Type 1 diabetes-associated cognitive decline: a meta-analysis and update of the current literature

Impact of Early Diabetic Ketoacidosis on the Developing Brain

OBJECTIVE

This study examined whether a history of diabetic ketoacidosis (DKA) is associated with changes in longitudinal cognitive and brain development in young children with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Cognitive and brain imaging data were analyzed from 144 children with type 1 diabetes, ages 4 to <10 years, who participated in an observational study of the Diabetes Research in Children Network (DirecNet). Participants were grouped according to history of DKA severity (none/mild or moderate/severe). Each participant had unsedated MRI scans and cognitive testing at baseline and 18 months.

RESULTS

In 48 of 51 subjects, the DKA event occurred at the time of onset, at an average of 2.9 years before study entry. The moderate/severe DKA group gained more total and regional white and gray matter volume over the observed 18 months compared with the none/mild group. When matched by age at time of enrollment and average HbA1c during the 18-month interval, participants who had a history of moderate/severe DKA compared with none/mild DKA were observed to have significantly lower Full Scale Intelligence Quotient scores and cognitive performance on the Detectability and Commission subtests of the Conners' Continuous Performance Test II and the Dot Locations subtest of the Children's Memory Scale.

CONCLUSIONS

A single episode of moderate/severe DKA in young children at diagnosis is associated with lower cognitive scores and altered brain growth. Further studies are needed to assess whether earlier diagnosis of type 1 diabetes and prevention of DKA may reduce the long-term effect of ketoacidosis on the developing brain.

Diabetes and Behavior in the 21st Century: Things That Make You Go "Hmmm . . . "

Editor's Note: This article is adapted from the address Dr. Wysocki delivered as the recipient of the American Diabetes Association's Richard R. Rubin Award for 2018. This award recognizes a behavioral researcher who has made outstanding, innovative contributions to the study and understanding of the behavioral aspects of diabetes in diverse populations. Dr. Wysocki delivered the address in June 2018 at the association's 78th Scientific Sessions in Orlando, Fla.

Clinically significant cognitive impairment in older adults with type 1 diabetes

AIMS

Little is known about cognition in older adults with type 1 diabetes. The aim of this study was to identify correlates of clinically significant cognitive impairment.

METHODS

Neuropsychological, diabetes-related and glycemic (HbA1c, Continuous Glucose Monitoring; CGM) data were collected from 201 older adults (≥60 years) with longstanding type 1 diabetes.

RESULTS

Clinically significant cognitive impairment (≥2 cognitive tests ≥1.5 SD below normative data) occurred in 48% of the sample. After controlling for age, gender, education and diabetes duration, we found that hypoglycemia unawareness, recent severe hypoglycemic events, any microvascular complication, higher HbA1c and CGM average nocturnal glucose were all associated with increased odds of clinically significant cognitive impairment (ORs = 1.01-2.61), while CGM nocturnal % time below 60 mg/dL was associated with a decreased odds of cognitive impairment (OR = 0.94). Diabetes duration, diagnosis age, daytime CGM, and lifetime severe hypoglycemic events were not related to cognitive impairment status.

CONCLUSIONS

Clinically significant cognitive impairment was common in older adults with type 1 diabetes. Diabetes-related correlates of cognitive impairment were identified, including hypoglycemia unawareness, recent severe hypoglycemic events, and CGM variables. Longitudinal research is needed to determine if these variables predict cognitive decline and if their modification alters outcomes.

Taurine Ameliorates High Glucose Induced Apoptosis in HT-22 Cells

Diabetes causes memory loss. Hippocampus is responsible for memory and increased apoptosis was found in diabetes patients. Taurine improved memory in diabetes condition. However, mechanism is unclear. In current study, hippocampal cell line HT-22 cells were subjected to analysis as five groups i.e. Control, High glucose (HG) at concentration of 150 mM, HG + 10 mM (T1), 20 mM (T2) and 40 mM (T3) taurine solution. TUNEL assay showed that HG increased the number of apoptotic cell significantly while taurine reduced apoptosis. Taurine increased phosphorylation of Akt in HT-22 cell treated with HG, and increased phosphorylation of Bad (p-Bad) was seen suggesting involvement of Akt/Bad signaling pathway. Expression of Bcl-2 was reduced in HG group but taurine improved this. Bax expression showed opposite trend. This indicated that taurine may reduce apoptosis by controlling balance of Bcl-2 and Bax. When the activation of Akt was blocked by using of perifosine, the effect of taurine disappears either partially or altogether. Thus, it was clear that taurine reduces apoptosis via Akt/Bad pathway in HT-22 cells exposed to HG which further improves downstream balance of Bcl-2 and Bax. This mechanism may be involved in apoptosis of hippocampus cells in diabetic condition.

Impaired cognitive processing speed in type 1 diabetic patients who had severe/recurrent hypoglycaemia

AIMS

To detect whether adults with type 1 diabetes mellitus (T1DM) have lower cognitive performance than healthy individuals and to detect risk factors for low cognitive performance.

METHODS

Twenty-six adults with T1DM and twenty-six healthy subjects matched for age, gender and educational level were compared for cognitive performance by a chronometric computerized test measuring visuo-spatial working memory (N-Back) and by two validated neuropsychological tests (Mini Mental State Examination, Animal Naming Test). Clinical data about diabetes duration, average daily insulin dosage, glycated haemoglobin, retinopathy, urine albumin-creatinine ratio, previous hypoglycaemic coma and awareness of hypoglycaemia were obtained from medical records. Basal pre-test glycemia and blood pressure were measured for each patient.

RESULTS

No differences were found between patients (n = 26) and healthy controls (n = 26) in neuropsychological tests. Within diabetic patients, those with impaired awareness of hypoglycaemia (n = 7) or history of coma in the recent 1-3 years (n = 5) had psychomotor slowing at the N-Back test (592 ± 35 vs. 452 ± 21 ms and 619 ± 40 vs. 462 ± 19 ms, respectively; both p < 0.01). The variables related to diabetic severity did not show a relationship with reaction times of the N-Back test.

CONCLUSION

Psychomotor speed slowing is detectable in patients with T1DM who have a history of previous hypoglycaemic episodes or coma.

The impact of type 1 diabetes on neural activity serving attention

Type 1 diabetes has been associated with alterations in attentional processing and other cognitive functions, and previous studies have found alterations in both brain structure and function in affected patients. However, these previous neuroimaging studies have generally examined older patients, particularly those with major comorbidities known to affect functioning independent of diabetes. The primary aim of the current study was to examine the neural dynamics of selective attention processing in a young group of patients with type 1 diabetes who were otherwise healthy (i.e., without major comorbidities). Our hypothesis was that these patients would exhibit significant aberrations in attention circuitry relative to closely matched controls. The final sample included 69 participants age 19-35 years old, 35 with type 1 diabetes and 34 matched nondiabetic controls, who completed an Eriksen flanker task while undergoing magnetoencephalography. Significant group differences in flanker interference activity were found across a network of brain regions, including the anterior cingulate, inferior parietal cortices, paracentral lobule, and the left precentral gyrus. In addition, neural activity in the anterior cingulate and the paracentral lobule was correlated with disease duration in patients with type 1 diabetes. These findings suggest that alterations in the neural circuitry underlying selective attention emerge early in the disease process and are specifically related to type 1 diabetes and not common comorbidities. These findings highlight the need for longitudinal studies in large cohorts to clarify the clinical implications of type 1 diabetes on cognition and the brain.

Is sex an influential factor in type-1 diabetes neurofunctional development? A preliminary study

The aim of the study was to evaluate the neurofunctional effect of gender in Type-1 Diabetes Mellitus (T1DM) patients during a Visual Spatial Working Memory (VSWM) task. The study included 28 participants with ages ranging from 17-28 years. Fourteen well-controlled T1DM patients (7 female) and 14 controls matched by age, sex, and education level were scanned performing a block-design VSWM paradigm. Behavioral descriptive analyses and mean comparisons were done, and between-group and condition functional activation patterns were also compared. Whole-brain cumulative BOLD signal (CumBS), voxel-wise BOLD level frequency, Euclidean distance, and divergence indices were also calculated. There were no significant differences between or within-group sex differences for correct responses and reaction times. Functional activation analyses showed that females had activation in more brain regions, and with larger clusters of cortical activations than males. Furthermore, BOLD activation was higher in males. Despite the preliminary nature of the present study given the relatively small sample size, current results acknowledge for the first time that sex might contribute to differences in functional activation in T1DM patients. Findings suggest that sex differences should be considered when studying T1DM-disease development.

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.

Glycemic extremes are related to cognitive dysfunction in children with type 1 diabetes: A meta-analysis

Aims/Introduction

To examine the magnitude and pattern of cognitive dysfunction in children with type 1 diabetes, and the possible effects associated with other disease variables, such as early onset diabetes, severe hypoglycemia and hyperglycemia.

Materials and Methods

We carried out a meta‐analysis using the Preferred Reporting Items for Systematic Reviews and Meta‐Analysis guidelines. We searched MedLine, Embase and PsycINFO to identify studies on cognitive function in children with type 1 diabetes that were published up until 30 September 2016. Effect sizes understood as the standardized mean differences between groups with diabetes and control groups (i.e., Hedges’ g) were calculated to quantify the extent of cognitive dysfunction in those groups consisting of children with diabetes.

Results

A total of 19 studies met our inclusion criteria, comprising 1,355 participants with type 1 diabetes and 696 controls. Compared with non‐diabetic controls, children with type 1 diabetes showed a significantly poorer cognitive performance overall (g = −0.46), as well as specific deficits in full‐scale intelligence (g = −1.06), attention (g = −0.60) and psychomotor speed (g = −0.46). Glycemic extremes were associated with poorer overall cognition (g = −0.18), as well as slightly lower performance in memory (g = −0.27).

Conclusions

We found that type 1 diabetes was associated with cognitive dysfunction characterized by a lowered intelligence, diminished attention and a slowing of psychomotor speed. Glycemic extremes, which are described as a period of high glucose levels and severe hypoglycemia, were related to cognitive dysfunction in children with type 1 diabetes.

A Systematic Review and Meta-analysis of Executive Function Performance in Type 1 Diabetes Mellitus

OBJECTIVE

The aims of the study were to examine the current evidence for executive function (EF) performance differences between groups with type 1 diabetes mellitus (T1DM) and nondiabetic control groups during adolescence and early adulthood and to explore the relationships between EF and diabetes-related risk factors.

METHODS

A systematic review of the literature examining EF performance in groups with T1DM was conducted according to the PRISMA guidelines. Electronic database searches for published and unpublished literature yielded a final set of 26 articles after application of inclusion and exclusion criteria. A meta-analysis was conducted on a subset of these articles (n = 17) comparing EF performance in T1DM and control groups, across a total sample size of 1619.

RESULTS

Sixteen of 26 studies found significantly lower EF on at least one task in groups with T1DM. Meta-analyses of the performance difference between T1DM groups and control groups without diabetes showed that inhibition (g = -0.28, p < .001), working memory (g = -0.34, p < .001), set-shifting (g = -0.31, p = .012), and overall EF performance across these domains (g = -0.42, p < .001) were all significantly lower in groups with T1DM. Performance on specific EF domains also seemed to be differentially associated with early age of diabetes onset, chronic hyperglycemia and its complications, and severe hypoglycemia.

CONCLUSIONS

T1DM and its associated risk factors are related to subtle impairments across the inhibition, working memory, and set-shifting domains of EF. Lower EF may be a key factor contributing to behavioral and clinical problems experienced by individuals with T1DM.

Type 1 Diabetes in Parents and Risk of Attention Deficit/Hyperactivity Disorder in Offspring: A Population-Based Study in Sweden

OBJECTIVE

To explore whether a family history of type 1 diabetes (T1D) is associated with an increased incidence of attention deficit/hyperactivity disorder (ADHD) in offspring.

RESEARCH DESIGN AND METHODS

Individuals with T1D were identified from the nationwide Swedish National Hospital Discharge Register and Swedish Outpatient Register in Sweden and were linked to the Swedish Multi-Generation Register to identify their offspring. Cox regression was used to calculate the hazard ratio (HR) of ADHD in offspring of patients with T1D compared with the general population.

RESULTS

A total of 15,615 individuals were born after their parents were diagnosed with T1D. After a set of confounding factors was controlled for, offspring of T1D patients had a significantly increased risk of ADHD with an HR of 1.29 (95% CI 1.15-1.42). Maternal T1D was associated with an enhanced risk of ADHD (HR 1.35 [95% CI 1.18-1.55]) compared with paternal T1D (HR 1.20 [95% CI 1.03-1.41]), but the difference was not statistically significant.

CONCLUSIONS

In this retrospective cohort study, we found that a parental history of T1D was associated with a 29% increased risk of being diagnosed with ADHD. However, the underlying mechanisms need to be explored in future studies.

Incidence and Risk Profile of Dementia in the Regions of Middle East and North Africa

BACKGROUND

The risk of dementia is reported as "epidemic" and "looming" over the Middle East and North Africa (MENA) region. For this, we performed a multi-language review and feasible analysis on the incidence of dementia to offer apt conclusions.

METHODS

Totally, 3 databases (Magiran, Scientific Information Database, and PubMed) and 1 non-database source (Google) were searched in French, English, and Persian by using specific keywords and their combinations. All searches were independent and had no restriction for the year or type of publication. We also calculated cumulative incidence of dementia for Egypt and Israel-Palestine from relevant prevalence estimates by using standard formula.

RESULTS

Little information on incidence was available, sparing Israel (2.4/100,000/year; pre-senile). Ten (48.0%) countries had none-to-little information (of any kind) on dementia, indicating considerable awareness deficit in this region. Cumulative incidence of dementia in Egypt and Israel-Palestine was 2.7% over 20 years (55 new cases) and 14.7% (130 new cases) over 6 years, respectively. In Lebanon, cumulative incidence was 7.5% over 20 years. Data looked across dementia-related factors (i.e., fertility rate, polygamy, violence, hypovitaminosis D, diabetes, hypertension, life expectancy, age structure) did not seem to support epidemic proportions of dementia for MENA.

CONCLUSIONS

MENA is youthful and dementia here is neither likely to be an epidemic nor looming over. The only possible exception might be Arab pocket in Israel. To us, previous attributions on dementia do not seem to be based on the realities of this region and, therefore, may prevent pragmatic addressal of dementia. Lastly, values-based collaborations are invited to jointly fill the awareness deficit in a unique low-cost manner.

Altered Integration of Structural Covariance Networks in Young Children With Type 1 Diabetes

Type 1 diabetes mellitus (T1D), one of the most frequent chronic diseases in children, is associated with glucose dysregulation that contributes to an increased risk for neurocognitive deficits. While there is a bulk of evidence regarding neurocognitive deficits in adults with T1D, little is known about how early-onset T1D affects neural networks in young children. Recent data demonstrated widespread alterations in regional gray matter and white matter associated with T1D in young children. These widespread neuroanatomical changes might impact the organization of large-scale brain networks. In the present study, we applied graph-theoretical analysis to test whether the organization of structural covariance networks in the brain for a cohort of young children with T1D (N = 141) is altered compared to healthy controls (HC; N = 69). While the networks in both groups followed a small world organization-an architecture that is simultaneously highly segregated and integrated-the T1D network showed significantly longer path length compared with HC, suggesting reduced global integration of brain networks in young children with T1D. In addition, network robustness analysis revealed that the T1D network model showed more vulnerability to neural insult compared with HC. These results suggest that early-onset T1D negatively impacts the global organization of structural covariance networks and influences the trajectory of brain development in childhood. This is the first study to examine structural covariance networks in young children with T1D. Improving glycemic control for young children with T1D might help prevent alterations in brain networks in this population. Hum Brain Mapp 37:4034-4046, 2016. © 2016 Wiley Periodicals, Inc.

Functional magnetic resonance imaging reveals differences in brain activation in response to thermal stimuli in diabetic patients with and without diabetic peripheral neuropathy

Introduction

Diabetes affects both the peripheral and central nervous systems. The aim of this study was to explore the changes in brain activity in response to thermal stimuli in diabetic patients with and without diabetic peripheral neuropathy (DPN) using functional magnetic resonance imaging (fMRI).

Methods

A total of 36 right-handed volunteers were enrolled: eight patients with Type-2 diabetes mellitus and DPN, 13 patients with Type-2 diabetes mellitus lacking DPN (NDPN patients), and 15 healthy volunteers (HV). Blood oxygenation level-dependent baseline scans were performed, first without any stimuli, and then with four sessions of thermal stimuli (0, 10, 34, and 44°C, in a random order) applied to the lateral side of the right lower extremity. There was a 240-s rest interval between each thermal stimulation. Each stimulation session consisted of three cycles of 30 s of stimulation followed by 30 s of rest. After each stimuli session, the participant rated pain and itch perception on a visual analog scale. The fMRI data series were analyzed by using Statistical Parametric Mapping 8 and Data Processing Assistant for Resting-State fMRI.

Results

In response to temperature stimuli, DPN patients showed stronger activation than HV and NDPN patients, not only in brain areas that participate in somatosensory pathways (right insula, left caudate nucleus, frontal gyrus, and cingulate cortex), but also in the cognition-related cerebral areas (right temporal lobe, left hippocampus, and left fusiform gyrus). Activation of vermis 1–3 was greater in NDPN patients than in HV in response to 0°C stimulation.

Conclusions

fMRI may be useful for the early detection of central nervous system impairment caused by DPN. Our results indicate that central nervous system impairment related to diabetic neuropathy may not be limited to motion- and sensation-related cortical regions. Cognition-associated cerebral regions such as the hippocampus and fusiform gyrus are also affected by functional changes caused by DPN. This suggests that fMRI can detect the early stages of cognitive impairment in DPN patients before the symptoms become clinically significant.

A longitudinal investigation of cognitive function in children and adolescents with type 1 diabetes mellitus

OBJECTIVE

Cross-sectional studies find altered cognition in youth with type 1 diabetes mellitus (T1DM). However, few longitudinal studies have examined the trajectories of their cognitive performance over time. The aims of this study were to explore longitudinal change in cognitive function in youth with T1DM as compared with nondiabetic sibling controls, and how glycemic control and age of onset influence cognitive performance over time.

METHODS

We assessed crystallized intelligence, visual-spatial ability, delayed memory, and processing speed at 3 time points using the same cognitive tasks in youth with T1DM and sibling controls. Hierarchical linear modeling examined relationships between diabetes, hyperglycemia (HbA1c values), age of onset, and cognition over 5.5 y.

RESULTS

Youth with diabetes performed worse than controls on visual-spatial ability and memory tasks over time, and did not improve as much in processing speed. Greater hyperglycemia was associated with lower crystallized intelligence and slower processing speed but better memory across all time points. There was a stronger negative relationship between hyperglycemia and visual-spatial ability for youth with earlier compared with later onset diabetes. Importantly, within-person decreases in hyperglycemia between time points were associated with improved visual-spatial ability and faster processing speed.

CONCLUSIONS

On average, differences in cognitive function between youth with T1DM and nondiabetic relatives are maintained or increase during childhood and adolescence. Hyperglycemia and age of onset can have negative effects on the developmental trajectories of cognitive processes in youth with T1DM. However, treatments that lower hyperglycemia may lead to improved cognitive function in youth with T1DM.

Lower cognitive performance among long-term type 1 diabetes survivors: A case-control study

OBJECTIVE

Patients with type 1 diabetes (T1D) have an increased risk of cognitive dysfunction. The cognitive decrement is believed to depend on macro- and microvascular complications and long disease duration. Some patients do not develop these complications, but still report cognitive symptoms. We examined if long-standing T1D without complications is associated with lower cognitive performance.

METHODS

A group of patients (n=43) with long-standing T1D (>30years) without micro- or macro vascular complications was compared with a non-diabetic control group (n=86) on six cognitive tests which probed episodic memory, semantic memory, episodic short-term memory, visual attention and psychomotor speed. Each patient was matched with two controls regarding age, gender and education. A linear mixed effect model was used to analyze the data.

RESULTS

The mean age was 57years and mean duration was 41years. Patients with diabetes had lower diastolic blood pressure but BMI, waist circumference, systolic blood pressure and smoking did not differ between groups. Patients had lower results than non-diabetic controls in episodic short-term memory (p<0.001) and also lower values on a test that mirrors visual attention and psychomotor speed (p=0.019).

CONCLUSIONS

Long-standing T1D was associated with lower cognitive performance, regardless of other diabetes-related complications.

Effect of verbal task complexity in a working memory paradigm in patients with type 1 diabetes. A fMRI study

Type 1 diabetes (T1D) is commonly diagnosed in childhood and adolescence, and the developing brain has to cope with its deleterious effects. Although brain adaptation to the disease may not result in evident cognitive dysfunction, the effects of T1D on neurodevelopment could alter the pattern of BOLD fMRI activation. The aim of this study was to explore the neural BOLD activation pattern in patients with T1D versus that of healthy matched controls while performing two visuospatial working memory tasks, which included a pair of assignments administered through a block design. In the first task (condition A), the subjects were shown a trial sequence of 3 or 4 white squares positioned pseudorandomly around a fixation point on a black background. After a fixed delay, a second corresponding sequence of 3 or 4 red squares was shown that either resembled (direct, 50%) or differed from (50%) the previous stimulation order. The subjects were required to press one button if the two spatial sequences were identical or a second button if they were not. In condition B, the participants had to determine whether the second sequence of red squares appeared in inverse order (inverse, 50%) or not (50%) and respond by pressing a button. If the latter sequence followed an order distinct from the inverse sequence, the subjects were instructed to press a different button. Sixteen patients with normal IQ and without diabetes complications and 16 healthy control subjects participated in the study. In the behavioral analysis, there were no significant differences between the groups in the pure visuo-spatial task, but the patients with diabetes exhibited poorer performance in the task with verbal stimuli (p < .001). However, fMRI analyses revealed that the patients with T1D showed significantly increased activation in the prefrontal inferior cortex, subcortical regions and the cerebellum (in general p < .001). These different activation patterns could be due to adaptive compensation mechanisms that are devoted to improving efficiency while solving more complex cognitive tasks.

Cognitive deficits associated with impaired awareness of hypoglycaemia in type 1 diabetes

AIMS/HYPOTHESIS

The aim of this study was to compare cognitive function in adults with type 1 diabetes who have impaired awareness of hypoglycaemia with those who have normal awareness of hypoglycaemia. A putative association was sought between cognitive test scores and a history of severe hypoglycaemia.

METHODS

A total of 68 adults with type 1 diabetes were included: 33 had impaired and 35 had normal awareness of hypoglycaemia, as confirmed by formal testing. The groups were matched for age, sex and diabetes duration. Cognitive tests of verbal memory, object-location memory, pattern separation, executive function, working memory and processing speed were administered.

RESULTS

Participants with impaired awareness of hypoglycaemia scored significantly lower on the verbal and object-location memory tests and on the pattern separation test (Cohen's d -0.86 to -0.55 [95% CI -1.39, -0.05]). Participants with impaired awareness of hypoglycaemia had reduced planning ability task scores, although the difference was not statistically significant (Cohen's d 0.57 [95% CI 0, 1.14]). Frequency of exposure to severe hypoglycaemia correlated with the number of cognitive tests that had not been performed according to instructions.

CONCLUSIONS/INTERPRETATION

Impaired awareness of hypoglycaemia was associated with diminished learning, memory and pattern separation. These cognitive tasks all depend on the hippocampus, which is vulnerable to neuroglycopenia. The findings suggest that hypoglycaemia contributes to the observed correlation between impaired awareness of hypoglycaemia and impaired cognition.

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.

Simvastatin ameliorates memory impairment and neurotoxicity in streptozotocin-induced diabetic mice

Diabetes comes with an additional burden of moderate to severe hyperlipidemia, but little is known about the effects of lipid-lowering therapy on diabetic complications such as diabetes-associated cognitive decline. Herein we investigated the effects of statins on memory impairment and neurotoxicity in streptozotocin-induced diabetic mice. Our data indicated that oral administration of simvastatin at 10 or 20mg/kg for 4weeks significantly ameliorated diabetes-associated memory impairment reflected by performance better in the Morris water maze and Y-maze tests. The further study showed that these treatments caused significant increase of peroxisome proliferator-activated receptors gamma and decrease of NF-κB p65 in nucleus of hippocampus and cortex, and ameliorated neuroinflammatory response as evidenced by less Iba-1-positive cells and lower inflammatory mediators including IL-1β, IL-6 and TNF-α as well as suppressed neuronal apoptosis as indicated by decreased TUNEL-positive cells, increased ratio of Bcl-2/Bax and decreased caspase-3 activity in the hippocampus and cortex. Moreover, simvastatin pronouncedly attenuated amyloidogenesis by decreasing amyloid-β, amyloid precursor protein (APP) and beta-site APP cleaving enzyme-1. As expected, treated with simvastatin, the diabetic mice exhibited significant improvement of hyperlipidemia rather than hyperglycemia. Our findings disclosed novel therapeutic potential of simvastatin for the diabetes-associated cognitive impairment.

Cognitive decline affects diabetic women

Introduction: DM provokes peripheral complications and changes in central nervous system. Central changes in the course of diabetes mellitus (DM) include changes in brain tissue structure, electrophysiological abnormalities but also disturbances in neurotransmission leading to cognitive decline.

Aim of the study: The aim of our study was to asses cognitive functioning of patients suffering from DM1 for at least 5 years but without any diagnosed complications.

Materials and methods: Cognitive functions were assessed in 59 patients (35 men) with Trail Making Test A (TMT A) and B (TMT B), Maze Test (MT), Stroop Test (SCWT) and Rey Auditory Verbal Learning Test (RAVLT). Mental disorders were excluded with Beck’s Depression Inventory (BT), Mini Mental State Examination (MMSE) and psychiatric examination.

Results: We stated that women, compared with men, presented worsening of executive functions, speed and motor control. Cognitive decline depended on number of episodes of at least moderate hypoglycemia and duration of disease. HbA1c below 8% resulted in better memory, speed and motor control. Cognitive decline was more escalated in the patients with atherogenic lipid profile.

Conclusions: It seems that even apparent lack of complications is not unambiguous with lack of cognitive decline and women seem to be more susceptible. DM1 affects young individuals, whose cognitive functions are in the course of the development, so it is important to find the underlying mechanisms and the areas of disturbed cognitive functioning and further investigations are needed.

Chronic peripheral inflammation, hippocampal neurogenesis, and behavior

Adult hippocampal neurogenesis is involved in memory and learning, and disrupted neurogenesis is implicated in cognitive impairment and mood disorders, including anxiety and depression. Some long-term peripheral illnesses and metabolic disorders, as well as normal aging, create a state of chronic peripheral inflammation. These conditions are associated with behavioral disturbances linked to disrupted adult hippocampal neurogenesis, such as cognitive impairment, deficits in learning and memory, and depression and anxiety. Pro-inflammatory cytokines released in the periphery are involved in peripheral immune system-to-brain communication by activating resident microglia in the brain. Activated microglia reduce neurogenesis by suppressing neuronal stem cell proliferation, increasing apoptosis of neuronal progenitor cells, and decreasing survival of newly developing neurons and their integration into existing neuronal circuits. In this review, we summarize evolving evidence that the state of chronic peripheral inflammation reduces adult hippocampal neurogenesis, which, in turn, produces the behavioral disturbances observed in chronic inflammatory disorders. As there are no data available on neurogenesis in humans with chronic peripheral inflammatory disease, we focus on animal models and, in parallel, consider the evidence of cognitive disturbance and mood disorders in human patients.

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.

Resting-state functional MR imaging shed insights into the brain of diabetes

Diabetes mellitus is a common metabolic disease which is associated with increasing risk for multiple cognitive declines. Alterations in brain functional connectivity are believed to be the mechanisms underlying the cognitive function impairments. During the past decade, resting-state functional magnetic resonance imaging (rs-fMRI) has been developed as a major tool to study brain functional connectivity in vivo. This paper briefly reviews the diabetes-associated cognitive impairment, analysis algorithms and clinical applications of rs-fMRI. We also provide future perspectives of rs-fMRI in diabetes.

Neurotrophins and cognitive functions in T1D compared with healthy controls: effects of a high-intensity exercise

Exercise is known to have beneficial effects on cognitive function. This effect is greatly favored by an exercise-induced increase in neurotrophic factors, such as brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1), especially with high-intensity exercises (HIE). As a complication of type 1 diabetes (T1D), a cognitive decline may occur, mostly ascribed to hypoglycaemia and chronic hyperglycaemia. Therefore, the purpose of this study was to examine the effects of acute HIE on cognitive function and neurotrophins in T1D and matched controls. Ten trained T1D (8 males, 2 females) participants and their matched (by age, sex, fitness level) controls were evaluated on 2 occasions after familiarization: a maximal test to exhaustion and an HIE bout (10 intervals of 60 s at 90% of their maximal wattage followed by 60 s at 50 W). Cognitive tests and analyses of serum BDNF, IGF-1, and free insulin were performed before and after HIE and following 30 min of recovery. At baseline, cognitive performance was better in the controls compared with the T1D participants (p < 0.05). After exercise, no significant differences in cognitive performance were detected. BDNF levels were significantly higher and IGF-1 levels were significantly lower in T1D compared with the control group (p < 0.05) at all time points. Exercise increased BDNF and IGF-1 levels in a comparable percentage in both groups (p < 0.05). In conclusion, although resting levels of serum BDNF and IGF-1 were altered by T1D, comparable increasing effects on BDNF and IGF-1 in T1D and healthy participants were found. Therefore, regularly repeating acute HIE could be a promising strategy for brain health in T1D.

Preventive effects of Salvia officinalis L. against learning and memory deficit induced by diabetes in rats: Possible hypoglycaemic and antioxidant mechanisms

Learning and memory impairment occurs in diabetes. Salvia officinalis L. (SO) has been used in Iranian traditional medicine as a remedy against diabetes. We hypothesized that chronic administration of SO (400, 600 and 800mg/kg, p.o.) and its principal constituent, rosmarinic acid, would affect on passive avoidance learning (PAL) and memory in streptozocin-induced diabetic and non-diabetic rats. We also explored hypoglycemic and antioxidant activities of SO as the possible mechanisms. Treatments were begun at the onset of hyperglycemia. PAL was assessed 30days later. Retention test was done 24h after training. At the end, animals were weighed and blood samples were drawn for further analyzing of glucose and oxidant/antioxidant markers. Diabetes induced deficits in acquisition and retrieval processes. SO (600 and 800mg/kg) and rosmarinic acid reversed learning and memory deficits induced by diabetes and improved cognition of healthy rats. While the dose of 400mg/kg had no effect, the higher doses and rosmarinic acid inhibited hyperglycemia and lipid peroxidation as well as enhanced the activity of antioxidant enzymes superoxide dismutase and catalase. SO prevented diabetes-induced acquisition and memory deficits through inhibiting hyperglycemia, lipid peroxidation as well as enhancing antioxidant defense systems. Therefore, SO and its principal constituent rosmarinic acid represent a potential therapeutic option against diabetic memory impairment which deserves consideration and further examination.

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.

Defining pathways for development of disease-modifying therapies in children with type 1 diabetes: a consensus report

Emerging data suggest that type 1 diabetes is a more aggressive disease in children than in adults, with important differences in pathophysiology and clinical course. Therefore, the efficacy of disease-modifying therapies may be different in the two populations. Understanding the developmental and regulatory pathways for type 1 diabetes-modifying therapies in children will enable industry, academia, funders, advocacy groups, and regulators to translate new science to clinical care. This consensus report characterizes the fundamental differences in type 1 diabetes between children and adults and proposes a thoughtful approach to better understand the development and regulatory pathways for type 1 diabetes therapies.

Naringin ameliorates cognitive deficits via oxidative stress, proinflammatory factors and the PPARγ signaling pathway in a type 2 diabetic rat model

Naringenin is a flavonoid polyphenolic compound, which facilitates the removal of free radicals, oxidative stress and inflammation. The present study aimed to obtain a better understanding of the effects of curcumin on the regulation of diabetes‑associated cognitive decline, and its underlying mechanisms. An experimental diabetes mellitus (DM) rat model was induced by streptozoticin (50 mg/kg). Following treatment with naringin (100 and 200 mg/kg) for 16 weeks, the body weight and blood glucose levels of the DM rats were measured. A morris water maze test was used to analyze the effects of naringin on the cognitive deficit of the DM rats. The levels of oxidative stress, proinflammatory factors, caspase‑3 and caspase‑9, and the protein expression of peroxisome proliferator‑activated receptor γ (PPARγ) were quantified in the DM rats using a commercially‑available kit and western blot assay, respectively. In addition, a GW9662 PPARγ inhibitor (0.3 mg/kg) was administered to the DM rats to determine whether PPARγ affected the effects of naringin on the cognitive deficit of the DM rats. The results demonstrated that naringin increased the body weight, blood glucose levels, and cognitive deficits of the DM rats. The levels of oxidative stress and proinflammatory factors in the naringin‑treated rats were significantly lower, compared with those of the DM rats. In addition, naringin activated the protein expression of PPARγ, and administration of the PPARγ inhibitor decreased the protein expression of PPARγ, and attenuated the effects of naringin on cognitive deficit. The results also demonstrated that naringin decreased the expression levels of caspase‑3 and caspase‑9 in the DM rats. These results suggested that naringin ameliorated cognitive deficits via oxidative stress, proinflammatory factors and the PPARγ signaling pathway in the type 2 diabetic rat model. Furthermore, oxidative stress, proinflammatory factors and PPARγ signaling may be involved in mediating these effects.

Patients with type 1 diabetes in Sweden experience more fatigue than the general population

Aims

Type 2 diabetes has been linked to fatigue, but results on type 1 diabetes are ambiguous. Our aim was to determine if type 1 diabetes is associated with fatigue and whether the fatigue is due to complications or to the disease itself.

Methods

The Multidimensional Fatigue Inventory (MFI-20), was submitted to all 435 adult patients with type 1 diabetes in the National Diabetes Register at the Sunderby Hospital clinic and to a control group of 2500 persons. The participation rate was 62% in both groups.

Results

Type 1 diabetes was associated with greater fatigue, with a 1.4-point difference (0.9–1.9, 95% CI) in general fatigue on a scale of 4–20. Type 1 diabetes was an independent predictor of fatigue, as were cardiovascular and cerebrovascular disease. Women with long diabetes duration but without complications experienced more fatigue than women in the general population (difference in general fatigue = 2.5, p = 0.021), whereas men showed no significant difference.

Conclusions

Type 1 diabetes is associated with greater fatigue, partly ascribed to vascular disease. Type 1 diabetes of long duration might be associated with fatigue regardless of classical complications, but further research is needed to confirm results.

Regional cerebral hemodynamic response to incremental exercise is blunted in poorly controlled patients with uncomplicated type 1 diabetes

OBJECTIVE

Cerebral vasoreactivity to pharmacologically induced hypercapnia is impaired in poorly controlled patients with type 1 diabetes but otherwise free from microangiopathy. However, whether this response is also compromised during exercise, a daily-life physiological condition challenging regional cerebral hemodynamics, is unknown. We aimed to investigate prefrontal cortex hemodynamics during incremental maximal exercise in patients with uncomplicated type 1 diabetes, taking into account long-term glycemic control as well as exercise- and diabetes-influenced vasoactive stimuli.

RESEARCH DESIGN AND METHODS

Two groups of patients (type 1 diabetes with adequate glycemic control [T1D-A], n = 8, HbA1c 6.8 ± 0.7% [51 ± 7.7 mmol/mol]; type 1 diabetes with inadequate glycemic control [T1D-I], n = 10, HbA1c 9.0 ± 0.7% [75 ± 7.7 mmol/mol]) were compared with 18 healthy control subjects (CON-A and CON-I) matched for physical activity and body composition. Throughout exercise, near-infrared spectroscopy allowed investigation of changes in oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), and total hemoglobin (THb) in the prefrontal cortex. Venous and arterialized capillary blood was sampled during exercise to assess for factors that may alter prefrontal cortex hemodynamics and oxygenation.

RESULTS

No differences were observed between T1D-A and CON-A, but VO2max was impaired (P < 0.05) and cerebral blood volume (THb) increase blunted (P < 0.05) in T1D-I compared with CON-I. Nonetheless, O2Hb appeared unaltered in T1D-I probably partly due to blunting of simultaneous neuronal oxygen extraction (i.e., a lower HHb increase; P < 0.05). There were no intergroup differences in arterial oxygen content, Paco2, pH, [K(+)], and free insulin levels.

CONCLUSIONS

Maximal exercise highlights subtle disorders of both hemodynamics and neuronal oxygenation in the prefrontal cortex of poorly controlled patients with type 1 diabetes. These findings may warn clinicians of brain endothelial dysfunction occurring even before overt microangiopathy during exercise.

Short and long term neuro-behavioral alterations in type 1 diabetes mellitus pediatric population

Type 1 diabetes mellitus (T1DM) is one of the most prevalent chronic conditions affecting individuals under the age of 18 years, with increasing incidence worldwide, especially among very young age groups, younger than 5. There is still no cure for the disease, and therapeutic goals and guidelines are a challenge. Currently, despite T1DM intensive management and technological interventions in therapy, the majority of pediatric patients do not achieve glycemic control goals. This leads to a potential prognosis of long term diabetic complications, nephrological, cardiac, ophthalmological and neurological. Unfortunately, the neurological manifestations, including neurocognitive and behavioral complications, may present soon after disease onset, during childhood and adolescence. These manifestations may be prominent, but at times subtle, thus they are often not reported by patients or physicians as related to the diabetes. Furthermore, the metabolic mechanism for such manifestations has been inconsistent and difficult to interpret in practical clinical care, as reported in several reviews on the topic of brain and T1DM. However, new technological methods for brain assessment, as well as the introduction of continuous glucose monitoring, provide new insights and information regarding brain related manifestations and glycemic variability and control parameters, which may impact the clinical care of children and youth with T1DM. This paper provides a comprehensive review of the most recently reported behavioral, cognitive domains, sleep related, electrophysiological, and structural alterations in children and adolescences from a novel point of view. The review focuses on reported impairments based on duration of T1DM, its timeline, and modifiable disease related risk parameters. These findings are not without controversy, and limitations of data are presented in addition to recommendations for future research direction.