White matter hyperintensities in middle-aged adults with childhood-onset type 1 diabetes

Cerebral Small Vessel Disease Is Associated With Smaller Brain Volumes in Adults With Type 1 Diabetes

Introduction: Type 1 diabetes has been linked to brain volume reductions as well as to cerebral small vessel disease (cSVD). This study concerns the relationship between normalized brain volumes (volume fractions) and cSVD, which has not been examined previously. Methods: We subjected brain magnetic resonance imaging studies of 187 adults of both sexes with Type 1 diabetes and 30 matched controls to volumetry and neuroradiological interpretation. Results: Participants with Type 1 diabetes had smaller thalami compared to controls without diabetes (p = 0.034). In subgroup analysis of the Type 1 diabetes group, having any sign of cSVD was associated with smaller cortical (p = 0.031) and deep gray matter volume fractions (p = 0.029), but a larger white matter volume fraction (p = 0.048). After correcting for age, the smaller putamen volume remained significant. Conclusions: We found smaller thalamus volume fractions in individuals with Type 1 diabetes as compared to those without diabetes, as well as reductions in brain volume fractions related to signs of cSVD in individuals with Type 1 diabetes.

Risk factors associated with cognitive performance and cognitive impairment in older adults with type 1 diabetes: Data from the Wireless Innovation for Seniors with Diabetes Mellitus (WISDM) study

BACKGROUND

Adults with type 1 diabetes (T1D) are considered at increased risk for cognitive impairment and accelerated brain aging. However, longitudinal data on cognitive impairment and dementia in this population are scarce.

OBJECTIVE

To identify risk factors associated with cognitive performance and cognitive impairment in a longitudinal sample of older adults with T1D.

METHODS

We analyzed data collected as part of the Wireless Innovation for Seniors with Diabetes Mellitus (WISDM) Study, in which 22 endocrinology practices participated. Randomized participants with T1D ≥60 years of age who completed at least one cognitive assessment were included in this study (n = 203). Cognitive impairment was classified using published recommendations.

RESULTS

Older age, male sex, non-private health insurance, worse daily functioning, diagnosis of neuropathy, and longer duration of diabetes were associated with worse cognitive performance, but not cognitive impairment. 49 % and 39 % of the sample met criteria for cognitive impairment at baseline and 52 weeks respectively. Of the participants that had data at both time points, 10 % were normal at baseline and impaired at 52 weeks and 22 % of participants (44 % of those classified with cognitive impairment at baseline) reverted to normal over 52 weeks.

CONCLUSION

This study indicated that several demographic and clinical characteristics are associated with worse cognitive performance in older adults with T1D, but there were no associations between these characteristics and cognitive impairment defined by NIH Toolbox cognitive impairment criteria. Caution is warranted when assessing cognition in older adults with T1D, as a large percentage of those identified as having cognitive impairment at baseline reverted to normal after 52 weeks. There is need for future studies on the interrelationship of cognition and aging to better understand the effects of T1D on cognitive health, to improve clinical monitoring and help mitigate the risk of dementia in this population.

Central nervous system microstructural alterations in Type 1 diabetes mellitus: A systematic review of diffusion Tensor imaging studies

AIMS

Type 1 diabetes mellitus (T1DM) is a chronic childhood disease with potentially persistent CNS disruptions. In this study, we aimed to systematically review diffusion tensor imaging studies in patients with T1DM to understand the microstructural effects of this entity on individuals' brains METHODS: We performed a systematic search and reviewed the studies to include the DTI studies in individuals with T1DM. The data for the relevant studies were extracted and a qualitative synthesis was performed.

RESULTS

A total of 19 studies were included, most of which showed reduced FA widespread in optic radiation, corona radiate, and corpus callosum, as well as other frontal, parietal, and temporal regions in the adult population, while most of the studies in the juvenile patients showed non-significant differences or a non-persistent pattern of changes. Also, reduced AD and MD in individuals with T1DM compared to controls and non-significant differences in RD were noted in the majority of studies. Microstructural alterations were associated with clinical profile, including age, hyperglycemia, diabetic ketoacidosis and cognitive performance.

CONCLUSION

T1DM is associated with microstructural brain alterations including reduced FA, MD, and AD in widespread brain regions, especially in association with glycemic fluctuations and in adult age.

The effect of problem-solving skills on blood glucose regulation and disease management in children with type 1 diabetes mellitus

OBJECTIVES

This cross-sectional study examined the relationship between problem-solving skills, glucose regulation, and disease management in children with type 1 diabetes mellitus (T1DM) as well as the role of depression in this association.

METHODS

The participants (n=54) were recruited from a diabetes camp. Problem-solving inventory (PSI), Beck depression inventory (BDI), and diabetes self-management profile (DSMP) were administered as tests. Forty-six participants who have been diagnosed with T1DM for at least a year and completed the survey were included in the analyses. Participants were categorized into high and low depression groups based on the median split. Student's t-test was used to detect demographic differences in groups. Linear regression models were used to examine the association between PSI, HbA1c, and DSMP. Regressions for PSI and DSMP were repeated in low and high-depression groups.

RESULTS

Of the 46 participants with T1DM, 52 % were female, with a mean age of 13.96 ± 1.94 (range 10-17). Avoidant and monitoring style of problem solving as well as the total score of PSI significantly predicted HbA1c levels. Impulsive and avoidant style of problem solving, problem-solving confidence, and total scores of PSI significantly predicted DSMP (p<0.05). The high depression group had a significantly higher DSMP score than the low depression group (p=0.001), with no difference in HbA1c levels (p=0.968). When the DSMP regressions were repeated, no significant associations were seen in the low depression group. Avoidant style of problem solving, problem-solving confidence, and the total score of PSI significantly predicted DSMP in the high depression group (p<0.005).

CONCLUSIONS

Problem solving-skills are essential in children with T1DM for a successful disease management. Depression modulates the association between the problem-solving and self-management profile.

Brain structure and function in the fourth decade of life after extremely low birth weight: An MRI and EEG study

OBJECTIVE

To examine potential long-term effects of extremely low birth weight (ELBW; ≤ 1000 g) on adult brain structure, brain function, and cognitive-behavioral performance.

METHODS

A subset of survivors from the prospectively-followed McMaster ELBW Cohort (n = 23, MBW = 816 g) and their peers born at normal birth weight (NBW; ≥ 2500 g; n = 14, MBW = 3361 g) provided T1-weighted magnetic resonance imaging (MRI) brain scans, resting electroencephalographic (EEG) recordings, and behavioral responses to a face-processing task in their early thirties.

RESULTS

Visual discrimination accuracy for human faces, resting EEG alpha power, and long-distance alpha coherence were lower in ELBW survivors than NBW adults, and volumes of white matter hypointensities (WMH) were higher. Across groups, face-processing performance was correlated positively with posterior EEG spectral power and long-distance alpha and theta coherence, and negatively with WMH. The associations between face-processing scores and parietal alpha power and theta coherence were reduced after adjustment for WMH.

CONCLUSIONS

Electrocortical activity, brain functional connectivity, and higher-order processing ability may be negatively affected by WMH burden, which is greater in adults born extremely preterm.

SIGNIFICANCE

Decrements in electrocortical activity and behavioral performance in adult ELBW survivors may be partly explained by increased WMH volumes in this vulnerable population.

Mechanical loading of the ventricular wall as a spatial indicator for periventricular white matter degeneration

Progressive white matter degeneration in periventricular and deep white matter regions appears as white matter hyperintensities (WMH) on MRI scans. To date, periventricular WMHs are often associated with vascular dysfunction. Here, we demonstrate that ventricular inflation resulting from cerebral atrophy and hemodynamic pulsation with every heartbeat leads to a mechanical loading state of periventricular tissues that significantly affects the ventricular wall. Specifically, we present a physics-based modeling approach that provides a rationale for ependymal cell involvement in periventricular WMH formation. Building on eight previously created 2D finite element brain models, we introduce novel mechanomarkers for ependymal cell loading and geometric measures that characterize lateral ventricular shape. We show that our novel mechanomarkers, such as maximum ependymal cell deformations and maximum curvature of the ventricular wall, spatially overlap with periventricular WMH locations and are sensitive predictors for WMH formation. We also explore the role of the septum pellucidum in mitigating mechanical loading of the ventricular wall by constraining the radial expansion of the lateral ventricles during loading. Our models consistently show that ependymal cells are stretched thin only in the horns of the ventricles irrespective of ventricular shape. We therefore pose that periventricular WMH etiology is strongly linked to the deterioration of the over-stretched ventricular wall resulting in CSF leakage into periventricular white matter. Subsequent secondary damage mechanisms, including vascular degeneration, exacerbate lesion formation and lead to progressive growth into deep white matter regions.

Evaluation of structural brain changes and their correlation with cognitive functions in adults with type 1 diabetes stratified by the age of diabetes onset: A cross-sectional study

BACKGROUND AND AIM

T1DM has a significant effect on brain structure and function. Age of onset of diabetes may be a critical factor mediating this impairment. We evaluated young adults with T1DM, stratified by the age of onset, for structural brain changes, hypothesizing that there may be a spectrum of white matter damage in these participants, compared to controls.

METHODS

We recruited adult patients (20-50 years of age at the time of study enrolment) with onset of T1DM before 18 years of age and at least ten years of schooling, along with controls having normoglycaemia. We compared the Diffusion Tensor Imaging parameters between patients and controls and evaluated their correlations with cognitive z scores, and glycemic measures.

RESULTS

We evaluated 93 individuals, 69 [age: 24.1 (±4.5) years, gender: 47.8% men, education: 14.7 ± 1.6 years] with T1DM and 24 [age: 27.8 (±5.4) years, gender: 58.3% men, education: 14.6 ± 1.9 years] without T1DM (controls). We did not find any significant correlation of fractional anisotropy (FA) with age at T1D diagnosis, duration of diabetes, current glycemic status, or domain-wise cognitive z scores. The FA was lower (but not statistically significant) in participants with T1DM when evaluated for the whole brain, individual lobes, hippocampi and amygdala.

CONCLUSION

Participants with T1DM do not show a significant difference in the brain white matter integrity when evaluated in a cohort of young adults with relatively few microvascular complications compared to controls.

Associations of Life's Simple 7 with cerebral white matter hyperintensities and microstructural integrity: UK Biobank cohort study

BACKGROUND AND PURPOSE

The American Heart Association Life's Simple 7 (LS7) metric was used to define optimal cardiovascular and brain health, but the associations with macrostructural hyperintensities and microstructural white matter damage are unclear. The objective was to determine the association of LS7 ideal cardiovascular health factors with macrostructural and microstructural integrity.

METHOD

A total of 37,140 participants with available LS7 and imaging data from UK Biobank were included in this study. Linear associations were implemented to examine the associations of LS7 score and subscores with white matter hyperintensity load (WMH) (WMH volume normalized by total white matter volume and logit-transformed) and diffusion imaging indices (fractional anisotropy [FA], mean diffusivity, orientation dispersion index [OD], intracellular volume fraction, isotropic volume fraction [ISOVF]).

RESULTS

In individuals (mean age 54.76 years; 19,697 females, 52.4%), higher LS7 score and subscores were strongly associated with lower WMH and microstructural white matter injury, including OD, ISOVF, FA. Both interaction analyses and stratified analyses of LS7 score and subscores with age and sex showed a strong association with microstructural damage markers, with remarkable age and sex differences. The association of OD was pronounced in females and populations younger than 50 years and FA, mean diffusivity and ISOVF were pronounced in males and populations older than 50 years.

CONCLUSION

These findings suggest that healthier LS7 profiles are associated with better profiles of both macrostructural and microstructural markers of brain health, and indicate that ideal cardiovascular health is associated with improved brain health.

Brain Structure Among Middle-aged and Older Adults With Long-standing Type 1 Diabetes in the DCCT/EDIC Study

OBJECTIVE

Individuals with type 1 diabetes mellitus (T1DM) are living to ages when neuropathological changes are increasingly evident. We hypothesized that middle-aged and older adults with long-standing T1DM will show abnormal brain structure in comparison with control subjects without diabetes.

RESEARCH DESIGN AND METHODS

MRI was used to compare brain structure among 416 T1DM participants in the Epidemiology of Diabetes Interventions and Complications (EDIC) study with that of 99 demographically similar control subjects without diabetes at 26 U.S. and Canadian sites. Assessments included total brain (TBV) (primary outcome), gray matter (GMV), white matter (WMV), ventricle, and white matter hyperintensity (WMH) volumes and total white matter mean fractional anisotropy (FA). Biomedical assessments included HbA1c and lipid levels, blood pressure, and cognitive assessments of memory and psychomotor and mental efficiency (PME). Among EDIC participants, HbA1c, severe hypoglycemia history, and vascular complications were measured longitudinally.

RESULTS

Mean age of EDIC participants and control subjects was 60 years. T1DM participants showed significantly smaller TBV (least squares mean ± SE 1,206 ± 1.7 vs. 1,229 ± 3.5 cm3, P < 0.0001), GMV, and WMV and greater ventricle and WMH volumes but no differences in total white matter mean FA versus control subjects. Structural MRI measures in T1DM were equivalent to those of control subjects who were 4-9 years older. Lower PME scores were associated with altered brain structure on all MRI measures in T1DM participants.

CONCLUSIONS

Middle-aged and older adults with T1DM showed brain volume loss and increased vascular injury in comparison with control subjects without diabetes, equivalent to 4-9 years of brain aging.

Glycemic control is not related to cerebral small vessel disease in neurologically asymptomatic individuals with type 1 diabetes

AIMS

To determine if medium- and long-term blood glucose control as well as glycemic variability, which are known to be strong predictors of vascular complications, are associated with underlying cerebral small vessel disease (cSVD) in neurologically asymptomatic individuals with type 1 diabetes.

METHODS

A total of 189 individuals (47.1% men; median age 40.0, IQR 33.0-45.2 years) with type 1 diabetes (median diabetes duration of 21.7, IQR 18.3-30.7 years) were enrolled in a cross-sectional retrospective study, as part of the Finnish Diabetic Nephropathy (FinnDiane) Study. Glycated hemoglobin (HbA_1c) values were collected over the course of ten years before the visit including a clinical examination, biochemical sampling, and brain magnetic resonance imaging. Markers of glycemic control, measured during the visit, included HbA_1c, fructosamine, and glycated albumin.

RESULTS

Signs of cSVD were present in 66 (34.9%) individuals. Medium- and long-term glucose control and glycemic variability did not differ in individuals with signs of cSVD compared to those without. Further, no difference in any of the blood glucose variables and cSVD stratified for cerebral microbleeds (CMBs) or white matter hyperintensities were detected. Neither were numbers of CMBs associated with the studied glucose variables. Additionally, after dividing the studied variables into quartiles, no association with cSVD was observed.

CONCLUSIONS

We observed no association between glycemic control and cSVD in neurologically asymptomatic individuals with type 1 diabetes. This finding was unexpected considering the large number of signs of cerebrovascular pathology in these people after two decades of chronic hyperglycemia and warrants further studies searching for underlying factors of cSVD.

Evaluation of Cognitive Deficits in Adults with Type 1 Diabetes Stratified by the Age of Diabetes Onset: A Cross-Sectional Study

INTRODUCTION

Type 1 diabetes (T1DM) is associated with cognitive deficits, and age at diagnosis is thought to play a substantial role. However, there are limited data for the cognitive performance in young adults, in relation to the age of diabetes onset. The lack of information is particularly striking in the context of developing regions.

METHODS

This cross-sectional study was performed from August 2018 to July 2020. We included adult participants with T1DM, stratified by the age of diabetes onset (till 6 years of age, between 7 to 12 years of age, and 13 to < 18 years of age) and compared them with the control group (no diabetes or pre-diabetes). We filled a structured case record proforma for all participants and recorded relevant socio-demographic and medical details. Detailed neuropsychological assessment with 13 psychological tests representing four cognitive domains was carried-(1) attention, working memory and executive functions; (2) learning and memory; (3) visuoperceptual functions; and (4) information processing speed.

RESULTS

We evaluated 100 individuals, 73 (men 48.0%) with T1DM and 27 (men 51.9%) without T1DM. After adjustment for age, gender and education, the mean differences in composite Z scores (for the four cognitive domains) between participants with T1DM and without T1DM were 0.08 for attention, working memory and executive functions (p = 0.614); 0.07 for learning and memory (p = 0.694); 0.05 for visuoperceptual (p = 0.784); and 0.22 for information processing speed (p = 0.305). No significant differences were found for the three subgroups of individuals with T1DM, when compared with the control group. Effect size (Cohen's d) for the individual tests (n = 13) ranged from - 0.36 to + 0.39, and none of the comparisons were statistically significant. Amongst the participants with T1DM, higher education had a significant positive association with three of the four cognitive domains evaluated.

CONCLUSIONS

To conclude, our findings suggest minimal differences in the cognitive functioning of patients with T1DM with different age of onset of diabetes compared to healthy controls, when evaluated in early adulthood. This is possibly the first study from South Asia with an in-depth and comprehensive assessment of cognitive functions in patients with T1DM, using a detailed neuropsychological battery.

Neural correlates of slower gait in middle-aged persons with childhood-onset type 1 diabetes mellitus: The impact of accelerated brain aging

AIMS

We aimed to determine if neuroimaging characteristics of gray and white matter are associated with gait speed in middle-aged individuals with childhood-onset type 1 diabetes (T1D), and whether associations are independent of diabetic peripheral neuropathy (DPN) status.

METHODS

In a cohort of 100 middle-aged adults with childhood-onset T1D (aged 49.2 ± 7.0 years, 50F/50M), we assessed cross-sectional associations of DPN, severity of white matter hyperintensities (WMH; Fazekas score), and regional gray matter volume (GMV) with gait speed. Associations were tested separately and combined in linear regression models adjusted for diabetes duration and locomotor risk factors.

RESULTS

Average gait speed was 1.3 m/s, with 52% of participants walking below the age-appropriate range of 1.3-1.5 m/s. In separate models, higher WMH severity (β = -0.27, p = 0.01) and smaller caudate GMV (β = -0.21, p = 0.04), but not DPN (β = -0.20, p = 0.08) were associated with slower gait speed. When combined, only WMH severity remained significant (β = -0.22, p = 0.04).

CONCLUSIONS

More than half of participants walked more slowly than expected based on age. Gait speed was slower among those with more severe WMH independent of locomotor risk factors. Gait slowing in middle-aged persons with T1D may reflect brain changes, and thus, deserve further attention.

Peak ependymal cell stretch overlaps with the onset locations of periventricular white matter lesions

Deep and periventricular white matter hyperintensities (dWMH/pvWMH) are bright appearing white matter tissue lesions in T2-weighted fluid attenuated inversion recovery magnetic resonance images and are frequent observations in the aging human brain. While early stages of these white matter lesions are only weakly associated with cognitive impairment, their progressive growth is a strong indicator for long-term functional decline. DWMHs are typically associated with vascular degeneration in diffuse white matter locations; for pvWMHs, however, no unifying theory exists to explain their consistent onset around the horns of the lateral ventricles. We use patient imaging data to create anatomically accurate finite element models of the lateral ventricles, white and gray matter, and cerebrospinal fluid, as well as to reconstruct their WMH volumes. We simulated the mechanical loading of the ependymal cells forming the primary brain-fluid interface, the ventricular wall, and its surrounding tissues at peak ventricular pressure during the hemodynamic cycle. We observe that both the maximum principal tissue strain and the largest ependymal cell stretch consistently localize in the anterior and posterior horns. Our simulations show that ependymal cells experience a loading state that causes the ventricular wall to be stretched thin. Moreover, we show that maximum wall loading coincides with the pvWMH locations observed in our patient scans. These results warrant further analysis of white matter pathology in the periventricular zone that includes a mechanics-driven deterioration model for the ventricular wall.

Carotid intima-media thickness and arterial stiffness in relation to cerebral small vessel disease in neurologically asymptomatic individuals with type 1 diabetes

AIMS

To determine if arterial functional and structural changes are associated with underlying cerebral small vessel disease in neurologically asymptomatic individuals with type 1 diabetes.

METHODS

We enrolled 186 individuals (47.8% men; median age 40.0, IQR 33.0-45.0 years) with type 1 diabetes (median diabetes duration of 21.6, IQR 18.2-30.3 years), and 30 age- and sex-matched healthy controls, as part of the Finnish Diabetic Nephropathy (FinnDiane) Study. All individuals underwent a biochemical work-up, brain magnetic resonance imaging (MRI), ultrasound of the common carotid arteries and arterial tonometry. Arterial structural and functional parameters were assessed by carotid intima-media thickness (CIMT), pulse wave velocity and augmentation index.

RESULTS

Cerebral microbleeds (CMBs) were present in 23.7% and white matter hyperintensities (WMHs) in 16.7% of individuals with type 1 diabetes. Those with type 1 diabetes and CMBs had higher median (IQR) CIMT 583 (525 - 663) μm than those without 556 (502 - 607) μm, p = 0.016). Higher CIMT was associated with the presence of CMBs (p = 0.046) independent of age, eGFR, ApoB, systolic blood pressure, albuminuria, history of retinal photocoagulation and HbA_1c. Arterial stiffness and CIMT were increased in individuals with type 1 diabetes and WMHs compared to those without; however, these results were not independent of cardiovascular risk factors.

CONCLUSIONS

Structural, but not functional, arterial changes are associated with underlying CMBs in asymptomatic individuals with type 1 diabetes.

Vof16-miR-205-Gnb3 axis regulates hippocampal neuron functions in cognitively impaired diabetic rats

Background

Diabetes is a chronic metabolic disease and an independent risk factor for cognitive damage. Non-protein coding RNAs, including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), are involved in various pathophysiological conditions.

Methods

In this study, cognitive impairment was induced in diabetics rats by streptozotocin (STZ) injection, and the differential lncRNAs and mRNAs in rat hippocampal tissue between control and STZ-treated groups were analyzed with microarray.

Results

In the hippocampus of STZ-treated diabetic rats, lncRNA Vof-16, and Gnb3 mRNA were significantly upregulated and silicon analysis showed that Vof-16 and miR-205 share the same miRNA response element (MRE). In addition, the overexpression of Vof-16 in primary hippocampal neurons inhibited the expression of miR-205, and vice versa. Dual luciferase assay verified the binding between Vof-16 and miR-205, and Vof-16 was seen to promote the proliferation of primary hippocampal neurons via sponging miR-205. Silicon analysis predicted that miR-205 could bind with Gnb3, which was verified with dual luciferase assay, and the overexpression of miR-205 could inhibit the protein level of Gnb3, which could be rescued by co-expression with Vof-16. In conclusion, lncRNA Vof-16 regulated Gnb3 expression by competitively binding to miR-205.

Conclusions

These results provided a novel regulation axis for the pathogenesis of STZ-induced diabetes.

The association between intraoperative hyperglycemia and cerebrovascular markers

BACKGROUND AND PURPOSE: Hyperglycemia can lead to an increased rate of apoptosis of microglial cells and to damaged neurons. The relation between hyperglycemia and cerebrovascular markers on MRI is unknown. Our aim was to study the association between intraoperative hyperglycemia and cerebrovascular markers. METHODS: In this further analysis of a subgroup investigation of the BIOCOG study, 65 older non-demented patients (median 72 years) were studied who underwent elective surgery of ≥ 60 minutes. Intraoperative blood glucose maximum was determined retrospectively in each patient. In these patients, preoperatively and at 3 months follow-up a MRI scan was performed and white matter hyperintensity (WMH) volume and shape, infarcts, and perfusion parameters were determined. Multivariable logistic regression analyses were performed to determine associations between preoperative cerebrovascular markers and occurrence of intraoperative hyperglycemia. Linear regression analyses were performed to assess the relation between intraoperative hyperglycemia and pre- to postoperative changes in WMH volume. Associations between intraoperative hyperglycemia and postoperative WMH volume at 3 months follow-up were also assessed by linear regression analyses. RESULTS: Eighteen patients showed intraoperative hyperglycemia (glucose maximum ≥ 150 mg/dL). A preoperative more smooth shape of periventricular and confluent WMH was related to the occurrence of intraoperative hyperglycemia [convexity: OR 33.318 (95 % CI (1.002 - 1107.950); p = 0.050]. Other preoperative cerebrovascular markers were not related to the occurrence of intraoperative hyperglycemia. Intraoperative hyperglycemia showed no relation with pre- to postoperative changes in WMH volume nor with postoperative WMH volume at 3 months follow-up. CONCLUSIONS: We found that a preoperative more smooth shape of periventricular and confluent WMH was related to the occurrence of intraoperative hyperglycemia. These findings may suggest that a similar underlying mechanism leads to a certain pattern of vascular brain abnormalities and an increased risk of hyperglycemia.

Moderation of the effect of glycemia on the risk of cardiovascular disease in type 1 diabetes: The DCCT/EDIC study

AIMS

We assessed whether and to what extent established cardiovascular disease (CVD) risk factors moderate (enhance/reduce) the effect of hyperglycemia on CVD outcomes in the long-term follow-up of the Diabetes Control and Complications Trial type 1 diabetes (T1D) cohort (N = 1441).

METHODS

Moderation of the effect of glycemia on subsequent risk of major adverse cardiovascular events (MACE: fatal or non-fatal myocardial infarction or stroke) and any-CVD (MACE plus confirmed angina, silent MI, revascularization, or congestive heart failure) was assessed separately using interaction terms between HbA1c and other risk factors in Cox proportional hazards models.

RESULTS

Over a median follow-up of 29 years, there were 120 MACE cases and 239 any-CVD cases. Higher pulse, higher triglycerides, use of calcium channel blockers, and presence of neuropathy individually enhanced (p < 0.01) the effect of glycemia on any-CVD. Higher pulse and triglyceride levels, albumin excretion rate, hypertension, and no family history of type 2 diabetes enhanced (p < 0.01) the effect of glycemia on MACE.

CONCLUSIONS

Such moderation analyses identify subgroups with increased CVD risk who might especially benefit from earlier and/or more intensive glycemic control. Interventions treating modifiable moderating factors may independently reduce the risk of CVD and also reduce the risk associated with a higher HbA1c.

Structural Alterations in Deep Brain Structures in Type 1 Diabetes

Even though well known in type 2 diabetes, the existence of brain changes in type 1 diabetes (T1D) and both their neuroanatomical and clinical features are less well characterized. To fill the void in the current understanding of this disease, we sought to determine the possible neural correlate in long-duration T1D at several levels, including macrostructural, microstructural cerebral damage, and blood flow alterations. In this cross-sectional study, we compared a cohort of 61 patients with T1D with an average disease duration of 21 years with 54 well-matched control subjects without diabetes in a multimodal MRI protocol providing macrostructural metrics (cortical thickness and structural volumes), microstructural measures (T1-weighted/T2-weighted [T1w/T2w] ratio as a marker of myelin content, inflammation, and edema), and cerebral blood flow. Patients with T1D had higher T1w/T2w ratios in the right parahippocampal gyrus, the executive part of both putamina, both thalami, and the cerebellum. These alterations were reflected in lower putaminal and thalamic volume bilaterally. No cerebral blood flow differences between groups were found in any of these structures, suggesting nonvascular etiologies of these changes. Our findings implicate a marked nonvascular disruption in T1D of several essential neural nodes engaged in both cognitive and motor processing.

Cholinergic white matter pathways make a stronger contribution to attention and memory in normal aging than cerebrovascular health and nucleus basalis of Meynert

The integrity of the cholinergic system plays a central role in cognitive decline both in normal aging and neurological disorders including Alzheimer's disease and vascular cognitive impairment. Most of the previous neuroimaging research has focused on the integrity of the cholinergic basal forebrain, or its sub-region the nucleus basalis of Meynert (NBM). Tractography using diffusion tensor imaging data may enable modelling of the NBM white matter projections. We investigated the contribution of NBM volume, NBM white matter projections, small vessel disease (SVD), and age to performance in attention and memory in 262 cognitively normal individuals (39-77 years of age, 53% female). We developed a multimodal MRI pipeline for NBM segmentation and diffusion-based tracking of NBM white matter projections, and computed white matter hypointensities (WM-hypo) as a marker of SVD. We successfully tracked pathways that closely resemble the spatial layout of the cholinergic system as seen in previous post-mortem and DTI tractography studies. We found that high WM-hypo load was associated with older age, male sex, and lower performance in attention and memory. A high WM-hypo load was also associated with lower integrity of the cholinergic system above and beyond the effect of age. In a multivariate model, age and integrity of NBM white matter projections were stronger contributors than WM-hypo load and NBM volume to performance in attention and memory. We conclude that the integrity of NBM white matter projections plays a fundamental role in cognitive aging. This and other modern neuroimaging methods offer new opportunities to re-evaluate the cholinergic hypothesis of cognitive aging.

Prognostic Significance of Pulse Pressure and Other Blood Pressure Components for Coronary Artery Disease in Type 1 Diabetes

BACKGROUND

To compare in individuals with type 1 diabetes the prediction of incident coronary artery disease (CAD) by components of resting blood pressure-systolic, diastolic, pulse pressure, and mean arterial pressure.

METHODS

In 605 participants without known CAD at baseline and followed sequentially for 25 years, we used Cox modeling built for each blood pressure component associated with incident CAD, overall and stratified by age (<35 and ≥35 years) or hemoglobin A1c (HbA1c) (<9% and ≥9%).

RESULTS

Baseline mean age and diabetes duration were 27 and 19 years, respectively. We observed an early asymptote and then fall in diastolic blood pressure in their late 30s and early 40s in this group of type 1 diabetes individuals, followed by an early rise of pulse pressure. Adjusted hazard ratios (HR) (95% con) for CAD associated with 1 SD pressure increase were 1.35 (1.17, 1.56) for systolic pressure; 1.30 (1.12, 1.51) for diastolic pressure; 1.20 (1.03, 1.39) for pulse pressure; and 1.35 (1.17, 1.56) for mean arterial pressure. Pulse pressure emerged as a strong predictor of CAD at age ≥ 35 years (HR: 1.49 [1.15, 1.94]) and for HbA1c ≥ 9% (HR: 1.32 [1.01, 1.72]).

CONCLUSIONS

Individuals with type 1 diabetes may manifest early vascular aging by an early decline in diastolic blood pressure and rise in pulse pressure, the latter parameter becoming a comparable to systolic blood pressure in predictor incident CAD in those aged over 35 years and those with poor glycemic control.

Depressive symptoms and cerebral microvascular disease in adults with Type 1 diabetes mellitus

AIM

To assess the prevalence of, and risk factors for, depressive symptoms, comparing a sample of middle-aged adults with and without juvenile-onset Type 1 diabetes mellitus, and to determine if depressive symptoms were associated with white matter hyperintensity volume among those with Type 1 diabetes.

METHODS

Depressive symptoms and white matter hyperintensities were compared between adults (age range 30-65 years) with juvenile-onset Type 1 diabetes (n=130) and adults without Type 1 diabetes (n=133). The association of Type 1 diabetes with depression was computed before and after adjustment for white matter hyperintensities. Among the Type 1 diabetes group, the primary associations of interest were between depressive symptoms (Beck Depression Inventory score ≥10) and white matter hyperintensities (n=71), hyperglycaemia and physical activity. Associations between depressive symptoms and diabetes-related complications, cognitive impairment, smoking and self-reported disability were examined. Analyses were controlled for education, sex, age and antidepressant use.

RESULTS

Depressive symptoms were more prevalent among those with vs those without Type 1 diabetes (28% vs 3%; P<0.001). White matter hyperintensities explained 40% of the association of Type 1 diabetes with depressive symptoms, while Type 1 diabetes had a direct effect of 68% on depressive symptoms. Among those with Type 1 diabetes, depressive symptoms were related to white matter hyperintensity volume, a 16-year average HbA1c ≥58 mmol/mol (7.5%), and lower physical activity levels. Associations with other characteristics were not significant.

CONCLUSION

These findings suggest a cerebrovascular origin for depressive symptoms in adults with Type 1 diabetes, perhaps triggered by hyperglycaemia. Future longitudinal studies should investigate whether targeting hyperglycaemia and physical inactivity alleviates depressive symptoms, possibly by slowing the development of cerebral microvascular disease, in people with Type 1 diabetes.

D-ribose is elevated in T1DM patients and can be involved in the onset of encephalopathy

Although many mechanisms have been proposed for diabetic encephalopathy in type 2 diabetes mellitus (T2DM), the risk factors for cognitive impairment in type 1 diabetes mellitus (T1DM) are less clear. Here, we show that streptozotocin (STZ)-induced T1DM rats showed cognitive impairment in both Y maze and Morris water maze assays, accompanied with D-ribose was significantly increased in blood and urine, in addition to D-glucose. Furthermore, advanced glycation end products (AGE), Tau hyperphosphorylation and neuronal death in the hippocampal CA4/DG region were detected in T1DM rats. The expression and activity of transketolase (TKT), an important enzyme in the pentose shunt, were decreased in the brain, indicating that TKT may be involved in D-ribose metabolism in T1DM. Support for these change was demonstrated by the activation of TKT with benfotiamine (BTMP) treatment. Decreased D-ribose levels but not D-glucose levels; markedly reduced AGE accumulation, Tau hyperphosphorylation, and neuronal death; and improved cognitive ability in T1DM rats were shown after BTMP administration. In clinical investigation, T1DM patients had high D-ribose levels in both urine and serum. Our work suggests that D-ribose is involved in the cognitive impairment in T1DM and may provide a potentially novel target for treating diabetic encephalopathy.

The effect of type 1 diabetes on the developing brain

The effect of type 1 diabetes on the developing brain is a topic of primary research interest. A variety of potential dysglycaemic insults to the brain can cause cellular and structural injury and lead to altered neuropsychological outcomes. These outcomes might be subtle in terms of cognition but appear to persist into adult life. Age and circumstance at diagnosis appear to play a substantial role in potential CNS injury. A history of diabetic ketoacidosis and chronic hyperglycaemia appear to be more injurious than previously suspected, whereas a history of severe hypoglycaemia is perhaps less injurious. Neurocognitive deficits manifest across multiple cognitive domains, including executive function and speed of information processing. Some evidence suggests that subtle brain injury might directly contribute to psychological and mental health outcomes. Impaired executive function and mental health, in turn, could affect patients' adherence and the ability to make adaptive lifestyle choices. Impaired executive functioning creates a potential feedback loop of diabetic dysglycaemia leading to brain injury, further impaired executive function and mental health, which results in suboptimal adherence, and further dysglycaemia. Clinicians dealing with patients with suboptimal glycaemic outcomes should be aware of these potential issues.

Basal ganglia cerebral blood flow associates with psychomotor speed in adults with type 1 diabetes

Type 1 diabetes is associated with slower psychomotor speed, but the neural basis of this relationship is not yet understood. The basal ganglia are a set of structures that are vulnerable to small vessel disease, particularly in individuals with type 1 diabetes. Thus, we examined the relationship between psychomotor speed and resting state resting cerebral blood flow in a sample of adults with diabetes onset during childhood (≤ 17 years of age). The sample included 77 patients (39 M, 38 F) with a mean age of 47.43 ± 5.72 years, age of onset at 8.50 ± 4.26 years, and duration of disease of 38.92 ± 4.18 years. Resting cerebral blood flow was quantified using arterial spin labeling. After covarying for sex, years of education and normalized gray matter volume, slower psychomotor speed was associated with lower cerebral blood flow in bilateral caudate nucleus-thalamus and a region in the superior frontal gyrus. These results suggest that the basal ganglia and frontal cortex may underlie slower psychomotor speed in individuals with type 1 diabetes.

Type 1 diabetes-associated cognitive impairment and diabetic peripheral neuropathy in Chinese adults: results from a prospective cross-sectional study

BACKGROUND

To compare neurocognitive functioning of Type 1 diabetic mellitus (T1DM) and healthy adults, and explore risk factors of cognitive dysfunction of T1DM patients, especially the association between cognitive impairment and diabetic peripheral neuropathy (DPN).

METHODS

Seventy T1DM (age: 32.17 ± 9.57 yr., duration: 8.99 ± 7.02 yr) patients and 48 healthy volunteers were included. All subjects received evaluation of MMSE and MoCA scales. Cognitive function of T1DM patients was evaluated in different cognitive domains. Risk factors affecting cognitive function were further explored.

RESULTS

Three patients with educational level ≤ 6-year were excluded from final analysis. Scores of both MMSE (28.4 ± 1.7 vs. 29.1 ± 1.0, P = 0.005) and MoCA scales (25.9 ± 2.7 vs.27.1 ± 2.4, P = 0.017) in T1DM group were lower than that in control group. For MMSE scale, scores of orientation (9.60 ± 0.79 vs.9.87 ± 0.39, P < 0.001) and language function (8.56 ± 0.65 vs.8.83 ± 0.38, P < 0.001) in T1DM groups were lower than that in control group. For MoCA scale, scores of attention and concentration (2.30 ± 0.74 vs.2.57 ± 0.58, P < 0.001), visuospatial/executive function (4.32 ± 0.91 vs.4.64 ± 0.63, P < 0.001), memory (2.96 ± 1.50 vs.3.66 ± 1.28, P < 0.001), language function (5.71 ± 0.69 vs.5.87 ± 0.39, P = 0.007), and abstraction (1.55 ± 0.68 vs.1.82 ± 0.42, P < 0.001) were lower in T1DM group than that in control group. Logistic regression showed age, fasting C peptide, educational level and nerve conduction velocity (NCV) were associated with cognitive dysfunction diagnosed by MoCA scores for the patients with type 1 diabetes.

CONCLUSIONS

T1DM adults had mild to moderate cognitive impairment, mainly presenting as dysfunctions of attention and concentration, visuospatial/executive, language, and abstraction. In addition to age, fasting C peptide level, and educational level, DPN, as a diabetic complication, was identified to be associated with cognitive impairments.

The presence of cerebral white matter lesions and lower skin microvascular perfusion predicts lower cognitive performance in type 1 diabetes patients with retinopathy but not in healthy controls-A longitudinal study

OBJECTIVE

Cognitive impairments in type 1 diabetes may result from hyperglycemia-associated cerebral microangiopathy. We aimed to identify cerebral microangiopathy and skin microvascular dysfunction-as a surrogate marker for generalized microvascular function-as predictors of cognitive performance over time.

METHODS

In this prospective cohort study, 25 type 1 diabetes patients with proliferative retinopathy and 25 matched healthy controls underwent neurocognitive testing at baseline and after follow-up (3.8 ± 0.8 years). At baseline, 1.5-T cerebral magnetic resonance imaging was used to detect WML and cerebral microbleeds. Skin capillary perfusion was assessed by means of capillary microscopy.

RESULTS

In type 1 diabetes patients, but not in healthy controls, the presence of WML (ß = -0.419; P = 0.037) as well as lower skin capillary perfusion (baseline: ß = 0.753; P < 0.001; peak hyperemia: ß = 0.743; P = 0.001; venous occlusion: ß = 0.675; P = 0.003; capillary recruitment: ß = 0.549; P = 0.022) at baseline was associated with lower cognitive performance over time, independent of age, sex, HbA1c, and severe hypoglycemia. The relationship between WML and lower cognitive performance was significantly reduced after adjusting for capillary perfusion.

CONCLUSIONS

These data fit the hypothesis that cerebral microangiopathy is a manifestation of generalized microvascular dysfunction, leading to lower cognitive performance.

Clinical and MRI Features of Cerebral Small-Vessel Disease in Type 1 Diabetes

OBJECTIVE

To assess the prevalence of cerebral small-vessel disease (SVD) in subjects with type 1 diabetes compared with healthy control subjects and to characterize the diabetes-related factors associated with SVD.

RESEARCH DESIGN AND METHODS

This substudy was cross-sectional in design and included 191 participants with type 1 diabetes and median age 40.0 years (interquartile range 33.0-45.1) and 30 healthy age- and sex-matched control subjects. All participants underwent clinical investigation and brain MRIs, assessed for cerebral SVD.

RESULTS

Cerebral SVD was more common in participants with type 1 diabetes than in healthy control subjects: any marker 35% vs. 10% (P = 0.005), cerebral microbleeds (CMBs) 24% vs. 3.3% (P = 0.008), white matter hyperintensities 17% vs. 6.7% (P = 0.182), and lacunes 2.1% vs. 0% (P = 1.000). Presence of CMBs was independently associated with systolic blood pressure (odds ratio 1.03 [95% CI 1.00-1.05], P = 0.035).

CONCLUSIONS

Cerebral SVD, CMBs in particular, is more common in young people with type 1 diabetes compared with healthy control subjects.

Glycemic Variability and Brain Glucose Levels in Type 1 Diabetes

The impact of glycemic variability on brain glucose transport kinetics among individuals with type 1 diabetes mellitus (T1DM) remains unclear. Fourteen individuals with T1DM (age 35 ± 4 years; BMI 26.0 ± 1.4 kg/m²; HbA_1c 7.6 ± 0.3) and nine healthy control participants (age 32 ± 4; BMI 23.1 ± 0.8; HbA_1c 5.0 ± 0.1) wore a continuous glucose monitor (Dexcom) to measure hypoglycemia, hyperglycemia, and glycemic variability for 5 days followed by ¹H MRS scanning in the occipital lobe to measure the change in intracerebral glucose levels during a 2-h glucose clamp (target glucose concentration 220 mg/dL). Hyperglycemic clamps were also performed in a rat model of T1DM to assess regional differences in brain glucose transport and metabolism. Despite a similar change in plasma glucose levels during the hyperglycemic clamp, individuals with T1DM had significantly smaller increments in intracerebral glucose levels (P = 0.0002). Moreover, among individuals with T1DM, the change in brain glucose correlated positively with the lability index (r = 0.67, P = 0.006). Consistent with findings in humans, streptozotocin-treated rats had lower brain glucose levels in the cortex, hippocampus, and striatum compared with control rats. These findings that glycemic variability is associated with brain glucose levels highlight the need for future studies to investigate the impact of glycemic variability on brain glucose kinetics.

Type 1 diabetes

Type 1 diabetes is a chronic autoimmune disease characterised by insulin deficiency and resultant hyperglycaemia. Knowledge of type 1 diabetes has rapidly increased over the past 25 years, resulting in a broad understanding about many aspects of the disease, including its genetics, epidemiology, immune and β-cell phenotypes, and disease burden. Interventions to preserve β cells have been tested, and several methods to improve clinical disease management have been assessed. However, wide gaps still exist in our understanding of type 1 diabetes and our ability to standardise clinical care and decrease disease-associated complications and burden. This Seminar gives an overview of the current understanding of the disease and potential future directions for research and care.

Altered Brain Dynamics in Patients With Type 1 Diabetes During Working Memory Processing

It is now generally accepted that diabetes increases the risk for cognitive impairment, but the precise mechanisms are poorly understood. A critical problem in linking diabetes to cognitive impairment is that patients often have multiple comorbidities (e.g., obesity, hypertension) that have been independently linked to cognitive deficits. In the study reported here we focused on young adults with and without type 1 diabetes who were virtually free of such comorbidities. The two groups were matched on major health and demographic factors, and all participants completed a verbal working memory task during magnetoencephalographic brain imaging. We hypothesized that patients would have altered neural dynamics in verbal working memory processing and that these differences would directly relate to clinical disease measures. Accordingly, we found that patients had significantly stronger neural responses in the superior parietal cortices during memory encoding and significantly weaker activity in parietal-occipital regions during maintenance compared with control subjects. Moreover, disease duration and glycemic control were both significantly correlated with neural responses in various brain regions. In conclusion, young healthy adults with type 1 diabetes already have aberrant neural processing relative to their peers without diabetes, using compensatory responses to perform the task, and glucose management and duration may play a central role.

Depressed mitochondrial function and electron transport Complex II-mediated H2O2 production in the cortex of type 1 diabetic rodents

AIMS

Abnormalities in mitochondrial function under diabetic conditions can lead to deficits in function of cortical neurons and their support cells exhibiting a pivotal role in the pathogenesis of several neurodegenerative disorders, including Alzheimer's disease. We aimed to assess mitochondrial respiration rates and membrane potential or H2O2 generation simultaneously and expression of proteins involved in mitochondrial dynamics, ROS scavenging and AMPK/SIRT/PGC-1α pathway activity in cortex under diabetic conditions.

METHODS

Cortical mitochondria from streptozotocin (STZ)-induced type 1 diabetic rats or mice, and aged-matched controls were used for simultaneous measurements of mitochondrial respiration rates and mitochondrial membrane potential (mtMP) or H2O2 using OROBOROS oxygraph. Measurements of enzymatic activities of respiratory complexes were performed using spectophotometry. Protein levels in cortical mitochondria and homogenates were determined by Western blotting.

RESULTS

Mitochondrial coupled respiration rates and FCCP-induced uncoupled respiration rates were significantly decreased in mitochondria of cortex of STZ-diabetic rats compared to controls. The mtMP in the presence of ADP was significantly depolarized and succinate-dependent respiration rates and H2O2 were significantly diminished in cortical mitochondria of diabetic animals compared to controls, accompanied with reduced expression of CuZn- and Mn-superoxide dismutase. The enzymatic activities of Complex I, II, and IV and protein levels of certain components of Complex I and II, mitofusin 2 (Mfn2), dynamin-related protein 1 (DRP1), P-AMPK, SIRT2 and PGC-1α were significantly diminished in diabetic cortex.

CONCLUSION

Deficits in mitochondrial function, dynamics, and antioxidant capabilities putatively mediated through sub-optimal AMPK/SIRT/PGC-1α signaling, are involved in the development of early sub-clinical neurodegeneration in the cortex under diabetic conditions.

Long-term changes in retinal vascular diameter and cognitive impairment in type 1 diabetes

OBJECTIVE

To assess associations between cognitive impairment and longitudinal changes in retinal microvasculature, over 18 years, in adults with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Participants of the Pittsburgh Epidemiology of Diabetes Complications Study received ≥3 fundus photographs between baseline (1986-1988) and time of cognitive assessment (2010-2015: N = 119; 52% male; mean age and type 1 diabetes duration 43 and 34 years, respectively). Central retinal arteriolar equivalent and central retinal venular equivalent were estimated via computer-based methods; overall magnitude and speed of narrowing were quantified as cumulative average and slope, respectively. Median regression models estimated associations of central retinal arteriolar equivalent and central retinal venular equivalent measures with cognitive impairment status, adjusted for type 1 diabetes duration. Interactions with HbA1c, proliferative retinopathy and white matter hyperintensities were assessed.

RESULTS

Compared with participants without cognitive impairment, those with clinically relevant cognitive impairment experienced 1.8% greater and 31.1% faster central retinal arteriolar equivalent narrowing during prior years (t = -2.93, p = 0.004 and t = -3.97, p < 0.0001, respectively). Interactions with HbA1c, proliferative retinopathy and white matter hyperintensities were not significant. No associations were found between central retinal arteriolar equivalent at baseline, at time of cognitive testing, or any central retinal venular equivalent measures, and cognitive impairment.

CONCLUSION

Long-term arterial retinal changes could indicate type 1 diabetes-related cognitive impairment. Studies examining longitudinal central retinal arteriolar equivalent changes as early biomarkers of cognitive impairment risk are warranted.

Hypoglycemia unawareness in type 1 diabetes suppresses brain responses to hypoglycemia

BACKGROUND

Among nondiabetic individuals, mild glucose decrements alter brain activity in regions linked to reward, motivation, and executive control. Whether these effects differ in type 1 diabetes mellitus (T1DM) patients with and without hypoglycemia awareness remains unclear.

METHODS

Forty-two individuals (13 healthy control [HC] subjects, 16 T1DM individuals with hypoglycemia awareness [T1DM-Aware], and 13 T1DM individuals with hypoglycemia unawareness [T1DM-Unaware]) underwent blood oxygen level-dependent functional MRI brain imaging during a 2-step hyperinsulinemic euglycemic (90 mg/dl)-hypoglycemic (60 mg/dl) clamp for assessment of neural responses to mild hypoglycemia.

RESULTS

Mild hypoglycemia in HC subjects altered activity in the caudate, insula, prefrontal cortex, and angular gyrus, whereas T1DM-Aware subjects showed no caudate and insula changes, but showed altered activation patterns in the prefrontal cortex and angular gyrus. Most strikingly, in direct contrast to HC and T1DM-Aware subjects, T1DM-Unaware subjects failed to show any hypoglycemia-induced changes in brain activity. These findings were also associated with blunted hormonal counterregulatory responses and hypoglycemia symptom scores during mild hypoglycemia.

CONCLUSION

In T1DM, and in particular T1DM-Unaware patients, there is a progressive blunting of brain responses in cortico-striatal and fronto-parietal neurocircuits in response to mild-moderate hypoglycemia. These findings have implications for understanding why individuals with impaired hypoglycemia awareness fail to respond appropriately to falling blood glucose levels.

FUNDING

This study was supported in part by NIH grants R01DK020495, P30 DK045735, K23DK109284, K08AA023545. The Yale Center for Clinical Investigation is supported by an NIH Clinical Translational Science Award (UL1 RR024139).

The diabetic brain and cognition

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

Statin use and cognitive function in middle-aged adults with type 1 diabetes

AIM

To test associations between statin use and cognitive impairment in adults with childhood-onset type 1 diabetes (T1D).

METHODS

In 2010-13, n = 108 middle-aged participants from ongoing observational Pittsburgh Epidemiology of Diabetes Complications Study underwent neurocognitive assessment (mean age and T1D duration of 49 and 41 years, respectively). All were diagnosed with childhood-onset (i.e., prior to age 18) T1D between 1950 and 1980 and were seen within one year of diagnosis at Children’s Hospital of Pittsburgh. Self-reported statin use (yes/no and if yes, name of statin) was collected biennially from parent study baseline (1986-1988) to time of neurocognitive testing. Logistic regression models tested associations between statin use groups and cognitive impairment (defined as having two or more cognitive test scores 1.5SD or worse than published norms) while linear regression models tested associations between statin use groups and cognitive domain z-scores (domains: Verbal IQ, memory, executive function, psychomotor speed, and visuo-construction). All models controlled for education and age. To address confounding by indication, models were repeated using a propensity score for statin use.

RESULTS

Of the 108 participants, 51 reported never using statins. Median duration of statin use among the 57 ever users was 6 years. These 57 ever statin users were split to create two groups (≤ or > median years of statin use): 1-6 years (n = 25), and 7-12 years (n = 32). Compared with never users, using statins 1-6 years tripled the odds of cognitive impairment (OR = 3.16; 95%CI: 0.93-10.72; P = 0.06) and using statins 7-12 years almost quintupled the odds of cognitive impairment (OR = 4.84; 95%CI: 1.63-14.44; P = 0.005). Compared with never users, using statins 1-6 or 7-12 years was related to worse performance in the memory domain (β = -0.52; P = 0.003, and -0.39; P = 0.014, respectively). Adjusting for coronary artery disease, low density lipoprotein cholesterol, and Apo E4 status did not substantially alter results, and none of these covariates were significantly related to cognitive outcomes (all P > 0.05). Propensity score analyses support that associations between poor cognitive outcomes and statin use were not due merely to confounding by indication.

CONCLUSION

Statin use was associated with cognitive impairment, particularly affecting memory, in these middle-aged adults with childhood-onset T1D, whom at this age, should not yet manifest age-related memory deficits.

Cognitive Variability during Middle-Age: Possible Association with Neurodegeneration and Cognitive Reserve

Objective: Increased variability in cognition with age has been argued as an indication of pathological processes. Focusing on early detection of neurodegenerative disorders, we investigated variability in cognition in healthy middle-aged adults. In order to understand possible determinants of this variability, we also investigated associations with cognitive reserve, neuroimaging markers, subjective memory complaints, depressive symptomatology, and gender.

Method: Thirty-one 50 ± 2 years old individuals were investigated as target group and deviation was studied in comparison to a reference younger group of 30 individuals 40 ± 2 years old. Comprehensive neuropsychological and structural imaging protocols were collected. Brain regional volumes and cortical thickness were calculated with FreeSurfer, white matter hyperintensities with CASCADE, and mean diffusivity with FSL.

Results: Across-individuals variability showed greater dispersion in lexical access, processing speed, executive functions, and memory. Variability in global cognition correlated with, reduced cortical thickness in the right parietal-temporal-occipital association cortex, and increased mean diffusivity in the cingulum bundle and right inferior fronto-occipital fasciculus. A trend was also observed for the correlation between global cognition and hippocampal volume and female gender. All these associations were influenced by cognitive reserve. No correlations were found with subjective memory complaints, white matter hyperintensities and depressive symptomatology. Across-domains and across-tasks variability was greater in several executive components and cognitive processing speed.

Conclusion: Variability in cognition during middle-age is associated with neurodegeneration in the parietal–temporal–occipital association cortex and white matter tracts connecting this to the prefrontal dorsolateral cortex and the hippocampus. Moreover, this effect is influenced by cognitive reserve. Studying variability offers valuable information showing that differences do not occur in the same magnitude and direction across individuals, cognitive domains and tasks. These findings may have important implications for early detection of subtle cognitive impairment and clinical interpretation of deviation from normality.

Cost-effectiveness of sensor-augmented pump therapy versus standard insulin pump therapy in patients with type 1 diabetes in Denmark

AIMS

The use of continuous subcutaneous insulin infusion (CSII) in type 1 diabetes (T1D) has increased in recent years. Sensor-augmented pump therapy (SAP) with low glucose suspend (LGS) (allowing temporary suspension of insulin delivery if blood glucose level falls below a pre-defined threshold level) provides additional benefits over CSII alone, but is associated with higher acquisition costs. Therefore, a cost-effectiveness analysis of SAP+LGS versus CSII in patients with T1D was performed.

METHODS

Analyses were performed using the CORE Diabetes Model in two different patient cohorts in Denmark, one with hyperglycemia at baseline and one with increased risk for hypoglycemic events. Clinical input data were sourced from published literature. The analysis was performed over a lifetime time horizon from a societal perspective. Future costs and clinical outcomes were discounted at 3% per annum.

RESULTS

In patients who were hyperglycemic at baseline the use of SAP+LGS versus CSII resulted in improved quality-adjusted life expectancy (12.44 versus 10.99 quality-adjusted life years [QALYs]) but higher mean lifetime costs (DKK 2,027,316 versus DKK 1,801,293) leading to an incremental cost-effectiveness ratio (ICER) of DKK 156,082 per QALY gained. For patients at increased risk for hypoglycemic events the ICER for SAP+LGS versus CSII was DKK 89,868 per QALY gained.

CONCLUSIONS

The ICER for SAP+LGS versus CSII falls below commonly cited willingness-to-pay thresholds. Therefore, in Denmark, the use of SAP+LGS is likely to be considered cost-effective relative to CSII for patients with T1D who are either hyperglycemic, despite CSII use, or who experience frequent severe hypoglycemic events.

Regional Gray Matter Volumes as Related to Psychomotor Slowing in Adults with Type 1 Diabetes

OBJECTIVE

Psychomotor slowing is a common cognitive complication in type 1 diabetes (T1D), but its neuroanatomical correlates and risk factors are unclear. In nondiabetic adults, smaller gray matter volume (GMV) and presence of white matter hyperintensities are associated with psychomotor slowing. We hypothesize that smaller GMV in prefronto-parietal regions explains T1D-related psychomotor slowing. We also inspect the contribution of microvascular disease and hyperglycemia.

METHODS

GMV, white matter hyperintensities (WMH), and glucose levels were measured concurrently with a test of psychomotor speed (Digit Symbol Substitution Test [DSST]) in 95 adults with childhood-onset T1D (mean age/duration = 49/41 years) and 135 similarly aged non-T1D adults. Linear regression models tested associations between DSST and regional GMV, controlling for T1D, sex, and education; a bootstrapping method tested whether regional GMV explained between-group differences in DSST. For the T1D cohort, voxel-based and a priori regions-of-interest methods further tested associations between GMV and DSST, adjusting for WMH, hyperglycemia, and age.

RESULTS

Bilateral putamen, but no other regions examined, significantly attenuated DSST differences between the cohorts (bootstrapped unstandardized indirect effects: -3.49, -3.26; 95% confidence interval = -5.49 to -1.80, -5.29 to -1.44, left and right putamen, respectively). Among T1D, DSST was positively associated with GMV of bilateral putamen and left thalamus. Neither WMH, hyperglycemia, age, nor other factors substantially modified these relationships.

CONCLUSIONS

For middle-aged adults with T1D and cerebral microvascular disease, GMV of basal ganglia may play a critical role in regulating psychomotor speed, as measured via DSST. Studies to quantify the impact of basal ganglia atrophy concurrent with WMH progression on psychomotor slowing are warranted.

Physical activity and hippocampal volume in middle-aged patients with type 1 diabetes

OBJECTIVE

To examine the cross-sectional association between physical activity (PA) and hippocampal volume in middle-aged adults with childhood-onset type 1 diabetes (T1D), and whether hyperglycemia and insulin sensitivity contribute to this relationship.

METHODS

We analyzed neuroimaging and self-reported PA data from 79 adults with T1D from the Pittsburgh Epidemiology of Diabetes Complications Study (mean age 50 years, mean duration 41 years) and 122 similarly aged adults without T1D (mean age 48 years). Linear regression models, controlling for intracranial volume, sex, education, and age, tested associations between PA and gray matter volumes of hippocampi and total brain in the 2 groups. For the T1D group, models further controlled for hyperglycemia and glucose disposal rate, a measure of insulin sensitivity.

RESULTS

PA was significantly lower in the T1D than in the non-T1D group (median [interquartile range] 952 kcal [420-2,044] vs 1,614 kcal [588-3,091], respectively). Higher PA was significantly associated with larger hippocampi for T1D, but not for non-T1D (standardized β [p values] from regression models adjusted for intracranial volume, sex, age, and education: 0.270 [p < 0.001] and 0.098 [p = 0.12], respectively). Neither hyperglycemia nor glucose disposal rate substantially modified this association. Relationships between PA and total brain gray matter volume were similar.

CONCLUSIONS

A cross-sectional association between higher PA and larger hippocampi is already detectable by middle age for these patients with T1D, and it appears robust to chronic hyperglycemia and insulin sensitivity. Proof-of-concept studies should investigate whether increasing PA preserves hippocampal volume and the mechanisms underlying the effects of PA on hippocampal volume.

Prefrontal-Parietal White Matter Volumes in Healthy Elderlies Are Decreased in Proportion to the Degree of Cardiovascular Risk and Related to Inhibitory Control Deficits

Cardiovascular risk (CVR) factors may be associated with poor cognitive functioning in elderlies and impairments in brain structure. Using MRI and voxel-based morphometry (VBM), we assessed regional white matter (WM) volumes in a population-based sample of individuals aged 65–75 years (n = 156), subdivided in three CVR subgroups using the Framingham Risk Score. Cognition was assessed using the Short Cognitive Performance Test. In high-risk subjects, we detected significantly reduced WM volume in the right juxtacortical dorsolateral prefrontal region compared to both low and intermediate CVR subgroups. Findings remained significant after accounting for the presence of the APOEε4 allele. Inhibitory control performance was negatively related to right prefrontal WM volume, proportionally to the degree of CVR. Significantly reduced deep parietal WM was also detected bilaterally in the high CVR subgroup. This is the first large study documenting the topography of CVR-related WM brain volume deficits. The significant association regarding poor response inhibition indicates that prefrontal WM deficits related to CVR are clinically meaningful, since inhibitory control is known to rely on prefrontal integrity.

Cognition in Adults and Older Adults With Type 1 Diabetes: Chicken or Egg?

IN BRIEF Cognitive impairment and cognitive decline are common in adults with type 1 diabetes. Although several diabetes-related variables have been associated with cognitive functioning in both cross-sectional and longitudinal studies, inconsistencies remain. This is particularly true in older adults. Cognitive impairment appears to be both a consequence of and a risk factor for poor diabetes self-management and associated glycemic outcomes. Interventions such as cognitive compensatory strategies, assistive technology, and simplified treatment regimens may limit the impact of cognitive impairment on self-management in adults and older adults with type 1 diabetes.

A Diffusion Tensor Imaging Study on White Matter Abnormalities in Patients with Type 2 Diabetes Using Tract-Based Spatial Statistics

BACKGROUND AND PURPOSE

Patients with type 2 diabetes mellitus have considerably higher risk of developing cognitive impairment and dementia. WM changes in these patients have been reported. Our aim was to demonstrate that gradual and continuous WM change and the associated cognitive decline in patients with type 2 diabetes mellitus can be captured by DTI parameters, which can be used to complement neuropsychological test scores in identifying patients with type 2 diabetes mellitus with and without mild cognitive impairment.

MATERIALS AND METHODS

Forty-two patients with type 2 diabetes mellitus, divided into a group with mild cognitive impairment (n = 20) and a group with normal cognition (n = 22), were enrolled with age-, sex-, and education-matched healthy controls (n = 26). 3T DTI followed by Tract-Based Spatial Statistics analysis was used to investigate the differences in fractional anisotropy, mean diffusivity, axial diffusivity (λ1), and radial diffusivity (λ23) among the groups. A receiver operating characteristic analysis assessed the performance of DTI parameters for separating the 2 groups with type 2 diabetes mellitus.

RESULTS

The whole-brain Tract-Based Spatial Statistics analysis revealed that 7.3% and 24.9% of the WM exhibited decreased fractional anisotropy and increased mean diffusivity (P < .05), respectively, between the diabetes mellitus with mild cognitive impairment and the diabetes mellitus with normal cognition groups, while considerably larger WM regions showed fractional anisotropy (36.6%) and mean diffusivity (58.8%) changes between the diabetes mellitus with mild cognitive impairment and the healthy control groups. These changes were caused primarily by an elevated radial diffusivity observed in the patients with diabetes mellitus with mild cognitive impairment. Radial diffusivity also exhibited subtle but statistically significant changes between the diabetes mellitus with normal cognition and the healthy control groups. Analyses on individual fiber tracts showed pronounced fractional anisotropy reduction and mean diffusivity elevation in regions related to cognitive functions. The receiver operating characteristic analysis on the right cingulum (hippocampus) showed that fractional anisotropy produced a larger area under the curve (0.832) than mean diffusivity (0.753) for separating mild cognitive impairment from normal cognition among patients with type 2 diabetes mellitus. When fractional anisotropy was combined with mean diffusivity, the area under the curve was further improved to 0.857.

CONCLUSIONS

DTI parameters can show a substantial difference between patients with type 2 diabetes mellitus with and without mild cognitive impairment, suggesting their potential use as an imaging marker for detecting cognitive decline in patients with type 2 diabetes mellitus. More important, DTI parameters may capture gradual and continuous WM changes that can be associated with early stages of cognitive decline in patients with type 2 diabetes mellitus before they can be diagnosed clinically by using conventional neuropsychological tests.

Complex mechanisms linking neurocognitive dysfunction to insulin resistance and other metabolic dysfunction

Scientific evidence has established several links between metabolic and neurocognitive dysfunction, and epidemiologic evidence has revealed an increased risk of Alzheimer’s disease and vascular dementia in patients with diabetes. In July 2015, the National Institute of Diabetes, Digestive, and Kidney Diseases gathered experts from multiple clinical and scientific disciplines, in a workshop entitled “The Intersection of Metabolic and Neurocognitive Dysfunction”, to clarify the state-of-the-science on the mechanisms linking metabolic dysfunction, and insulin resistance and diabetes in particular, to neurocognitive impairment and dementia. This perspective is intended to serve as a summary of the opinions expressed at this meeting, which focused on identifying gaps and opportunities to advance research in this emerging area with important public health relevance.

Longitudinal Evaluation of Cognitive Functioning in Young Children with Type 1 Diabetes over 18 Months

OBJECTIVES

Decrements in cognitive function may already be evident in young children with type 1 diabetes (T1D). Here we report prospectively acquired cognitive results over 18 months in a large cohort of young children with and without T1D.

METHODS

A total of 144 children with T1D (mean HbA1c: 7.9%) and 70 age-matched healthy controls (mean age both groups 8.5 years; median diabetes duration 3.9 years; mean age of onset 4.1 years) underwent neuropsychological testing at baseline and after 18-months of follow-up. We hypothesized that group differences observed at baseline would be more pronounced after 18 months, particularly in those T1D patients with greatest exposure to glycemic extremes.

RESULTS

Cognitive domain scores did not differ between groups at the 18 month testing session and did not change differently between groups over the follow-up period. However, within the T1D group, a history of diabetic ketoacidosis (DKA) was correlated with lower Verbal IQ and greater hyperglycemia exposure (HbA1c area under the curve) was inversely correlated to executive functions test performance. In addition, those with a history of both types of exposure performed most poorly on measures of executive function.

CONCLUSIONS

The subtle cognitive differences between T1D children and nondiabetic controls observed at baseline were not observed 18 months later. Within the T1D group, as at baseline, relationships between cognition (Verbal IQ and executive functions) and glycemic variables (chronic hyperglycemia and DKA history) were evident. Continued longitudinal study of this T1D cohort and their carefully matched healthy comparison group is planned.

Variations in Brain Volume and Growth in Young Children With Type 1 Diabetes

Early-onset type 1 diabetes may affect the developing brain during a critical window of rapid brain maturation. Structural MRI was performed on 141 children with diabetes (4-10 years of age at study entry) and 69 age-matched control subjects at two time points spaced 18 months apart. For the children with diabetes, the mean (±SD) HbA1c level was 7.9 ± 0.9% (63 ± 9.8 mmol/mol) at both time points. Relative to control subjects, children with diabetes had significantly less growth of cortical gray matter volume and cortical surface area and significantly less growth of white matter volume throughout the cortex and cerebellum. For the population with diabetes, the change in the blood glucose level at the time of scan across longitudinal time points was negatively correlated with the change in gray and white matter volumes, suggesting that fluctuating glucose levels in children with diabetes may be associated with corresponding fluctuations in brain volume. In addition, measures of hyperglycemia and glycemic variation were significantly negatively correlated with the development of surface curvature. These results demonstrate that early-onset type 1 diabetes has widespread effects on the growth of gray and white matter in children whose blood glucose levels are well within the current treatment guidelines for the management of diabetes.

Brain Activation and Psychomotor Speed in Middle-Aged Patients with Type 1 Diabetes: Relationships with Hyperglycemia and Brain Small Vessel Disease

Slower psychomotor speed is very common in patients with type 1 diabetes mellitus (T1D), but the underlying mechanisms are not clear. We propose that hyperglycemia is associated with slower psychomotor speed via disruption of brain activation. Eighty-five adults (48% women, mean age: 49.0 years, mean duration: 40.8) with childhood onset T1D were recruited for this cross-sectional study. Median response time in seconds (longer = worse performance) and brain activation were measured while performing a psychomotor speed task. Exposure to hyperglycemia, measured as glycosylated hemoglobin A1c, was associated with longer response time and with higher activation in the inferior frontal gyrus and primary sensorimotor and dorsal cingulate cortex. Higher activation in inferior frontal gyrus, primary sensorimotor cortex, thalamus, and cuneus was related to longer response times; in contrast, higher activation in the superior parietal lobe was associated with shorter response times. Associations were independent of small vessel disease in the brain or other organs. In this group of middle-aged adults with T1D, the pathway linking chronic hyperglycemia with slower processing speed appears to include increased brain activation, but not small vessel disease. Activation in the superior parietal lobe may compensate for dysregulation in brain activation in the presence of hyperglycemia.