Spatial patterns of structural brain changes in type 2 diabetic patients and their longitudinal progression with intensive control of blood glucose

An unexpected interaction between diabetes and cardiovascular diseases on cognitive function: A cross-sectional study

OBJECTIVE

Impaired cognitive function in older individuals significantly affects quality of life. The interaction between comorbid diabetes and cardiovascular disease (CVD) and its impact on cognitive impairment remains unclear.

METHODS

This study analyzed 2564 subjects from the National Health and Nutrition Examination Survey dataset. Cognitive function was measured using various scores, including CERAD Total Score, CERAD Delayed Recall Score (CDRS), Animal Fluency Total Score, and Digit Symbol Score. Multiple regression models were constructed to explore the relationship between different diseases and cognitive function, considering covariates such as age, sex, education, body mass index, alcohol intake, smoking, physical activity, kidney function, and hypertension.

RESULTS

After adjusting for multiple factors, the presence of CVD, diabetes, or both showed a significant negative association with the total cognitive score. The CDRS was associated with both CVD and diabetes. The Digit Symbol score was associated with the presence of CVD, diabetes, or both. No significant differences were found between patients with diabetes and CVD in cognitive test results. An interaction between CVD and diabetes was observed in relation to the CDRS but not in other test scores or the total score.

CONCLUSION

The individual impact of each disease on cognitive function was not significant. However, an interaction between CVD and diabetes was found when both diseases coexisted, specifically in relation to delayed learning ability.

Diabetes mellitus in older persons with neurocognitive disorder: overtreatment prevalence and associated structural brain MRI findings

BACKGROUND

Tight diabetes control is often applied in older persons with neurocognitive disorder resulting in increased hypoglycemic episodes but little is known about the pattern of brain injury in these overtreated patients. This study aims to: (a) quantify the prevalence of diabetes overtreatment in cognitively impaired older adults in a clinical population followed in an academic memory clinic (b) identify risk factors contributing to overtreatment; and (c) explore the association between diabetes overtreatment and specific brain region volume changes.

METHODS

Retrospective study of older patients with type 2 diabetes and cognitive impairment who were diagnosed in a memory clinic from 2013 to 2020. Patients were classified into vulnerable and dependent according to their health profile. Overtreatment was defined when glycated hemoglobin was under 7% for vulnerable and 7.6% for dependent patients. Characteristics associated to overtreatment were examined in multivariable analysis. Grey matter volume in defined brain regions was measured from MRI using voxel-based morphometry and compared in patients over- vs. adequately treated.

RESULTS

Among 161 patients included (median age 76.8 years, range 60.8-93.3 years, 32.9% women), 29.8% were considered as adequately treated, 54.0% as overtreated, and 16.2% as undertreated. In multivariable analyses, no association was observed between diabetes overtreatment and age or the severity of cognitive impairment. Among patients with neuroimaging data (N = 71), associations between overtreatment and grey matter loss were observed in several brain regions. Specifically, significant reductions in grey matter were found in the caudate (adj β coeff: -0.217, 95%CI: [-0.416 to -0.018], p = .033), the precentral gyri (adj βcoeff:-0.277, 95%CI: [-0.482 to -0.073], p = .009), the superior frontal gyri (adj βcoeff: -0.244, 95%CI: [-0.458 to -0.030], p = .026), the calcarine cortex (adj βcoeff:-0.193, 95%CI: [-0.386 to -0.001], p = .049), the superior occipital gyri (adj βcoeff: -0.291, 95%CI: [-0.521 to -0.061], p = .014) and the inferior occipital gyri (adj βcoeff: -0.236, 95%CI: [-0.456 to - 0.015], p = .036).

CONCLUSION

A significant proportion of older patients with diabetes and neurocognitive disorder were subjected to excessively intensive treatment. The association identified with volume loss in several specific brain regions highlights the need to further investigate the potential cerebral damages associated with overtreatment and related hypoglycemia in larger sample.

Irreversible atrophy in memory brain regions over 7 years is predicted by glycemic control in type 2 diabetes without mild cognitive impairment

Memory-related impairments in type 2 diabetes may be mediated by insulin resistance and hyperglycemia. Previous cross-sectional studies have controversially suggested a relationship between metabolic control and a decrease in hippocampal volumes, but only longitudinal studies can test this hypothesis directly. We performed a longitudinal morphometric study to provide a direct test of a possible role of higher levels of glycated hemoglobin with long term brain structural integrity in key regions of the memory system - hippocampus, parahippocampal gyrus and fusiform gyrus. Grey matter volume was measured at two different times - baseline and after ~7 years. We found an association between higher initial levels of HbA1C and grey matter volume loss in all three core memory regions, even in the absence of mild cognitive impairment. Importantly, these neural effects persisted in spite of the fact that patients had significantly improved their glycemic control. This suggests that early high levels of HbA1c might be irreversibly associated with subsequent long-term atrophy in the medial temporal cortex and that early intensive management is critical.

Prevalence of sarcopenic obesity in patients with diabetes and adverse outcomes: A systematic review and meta-analysis

BACKGROUND & AIMS

Sarcopenic obesity (SO), which refers to the coexistence of sarcopenia and obesity. The aim of this systematic review and meta-analysis was first to assess the prevalence of SO in patients with diabetes, and second, to evaluate possible adverse outcomes.

METHODS

This study was conducted in adherence to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines and the data were collated by means of meta-analysis and narrative synthesis. We comprehensively and systematically searched PubMed, Embase, Web of Science, CBM, CNKI, Wanfang Database from the establishment of the database to December 2022, and collected related studies on SO in patients with diabetes. Using Stata 16.0 software to pool the estimates for the prevalence of SO in patients with diabetes, and a descriptive systematic review of possible adverse outcomes was performed.

RESULTS

The prevalence of 20 included studies were pooled by a random-effects model, which showed that the prevalence of SO in patients with diabetes was 27%. Subgroup analyses showed that the prevalence of SO was higher among studies using BIA (24%) to assess muscle mass, and those focused on literature of moderate-quality (29%), being published from 2013 to 2016 (29%), female patients with diabetes (17%), North Americans (30%). SO in patients with diabetes can lead to adverse outcomes including decreased glomerular filtration rate, massive proteinuria, cognitive decline, and insulin resistance.

CONCLUSION

The systematic review and meta-analysis revealed a prevalence of 27% for SO in patients with diabetes, and it is associated with potential serious adverse outcomes. Therefore, we should attach importance to the screening of SO in patients with diabetes and early detection of susceptible groups, then selecting appropriate interventions to reduce the occurrence of it and various adverse outcomes in this demographic.

The Role of Iron Overload in Diabetic Cognitive Impairment: A Review

It is well documented that diabetes mellitus (DM) is strongly associated with cognitive decline and structural damage to the brain. Cognitive deficits appear early in DM and continue to worsen as the disease progresses, possibly due to different underlying mechanisms. Normal iron metabolism is necessary to maintain normal physiological functions of the brain, but iron deposition is one of the causes of some neurodegenerative diseases. Increasing evidence shows that iron overload not only increases the risk of DM, but also contributes to the development of cognitive impairment. The current review highlights the role of iron overload in diabetic cognitive impairment (DCI), including the specific location and regulation mechanism of iron deposition in the diabetic brain, the factors that trigger iron deposition, and the consequences of iron deposition. Finally, we also discuss possible therapies to improve DCI and brain iron deposition.

Polyphenols and Neurodegenerative Diseases: Potential Effects and Mechanisms of Neuroprotection

The increase in people's longevity has, consequently, led to more brain involvement and neurodegenerative diseases, which can become complicated and lead to chronic degenerative diseases, thereby presenting greater public health problems. Medicinal plants have been used since ancient times and contain high concentrations of molecules, including polyphenols. It has been proven that polyphenols, which are present in various natural sources can provide curative effects against various diseases and brain disorders through neuroprotective effects. These neuroprotective effects are mainly attributed to their ability to cross the blood-brain barrier, eliminate reactive oxygen species, and cause the chelation of metal ions. Polyphenols increase the concentration of neurotrophic factors and bind directly to the membrane receptors of these neurotrophic factors, to modulate and activate the signaling cascades that allow the plasticity, survival, proliferation, and growth of neuronal cells, thereby allowing for better learning, memory, and cognition. Moreover, polyphenols have no serious adverse side effects resulting from their consumption.

A randomized controlled trial to test the efficacy of a diabetes behavioral intervention to prevent memory decline in older blacks/African Americans with diabetes and mild cognitive impairment

BACKGROUND

The prevalence of dementia in Blacks/African Americans (AAs) is almost twice that of Whites. Inequities in access to health care, socioeconomic conditions, and diabetes contribute to this disparity. Poorly controlled diabetes, which is more prevalent in Blacks/AAs, causes microvascular disease and neurodegeneration and increases dementia risk. Improving glycemic control, therefore, may prevent cognitive decline. To address this issue, we developed Diabetes Regulation for Eyesight and Memory (DREAM), a community health worker (CHW)-led behavioral intervention to improve diabetes self-management and thereby prevent cognitive decline. DREAM consists of home-based diabetes education, goal setting, and telehealth visits with a diabetes nurse educator. Exploratory aims will investigate whether APOE genotype moderates and retinal biomarkers mediate treatment effects. This report describes the trial's rationale, methodology, and study procedures. (clinicaltrials.gov identifier NCT04259047).

METHODS

This randomized controlled trial will test the efficacy of DREAM to prevent decline in memory (primary outcome) in Blacks/AAs aged 65+ with poorly controlled diabetes and Mild Cognitive Impairment (MCI). Two hundred participants will be randomized to DREAM or an attention control condition, and will receive 11 in-home treatment sessions over two years. Outcome data are collected at 6, 12, 18, and 24 months. The primary outcome is verbal learning as measured by Hopkins Verbal Learning Test (HVLT) Total Recall scores. Participants will have retinal imaging at baseline, 12, and 24 months.

CONCLUSIONS

This research aims to prevent cognitive decline in older Blacks/AAs with diabetes and MCI. If successful, this research will preserve health in an underserved population and reduce racial health disparities.

Altered cortical thickness, degree centrality, and functional connectivity in middle-age type 2 diabetes mellitus

PURPOSE

This study aimed to investigate the changes in brain structure and function in middle-aged patients with type 2 diabetes mellitus (T2DM) using morphometry and blood oxygen level-dependent functional magnetic resonance imaging (BOLD-fMRI).

METHODS

A total of 44 middle-aged patients with T2DM and 45 matched healthy controls (HCs) were recruited. Surface-based morphometry (SBM) was used to evaluate the changes in brain morphology. Degree centrality (DC) and functional connectivity (FC) were used to evaluate the changes in brain function.

RESULTS

Compared with HCs, middle-aged patients with T2DM exhibited cortical thickness reductions in the left pars opercularis, left transverse temporal, and right superior temporal gyri. Decreased DC values were observed in the cuneus and precuneus in T2DM. Hub-based FC analysis of these regions revealed lower connectivity in the bilateral hippocampus and parahippocampal gyrus, left precuneus, as well as left frontal sup.

CONCLUSION

Cortical thickness, degree centrality, as well as functional connectivity were found to have significant changes in middle-aged patients with T2DM. Our observations provide potential evidence from neuroimaging for analysis to examine diabetes-related brain damage.

Convolutional Neural Networks for Classification of T2DM Cognitive Impairment Based on Whole Brain Structural Features

Purpose

Cognitive impairment is generally found in individuals with type 2 diabetes mellitus (T2DM). Although they may not have visible symptoms of cognitive impairment in the early stages of the disorder, they are considered to be at high risk. Therefore, the classification of these patients is important for preventing the progression of cognitive impairment.

Methods

In this study, a convolutional neural network was used to construct a model for classifying 107 T2DM patients with and without cognitive impairment based on T1-weighted structural MRI. The Montreal cognitive assessment score served as an index of the cognitive status of the patients.

Results

The classifier could identify T2DM-related cognitive decline with a classification accuracy of 84.85% and achieved an area under the curve of 92.65%.

Conclusions

The model can help clinicians analyze and predict cognitive impairment in patients and enable early treatment.

Long-term exposure to high glucose induces changes in the expression of AMPA receptor subunits and glutamate transmission in primary cultured cortical neurons

Hyperglycemia, which occurs under the diabetic conditions, induces serious diabetic complications. Diabetic encephalopathy has been defined as one of the major complications of diabetes, and is characterized by neurochemical and neurodegenerative changes. However, little is known about the effect of long-term exposure to high glucose on neuronal cells. In the present study, we showed that exposure to glutamate (100 mM) for 7 days induced toxicity in primary cortical neurons using the MTT assay. Additionally, high glucose increased the sensitivity of AMPA- or NMDA-induced neurotoxicity, and decreased extracellular glutamate levels in primary cortical neurons. In Western blot analyses, the protein levels of the GluA1 and GluA2 subunits of the AMPA receptor as well as synaptophysin in neurons treated with high glucose were significantly increased compared with the control (25 mM glucose). Therefore, long-term exposure to high glucose induced neuronal death through the disruption of glutamate homeostasis.

The Effect of Type-2 Diabetes on Cognitive Status and the Role of Anti-diabetes Medications

Type-2 diabetes mellitus prevalence is constantly increasing; this is explained by the increase of its risk factors and the amelioration of its management. Therefore, people are living longer with diabetes mellitus, which, in turn, has revealed new complications of the disease. Dementia is represented mainly by Alzheimer's disease and is an interesting topic of study. Accordingly, statistics have shown that dementia incidence is doubled in diabetic patients. The establishment of a relation between type-2 diabetes mellitus was studied on several levels in both humans and animal subjects. First, insulin receptors were found in the brain, especially the hippocampus, and insulin transport to the brain is mainly accomplished through the blood-brain barrier. Secondly, several studies showed that insulin affects multiple neurotransmitters in favor of promoting memory and cognition status. Thirdly, multiple pathological studies showed that insulin and Alzheimer's disease share many common lesions in the brain, such as beta-amyloid plaques, amylin-Aβ plaques, hyper-phosphorylated tau protein, and brain atrophy, especially in the hippocampus. After recognizing the positive effect of insulin on cognitive status, and the harmful effect of insulin resistance on cognitive status, multiple studies were focused on the role of anti-diabetes medications in fighting dementia. Consequently, these studies showed a positive impact of oral anti-diabetes medication, as well as insulin in limiting the progression of dementia and promoting cognitive status. Moreover, their effects were also noticed on limiting the pathological lesions of Alzheimer's disease. Accordingly, we can consider type-2 diabetes mellitus as a risk factor for dementia and Alzheimer's disease. Therefore, this can be used on the pharmaceutical level by the promising implication of antidiabetics as a treatment of dementia and Alzheimer's disease or at least to limit its progression. However, multiple clinical studies should be dedicated to proving the true benefits of anti-diabetes medications in treating dementia before they can be used in reality.

Altered Gray Matter Volume, Functional Connectivity, and Degree Centrality in Early-Onset Type 2 Diabetes Mellitus

Background: Structural and functional brain alterations that underlie cognitive decline have been observed in elderly adults with type 2 diabetes mellitus (T2DM); however, whether these alterations can be observed in patients with early-onset T2DM remains unclear. Therefore, we aimed to describe the abnormalities in brain volume and functional patterns in patients with early-onset T2DM in the present study.

Methods: We enrolled 20 patients with early-onset T2DM and 20 healthy controls (HCs). Changes in brain volume were assessed using voxel-based morphology (VBM), while changes in brain function were assessed using degree centrality (DC) and functional connectivity (FC).

Results: Compared to HCs, patients with early-onset T2DM exhibited gray matter reductions in the left orbital superior, middle, and inferior frontal gyri as well as the right superior frontal gyrus. The gray matter reductions in the right superior frontal gyrus were negatively associated with the urine albumin to creatinine ratio. Furthermore, increased DC values were observed in the left superior temporal gyrus, left Heschl gyrus, and left hippocampus in patients with early-onset T2DM. An FC analysis of these regions revealed elevated connectivity in the right precuneus, left inferior parietal gyrus, left Heschl gyrus, bilateral post-central gyrus, bilateral insula, bilateral superior temporal gyrus, and bilateral medial and paracingulate gyrus. Furthermore, the FC of the hubs to the superior temporal gyrus, insula, and Heschl gyrus was increased and positively correlated with trail making test-B.

Conclusion: Decreased local gray matter volume and increased DC and FC may represent the neurobiological mechanism underlying cognitive dysfunction in patients with early-onset T2DM.

Glycemic Control, Diabetic Complications, and Risk of Dementia in Patients With Diabetes: Results From a Large U.K. Cohort Study

OBJECTIVE

Type 2 diabetes is an established risk factor for dementia. However, the roles of glycemic control and diabetic complications in the development of dementia have been less well substantiated. This large-scale cohort study aims to examine associations of longitudinal HbA_1c levels and diabetic complications with the risk of dementia incidence among patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Data of eligible patients with diabetes, aged ≥50 years in the U.K. Clinical Practice Research Datalink from 1987 to 2018, were analyzed. Time-varying Cox regressions were used to estimate adjusted hazard ratios (HRs) and 95% CIs for dementia risk.

RESULTS

Among 457,902 patients with diabetes, 28,627 (6.3%) incident dementia cases were observed during a median of 6 years' follow-up. Patients with recorded hypoglycemic events or microvascular complications were at higher risk of dementia incidence compared with those without such complications (HR 1.30 [95% CI 1.22-1.39] and 1.10 [1.06-1.14], respectively). The HbA_1c level, modeled as a time-varying exposure, was associated with increased dementia risk (HR 1.08 [95% CI 1.07-1.09] per 1% HbA_1c increment) among 372,287 patients with diabetes with postdiagnosis HbA_1c records. Similarly, a higher coefficient of variation of HbA_1c during the initial 3 years of follow-up was associated with higher subsequent dementia risk (HR 1.03 [95% CI 1.01-1.04] per 1-SD increment).

CONCLUSIONS

Higher or unstable HbA_1c levels and the presence of diabetic complications in patients with type 2 diabetes are associated with increased dementia risk. Effective management of glycemia might have a significant role in maintaining cognitive health among older adults with diabetes.

Citrus Polyphenols in Brain Health and Disease: Current Perspectives

In addition to essential micronutrients such as vitamin C, citrus fruits represent a considerably rich source of non-essential bioactive compounds, in particular flavanones which form a sub-set of the flavonoid group. Preclinical studies have demonstrated the neuroprotective potential of citrus flavonoids and have highlighted both the well-established (anti-inflammatory and anti-oxidative properties), and newly emerging (influence upon blood-brain barrier function/integrity) mechanistic actions by which these neurological effects are mediated. Encouragingly, results from human studies, although limited in number, appear to support this preclinical basis, with improvements in cognitive performance and disease risk observed across healthy and disease states. Therefore, citrus fruits - both as whole fruit and 100% juices - should be encouraged within the diet for their potential neurological benefit. In addition, there should be further exploration of citrus polyphenols to establish therapeutic efficacy, particularly in the context of well-designed human interventions.

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.

Glucose control and cognitive and physical function in adults 80+ years of age with diabetes

INTRODUCTION

We modeled associations between glycated hemoglobin (HbA1c) levels (<7%, 7% to 8%, and >8%) and cognitive and physical function among adults 80+ years of age with diabetes and determined whether associations differ by frailty, multimorbidity, and disability.

METHODS

A total of 316, adults with diabetes, 80+ years of age, were from the Adult Changes in Thought Study. The Cognitive Abilities Screening Instrument Item Response Theory (CASI-IRT) measured cognition. Short performance-based physical function (sPPF) and gait speed measured physical function. Glycosylated hemoglobin (HbA1c) levels were from clinical measurements. Analyses estimated associations between average HbA1c levels (<7%, 7% to 8%, and >8%) and functional outcomes using linear regressions estimated with generalized estimating equations.

RESULTS

sPPF scores did not differ significantly by HbA1c levels. Gait speed did, but only for non-frail individuals; those with HbA1c >8% were slower (-0.10 m/s [95% CI, -0.16 to -0.04]) compared to those with HbA1c 7% to 8%. The association between HbA1c and CASI-IRT varied with age (interaction P = 0.04). At age 80, for example, relative to people with HbA1c levels of 7% to 8%, CASI-IRT scores were, on average, 0.18 points lower (95% CI, -0.35 to -0.02) for people with HbA1c <7% and 0.22 points lower (95% CI, -0.40 to -0.05) for people with HbA1c >8%. At older ages, these estimated differences were attenuated. Estimated associations were not modified by multimorbidity or disability.

DISCUSSION

Moderate HbA1c levels of 7% to 8% were associated with better cognition in early but not late octogenarians with diabetes. Furthermore, HbA1c >8% was associated with slower gait speed among those without frailty. These results add to an evidence base for determining glucose targets for very old adults with diabetes.

Prefrontal cortex brain damage and glycemic control in patients with type 2 diabetes

BACKGROUND

This study examined brain tissue integrity in sites that controls cognition (prefrontal cortices; PFC) and its relationships to glycemic outcomes in adults with type 2 diabetes mellitus (T2DM).

METHODS

We examined 28 T2DM patients (median age 57.1 years; median body mass index [BMI] 30.6 kg/m2 ;11 males) and 47 healthy controls (median age 55.0 years; median BMI 25.8 kg/m2 ; 29 males) for cognition (Montreal Cognitive Assessment [MoCA]), glycemic control (hemoglobin A1c [HbA1c]), and PFC tissue status via brain magnetic resonance imaging (MRI). High-resolution T1-weighted images were collected using a 3.0-Tesla MRI scanner, and PFC tissue changes (tissue density) were examined with voxel-based morphometry procedures.

RESULTS

Reduced PFC density values were observed in T2DM patients compared to controls (left, 0.41 ± 0.02 mm3 /voxel vs 0.44 ± 0.02 mm3 /voxel, P < 0.001; right, 0.41 ± 0.03 mm3 /voxel vs 0.45 ± 0.02 mm3 /voxel, P < 0.001). PFC density values were positively correlated with cognition; left PFC region (r = 0.53, P = 0.005) and right PFC region (r = 0.56, P = 0.003), with age and sex as covariates. Significant negative correlations were found between PFC densities and HbA1c values; left PFC region (r = -0.39, P = 0.049) and right PFC region (r = -0.48, P = 0.01), with age and sex as covariates.

CONCLUSIONS

T2DM patients showed PFC brain tissue damage, which is associated with cognitive deficits and poor glycemic control. Further research is needed to identify causal relationships between HbA1c, cognition, and brain changes in T2DM and to evaluate the impact of interventions to prevent brain tissue injury or neuroregeneration in this high-risk patient population, to eventually preserve or enhance cognition and improve glucose outcomes.

Brain and Body: A Review of Central Nervous System Contributions to Movement Impairments in Diabetes

Diabetes is associated with a loss of somatosensory and motor function, leading to impairments in gait, balance, and manual dexterity. Data-driven neuroimaging studies frequently report a negative impact of diabetes on sensorimotor regions in the brain; however, relationships with sensorimotor behavior are rarely considered. The goal of this review is to consider existing diabetes neuroimaging evidence through the lens of sensorimotor neuroscience. We review evidence for diabetes-related disruptions to three critical circuits for movement control: the cerebral cortex, the cerebellum, and the basal ganglia. In addition, we discuss how central nervous system (CNS) degeneration might interact with the loss of sensory feedback from the limbs due to peripheral neuropathy to result in motor impairments in individuals with diabetes. We argue that our understanding of movement impairments in individuals with diabetes is incomplete without the consideration of disease complications in both the central and peripheral nervous systems. Neuroimaging evidence for disrupted central sensorimotor circuitry suggests that there may be unrecognized behavioral impairments in individuals with diabetes. Applying knowledge from the existing literature on CNS contributions to motor control and motor learning in healthy individuals provides a framework for hypothesis generation for future research on this topic.

BRAIN FUNCTION ALTERATIONS IN PATIENTS WITH DIABETIC NEPHROPATHY COMPLICATED BY RETINOPATHY UNDER RESTING STATE CONDITIONS ASSESSED BY VOXEL-MIRRORED HOMOTOPIC CONNECTIVITY

Objective: The voxel-mirrored homologous connection (VHMC) technique was applied to detect resting brain function alterations in patients with diabetic nephropathy and retinopathy (DNR), and their relationships with clinical manifestations in the kidneys and eyes are discussed. Methods: Twenty-two patients with DNR and 22 healthy controls (HCs) similarly matched in age, sex, and educational background were recruited. Resting-state functional magnetic resonance imaging scans were performed for all subjects. Retinal fundus photography and renal biopsy were employed to observe the clinical features of the kidney and retina. Pearson correlation analysis was used to analyze the relationship between clinical manifestations and experimental results. Results: Compared with the HCs, patients with DNR showed decreased mean VMHC values in the bilateral middle temporal gyrus, bilateral middle occipital gyrus (BMOG), and bilateral medial frontal gyrus. The receiver operating characteristic curve analysis of each brain region confirmed that the accuracy of the area under the curve was excellent. The results showed that the average VHMC value of BMOG signals was positively correlated with the urinary protein to creatinine ratio in female subjects (r = 0.626; P<.05). Nonetheless, no such correlation was noted among the male subjects. Conclusion: There were significant changes in brain function in DNR patients compared to the control group. Changes in the central nervous system in patients with DNR were mainly due to the dual negative effects of kidney function and diabetes mellitus. Abbreviations: ACR = albumin/creatinine ratio; BMFG = bilateral medial frontal gyrus; BMOG = bilateral middle occipital gyrus; BMTG = bilateral middle temporal gyrus; DN = diabetic nephropathy; DNR = diabetic nephropathy complicated by retinopathy; DR = diabetic retinopathy; fMRI = functional magnetic resonance imaging; HC = healthy control; MRI = magnetic resonance imaging; PCR = protein to creatinine ratio; ROC = receiver operating characteristic; VHMC = voxel-mirrored homologous connection.

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.

Compensatory Hippocampal Connectivity in Young Adults With Early-Stage Type 2 Diabetes

CONTEXT

Middle-aged to elderly patients with type 2 diabetes mellitus (T2DM) exhibit reduced functional connectivity and brain atrophy underlying cognitive decrements; however, little is known about brain abnormalities in young patients.

OBJECTIVE

To detect brain anatomical and functional changes in young patients with T2DM during the early disease stage.

DESIGN

Case-control study.

SETTING

Tertiary referral hospital.

PARTICIPANTS

Thirty-five young patients with T2DM (<40 years of age) with no detectable microangiopathy and 32 nondiabetic control subjects.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Subjects underwent neuropsychological assessments and structural and resting-state functional MRI. Both voxel-based morphometry and resting-state functional connectivity analyses were performed.

RESULTS

No significant differences in brain volume were observed between the patients with T2DM and the controls after controlling for age, sex, education, and body mass index. Compared with the controls, the patients showed greater connectivity of the left hippocampus with the left inferior frontal gyrus and the left inferior parietal lobule. Moreover, the enhanced functional connectivity of left hippocampus with the left inferior frontal gyrus significantly correlated with disease severity (urinary albumin-to-creatinine ratio) (r = 0.613, P < 0.001) and executive function (completion time of Stroop Color and Word Test) (r = -0.461, P = 0.005) after false discovery rate correction.

CONCLUSIONS

Our findings suggest an adaptive compensation of brain function to counteract the insidious cognitive decrements during the early stage of T2DM. Additionally, the functional alterations occurring before changes in brain structure and peripheral microangiopathy might serve as early biomarkers related to cognitive decrements.

Reduced Gray Matter Volume of the Thalamus and Hippocampal Region in Elderly Healthy Adults with no Impact of APOE ɛ4: A Longitudinal Voxel-Based Morphometry Study

BACKGROUND

Many cross-sectional voxel-based morphometry (VBM) investigations have shown significant inverse correlations between chronological age and gray matter (GM) volume in several brain regions in healthy humans. However, few VBM studies have documented GM decrements in the healthy elderly with repeated MRI measurements obtained in the same subjects. Also, the extent to which the APOE ɛ4 allele influences longitudinal findings of GM reduction in the healthy elderly is unclear.

OBJECTIVE

Verify whether regional GM changes are associated with significant decrements in cognitive performance taking in account the presence of the APOE ɛ4 allele.

METHODS

Using structural MRI datasets acquired in 55 cognitively intact elderly subjects at two time-points separated by approximately three years, we searched for voxels showing significant GM reductions taking into account differences in APOE genotype.

RESULTS

We found global GM reductions as well as regional GM decrements in the right thalamus and left parahippocampal gyrus (p < 0.05, family-wise error corrected for multiple comparisons over the whole brain). These findings were not affected by APOE ɛ4.

CONCLUSIONS

Irrespective of APOE ɛ4, longitudinal VBM analyses show that the hippocampal region and thalamus are critical sites where GM shrinkage is greater than the degree of global volume reduction in healthy elderly subjects.

Inflammation associated with volume reduction in the gray matter and hippocampus of older patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) and aging appear to be associated with inflammatory activation. Inflammatory processes might affect hippocampal function, neurogenesis, and gray matter loss. This study investigated the relationship between BD-specific brain regions and the total gray matter volume, peripheral inflammatory markers, and clinical features in older patients with BD.

METHODS

We recruited euthymic patients with bipolar I disorder aged ≥50 years to undergo whole-brain magnetic resonance imaging. Each brain region was divided by an individual's total intracranial volume to obtain that brain region's volume in percentage relative to the total intracranial volume. We measured the plasma levels of soluble tumor necrosis factor receptor-1 (sTNF-R1), soluble interleukin (IL)-2 receptor (sIL-2R), sIL-6R, IL-1β, and IL-1 receptor antagonist when patients were euthymic. Clinical data were obtained by reviewing available medical records and interviewing patients along with their reliable others.

RESULTS

There were 32 patients with a mean age of 61.2 ± 8.3 years and a mean age at illness onset of 33.4 ± 13.8 years in this study. Stepwise regression showed that the right hippocampal volume was negatively associated with the levels of sIL-2R and sTNF-R1. The left hippocampal volume were negatively associated with the sIL-2R level and body mass index. The total gray matter volume had an inverse relationship with sTNF-R1 and IL-1β levels. The duration of bipolar illness, lithium treatment, and antipsychotic use were not associated with hippocampal and total gray matter volumes.

CONCLUSIONS

It is suggested that persistent inflammation is associated with reduction of hippocampal and gray matter volumes in older patients with BD. This phenomenon is supported by increases in sTNF-R1, sIL-2R, and IL-1β levels. Neuroinflammation due to aging, obesity, and BD pathophysiology may play a role in BD neuroprogression across the life span.

Accelerated executive functions decline and gray matter structural changes in middle-aged type 1 diabetes mellitus patients with proliferative retinopathy

BACKGROUND

The aim of the present study was to determine trajectories of cognitive and cortical changes over time in middle-aged patients with type 1 diabetes mellitus (T1DM) and proliferative retinopathy.

METHODS

Twenty-five patients and 25 controls underwent neuropsychological assessment and neuroimaging twice in a mean (±SD) of 3.56 ± 0.65 and 3.94 ± 0.91 years, respectively (P = 0.098). Cognitive assessment included the domains of general cognitive ability, memory, information processing speed, executive functions, attention, and motor and psychomotor speed. Symmetrized percentage change in local cortical thickness, surface area, and volume was determined using the FreeSurfer 6 vertex-wise general linear model method. Analyses were performed uncorrected and corrected for baseline systolic blood pressure and depressive symptoms.

RESULTS

In patients versus controls, accelerated executive function decline was accompanied by, but not related to, lower left frontal and temporal surface area, left parietal and right frontal thickness, and bilateral frontal and right posterior cingulate volume (family-wise error [FWE]-corrected P < 0.05 for all). In patients, lower executive performance was related to loss of right precuneus surface area (P_FWE  = 0.005). Higher HbA1c during follow-up was related to executive function decline (r = -0.509, P = 0.016) and loss of left hemisphere surface area (r_{corrected analysis}  = -0.555, P = 0.007).

CONCLUSIONS

After 3.5 years of follow-up, middle-aged T1DM patients with proliferative retinopathy, mild focal changes in executive functions, and cortical structure were found, which may indicate accelerated aging.

Examining stability of independent component analysis based on coefficient and component matrices for voxel-based morphometry of structural magnetic resonance imaging

Independent component analysis (ICA) on group-level voxel-based morphometry (VBM) produces the coefficient matrix and the component matrix. The former contains variability among multiple subjects for further statistical analysis, and the latter reveals spatial maps common for all subjects. ICA algorithms converge to local optimization points in practice and the mostly applied stability investigation approach examines the stability of the extracted components. We found that the practically stable components do not guarantee to produce the practically stable coefficients of ICA decomposition for the further statistical analysis. Consequently, we proposed a novel approach including two steps: (1), the stability index for the coefficient matrix and the stability index for the component matrix were examined, respectively; (2) the two indices were multiplied to analyze the stability of ICA decomposition. The proposed approach was used to study the sMRI data of Type II diabetes mellitus group and the healthy control group (HC). Group differences in VBM were found in the superior temporal gyrus. Besides, it was revealed that the VBMs of the region of the HC group were significantly correlated with Montreal Cognitive Assessment (MoCA) describing the level of cognitive disorder. In contrast to the widely applied approach to investigating the stability of the extracted components for ICA decomposition, we proposed to examine the stability of ICA decomposition by fusion the stability of both coefficient matrix and the component matrix. Therefore, the proposed approach can examine the stability of ICA decomposition sufficiently.

Relationships between cerebral structure and cognitive function in African Americans with type 2 diabetes

BACKGROUND

Relationships between cognitive function and brain structure remain poorly defined in African Americans with type 2 diabetes.

METHODS

Cognitive testing and cerebral magnetic resonance imaging in African Americans from the Diabetes Heart Study Memory IN Diabetes (n = 480) and Action to Control Cardiovascular Risk in Diabetes MIND (n = 104) studies were examined for associations. Cerebral gray matter volume (GMV), white matter volume (WMV) and white matter lesion volume (WMLV) and cognitive performance (Mini-mental State Exam [MMSE and 3MSE], Digit Symbol Coding (DSC), Stroop test, and Rey Auditory Verbal Learning Test) were recorded. Multivariable models adjusted for age, sex, BMI, scanner, intracranial volume, education, diabetes duration, HbA1c, LDL-cholesterol, smoking, hypertension and cardiovascular disease assessed associations between cognitive tests and brain volumes by study and meta-analysis.

RESULTS

Mean(SD) participant age was 60.1(7.9) years, diabetes duration 12.1(7.7) years, and HbA1c 8.3(1.7)%. In the fully-adjusted meta-analysis, lower GMV associated with poorer global performance on MMSE/3MSE (β̂ = 7.1 × 10-3, SE 2.4 × 10-3, p = 3.6 × 10-3), higher WMLV associated with poorer performance on DSC (β̂ = -3 × 10-2, SE 6.4 × 10-3, p = 5.2 × 10-5) and higher WMV associated with poorer MMSE/3MSE performance (β̂ = -7.1 × 10-3, SE = 2.4 × 10-3, p = 3.6 × 10-3).

CONCLUSIONS

In African Americans with diabetes, smaller GMV and increased WMLV associated with poorer performance on tests of global cognitive and executive function. These data suggest that WML burden and gray matter atrophy associate with cognitive performance independent of diabetes-related factors in this population.

Brain atrophy in middle-aged subjects with Type 2 diabetes mellitus, with and without microvascular complications

BACKGROUND

The rapid rise in Type 2 diabetes mellitus (T2DM) among young adults makes it important to understand structural changes in the brain at a presenile stage. This study examined global and regional brain atrophy in middle-aged adults with T2DM, with a focus on those without clinical evidence of microvascular complications.

METHODS

The study recruited 66 dementia-free middle-aged subjects (40 with T2DM, 26 healthy volunteers [HVs]). Patients were grouped according to the presence (T2DM-C; n = 20) or absence (T2DM-NC; n = 20) of diabetic microvascular complications. Global brain volume (including gray matter [GM] and white matter) was calculated based on voxel-based morphometry analysis. Regional GM volumes were further extracted using the anatomical automatic labeling template.

RESULTS

There was a significant difference in global brain volume among groups (P = 0.003, anova). Global brain volume was lower in T2DM-C patients than in both T2DM-NC patients and HVs (mean [±SD] 0.720 ± 0.024 vs 0.736 ± 0.021 and 0.743 ± 0.019, respectively; P = 0.032 and P = 0.001, respectively). Regional analysis showed significant GM atrophy in the right Rolandic operculum (t = 3.42, P = 0.001) and right superior temporal gyrus (t = 2.803, P = 0.007) in T2DM-NC patients compared with age- and sex-matched HVs.

CONCLUSIONS

Brain atrophy is present in dementia-free middle-aged adults with T2DM. Regional brain atrophy appears to be developing even in those with no clinical evidence of microvascular disturbances. The brain seems to be particularly vulnerable to metabolic disorders prior to peripheral microvascular pathologies associated with other target organs.

Vascular Contributions to Cognitive Impairment in Late Life

Cerebrovascular disease (CVD) is the second leading cause of cognitive impairment in late life. Structural neuroimaging offers the most sensitive and specific biomarkers for hemorrhages and infarcts, but there are significant limitations in its ability to detect microvascular disease, microinfarcts, dynamic changes in the blood-brain barrier, and preclinical cerebrovascular disease. Autopsy studies disclose the common co-occurrence of vascular and neurodegenerative conditions, suggesting that in late life, a multifactorial approach to cognitive impairment may be more appropriate than traditional dichotomous classifications. Management of vascular risk factors remains a proven and practical approach to reducing acute and progressive cognitive impairment and dementia.

Abnormal subcortical nuclei shapes in patients with type 2 diabetes mellitus

OBJECTIVES

Type 2 diabetes mellitus (T2DM) increases the risk of brain atrophy and dementia. We aimed to elucidate deep grey matter (GM) structural abnormalities and their relationships with T2DM cognitive deficits by combining region of interest (ROI)-based volumetry, voxel-based morphometry (VBM) and shape analysis.

METHODS

We recruited 23 T2DM patients and 24 age-matched healthy controls to undergo T1-weighted structural MRI scanning. Images were analysed using the three aforementioned methods to obtain deep GM structural shapes and volumes. Biochemical and cognitive assessments were made and were correlated with the resulting metrics.

RESULTS

Shape analysis revealed that T2DM is associated with focal atrophy in the bilateral caudate head and dorso-medial part of the thalamus. ROI-based volumetry only detected thalamic volume reduction in T2DM when compared to the controls. No significant between-group differences were found by VBM. Furthermore, a worse performance of cognitive processing speed correlated with more severe GM atrophy in the bilateral dorso-medial part of the thalamus. Also, the GM volume in the bilateral dorso-medial part of the thalamus changed negatively with HbA_1c.

CONCLUSIONS

Shape analysis is sensitive in identifying T2DM deep GM structural abnormalities and their relationships with cognitive impairments, which may greatly assist in clarifying the neural substrate of T2DM cognitive dysfunction.

KEY POINTS

• Type 2 diabetes mellitus is accompanied with brain atrophy and cognitive dysfunction • Deep grey matter structures are essential for multiple cognitive processes • Shape analysis revealed local atrophy in the dorso-medial thalamus and caudatum in patients • Dorso-medial thalamic atrophy correlated to cognitive processing speed slowing and high HbA1c. • Shape analysis has advantages in unraveling neural substrates of diabetic cognitive deficits.

HbA1c levels as a function of emotional regulation and emotional intelligence in patients with type 2 diabetes

AIMS

Understanding the role of emotion in glycemic control may be critical for the long-term treatment of patients with type 2 diabetes (T2D). In this study we investigated the relationship between measures of emotional regulation and emotional intelligence and HbA1c levels in adult patients with T2 diabetes.

METHODS

100 adult patients with T2 diabetes completed assessments of emotional regulation (i.e., affect intensity/lability) and emotional intelligence and were then correlated with HbA1c levels with several relevant covariates.

RESULTS

HbA1c levels were significantly associated with affect intensity (AI: r=.24, p=.018) and with emotional intelligence (EI: r=-.29, p=.004), but not affect lability. These results were the same even after adding income, state depression scores, insulin-dependent status, serum cholesterol, diabetes literacy and self-care as covariates (AI: β=.33, p=.001; EI: β=-.31, p=.002). Diabetes self-care, but not diabetes literacy, was also associated with HbA1c levels (β=-.29, p=.003).

CONCLUSIONS

These data suggest that aspects of emotional regulation and emotional intelligence play a role in glycemic control in adult patients with T2 diabetes and do so even in the context of several variables relevant to diabetes. If so, interventions that can reduce affect intensity and/or increase emotional intelligence may represent a new strategy in the glycemic control of adult patients with T2 diabetes.

Diabetes and Cognitive Impairment

Both type 1 (T1DM) and type 2 diabetes mellitus (T2DM) have been associated with reduced performance on multiple domains of cognitive function and with evidence of abnormal structural and functional brain magnetic resonance imaging (MRI). Cognitive deficits may occur at the very earliest stages of diabetes and are further exacerbated by the metabolic syndrome. The duration of diabetes and glycemic control may have an impact on the type and severity of cognitive impairment, but as yet we cannot predict who is at greatest risk of developing cognitive impairment. The pathophysiology of cognitive impairment is multifactorial, although dysfunction in each interconnecting pathway ultimately leads to discordance in metabolic signaling. The pathophysiology includes defects in insulin signaling, autonomic function, neuroinflammatory pathways, mitochondrial (Mt) metabolism, the sirtuin-peroxisome proliferator-activated receptor-gamma co-activator 1α (SIRT-PGC-1α) axis, and Tau signaling. Several promising therapies have been identified in pre-clinical studies, but remain to be validated in clinical trials.

Diagnostic potential of structural neuroimaging for depression from a multi-ethnic community sample

BACKGROUND

At present, we do not have any biological tests which can contribute towards a diagnosis of depression. Neuroimaging measures have shown some potential as biomarkers for diagnosis. However, participants have generally been from the same ethnic background while the applicability of a biomarker would require replication in individuals of diverse ethnicities.

AIMS

We sought to examine the diagnostic potential of the structural neuroanatomy of depression in a sample of a wide ethnic diversity.

METHOD

Structural magnetic resonance imaging (MRI) scans were obtained from 23 patients with major depressive disorder in an acute depressive episode (mean age: 39.8 years) and 20 matched healthy volunteers (mean age: 38.8 years). Participants were of Asian, African and Caucasian ethnicity recruited from the general community.

RESULTS

Structural neuroanatomy combining white and grey matter distinguished patients from controls at the highest accuracy of 81% with the most stable pattern being at around 70%. A widespread network encompassing frontal, parietal, occipital and cerebellar regions contributed towards diagnostic classification.

CONCLUSIONS

These findings provide an important step in the development of potential neuroimaging-based tools for diagnosis as they demonstrate that the identification of depression is feasible within a multi-ethnic group from the community.

DECLARATION OF INTERESTS

C.H.Y.F. has held recent research grants from Eli Lilly and Company and GlaxoSmithKline. L.M. is a former employee and stockholder of Eli Lilly and Company.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Gray matter alterations and correlation of nutritional intake with the gray matter volume in prediabetes

The neurophysiology of prediabetes plays an important role in preventive medicine. The dysregulation of glucose metabolism is likely linked to changes in neuron-related gray matter. Therefore, we designed this study to investigate gray matter alterations in medication-naive prediabetic patients. We expected to find alterations in the gray matter of prediabetic patients.A total of 64 prediabetic patients and 54 controls were enrolled. All subjects received T1 scans using a 3-T magnetic resonance imaging machine. Subjects also completed nutritional intake records at the 24-hour and 3-day time points to determine their carbohydrate, protein, fat, and total calorie intake. We utilized optimized voxel-based morphometry to estimate the gray matter differences between the patients and controls. In addition, the preprandial serum glucose level and the carbohydrate, protein, fat, and total calorie intake levels were tested to determine whether these parameters were correlated with the gray matter volume.Prediabetic patients had lower gray matter volumes than controls in the right anterior cingulate gyrus, right posterior cingulate gyrus, left insula, left super temporal gyrus, and left middle temporal gyrus (corrected P < 0.05; voxel threshold: 33). Gray matter volume in the right anterior cingulate was also negatively correlated with the preprandial serum glucose level gyrus in a voxel-dependent manner (r = -0.501; 2-tailed P = 0.001).The cingulo-temporal and insula gray matter alterations may be associated with the glucose dysregulation in prediabetic patients.

Diabetes, Gray Matter Loss, and Cognition in the Setting of Parkinson Disease

RATIONALE AND OBJECTIVES

Parkinson disease (PD) is a progressive neurodegenerative disorder affecting motor and cognitive functions. Prior studies showed that patients with PD and diabetes (DM) demonstrate worse clinical outcomes compared to nondiabetic subjects with PD. Our study aimed at defining the relationship between DM, gray matter volume, and cognition in patients with PD.

MATERIALS AND METHODS

This study included 36 subjects with PD (12 with DM, 24 without DM, mean age = 66). Subjects underwent high-resolution T1-weighted brain magnetic resonance imaging, [(11)C]dihydrotetrabenazine positron emission tomography imaging to quantify nigrostriatal dopaminergic denervation, clinical, and cognitive assessments. Magnetic resonance images were postprocessed to determine total and lobar cortical gray matter volumes. Cognitive testing scores were converted to z-scores for specific cognitive domains and a composite global cognitive z-score based on normative data computed. Analysis of covariance, accounting for effects of age, gender, intracranial volume, and striatal [(11)C]dihydrotetrabenazine binding, was used to test the relationship between DM and gray matter volumes.

RESULTS

Impact of DM on total gray matter volume was significant (P = 0.02). Post hoc analyses of lobar cortical gray matter volumes revealed that DM was more selectively associated with lower gray matter volumes in the frontal regions (P = 0.01). Cognitive post hoc analyses showed that interaction of total gray matter volume and DM status was significantly associated with composite (P = 0.007), executive (P = 0.02), and visuospatial domain cognitive z-scores (P = 0.005). These associations were also significant for the frontal cortical gray matter.

CONCLUSION

DM may exacerbate brain atrophy and cognitive functions in PD with greater vulnerability in the frontal lobes. Given the high prevalence of DM in the elderly, delineating its effects on patient outcomes in the PD population is of importance.

Advanced brain aging: relationship with epidemiologic and genetic risk factors, and overlap with Alzheimer disease atrophy patterns

We systematically compared structural imaging patterns of advanced brain aging (ABA) in the general-population, herein defined as significant deviation from typical BA to those found in Alzheimer disease (AD). The hypothesis that ABA would show different patterns of structural change compared with those found in AD was tested via advanced pattern analysis methods. In particular, magnetic resonance images of 2705 participants from the Study of Health in Pomerania (aged 20-90 years) were analyzed using an index that captures aging atrophy patterns (Spatial Pattern of Atrophy for Recognition of BA (SPARE-BA)), and an index previously shown to capture atrophy patterns found in clinical AD (Spatial Patterns of Abnormality for Recognition of Early Alzheimer's Disease (SPARE-AD)). We studied the association between these indices and risk factors, including an AD polygenic risk score. Finally, we compared the ABA-associated atrophy with typical AD-like patterns. We observed that SPARE-BA had significant association with: smoking (P<0.05), anti-hypertensive (P<0.05), anti-diabetic drug use (men P<0.05, women P=0.06) and waist circumference for the male cohort (P<0.05), after adjusting for age. Subjects with ABA had spatially extensive gray matter loss in the frontal, parietal and temporal lobes (false-discovery-rate-corrected q<0.001). ABA patterns of atrophy were partially overlapping with, but notably deviating from those typically found in AD. Subjects with ABA had higher SPARE-AD values; largely due to the partial spatial overlap of associated patterns in temporal regions. The AD polygenic risk score was significantly associated with SPARE-AD but not with SPARE-BA. Our findings suggest that ABA is likely characterized by pathophysiologic mechanisms that are distinct from, or only partially overlapping with those of AD.

Effects of Hormone Therapy on Brain Volumes Changes of Postmenopausal Women Revealed by Optimally-Discriminative Voxel-Based Morphometry

Backgrounds

The Women's Health Initiative Memory Study Magnetic Resonance Imaging (WHIMS-MRI) provides an opportunity to evaluate how menopausal hormone therapy (HT) affects the structure of older women’s brains. Our earlier work based on region of interest (ROI) analysis demonstrated potential structural changes underlying adverse effects of HT on cognition. However, the ROI-based analysis is limited in statistical power and precision, and cannot provide fine-grained mapping of whole-brain changes.

Methods

We aimed to identify local structural differences between HT and placebo groups from WHIMS-MRI in a whole-brain refined level, by using a novel method, named Optimally-Discriminative Voxel-Based Analysis (ODVBA). ODVBA is a recently proposed imaging pattern analysis approach for group comparisons utilizing a spatially adaptive analysis scheme to accurately locate areas of group differences, thereby providing superior sensitivity and specificity to detect the structural brain changes over conventional methods.

Results

Women assigned to HT treatments had significant Gray Matter (GM) losses compared to the placebo groups in the anterior cingulate and the adjacent medial frontal gyrus, and the orbitofrontal cortex, which persisted after multiple comparison corrections. There were no regions where HT was significantly associated with larger volumes compared to placebo, although a trend of marginal significance was found in the posterior cingulate cortical area. The CEE-Alone and CEE+MPA groups, although compared with different placebo controls, demonstrated similar effects according to the spatial patterns of structural changes.

Conclusions

HT had adverse effects on GM volumes and risk for cognitive impairment and dementia in older women. These findings advanced our understanding of the neurobiological underpinnings of HT effects.

White matter hyperintensities and imaging patterns of brain ageing in the general population

White matter hyperintensities are associated with increased risk of dementia and cognitive decline. The current study investigates the relationship between white matter hyperintensities burden and patterns of brain atrophy associated with brain ageing and Alzheimer's disease in a large populatison-based sample (n = 2367) encompassing a wide age range (20-90 years), from the Study of Health in Pomerania. We quantified white matter hyperintensities using automated segmentation and summarized atrophy patterns using machine learning methods resulting in two indices: the SPARE-BA index (capturing age-related brain atrophy), and the SPARE-AD index (previously developed to capture patterns of atrophy found in patients with Alzheimer's disease). A characteristic pattern of age-related accumulation of white matter hyperintensities in both periventricular and deep white matter areas was found. Individuals with high white matter hyperintensities burden showed significantly (P < 0.0001) lower SPARE-BA and higher SPARE-AD values compared to those with low white matter hyperintensities burden, indicating that the former had more patterns of atrophy in brain regions typically affected by ageing and Alzheimer's disease dementia. To investigate a possibly causal role of white matter hyperintensities, structural equation modelling was used to quantify the effect of Framingham cardiovascular disease risk score and white matter hyperintensities burden on SPARE-BA, revealing a statistically significant (P < 0.0001) causal relationship between them. Structural equation modelling showed that the age effect on SPARE-BA was mediated by white matter hyperintensities and cardiovascular risk score each explaining 10.4% and 21.6% of the variance, respectively. The direct age effect explained 70.2% of the SPARE-BA variance. Only white matter hyperintensities significantly mediated the age effect on SPARE-AD explaining 32.8% of the variance. The direct age effect explained 66.0% of the SPARE-AD variance. Multivariable regression showed significant relationship between white matter hyperintensities volume and hypertension (P = 0.001), diabetes mellitus (P = 0.023), smoking (P = 0.002) and education level (P = 0.003). The only significant association with cognitive tests was with the immediate recall of the California verbal and learning memory test. No significant association was present with the APOE genotype. These results support the hypothesis that white matter hyperintensities contribute to patterns of brain atrophy found in beyond-normal brain ageing in the general population. White matter hyperintensities also contribute to brain atrophy patterns in regions related to Alzheimer's disease dementia, in agreement with their known additive role to the likelihood of dementia. Preventive strategies reducing the odds to develop cardiovascular disease and white matter hyperintensities could decrease the incidence or delay the onset of dementia.

Bipolar disorders, type 2 diabetes mellitus, and the brain

PURPOSE OF REVIEW

Type 2 diabetes mellitus (T2DM) negatively affects brain structure and function. Meta-analytical data show that relative to age and sex matched non-psychiatric controls, patients with bipolar disorders have double the risk of T2DM. We review the evidence for association between T2DM and adverse clinical and brain imaging changes in bipolar disorders and summarize studies investigating effects of diabetes treatment on psychiatric and brain outcomes.

RECENT FINDINGS

Participants with bipolar disorders and T2DM or insulin resistance demonstrate greater morbidity, chronicity and disability, and lower treatment response to Li. Bipolar disorders complicated by insulin resistance/T2DM are associated with smaller hippocampal and cortical gray matter volumes and lower prefrontal N-acetyl aspartate (neuronal marker). Treatment of T2DM yields preservation of brain gray matter and insulin sensitizers, such as pioglitazone, improve symptoms of depression in unipolar or bipolar disorders.

SUMMARY

T2DM or insulin resistance frequently cooccur with bipolar disorders and are associated with negative psychiatric clinical outcomes and compromised brain health. This is clinically concerning, as patients with bipolar disorders have an increased risk of metabolic syndrome and yet often receive suboptimal medical care. At the same time treatment of T2DM and insulin resistance has positive effects on psychiatric and brain outcomes. These findings create a rich agenda for future research, which could enhance psychiatric pharmacopeia and directly impact patient care.

[Diabetes mellitus and the central nervous system]

The review considers the current views on the central nervous system (CNS) in diabetes mellitus (DM). It discusses an attitude towards the term 'diabetic encephalopathy'. The data of investigations of cognitive functions in types 1 and 2 DM and the brain structural imaging results obtained using up-to-date technologies are considered. The results of studies of the factors that induce cerebral changes in DM and their associated cognitive impairments are given. There is evidence that hyperglycemia has a more considerable impact on the above processes than hypoglycemia; other possible factors, apart from blood glucose control, are set out. The current views on the function of insulin in the CNS and the relationship of central insulin resistance to Alzheimer's disease are outlined. There are current data on intranasal insulin application that is still exploratory, but, as might be judged from the findings, may by a promising method for the treatment and prevention of cognitive decline in both patients with DM and those without this condition.

The roles of lipid and glucose metabolism in modulation of β-amyloid, tau, and neurodegeneration in the pathogenesis of Alzheimer disease

Diabetes is a risk factor for Alzheimer disease (AD). Apolipoprotein E (ApoE) and several genes related to AD have recently been identified by genome-wide association studies (GWAS) as being closely linked to lipid metabolism. Lipid metabolism and glucose-energy metabolism are closely related. Here, we review the emerging evidence regarding the roles of lipid and glucose metabolism in the modulation of β-amyloid, tau, and neurodegeneration during the pathogenesis of AD. Disruption of homeostasis of lipid and glucose metabolism affects production and clearance of β-amyloid and tau phosphorylation, and induces neurodegeneration. A more integrated understanding of the interactions among lipid, glucose, and protein metabolism is required to elucidate the pathogenesis of AD and to develop next-generation therapeutic options.