC. Subclinical cerebrovascular risk factors (systolic blood pressure and blood glucose) were negatively associated with FA in frontal callosal, limbic, and thalamic radiation regions which correlated with executive dysfunction and slower processing speed, suggesting their contribution to age-related cognitive decline. Hum Brain Mapp 38:3472-3490, 2017. © 2017 Wiley Periodicals, Inc.

Brain glucose metabolism: Role of Wnt signaling in the metabolic impairment in Alzheimer's disease

The brain is an organ that has a high demand for glucose. In the brain, glucose is predominantly used in energy production, with almost 70% of the energy used by neurons. The importance of the energy requirement in neurons is clearly demonstrated by the fact that all neurodegenerative disorders exhibit a critical metabolic impairment that includes decreased glucose uptake/utilization and decreased mitochondrial activity, with a consequent diminution in ATP production. In fact, in Alzheimer's disease, the measurement of the general metabolic rate of the brain has been reported to be an accurate tool for diagnosis. Additionally, the administration of metabolic activators such as insulin/glucagon-like peptide 1 can improve memory/learning performance. Despite the importance of energy metabolism in the brain, little is known about the cellular pathways involved in the regulation of this process. Several reports postulate a role for Wnt signaling as a general metabolic regulator. Thus, in the present review, we discuss the antecedents that support the relationship between Wnt signaling and energy metabolism in the Alzheimer's disease.

The Effect of Diabetes on Cortical Function in Stroke: Implications for Poststroke Plasticity

Diabetes may impair the capacity for neuroplasticity such that patients experience a slower and poorer recovery after stroke. The current study investigated changes in cortical function in stroke patients with diabetes to determine how this comorbidity may affect poststroke cortical plasticity and thereby functional recovery. From a cohort of 57 participants, threshold-tracking transcranial magnetic stimulation was used to assess cortical function over the ipsilateral and contralesional hemispheres in 7 patients with diabetes after an acute stroke compared with 12 stroke patients without diabetes. Cortical function was also assessed in 8 patients with diabetes without stroke and 30 normal control subjects. After acute stroke, short-interval intracortical inhibition (SICI) was reduced over both motor cortices in stroke patients without diabetes compared with normal control patients, while in stroke patients with diabetes, SICI was only reduced over the contralesional but not the ipsilesional cortex compared with control patients with diabetes. In addition, SICI was significantly reduced in the control patients with diabetes compared with normal control patients. These results have demonstrated the absence of ipsilesional cortical excitability change after diabetic strokes, suggesting impaired capacity for neuroplasticity over this hemisphere as a consequence of a "double-hit" phenomenon because of preexisting alterations in cortical function in nonstroke patients with diabetes. The reliance on reorganization over the contralesional cortex after stroke will likely exert influence on poststroke recovery in patients with diabetes.

Diabetic aggravation of stroke and animal models

Cerebral ischemia in diabetics results in severe brain damage. Different animal models of cerebral ischemia have been used to study the aggravation of ischemic brain damage in the diabetic condition. Since different disease conditions such as diabetes differently affect outcome following cerebral ischemia, the Stroke Therapy Academic Industry Roundtable (STAIR) guidelines recommends use of diseased animals for evaluating neuroprotective therapies targeted to reduce cerebral ischemic damage. The goal of this review is to discuss the technicalities and pros/cons of various animal models of cerebral ischemia currently being employed to study diabetes-related ischemic brain damage. The rational use of such animal systems in studying the disease condition may better help evaluate novel therapeutic approaches for diabetes related exacerbation of ischemic brain damage.

Diabetes, adult neurogenesis and brain remodeling: New insights from rodent and zebrafish models

The prevalence of diabetes rapidly increased during the last decades in association with important changes in lifestyle. Diabetes and hyperglycemia are well-known for inducing deleterious effects on physiologic processes, increasing for instance cardiovascular diseases, nephropathy, retinopathy and foot ulceration. Interestingly, diabetes also impairs brain morphology and functions such as (1) decreased neurogenesis (proliferation, differentiation and cell survival), (2) decreased brain volumes, (3) increased blood-brain barrier leakage, (4) increased cognitive impairments, as well as (5) increased stroke incidence and worse neurologic outcomes following stroke. Importantly, diabetes is positively associated with a higher risk to develop Alzheimer disease. In this context, we aim at reviewing the impact of diabetes on neural stem cell proliferation, newborn cell differentiation and survival in a homeostatic context or following stroke. We also report the effects of hyper- and hypoglycemia on the blood-brain barrier physiology through modifications of tight junctions and transporters. Finally, we discuss the implication of diabetes on cognition and behavior.

Type 2 diabetes mellitus is associated with brain atrophy and hypometabolism in the ADNI cohort

OBJECTIVE

We investigated type 2 diabetes mellitus (T2DM) as a risk factor for brain atrophy and glucose hypometabolism in older adults with or at risk of cognitive impairment.

METHODS

Participants with the T2DM were identified from the Alzheimer's Disease Neuroimaging Initiative (ADNI-1/GO/2 cohorts). Analysis of covariance models were used to compare participants with and without T2DM, controlling for potential confounding factors.

RESULTS

Whole brain volume and whole brain [(18)F]-fluorodeoxyglucose (FDG) uptake were significantly different as a function of T2DM status, independent of baseline clinical diagnosis. On post hoc analysis, a lower whole brain volume was seen in participants with both mild cognitive impairment (MCI) and T2DM (n = 76) compared with participants who had MCI but not T2DM (n = 747; p = 0.009). Similarly, mean FDG uptake in gray matter and white matter was lower in participants with both MCI and T2DM (n = 72) than in participants with MCI without T2DM (n = 719; p = 0.04). Subsequent regional analysis revealed that the decreased FDG uptake in participants with both MCI and T2DM was mainly manifested in 3 brain regions: frontal lobe, sensory motor cortex, and striatum.

CONCLUSIONS

T2DM may accelerate cognition deterioration in patients with MCI by affecting glucose metabolism and brain volume.

Analysis of the relationships between type 2 diabetes status, glycemic control, and neuroimaging measures in the Diabetes Heart Study Mind

AIMS

To examine the relationships between type 2 diabetes (T2D) status, glycemic control, and T2D duration with magnetic resonance imaging (MRI)-derived neuroimaging measures in European Americans from the Diabetes Heart Study (DHS) Mind cohort.

METHODS

Relationships were examined using marginal models with generalized estimating equations in 784 participants from 514 DHS Mind families. Fasting plasma glucose, glycated hemoglobin, and diabetes duration were analyzed in 682 participants with T2D. Models were adjusted for potential confounders, including age, sex, history of cardiovascular disease, smoking, educational attainment, and use of statins or blood pressure medications. Association was tested with gray and white matter volume, white matter lesion volume, gray matter cerebral blood flow, and white and gray matter fractional anisotropy and mean diffusivity.

RESULTS

Adjusting for multiple comparisons, T2D status was associated with reduced white matter volume (p = 2.48 × 10(-6)) and reduced gray and white matter fractional anisotropy (p ≤ 0.001) in fully adjusted models, with a trend toward increased white matter lesion volume (p = 0.008) and increased gray and white matter mean diffusivity (p ≤ 0.031). Among T2D-affected participants, neither fasting glucose, glycated hemoglobin, nor diabetes duration were associated with the neuroimaging measures assessed (p > 0.05).

CONCLUSIONS

While T2D was significantly associated with MRI-derived neuroimaging measures, differences in glycemic control in T2D-affected individuals in the DHS Mind study do not appear to significantly contribute to variation in these measures. This supports the idea that the presence or absence of T2D, not fine gradations of glycemic control, may be more significantly associated with age-related changes in the brain.

The Effect of Diabetes Mellitus on Apoptosis in Hippocampus: Cellular and Molecular Aspects

Background:

Diabetes mellitus is associated with cognitive deficits in humans and animals. These deficits are paralleled by neurophysiological and structural changes in brain. In diabetic animals, impairments of spatial learning, memory, and cognition occur in association with distinct changes in hippocampus, a key brain area for many forms of learning and memory and are particularly sensitive to changes in glucose homeostasis. However, the multifactorial pathogenesis of diabetic encephalopathy is not yet completely understood. Apoptosis plays a crucial role in diabetes-induce neuronal loss in hippocampus.

Methods:

The effects of diabetes on hippocampus and cognitive/behavioral dysfunctions in experimental models of diabetes are reviewed, with a focus on the negative impact on increased neuronal apoptosis and related cellular and molecular mechanisms.

Results:

Of all articles that were assessed, most of the experimental studies clearly showed that diabetes causes neuronal apoptosis in hippocampus through multiple mechanisms, including oxidative stress, inhibition of caspases, disturbance in expression of apoptosis regulator genes, as well as deficits in mitochondrial function. The balance between pro-apoptotic and anti-apoptotic signaling may determine the neuronal apoptotic outcome in vitro and in vivo models of experimental diabetes.

Conclusions:

Dissecting out the mechanisms responsible for diabetes-related changes in the hippocampal cell apoptosis helps improve treatment of impaired cognitive and memory functions in diabetic individuals.

Associations between anxiety and depression symptoms and cognitive testing and neuroimaging in type 2 diabetes

AIMS

Anxiety, depression, accelerated cognitive decline, and increased risk of dementia are observed in individuals with type 2 diabetes. Anxiety and depression may contribute to lower performance on cognitive tests and differences in neuroimaging observed in individuals with type 2 diabetes.

METHODS

These relationships were assessed in 655 European Americans with type 2 diabetes from 504 Diabetes Heart Study families. Participants completed cognitive testing, brain magnetic resonance imaging, the Brief Symptom Inventory Anxiety subscale, and the Center for Epidemiologic Studies Depression-10.

RESULTS

In analyses adjusted for age, sex, educational attainment, and use of psychotropic medications, individuals with comorbid anxiety and depression symptoms had lower performance on all cognitive testing measures assessed (p≤0.005). Those with both anxiety and depression also had increased white matter lesion volume (p=0.015), decreased gray matter cerebral blood flow (p=4.43×10(-6)), decreased gray matter volume (p=0.002), increased white and gray matter mean diffusivity (p≤0.001), and decreased white matter fractional anisotropy (p=7.79×10(-4)). These associations were somewhat attenuated upon further adjustment for health status related covariates.

CONCLUSIONS

Comorbid anxiety and depression symptoms were associated with cognitive performance and brain structure in a European American cohort with type 2 diabetes.

Selectively Disrupted Functional Connectivity Networks in Type 2 Diabetes Mellitus

BACKGROUND

The high prevalence of type 2 diabetes mellitus (T2DM) in individuals over 65 years old and cognitive deficits caused by T2DM have attracted broad attention. The pathophysiological mechanism of T2DM-induced cognitive impairments, however, remains poorly understood. Previous studies have suggested that the cognitive impairments can be attributed not only to local functional and structural abnormalities but also to specific brain networks. Thus, our aim is to investigate the changes of global networks selectively affected by T2DM.

METHODS

A resting state functional network analysis was conducted to investigate the intrinsic functional connectivity in 37 patients with diabetes and 40 healthy controls who were recruited from local communities in Beijing, China.

RESULTS

We found that patients with T2DM exhibited cognitive function declines and functional connectivity disruptions within the default mode network, left frontal parietal network, and sensorimotor network. More importantly, the fasting glucose level was correlated with abnormal functional connectivity.

CONCLUSION

These findings could help to understand the neural mechanisms of cognitive impairments in T2DM and provide potential neuroimaging biomarkers that may be used for early diagnosis and intervention in cognitive decline.

Vascular factors and multiple measures of early brain health: CARDIA brain MRI study

OBJECTIVE

To identify early changes in brain structure and function that are associated with cardiovascular risk factors (CVRF).

DESIGN

Cross-sectional brain Magnetic Resonance I (MRI) study.

SETTING

Community based cohort in three U.S. sites.

PARTICIPANTS

A Caucasian and African-American sub-sample (n= 680; mean age 50.3 yrs) attending the 25 year follow-up exam of the Coronary Artery Risk Development in Young Adults Study.

PRIMARY AND SECONDARY OUTCOMES

3T brain MR images processed for quantitative estimates of: total brain (TBV) and abnormal white matter (AWM) volume; white matter fractional anisotropy (WM-FA); and gray matter cerebral blood flow (GM-CBF). Total intracranial volume is TBV plus cerebral spinal fluid (TICV). A Global Cognitive Function (GCF) score was derived from tests of speed, memory and executive function.

RESULTS

Adjusting for TICV and demographic factors, current smoking was significantly associated with lower GM-CBF and TBV, and more AWM (all <0.05); SA with lower GM-CBF, WM-FA and TBV (p=0.01); increasing BMI with decreasing GM-CBF (p<0003); hypertension with lower GM-CBF, WM-FA, and TBV and higher AWM (all <0.05); and diabetes with lower TBV (p=0.007). The GCS was lower as TBV decreased, AWM increased, and WM-FA (all p<0.01).

CONCLUSION

In middle age adults, CVRF are associated with brain health, reflected in MRI measures of structure and perfusion, and cognitive functioning. These findings suggest markers of mid-life cardiovascular and brain health should be considered as indication for early intervention and future risk of late-life cerebrovascular disease and dementia.

Prediabetes and associated disorders

Prediabetes represents an elevation of plasma glucose above the normal range but below that of clinical diabetes. Prediabetes includes individuals with IFG, IGT, IFG with IGT and elevated HbA1c levels. Insulin resistance and β-cell dysfunction are characteristic of this disorder. The diagnosis of prediabetesis is vital as both IFG and IGT are indeed well-known risk factors for type 2 diabetes with a greater risk in the presence of combined IFG and IGT. Furthermore, as will be illustrated in this review, prediabetes is associated with associated disorders typically only considered in with established diabetes. These include cardiovascular disease, periodontal disease, cognitive dysfunction, microvascular disease, blood pressure abnormalities, obstructive sleep apnea, low testosterone, metabolic syndrome, various biomarkers, fatty liver disease, and cancer. As the vast majority of individuals with prediabetes are unaware of their diagnosis, it is therefore vital that the associated conditions are identified, particularly in the presence of mild hyperglycemia, so they may benefit from early intervention.

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.

The cross-sectional and longitudinal associations of diabetic retinopathy with cognitive function and brain MRI findings: the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial

OBJECTIVE

Longitudinal evidence linking diabetic retinopathy with changes in brain structure and cognition is sparse. We used data from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial to determine whether diabetic retinopathy at baseline predicted changes in brain structure or cognition 40 months later.

RESEARCH DESIGN AND METHODS

Participants from the ACCORD-MIND and ACCORD-Eye substudies were included in analyses of cognition (n = 1,862) and MRI-derived brain variables (n = 432). Retinopathy was categorized as none, mild nonproliferative, or moderate/severe. Tests of cognition included the Mini-Mental State Examination (MMSE), Digit Symbol Substitution Test (DSST), Rey Auditory Verbal Learning Test, and Stroop test. Primary brain outcomes were gray matter and abnormal white matter volumes.

RESULTS

Baseline retinopathy was associated with lower gray matter volume (adjusted means of 470, 466, and 461 cm(3) for none, mild, and moderate/severe retinopathy, respectively; P = 0.03). Baseline retinopathy also predicted a greater change in MMSE and DSST scores at 40 months in each retinopathy category (MMSE: -0.20, -0.57, and -0.42, respectively [P = 0.04]; DSST: -1.30, -1.84, and -2.89, respectively [P = 0.01]).

CONCLUSIONS

Diabetic retinopathy is associated with future cognitive decline in people with type 2 diabetes. Although diabetic retinopathy is not a perfect proxy for diabetes-related brain and cognitive decline, patients with type 2 diabetes and retinopathy represent a subgroup at higher risk for future cognitive decline.