A 4 year follow-up study of cognitive functioning in patients with type 2 diabetes mellitus

Periphery Biomarkers Predicting Conversion of Type 2 Diabetes to Pre-Alzheimer-Like Cognitive Decline: A Multicenter Follow-Up Study

Background

The prevalence of Alzheimer's disease (AD) is increasing, therefore, identifying biomarkers to predict those vulnerable to AD is imperative. Type 2 diabetes (T2D) serves as an independent risk factor for AD. Early prediction of T2D patients who may be more susceptible to AD, so as to achieve early intervention, is of great significance to reduce the prevalence of AD.

Objective

To establish periphery biomarkers that could predict conversion of T2D into pre-AD-like cognitive decline.

Methods

A follow-up study was carried out from 159 T2D patients at baseline. The correlations of cognitive states (by MMSE score) with multi-periphery biomarkers, including APOE genotype, plasma amyloid-β level, platelet GSK-3β activity, and olfactory score were analyzed by logistic regression. ROC curve was used for establishing the prediction model. Additionally, MRI acquired from 38 T2D patients for analyzing the correlation among cognitive function, biomarkers and brain structure.

Results

Compared with the patients who maintained normal cognitive functions during the follow-up period, the patients who developed MCI showed worse olfactory function, higher platelet GSK-3β activity, and higher plasma Aβ42/Aβ40 ratio. We conducted a predictive model which T2D patients had more chance of suffering from pre-AD-like cognitive decline. The MRI data revealed MMSE scores were positively correlated with brain structures. However, platelet GSK-3β activity was negatively correlated with brain structures.

Conclusions

Elevated platelet GSK-3β activity and plasma Aβ42/Aβ40 ratio with reduced olfactory function are correlated with pre-AD-like cognitive decline in T2D patients, which used for predicting which T2D patients will convert into pre-AD-like cognitive decline in very early stage.

A systematic review of preclinical studies exploring the role of insulin signalling in executive function and memory

Beside its involvement in somatic dysfunctions, altered insulin signalling constitutes a risk factor for the development of mental disorders like Alzheimer's disease and obsessive-compulsive disorder. While insulin-related somatic and mental disorders are often comorbid, the fundamental mechanisms underlying this association are still elusive. Studies conducted in rodent models appear well suited to help decipher these mechanisms. Specifically, these models are apt to prospective studies in which causative mechanisms can be manipulated via multiple tools (e.g., genetically engineered models and environmental interventions), and experimentally dissociated to control for potential confounding factors. Here, we provide a narrative synthesis of preclinical studies investigating the association between hyperglycaemia - as a proxy of insulin-related metabolic dysfunctions - and impairments in working and spatial memory, and attention. Ultimately, this review will advance our knowledge on the role of glucose metabolism in the comorbidity between somatic and mental illnesses.

Household Food Insecurity and Cognition in Youth and Young Adults with Youth-Onset Diabetes

Objective

We evaluated the association of household food insecurity (FI) with cognition in youth and young adults with type 1 diabetes (T1D) or type 2 diabetes (T2D).

Design

In this cross-sectional study, age-adjusted scores for composite Fluid Cognition, and sub-domain scores for Receptive Language and Inhibitory Control and Attention, were modeled stratified by diabetes-type using linear regression, with FI in the past year as the predictor, controlling for covariates. Tests for processing speed, inhibitory control/attention, working memory, episodic memory, and cognitive flexibility were administered to measure composite Fluid Cognition score. The NIHT-CB Picture Vocabulary Test was used to assess Crystallized Cognition score and rapid identification of congruent versus noncongruent items were used to assess Inhibitory Control and Attention score.

Setting

The SEARCH for Diabetes in Youth study, representative of 5 U.S. states.

Participants

Included 1574 youth and young adults with T1D or T2D, mean age of 21 years, mean diabetes duration of 11 years, 51% non-Hispanic white, and 47% had higher HbA1c levels (>9% HbA1c).

Results

Approximately 18% of the 1,240 participants with T1D and 31% of the 334 with T2D experienced FI. The food-insecure group with T1D had a lower composite Fluid Cognition score (β= -2.5, 95% confidence interval (CI)= -4.8, -0.1) and a lower Crystallized Cognition score (β= -3.4, CI= -5.6, -1.3) than food-secure peers. Findings were attenuated to non-significance after adjustment for demographics. Among T2D participants, no associations were observed. In participants with T1D effect modification by glycemic levels were found in the association between FI and composite Fluid Cognition score but adjustment for socioeconomic characteristics attenuated the interaction (p=0.0531).

Conclusions

Food-insecure youth and young adults with T1D or T2D did not have different cognition compared to those who were food-secure after adjustment for confounders. Longitudinal research is needed to further understand relations amongst these factors.

Neuroactive Steroid-Gut Microbiota Interaction in T2DM Diabetic Encephalopathy

The pathological consequences of type 2 diabetes mellitus (T2DM) also involve the central nervous system; indeed, T2DM patients suffer from learning and memory disabilities with a higher risk of developing dementia. Although several factors have been proposed as possible contributors, how neuroactive steroids and the gut microbiome impact brain pathophysiology in T2DM remain unexplored. On this basis, in male Zucker diabetic fatty (ZDF) rats, we studied whether T2DM alters memory abilities using the novel object recognition test, neuroactive steroid levels by liquid chromatography-tandem mass spectrometry, hippocampal parameters using molecular assessments, and gut microbiome composition using 16S next-generation sequencing. Results obtained reveal that T2DM worsens memory abilities and that these are correlated with increased levels of corticosterone in plasma and with a decrease in allopregnanolone in the hippocampus, where neuroinflammation, oxidative stress, and mitochondrial dysfunction were reported. Interestingly, our analysis highlighted a small group of taxa strictly related to both memory impairment and neuroactive steroid levels. Overall, the data underline an interesting role for allopregnanolone and microbiota that may represent candidates for the development of therapeutic strategies.

Insulin and Disorders of Behavioural Flexibility

Behavioural inflexibility is a symptom of neuropsychiatric and neurodegenerative disorders such as Obsessive-Compulsive Disorder, Autism Spectrum Disorder and Alzheimer's Disease, encompassing the maintenance of a behaviour even when no longer appropriate. Recent evidence suggests that insulin signalling has roles apart from its regulation of peripheral metabolism and mediates behaviourally-relevant central nervous system (CNS) functions including behavioural flexibility. Indeed, insulin resistance is reported to generate anxious, perseverative phenotypes in animal models, with the Type 2 diabetes medication metformin proving to be beneficial for disorders including Alzheimer's Disease. Structural and functional neuroimaging studies of Type 2 diabetes patients have highlighted aberrant connectivity in regions governing salience detection, attention, inhibition and memory. As currently available therapeutic strategies feature high rates of resistance, there is an urgent need to better understand the complex aetiology of behaviour and develop improved therapeutics. In this review, we explore the circuitry underlying behavioural flexibility, changes in Type 2 diabetes, the role of insulin in CNS outcomes and mechanisms of insulin involvement across disorders of behavioural inflexibility.

Research Progress on Lipocalin-2 in Diabetic Encephalopathy

Diabetic encephalopathy is a central nervous complication of diabetes mellitus which is characterized by cognitive impairment and structural and neurochemical abnormalities, which is easily neglected. Lipocalin-2 (LCN2) is a 25 kDa transporter in the lipocalin family that can transport small molecules, including fatty acids, iron, steroids, and lipopolysaccharides in the circulation. Recently, LCN2 has been found to be a significant regulator of insulin resistance and glucose homeostasis. Numerous studies have shown that LCN2 is connected to central nervous system abnormalities, including neuroinflammation and neurodegeneration, while the latest researches have found that LCN2 is closely related to the development of diabetic encephalopathy. Nevertheless, its precise role in the pathogenesis of diabetic encephalopathy remains to be determined. In this paper, we review recent evidence on the role of LCN2 in diabetic encephalopathy from multiple perspectives in order to decipher the impact of LCN2 in both the aetiology and treatment of diabetic encephalopathy.

Independent and interactive effect of type 2 diabetes and hypertension on memory functions in middle aged adults

BACKGROUND

The study distinguishes the effect of type 2 diabetes and hypertension on cognitive functions when the two diseases are alone or when they occur together, compared to healthy individuals.

METHODS

A total of 143 middle-aged adults were screened using the Wechsler Memory Scale - Revised psychometric test (verbal memory, visual memory, attention/concentration and delayed memory). Participants were divided into four groups based on their diseases: patients with type 2 diabetes (36), patients with hypertension (30), patients having both diseases (33), and healthy controls (44).

RESULTS

This study found no differences among investigated groups in verbal and visual memory, however, hypertension and both-disease group performed unfavorably compared to patients with diabetes and to healthy individuals in attention/concentration and delayed memory.

CONCLUSIONS

The findings of this study suggest that there is a relationship between hypertension and cognitive dysfunction, whereas type 2 diabetes without consequences was not proved to have an association with cognitive decline in middle-aged people.

Evaluation of altered brain activity in type 2 diabetes using various indices of brain function: A resting-state functional magnetic resonance imaging study

Background

Type 2 diabetes mellitus (T2DM) has been identified as a risk factor that increases the rate of cognitive decline. Previous studies showed that patients with T2DM had brain function alterations based on a single index of resting-state functional magnetic resonance imaging (rs-fMRI). The present study aimed to explore spontaneous brain activity in patients with T2DM by comparing various rs-fMRI indices, and to determine the relationship between these changes and cognitive dysfunction.

Methods

A total of 52 patients with T2DM and age- and sex-matched control participants were included in this study. The amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), and voxel-mirrored homotopic connectivity (VMHC) values were calculated to represent the status of spontaneous neural activity. The Montreal Cognitive Assessment (MoCA) was used for the rapid evaluation of cognition in all subjects. Pearson correlation and mediation analyses were conducted to investigate the relationship between rs-fMRI indices and clinical parameters such as fasting glucose, disease duration, and MoCA.

Results

Patients with T2DM had alterations of concordant spontaneous brain activity in brain areas including the bilateral cerebellum posterior lobe, the left inferior temporal gyrus (ITG.L), the parahippocampal gyrus, and the left supplementary motor area (SMA.L). The indices were significantly correlated to each other in most of the detected brain areas. Positive correlations were observed between fasting glucose and neural activity in the surrounding areas of the left insula and the inferior frontal gyrus. MoCA scores were negatively correlated with the ReHo values extracted from the left anterior occipital lobe and the superior cerebellar cortex and were positively correlated with VMHC values extracted from the left caudate and the precentral gyrus (PreCG). No significant mediation effect of abnormal brain activity was found in the relationship between clinical parameters and MoCA scores.

Conclusion

The current study demonstrated the functional concordance of abnormal brain activities in patients with T2DM by comparing ALFF, ReHo, and VMHC measurements. Widespread abnormalities mainly involved in motor and sensory processing functions may provide insight into examining T2DM-related neurological pathophysiology.

Impact of dysglycemia and obesity on the brain in adolescents with and without type 2 diabetes: A pilot study

OBJECTIVE

Both diabetes and obesity can affect the brain, yet their impact is not well characterized in children with type 2 (T2) diabetes and obesity. This pilot study aims to explore differences in brain function and cognition in adolescents with T2 diabetes and obesity and nondiabetic controls with obesity and lean controls.

RESEARCH DESIGN AND METHODS

Participants were 12-17 years old (5 T2 diabetes with obesity [mean HgbA1C 10.9%], 6 nondiabetic controls with obesity and 10 lean controls). Functional MRI (FMRI) during hyperglycemic/euglycemic clamps was performed in the T2 diabetes group.

RESULTS

When children with obesity, with and without diabetes, were grouped (mean BMI 98.8%), cognitive scores were lower than lean controls (BMI 58.4%) on verbal, full scale, and performance IQ, visual-spatial and executive function tests. Lower scores correlated with adiposity and insulin resistance but not HgbA1C. No significant brain activation differences during task based and resting state FMRI were noted between children with obesity (with or without diabetes) and lean controls, but a notable effect size for the visual-spatial working memory task and resting state was observed.

CONCLUSIONS

In conclusion, our pilot study suggests that obesity, insulin resistance, and dysglycemia may contribute to relatively poorer cognitive function in adolescents with T2 diabetes and obesity. Further studies with larger sample size are needed to assess if cognitive decline in children with obesity, with and without T2 diabetes, can be prevented or reversed.

Influence of genetic and cardiometabolic risk factors in Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder. Cardiometabolic and genetic risk factors play an important role in the trajectory of AD. Cardiometabolic risk factors including diabetes, mid-life obesity, mid-life hypertension and elevated cholesterol have been linked with cognitive decline in AD subjects. These potential risk factors associated with cerebral metabolic changes which fuel AD pathogenesis have been suggested to be the reason for the disappointing clinical trial results. In appreciation of the risks involved, using search engines such as PubMed, Scopus, MEDLINE and Google Scholar, a relevant literature search on cardiometabolic and genetic risk factors in AD was conducted. We discuss the role of genetic as well as established cardiovascular risk factors in the neuropathology of AD. Moreover, we show new evidence of genetic interaction between several genes potentially involved in different pathways related to both neurodegenerative process and cardiovascular damage.

Potential mechanism of the Shunaoxin pill for preventing cognitive impairment in type 2 diabetes mellitus

Objective

This study aims to analyze the efficacy and mechanism of action of the Shunaoxin pill in preventing cognitive impairment in diabetic patients using network pharmacology.

Methods

The main active compounds of the Shunaoxin pills and their action targets were identified via the TCMSP and Batman-TCM databases. The GEO database was used to identify the genes in type 2 diabetic individuals associated with cognitive impairment. Subsequently, a common target protein-protein interaction (PPI) network was constructed using the STRING database, and targets associated with diabetes and cognitive impairment were screened by performing a topological analysis of the PPI network. The AutoDock Vina software was used for molecular docking to evaluate the reliability of the bioinformatic analysis predictions and validate the interactions between the active ingredients of the Shunaoxin pill and proteins associated with diabetes and cognitive impairment.

Results

Based on the TCMSP and Batman-Tcm platform, 48 active ingredients of the Shunaoxin pill were identified, corresponding to 222 potential action targets. Further analysis revealed that 18 active components of the Shunaoxin pill might contribute to cognitive impairment in type 2 diabetic patients. Molecular docking simulations demonstrated that the active ingredients of the Shunaoxin pill (hexadecanoic acid, stigmasterol, beta-sitosterol, and angelicin) targeted four core proteins: OPRK1, GABRA5, GABRP, and SCN3B.

Conclusion

Active ingredients of the Shunaoxin pill may alleviate cognitive impairment in diabetic patients by targeting the proteins OPRK1, GABRA5, GABRP, and SCN3B.

Chronic kidney disease and cognitive decline in patients with type 2 diabetes at elevated cardiovascular risk

AIMS

We addressed the question whether chronic kidney disease (CKD) may contribute to cognitive decline in type 2 diabetes.

METHODS

Participants with type 2 diabetes with elevated cardiovascular risk or CKD from cognition substudies of two large trials were studied prospectively (CARMELINA: n = 2666, mean ± SD age 68.1 ± 8.7 years, CAROLINA: n = 4296; 64.7 ± 9.4 years). Estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR) at baseline were related to cognitive performance (Mini-Mental State Examination (MMSE) and attention and executive functioning score (A&E)) in linear regression analyses, adjusted for demographics, cardiovascular risk factors and treatment, at baseline and follow-up.

RESULTS

CKD at baseline was more common in CARMELINA than CAROLINA (eGFR<60 in 72.6 % and 19.6 %, macroalbuminuria in 35.0 % and 4.1 %, respectively). Baseline eGFR was related to A&E in CARMELINA (b = 0.02 per 10 ml/min/1.73m², 95%CI [0.01,0.03]). Baseline UACR was related to A&E in CAROLINA (b = -0.01 per doubling of UACR mg/g, 95%CI [-0.02,-0.002]). Baseline UACR predicted decline in A&E in CAROLINA (median 6.1 years follow-up; b = -0.01, 95%CI [-0.03,-0.0001] per doubling of UACR mg/g).

CONCLUSIONS

eGFR and UACR were associated with A&E in two cohorts with type 2 diabetes, enriched for CKD and cardiovascular disease. The small effect size estimates indicate limited impact of kidney dysfunction on cognition in this setting.

GOV IDENTIFIERS

NCT01897532 NCT01243424.

Diabetes and associated cognitive disorders: Role of the Hypothalamic-Pituitary Adrenal axis

Both diabetes types, types 1 and 2, are associated with cognitive impairments. Each period of life is concerned, and this is an increasing public health problem. Animal models have been developed to investigate the biological actors involved in such impairments. Many levels of the brain function (structure, volume, neurogenesis, neurotransmission, behavior) are involved. In this review, we detailed the part potentially played by the Hypothalamic-Pituitary Adrenal axis in these dysfunctions. Notably, regulating glucocorticoid levels, their receptors and their bioavailability appear to be relevant for future research studies, and treatment development.

Could salt intake directly affect the cerebral microvasculature in hypertension?

OBJECTIVES

Excess dietary salt and chronic kidney disease (CKD) are acknowledged stroke risk factors. The development of small vessel disease, similarly affecting the cerebral and renal microvasculatures, may be an important mechanistic link underlying this interaction. Therefore, we aimed to evaluate if the dietary salt intake and markers of CKD (estimated glomerular filtration rate, albuminuria) relate to transcranial Doppler (TCD) markers of cerebral small vessel disease (CSVD) in hypertensive patients.

MATERIALS AND METHODS

Fifty-six hypertensive patients (57% with diabetes) underwent TCD monitoring in the middle (MCA) and posterior (PCA) cerebral arteries for evaluating neurovascular coupling (NVC), dynamic cerebral autoregulation (dCA), and vasoreactivity to carbon dioxide (VRCO₂). We investigated the relation between renal parameters and TCD studies using Pearson's correlation coefficient and linear regression analyses.

RESULTS

There were no associations between dCA, VRCO₂, NVC, and renal function tests. However, there was a negative association between the daily salt intake and the natural frequency during visual stimulation (r²=0.101, ß=-0.340, p=0.035), indicative of increased rigidity of the cerebral resistance vessels that react to cognitive activation.

CONCLUSIONS

In this cross-sectional study, we found an association between excess dietary salt consumption and CSVD in hypertensive patients. Future research is needed to evaluate whether the natural frequency could be an early, non-invasive, surrogate marker for microvascular dysfunction in hypertension.

Type 2 diabetes mellitus and cognitive decline in older adults in Germany - results from a population-based cohort

Background

A large body of evidence supports a link between type 2 diabetes mellitus (T2DM) and cognitive function, including dementia. However, longitudinal studies on the association between T2DM and decline of cognitive function are scarce and reported mixed results, and we hence set out to investigate the cross-sectional and longitudinal association between T2DM and global as well as domain-specific cognitive performance.

Methods

We used multivariable regression models to assess associations of T2DM with cognitive performance and cognitive decline in a subsample of a population-based prospective cohort study (ESTHER). This subsample (n = 732) was aged 70 years and older and had participated in telephone-based cognitive function assessment (COGTEL) measuring global and domain-specific cognitive performance during the 5- and 8-year follow-up.

Results

Total COGTEL scores of patients with prevalent T2DM were 27.4 ± 8.3 and 29.4 ± 8.7 at the 5- and 8-year measurements, respectively, and were roughly two points lower than those of T2DM-free participants after adjustment for age and sex. In cross-sectional models, after adjustment for several potential confounders, performance in verbal short-term and long-term memory tasks was statistically significantly lower in participants with T2DM, but the association was attenuated after further adjustment for vascular risk factors. The difference in total COGTEL scores reflecting global cognitive function by T2DM status after full adjustment for confounders and vascular risk factors was equivalent to a decrement in global cognitive function associated with a four-year age difference. In longitudinal models, a statistically significantly stronger cognitive decline in patients with T2DM was observed for working memory.

Conclusions

In this sample of older individuals, T2DM was associated with worse performance and stronger decline in a cognitive function test. Memory-related domains were found to be particularly sensitive to T2DM. Further large-scale prospective studies are needed to clarify potential T2DM-related predictors of cognitive decline and possible consequences on the abilities to perform patient self-management tasks in diabetes care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03151-y.

Lacunes and type 2 diabetes mellitus have a joint effect on cognitive impairment: a retrospective study

Objective

To evaluate the joint effects of cerebral small vessel disease (CSVD)-related imaging biomarkers in patients of type 2 diabetes mellitus (T2DM) with cognitive impairment.

Methods

This study is a retrospective cohort study. A total of 227 participants (115 patients with T2DM and 112 healthy control subjects) were enrolled in this study. Cognitive function assessments were evaluated using the Mini-Mental State Examination and the Montreal Cognitive Assessment. The burden of CSVD markers, including the lacunes, white matter hyperintensities (WMH), cerebral microbleeds (CMBs), and enlarged perivascular spaces (PVS), was identified by magnetic resonance imaging and evaluated using small vessel disease (SVD) scores (0-4). The subjects were divided into two groups based on the results of the cognitive function assessments. The synergy index was used to estimate the biological interactions between T2DM and lacunes.

Results

There was a significant correlation between T2DM and cognitive impairment (p < 0.001, χ² test). In patients with diabetes, cognitive impairment was significantly associated with both the presence of lacunes (p < 0.01, χ² test) and increased total SVD burden scores (p < 0.01, χ² test). Regarding CMBs, only the existence of lobar CMBs was correlated with cognitive impairment (p < 0.05, χ² test). The joint effect tended to be larger than the independent effects of T2DM and lacunes on cognitive impairment (adjusted odds ratio [OR]: 7.084, 95% CI [2.836-17.698]; synergy index: 10.018, 95% CI [0.344-291.414]).

Conclusions

T2DM and the presence of lacunes are significantly correlated with cognitive impairment. There was a joint effect of T2DM and lacunes on cognitive impairment.

Females with type 2 diabetes are at higher risk for accelerated cognitive decline than males: CAROLINA-COGNITION study

BACKGROUND AND AIM

Cognitive dysfunction is increasingly recognized as an important comorbidity of type 2 diabetes (T2D). We aimed to establish if the risk of accelerated cognitive decline (ACD) is higher in females with T2D than males.

METHODS AND RESULTS

3163 participants (38% female) with T2D from the cognition substudy of CAROLINA® (NCT01243424) were included (mean age 64.4 ± 9.2 years; T2D duration 7.6 ± 6.1 years). The cognitive outcome was occurrence of ACD at end of follow-up, defined as a regression based index score ≤16th percentile on either the Mini-Mental State Examination (MMSE) or a composite measure of attention and executive functioning (Trail Making and Verbal Fluency Test). Potential confounders, were taken into account at an individual patient level. Logistic regression analysis was used to investigate ACD risk by sex. We assessed potential mediators for sex differences in ACD using Causal Mediation Analysis (CMA). After a median follow-up duration of 6.1 ± 0.7 years, 361 (30.0%) females compared to 494 (25.2%) males exhibited ACD (OR 1.27 [95%CI 1.08-1.49], p = .003). Depressive symptoms, which were more common in females (24.3% vs 12.5%), mediated between sex and ACD (mediation effect 20.3%, p = 0.03). There were no other significant mediators.

CONCLUSION

Females with T2D had a higher risk of ACD compared to males. This was partly explained by depressive symptoms. After evaluation of vascular and diabetes-related risk factors, complications and treatment, a major share of the higher risk of ACD in females remained unexplained. Our results highlight the need for further research on causes of sex-specific ACD in T2D.

Altered Structural and Functional MRI Connectivity in Type 2 Diabetes Mellitus Related Cognitive Impairment: A Review

Type 2 diabetes mellitus (T2DM) is associated with cognitive impairment in many domains. There are several pieces of evidence that changes in neuronal neuropathies and metabolism have been observed in T2DM. Structural and functional MRI shows that abnormal connections and synchronization occur in T2DM brain circuits and related networks. Neuroplasticity and energy metabolism appear to be principal effector systems, which may be related to amyloid beta (Aβ) deposition, although there is no unified explanation that includes the complex etiology of T2DM with cognitive impairment. Herein, we assume that cognitive impairment in diabetes may lead to abnormalities in neuroplasticity and energy metabolism in the brain, and those reflected to MRI structural connectivity and functional connectivity, respectively.

Comparison of cognitive status of diabetic and non-diabetic elderly in the last ten years in primary health care in Iran

Introduction. Cognitive disorders and chronic diseases such as diabetes are common problems of aging. The aim of this study was to determine and compare the cognitive status of diabetic and non-diabetic elderly in the past ten years in primary health care in Iran. Method: This cross-sectional study was performed on people aged 60 years and older in Kerman, Iran in 2020. In total, this study was performed on 200 patients (100 diabetic and 100 non-diabetic) meeting inclusion criteria. The Short Mental Status Questionnaire (MMSE) and The Informant Questionnaire for Cognitive Decline in the Elderly (IQCODE) were used to assess cognitive function. The validity and reliability of the questionnaires were confirmed in this study. Data were analyzed using Chi-square, T-test, and ANOVA analysis in SPSS 21 software. Results. The results showed that there was a statistically significant difference between diabetic and non-diabetic groups in the current cognitive status and cognitive status in the last ten years. The mean scores of cognitive function from the short mental status questionnaire in the diabetic group were lower than in the non-diabetic group (p = 0.001). The mean scores of the cognitive deficit screening questionnaire in diabetic elderly were higher than in non-diabetic elderly (p < 0.001). Conclusion. Based on the results of this study, health care providers and family physicians should focus on controlling diabetes and identifying any cognitive impairment in the early stages of comprehensive care of diabetic patients.

Sport reduziert den diabetesassoziierten Verlust kognitiver Fähigkeiten bei Typ-2-Diabetes-Patienten

Kognitive Defizite entwickeln sich bei T2D-Patienten häufig auf dem Boden metabolischer Störungen. Neben den eher mild ausfallenden, aber klinisch relevanten diabetesassoziierten kognitiven Dysfunktionen geht T2 D ebenfalls mit einem erhöhten Risiko für Demenz verschiedener Ursachen einher. Die zugrunde liegenden Mechanismen, die zu einer diabetesassoziierten kognitiven Dysfunktion führen, sind nicht vollständig geklärt. Trainingsinterventionen bieten die Möglichkeit, mögliche metabolische Risikofaktoren zu verringern und gleichzeitig dadurch die diabetesassoziierten kognitiven Verschlechterungen zu reduzieren. Unklar ist allerdings noch, welche Trainingsart und -intensität den größten gesundheitlichen Nutzen bringt, da bisherige Studienergebnisse wegen unterschiedlicher Kohorten, Interventionsmethoden und Interventionsdauern schwer zu vergleichen sind.

Adolescent cognitive function and incident early-onset type 2 diabetes

BACKGROUND

Cognitive function among apparently healthy adolescents has been associated with cardiovascular morbidity and mortality. We examined the relationship between global and subdomain cognitive scores in adolescence and early-onset type 2 diabetes (T2D) in men and women.

METHODS

A nationwide, population-based study of 971,677 Israeli born adolescents (56% men; mean age 17.4 years) who were medically examined and their cognitive performance was assessed before compulsory military service during 1992-2010. Data included global and subdomain cognitive Z-scores (problem-solving, verbal abstraction and categorization, verbal comprehension, and mathematical abilities). Data were linked to the Israeli National Diabetes Registry. The relations between global and subdomain scores and incident T2D was determined using Cox proportional hazard models and logistic regression models. Analyses were conducted separately for men and women.

FINDINGS

During 16,095,122 person-years, 3,570 individuals developed T2D. After adjustment, those in the low compared to the high quintile of global cognitive Z-score had the highest risk for T2D; HR 2.46, (95% CI 2.10-2.88) for men and 2.33 (95% CI 1.88-2.89) for women. A one-unit lower global cognitive Z-score was associated with 1.41 (95% CI 1.34-1.48) and 1.46 (95% CI 1.36-1.56) increased risks for men and women, respectively. The relationship was noted for the cognitive subdomains scores as well as for the global cognitive score, with no heterogeneity across cognitive subdomains.

INTERPRETATION

This large nationally representative cohort suggests relationship between global, as well as subdomain cognitive scores in late adolescence, and incident early onset T2D in both sexes, which was independent of socioeconomic status.

Glycemic Dysregulations Are Associated With Worsening Cognitive Function in Older Participants at High Risk of Cardiovascular Disease: Two-Year Follow-up in the PREDIMED-Plus Study

Introduction

Type 2 diabetes has been linked to greater cognitive decline, but other glycemic parameters such as prediabetes, diabetes control and treatment, and HOMA-IR and HbA1c diabetes-related biomarkers have shown inconsistent results. Furthermore, there is limited research assessing these relationships in short-term studies. Thus, we aimed to examine 2-year associations between baseline diabetes/glycemic status and changes in cognitive function in older participants at high risk of cardiovascular disease.

Methods

We conducted a 2-year prospective cohort study (n=6,874) within the framework of the PREDIMED-Plus study. The participants (with overweight/obesity and metabolic syndrome; mean age 64.9 years; 48.5% women) completed a battery of 8 cognitive tests, and a global cognitive function Z-score (GCF) was estimated. At baseline, participants were categorized by diabetes status (no-diabetes, prediabetes, and <5 or ≥5-year diabetes duration), and also by diabetes control. Furthermore, insulin resistance (HOMA-IR) and glycated hemoglobin (HbA1c) levels were measured, and antidiabetic medications were recorded. Linear and logistic regression models, adjusted by potential confounders, were fitted to assess associations between glycemic status and changes in cognitive function.

Results

Prediabetes status was unrelated to cognitive decline. However, compared to participants without diabetes, those with ≥5-year diabetes duration had greater reductions in GCF (β=-0.11 (95%CI -0.16;-0.06)], as well as in processing speed and executive function measurements. Inverse associations were observed between baseline HOMA-IR and changes in GCF [β=-0.0094 (95%CI -0.0164;-0.0023)], but also between HbA1c levels and changes in GCF [β=-0.0085 (95%CI -0.0115, -0.0055)], the Mini-Mental State Examination, and other executive function tests. Poor diabetes control was inversely associated with phonologic fluency. The use of insulin treatment was inversely related to cognitive function as measured by the GCF [β=-0.31 (95%CI -0.44, -0.18)], and other cognitive tests.

Conclusions

Insulin resistance, diabetes status, longer diabetes duration, poor glycemic control, and insulin treatment were associated with worsening cognitive function changes in the short term in a population at high cardiovascular risk.

Clinical Trial Registration

http://www.isrctn.com/ISRCTN89898870, identifier ISRCTN: 89898870.

Gray Matter Abnormalities in Type 1 and Type 2 Diabetes: A Dual Disorder ALE Quantification

Aims/hypothesis: Diabetes mellitus (DM) is associated with comorbid brain disorders. Neuroimaging studies in DM revealed neuronal degeneration in several cortical and subcortical brain regions. Previous studies indicate more pronounced brain alterations in type 2 diabetes mellitus (T2DM) than in type 1 diabetes mellitus (T1DM). However, a comparison of both types of DM in a single analysis has not been done so far. The aim of this meta-analysis was to conduct an unbiased objective investigation of neuroanatomical differences in DM by combining voxel-based morphometry (VBM) studies of T1DM and T2DM using dual disorder anatomical likelihood estimation (ALE) quantification.

Methods: PubMed, Web of Science and Medline were systematically searched for publications until June 15, 2020. VBM studies comparing gray matter volume (GMV) differences between DM patients and controls at the whole-brain level were included. Study coordinates were entered into the ALE meta-analysis to investigate the extent to which T1DM, T2DM, or both conditions contribute to gray matter volume differences compared to controls.

Results: Twenty studies (comprising of 1,175 patients matched with 1,013 controls) were included, with seven studies on GMV alterations in T1DM and 13 studies on GMV alterations in T2DM. ALE analysis revealed seven clusters of significantly lower GMV in T1DM and T2DM patients relative to controls across studies. Both DM subtypes showed GMV reductions in the left caudate, right superior temporal lobe, and left cuneus. Conversely, GMV reductions associated exclusively with T2DM (>99% contribution) were found in the left cingulate, right posterior lobe, right caudate and left occipital lobe. Meta-regression revealed no significant influence of study size, disease duration, and HbA1c values.

Conclusions/interpretation: Our findings suggest a more pronounced gray matter atrophy in T2DM compared to T1DM. The increased risk of microvascular or macrovascular complications, as well as the disease-specific pathology of T2DM may contribute to observed GMV reductions.

Systematic Review Registration: [PROSPERO], identifier [CRD42020142525].

Association of Vitamin D Level and Nerve Conduction Study Parameters with Cognitive Function in Diabetic Neuropathy Patients

BACKGROUND: Type 2 diabetes mellitus (T2DM) and its major long-term complication, diabetic polyneuropathy (DPN), continue to be a major global health problem and are important contributors of significant disability worldwide. Vitamin D plays a significant role in their pathogenesis as well as in the development of dementia in non-diabetic patients. Nevertheless, the role of Vitamin D in the development of cognitive impairment in DPN patients has not yet been extensively studied. AIM: We aimed to investigate the association between Vitamin D level and cognitive function in DPN patients and to evaluate several potential contributor factors to cognition, including demographic factors, glycemic control, and nerve conduction study (NCS) parameters. METHODS: Thirty-one DPN patients were included in this cross-sectional study. Patients were recruited from the outpatient endocrinology and neurology clinic of Haji Adam Malik General Hospital Medan Indonesia. We used the diabetic neuropathy examination (DNE) scale, diabetic neuropathy symptom (DNS) scale, and NCS to determine the presence and severity of the neuropathy. We measured the levels of Vitamin D, random blood sugar, and glycated hemoglobin (HbA1c). Cognitive function was assessed using the Indonesian version of Montreal Cognitive Assessment (MoCA-INA), trail making test A and B (TMT A and TMT B), and verbal fluency test. RESULTS: Most of the patients were female (80.6%), with a mean age of 55.71 ± 8.34 years. The proportion of patients with abnormal cognitive function was higher than cognitively unimpaired patients. The mean of MoCA-INA score and level of Vitamin D was lower than normal, 23.32 ± 3.00 and 24.91 ± 13.59 ng/ml, respectively. Using the Pearson correlation test, we did not find any significant association of Vitamin D level, NCS parameters, and other clinical characteristics with global cognitive function. Age and level of education were significantly associated with MoCA-INA score. Blood sugar level was significantly higher in patients with normal TMT-A and TMT-B tests compared to patients with abnormal results. CONCLUSION: Vitamin D and NCS parameters are not associated with cognitive function. Of the demographic and clinical characteristics, a significant association exists between age, level of education, and blood sugar level and cognition. This might suggest the complexity underlying cognitive impairment in T2DM patients.

The Relationship Between Glucose Control and Cognitive Function in People With Diabetes After a Lacunar Stroke

CONTEXT

Lacunar strokes and diabetes are risk factors for cognitive dysfunction. Elucidating modifiable risk factors for cognitive dysfunction has great public health implications. One factor may be glycemic status, as measured by glycated hemoglobin (A1c).

OBJECTIVE

The aim of this study was to assess the relationship between A1c and cognitive function in lacunar stroke patients with diabetes.

METHODS

The effect of baseline and follow-up A1c on the baseline and the change in Cognitive Assessment Screening Instrument (CASI) score over time among participants with a median of 2 cognitive assessments (range, 1-5) was examined in 942 individuals with diabetes and a lacunar stroke who participated in the Secondary Prevention of Small Subcortical Strokes (SPS3) trial (ClinicalTrials.gov No. NCT00059306).

RESULTS

Every 1% higher baseline A1c was associated with a 0.06 lower standardized CASI z score (95% CI, -0.101 to -0.018). Higher baseline A1c values were associated with lower CASI z scores over time (P for interaction = .037). A 1% increase in A1c over time corresponded with a CASI score decrease of 0.021 (95% CI, -0.0043 to -0.038) during follow-up. All these remained statistically significant after adjustment for age, sex, education, race, depression, hypertension, hyperlipidemia, body mass index, cardiovascular disease, obstructive sleep apnea, diabetic retinopathy, nephropathy insulin use, and white-matter abnormalities.

CONCLUSION

This analysis of lacunar stroke patients with diabetes demonstrates a relationship between A1c and change in cognitive scores over time. Intervention studies are needed to delineate whether better glucose control could slow the rate of cognitive decline in this high-risk population.

From Metabolic Syndrome to Neurological Diseases: Role of Autophagy

Metabolic syndrome is not a single pathology, but a constellation of cardiovascular disease risk factors including: central and abdominal obesity, systemic hypertension, insulin resistance (or type 2 diabetes mellitus), and atherogenic dyslipidemia. The global incidence of Metabolic syndrome is estimated to be about one quarter of the world population; for this reason, it would be desirable to better understand the underlying mechanisms involved in order to develop treatments that can reduce or eliminate the damage caused. The effects of Metabolic syndrome are multiple and wide ranging; some of which have an impact on the central nervous system and cause neurological and neurodegenerative diseases. Autophagy is a catabolic intracellular process, essential for the recycling of cytoplasmic materials and for the degradation of damaged cellular organelle. Therefore, autophagy is primarily a cytoprotective mechanism; even if excessive cellular degradation can be detrimental. To date, it is known that systemic autophagic insufficiency is able to cause metabolic balance deterioration and facilitate the onset of metabolic syndrome. This review aims to highlight the current state of knowledge regarding the connection between metabolic syndrome and the onset of several neurological diseases related to it. Furthermore, since autophagy has been found to be of particular importance in metabolic disorders, the probable involvement of this degradative process is assumed to be responsible for the attenuation of neurological disorders resulting from metabolic syndrome.

The Impact of Intermittent Fasting on Brain-Derived Neurotrophic Factor, Neurotrophin 3, and Rat Behavior in a Rat Model of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is known to be associated with an increased risk of dementia, specifically Alzheimer’s disease and vascular dementia. Intermittent fasting (IF) has been proposed to produce neuroprotective effects through the activation of several signaling pathways. In this study, we investigated the effect of IF on rat behavior in type 2 diabetic rats. Forty male Wistar Kyoto rats were divided into four groups (n = 10 for each): the ad libitum (Ad) group, the intermittent fasting group (IF), the streptozotocin-induced diabetic 2 group (T2DM) fed a high-fat diet for 4 weeks followed by a single intraperitoneal (i.p.) injection of streptozotocin (STZ) 25 mg kg⁻¹, and the diabetic group with intermittent fasting (T2DM+IF). We evaluated the impact of 3 months of IF (16 h of food deprivation daily) on the levels of brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), serotonin, dopamine, and glutamate in the hippocampus, and rat behavior was assessed by the forced swim test and elevated plus maze. IF for 12 weeks significantly increased (p < 0.05) the levels of NT3 and BDNF in both control and T2DM rats. Additionally, it increased serotonin, dopamine, and glutamic acid in diabetic rats. Moreover, IF modulated glucose homeostasis parameters, with a significant decrease (p < 0.05) in insulin resistance and downregulation of serum corticosterone level. Interestingly, T2DM rats showed a significant increase in anxiety and depression behaviors, which were ameliorated by IF. These findings suggest that IF could produce a potentially protective effect by increasing the levels of BDNF and NT3 in both control and T2DM rats. IF could be considered as an additional therapy for depression, anxiety, and neurodegenerative diseases.

Connecting vascular aging and frailty in Alzheimer's disease

Aging plays an important role in the etiology of the most common age-related diseases (ARDs), including Alzheimer's disease (AD). The increasing number of AD patients and the lack of disease-modifying drugs warranted intensive research to tackle the pathophysiological mechanisms underpinning AD development. Vascular aging/dysfunction is a common feature of almost all ARDs, including cardiovascular (CV) diseases, diabetes and AD. To this regard, interventions aimed at modifying CV outcomes are under extensive investigation for their pleiotropic role in ameliorating and slowing down cognitive impairment in middle-life and elderly individuals. Evidence from observational and clinical studies confirm the notion that the earlier the interventions are conducted, the most favorable are the effects on cognitive function. Therefore, epidemiological research should focus on the early detection of deviations from a healthy cognitive aging trajectory, through the stratification of adult individuals according to the rate of aging. Here, we review the interplay between vascular and cognitive dysfunctions associated with aging, to disentangle the complex mechanisms underpinning the development and progression of neurodegenerative disorders, with a specific focus on AD.

Gait Speed and Evolution of Verbal Fluencies in Frail or Prefrail Older People with Type 2 Diabetes. A Pilot Study

OBJECTIVES

Type 2 diabetes (T2D) is a risk factor of frailty and cognitive impairment. Impaired gait in older people is associated with incident vascular dementia. We aimed to assess whether in frail or prefrail older subjects with T2D, lower gait speed can be associated with faster cognitive decline.

DESIGN

Case-control study nested in a large randomized control trial (RCT, MID-frail); post hoc analysis.

SETTING AND PARTICIPANTS

Older frail and prefrail subjects (>70y) with T2D and with no history of cognitive problems were enrolled in a single recruiting center. Participants were divided into two groups depending on their walking speed - above (fast walkers) or below (slow walkers) using a cut off of 1 m/sec.

MEASURE

Cognitive function was assessed at baseline and during follow-up with the MMSE, category and letter fluencies at 15 sec (initiation) and 15-60 sec (late).

RESULTS

48 subjects were included, 22 were fast walkers, 26 were slow walkers. The mean follow-up was 60.9 (SD 17.5) weeks. The baseline 0-15 sec letter fluency was higher in fast walkers (p=0.008). There was no difference at baseline with MMSE scores and category fluency. The MID-Frail intervention did not change the evolution of any cognitive changes. Comparisons were adjusted for age, sex and baseline performance, and showed a steeper decline of category fluency score in slow walkers (fast walkers +0.04 (-1.49 to1.56) compared with -0.89 (-2.15 to 0.38), p=0.049) with a moderate effect size.

CONCLUSION

In frail or prefrail older adults with diabetes, we observed a decline in category fluency in those with low gait speed.

Altered regional homogeneity and functional brain networks in Type 2 diabetes with and without mild cognitive impairment

Patients with Type-2 Diabetes Mellitus (T2DM) have a considerably higher risk of developing mild cognitive impairment (MCI) and dementia. The initial symptoms are very insidious at onset. We investigated the alterations in spontaneous brain activity and network connectivity through regional homogeneity (ReHo) and graph theoretical network analyses, respectively, of resting-state functional Magnetic Resonance Imaging (rs-fMRI) in T2DM patients with and without MCI, so as to facilitate early diagnose. Twenty-five T2DM patients with MCI (DM-MCI), 25 T2DM patients with normal cognition (DM-NC), 27 healthy controls were enrolled. Whole-brain ReHo values were calculated and topological properties of functional networks were analyzed. The DM-MCI group exhibited decreased ReHo in the left inferior/middle occipital gyrus and right inferior temporal gyrus, and increased ReHo in frontal gyrus compared to the DM-NCs. Significant correlations were found between ReHo values and clinical measurements. The DM-MCI group illustrated greater clustering coefficient/local efficiency and altered nodal characteristics (efficiency, degree and betweenness), which increased in certain occipital, temporal and parietal regions but decreased in the right inferior temporal gyrus, compared to the DM-NCs. The altered ReHo and impaired network organization may underlie the impaired cognitive functions in T2DM and suggesting a compensation mechanism. These rs-fMRI measures have the potential as biomarkers of disease progression in diabetic encephalopathy.

Association between microstructural white matter abnormalities and cognitive functioning in patients with type 2 diabetes mellitus: a diffusion tensor imaging study

Background

Diffusion tensor imaging (DTI) technique is important for exploring more sensitive imaging-based biomarkers in prevention and early treatment of cognitive dysfunction induced by type 2 diabetes mellitus (DM).

Objectives

To predict early cognitive dysfunction and detection of microstructural white matter changes in patients with type 2 DM by diffusion tensor imaging.

Patients and methods

A case-control study included thirty patients aged ≥ 18 years old of both sexes with type 2 DM and 30 controls. All subjects underwent to Montreal Cognitive Assessment (MoCA) “Arabic version”: to detect mild cognitive impairment (MCI) and diffusion tensor imaging study (DTI).

Results

Mild cognitive impairment is related to type 2 DM (56.7% of diabetic group), reduced fractional anisotropy (FA) values, and elevated mean diffusivity (MD) values were related to cognitive impairment evaluated through Montreal Cognitive Assessment (MoCA) in patients with type 2 DM.

Conclusion

The integrity of the white matter measured using DTI vary in MCI diabetics compared with non-MCI diabetics. Such changes have major implications on the cognitive function.

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

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

The Association between HbA1c Levels, Olfactory Memory and Cognition in Normal, Pre-Diabetic and Diabetic Persons

BACKGROUND AND AIM

Recent data have shown that olfactory dysfunction is strongly related to Alzheimer's Disease (AD) that is often preceded by olfactory deficits suggesting that olfactory dysfunction might represent an early indicator of future cognitive in prediabetes.

METHODS

We have applied to a group of normal (n=15), prediabetic (n=16) and type 2 diabetic outpatients (n=15) olfactory testing, 1.5-T MRI scanner and detailed cognitive evaluation including the standard Mini-Mental State Examination (MMSE) form, Short Blessed Test (SBT), Letter Fluency Test (LFT) and the category fluency test with animal, Fruit and Vegetable Naming (CFT).

RESULTS

We have shown that Odour Threshold (OT), Discrimination (OD), and Identification (OI) scores and most cognitive test results were significantly different in the prediabetes and diabetes group compared to those in the control group. OD and OT were significantly different between the prediabetes and diabetes group, although the cognitive test results were only significantly different in the prediabetes and diabetes group compared to those in the control group. In evaluating the association between OI, OT, OD scores and specific cognitive tests, we have found, that impaired olfactory identification was the only parameter that correlated significantly with the SBT both in the pre-diabetes and diabetes group. Although spot glucose values were only correlated with OT, HbA1c levels were correlated with OT, OD, and OI, as well as results of the letter fluency test suggesting that HbA1c levels rather than the spot glucose values play a critical role in specific cognitive dysfunction.

CONCLUSION

To the best of our knowledge, this is the first prospective study to demonstrate a strong association between olfactory dysfunction and specific memory impairment in a population with prediabetes and diabetes suggesting that impaired olfactory identification might play an important role as a specific predictor of memory decline.

Diabetes-specific dementia risk score (DSDRS) predicts cognitive performance in patients with type 2 diabetes at high cardio-renal risk

AIM

To investigate the relationship between the diabetes-specific dementia risk score (DSDRS) and concurrent and future cognitive impairment (CI) in type 2 diabetes (T2D).

METHODS

DSDRS were calculated for participants with T2D aged ≥60 years from the CARMELINA-cognition substudy (ClinicalTrials.gov Identifier: NCT01897532). Cognitive assessment included Mini-Mental State Examination (MMSE) and a composite attention and executive functioning score (A&E). The relation between baseline DSDRS and probability of CI (MMSE < 24) and variation in cognitive performance was assessed at baseline (n = 2241) and after 2.5 years follow-up in patients without baseline CI (n = 1312).

RESULTS

Higher DSDRS was associated with a higher probability of CI at baseline (OR = 1.17 per point, 95% CI 1.12-1.22) and follow-up (OR = 1.24 per point, 95% CI 1.14-1.35). Moreover, in patients without baseline CI, higher DSDRS was also associated with lower baseline cognitive performance (MMSE: F(1, 1930) = 47.07, p < .0001, R² = 0.02); A&E z-score: (F(1, 1871) = 33.44 p < .0001, R² = 0.02) and faster cognitive decline at follow-up (MMSE: F(3, 1279) = 38.41, p < .0001; A&E z-score: F(3, 1206) = 148.48, p < .0001).

CONCLUSIONS

The DSDRS identifies patients with T2D at risk of concurrent as well as future CI. The DSDRS may thus be a supportive tool in screening strategies for cognitive dysfunction in patients with T2D.

The type 2 diabetes-specific dementia risk score (DSDRS) is associated with frailty, cognitive and functional status amongst Mexican community-dwelling older adults

Background

The type 2 diabetes (T2D) specific dementia-risk score (DSDRS) was developed to evaluate dementia risk in older adults with T2D. T2D-related factors have been shown increase the risk of age-related conditions, which might also increase dementia risk. Here, we investigate the associations of DSDRS with frailty, disability, quality of life (QoL) and cognition in community-dwelling older adults with T2D.

Methods

We included 257 community-dwelling older adults with T2D to evaluate the association between DSDRS and Mini-mental state examination (MMSE), Isaac’s set-test (IST), clock drawing test (CDT), quality of life (SF-36), risk of malnutrition (Mini-Nutritional Assessment or MNA), as well as frailty, Katz’ and Lawton-Brody scores. We also assessed the phenotype and correlates of high-estimated dementia risk by assessing individuals with DSDRS >75th age-specific percentiles.

Results

Mean age of participants was 78.0 ± 6.2 years. DSDRS showed a significant correlation with MMSE test, IST, CDT, SF-36, MNA, Lawton-Brody and Katz scores, and an increasing number of frailty components. DSDRS was higher among frail, pre-frail, and subjects with limited ADL and IADL (p < 0.001). Participants with DSDRS >75th age-specific percentiles had lower education, MMSE, IST, SF-36, MNA, Katz, Lawton-Brody, and higher frailty scores. High-estimated 10-year dementia risk was associated with ADL and IADL disability, frailty and risk of malnutrition. When assessing individual components of DSDRS, T2D-related microvascular complications were associated to all outcome measures.

Conclusion

The DSDRS is associated with frailty, disability, malnutrition and lower cognitive performance. These findings support that T2D-related factors have significant burden on functional status, QoL, disability and dementia risk.

Elevated Plasma Level of D-dimer Predicts the High Risk of Early Cognitive Impairment in Type 2 Diabetic Patients as Carotid Artery Plaques become Vulnerable or Get Aggravated

BACKGROUND AND OBJECTIVE

D-dimer prompts fibrinolysis system, which is involved in Alzheimer's disease and the complications of type 2 diabetic patients, especially among those with carotid artery plaques. Hence, this study aims to investigate the role of D-dimer in early cognitive impairment among type 2 diabetic patients with carotid artery plaques.

METHODS

A total of 175 Chinese patients with type 2 diabetes were recruited and divided into two groups according to the Montreal Cognitive Assessment score. Demographic data were collected, plasma D-dimer was tested through VIDAS D-dimer New, neuropsychological tests were examined, and carotid artery plaques were detected by ultrasound and further stratified by vulnerability and level.

RESULTS

A total of 67 types 2 diabetic patients with Mild Cognitive Impairment (MCI) displayed significantly increased plasma D-dimer levels compared with their health-cognition controls (p = 0.011). Plasma D-dimer concentration was negatively related with Digit Span Test scores in diabetic patients with vulnerable plaques (r=-0.471, p=0.023) and Stroop Color Word Test C (number) in diabetic patients with stable plaques (r=-0.482, p<0.001). Multivariable regression analysis further showed that D-dimer concentration was an independent factor of diabetic MCI with carotid artery plaque (p=0.005), and D-dimer concentration especially contributed to the high risk of MCI with vulnerable plaques (p=0.028) or high levels of carotid plaque (p=0.023).

CONCLUSION

Elevated D-dimer level predicts the high risk of early cognitive impairment in type 2 diabetic patients with carotid artery plaques, especially vulnerable plaques or high levels of carotid plaques.

Post-traumatic stress disorder: A differential diagnostic consideration for COVID-19 survivors

Objective: SARS-CoV-2 infection and its oft-associated illness COVID-19 may lead to neuropsychological deficits, either through direct mechanisms (i.e., neurovirulance) or indirect mechanisms, most notably complications caused by the virus (e.g., stroke) or medical procedures (e.g., intubation). The history of past human coronavirus outbreaks resulting in similar health emergencies suggests there will be a substantial prevalence of post-traumatic stress disorder (PTSD) among COVID-19 survivors. To prepare neuropsychologists for the difficult task of differentiating PTSD-related from neuropathology-related deficits in the oncoming wave of COVID-19 survivors, we integrate research across a spectrum of related areas.Methods: Several areas of literature were reviewed: psychiatric, neurologic, and neuropathological outcomes of SARS and MERS patients; neurological outcomes in COVID-19 survivors; PTSD associated with procedures common to COVID-19 patients; and differentiating neuropsychological deficits due to PTSD from those due to acquired brain injuries in other patient groups.Conclusions: Heightened risk of PTSD occurred in MERS and SARS survivors. While data concerning COVID-19 is lacking, PTSD is known to occur in patient groups who undergo similar hospital courses, including ICU survivors, patients who are intubated and mechanically ventilated, and those that experience delirium. Research with patients who develop PTSD in the context of mild traumatic brain injury further suggests that PTSD may account for some or all of a patient's subjective cognitive complaints and neuropsychological test performance. Recommendations are provided for assessing PTSD in the context of COVID-19.

Association of diabetes status with cognitive impairment in two Chinese rural communities

BACKGROUND AND PURPOSE

Diabetes may be one of the risk factors of cognitive impairment. In this study, we aimed to investigate the relationship between diabetes status and cognitive impairment among the middle-aged and elderly population (≥40 years) in Chinese rural communities.

METHODS

A sample of 3392 participants aged 40 years or older from the China National Stroke Prevention Project (CSPP) between 2015 and 2017 were enrolled in this study. Cognitive function was assessed by the Beijing edition of the Montreal cognitive assessment (MoCA) scale. Cognitive impairment was diagnosed as a MoCA score < 26. Diabetes status was divided into three groups------Normal: fasting plasma glucose (FPG) ≤ 5.5 mmol/L, Prediabetes: 5.6 ≤ FPG ≤ 6.9 mmol/L, Diabetes: FPG ≥ 7.0 mmol/L or with a history of diabetes. Multivariate logistic regression was used to analyze the association between diabetes status and cognitive impairment.

RESULTS

Out of the 3392 enrolled participants, 2023(59.6%) had cognitive impairment, 1586(46.8%) had abnormal fasting plasma glucose including 867(25.6%) prediabetes and 719(21.2%) diabetes. After adjusting for potential risk factors, we found prediabetes (OR: 1.22, 95%CI: 1.03-1.45) and diabetes (OR: 1.28, 95%CI: 1.06-1.55) are all associated with cognitive impairment, especially in the domains of language (prediabetes: OR: 1.14, 95%CI: 1.05-1.25; diabetes: OR:1.13, 95%CI: 1.03-1.24), visuospatial/executive functions (diabetes: OR: 1.50, 95%CI: 1.22-1.84) and attention (diabetes: OR: 1.15, 95%CI: 1.02-1.31).

CONCLUSIONS

In this large community-based study, we found diabetes status may be an independent risk factor for cognitive impairment, particularly in domains of language, visuospatial/executive functions, and attention.

Zonisamide Ameliorates Cognitive Impairment by Inhibiting ER Stress in a Mouse Model of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) increases the risk of Alzheimer’s disease (AD)-like dementia and pathology. Endoplasmic reticulum stress (ERS) plays a key role in the development of cognitive impairment in T2DM. Zonisamide (ZNS) was found to suppress ERS-induced neuronal cell damage in the experimental models of Parkinson’s disease (PD). However, the protective effect of Zonisamide in the treatment of diabetes-related dementia is not determined. Here, we studied whether ZNS can attenuate cognitive impairments in T2DM mice. C57BL/6J mice were fed with a high-fat diet (HFD) and received one intraperitoneal injection of streptozotocin (STZ) to develop T2DM. After the 9-week diet, the mice were orally gavaged with ZNS or vehicle for 16 consecutive weeks. We found that ZNS improved spatial learning and memory ability and slightly attenuated hyperglycemia. In addition, the expression levels of synaptic-related proteins, such as postsynaptic density 95 (PSD95) and synaptophysin, were increased along with the activation of the cyclic AMP response element-binding (CREB) protein and cAMP-dependent protein kinase (PKA) both in the hippocampus and cortex of T2DM mice. Meanwhile, ZNS attenuated Aβ deposition, Tau hyperphosphorylation at Ser-396/404, and also decreased the activity of Tau upstream kinases including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). Moreover, ZNS also decreased the ERS hallmark protein levels. These data suggest that ZNS can efficiently prevent cognitive impairment and improve AD-like pathologies by attenuating ERS in T2DM mice.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Diabetes, Cognitive Decline, and Mild Cognitive Impairment Among Diverse Hispanics/Latinos: Study of Latinos-Investigation of Neurocognitive Aging Results (HCHS/SOL)

OBJECTIVE

Hispanics/Latinos are the largest ethnic/racial group in the U.S., have the highest prevalence of diabetes, and are at increased risk for neurodegenerative disorders. Currently, little is known about the relationship between diabetes and cognitive decline and disorders among diverse Hispanics/Latinos. The purpose of this study is to clarify these relationships in diverse middle-aged and older Hispanics/Latinos.

RESEARCH DESIGN AND METHODS

The Study of Latinos-Investigation of Neurocognitive Aging (SOL-INCA) is an ancillary study of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). HCHS/SOL is a multisite (Bronx, NY; Chicago, IL; Miami, FL; and San Diego, CA), probability-sampled (i.e., representative of targeted populations), and prospective cohort study. Between 2016 and 2018, SOL-INCA enrolled diverse Hispanics/Latinos aged ≥50 years (n = 6,377). Global cognitive decline and mild cognitive impairment (MCI) were the primary outcomes.

RESULTS

Prevalent diabetes at visit 1, but not incident diabetes at visit 2, was associated with significantly steeper global cognitive decline (β_GC = -0.16 [95% CI -0.25; -0.07]; P < 0.001), domain-specific cognitive decline, and higher odds of MCI (odds ratio 1.74 [95% CI 1.34; 2.26]; P < 0.001) compared with no diabetes in age- and sex-adjusted models.

CONCLUSIONS

Diabetes was associated with cognitive decline and increased MCI prevalence among diverse Hispanics/Latinos, primarily among those with prevalent diabetes at visit 1. Our findings suggest that significant cognitive decline and MCI may be considered additional disease complications of diabetes among diverse middle-aged and older Hispanics/Latinos.

Effect of Fixed-Density Thresholding on Structural Brain Networks: A Demonstration in Cerebral Small Vessel Disease

A popular solution to control for edge density variability in structural brain network analysis is to threshold the networks to a fixed density across all subjects. However, it remains unclear how this type of thresholding affects the basic network architecture in terms of edge weights, hub location, and hub connectivity and, especially, how it affects the sensitivity to detect disease-related abnormalities. We investigated these two questions in a cohort of patients with cerebral small vessel disease and age-matched controls. Brain networks were reconstructed from diffusion magnetic resonance imaging data using deterministic fiber tractography. Networks were thresholded to a fixed density by removing edges with the lowest number of streamlines. We compared edge length (mm), fractional anisotropy (FA), proportion of hub connections, and hub location between the unthresholded and the thresholded networks of each subject. Moreover, we compared weighted graph measures of global and local connectivity obtained from the (un)thresholded networks between patients and controls. We performed these analyses over a range of densities (2-20%). Results indicate that fixed-density thresholding disproportionally removes edges composed of long streamlines, but is independent of FA. The edges removed were not preferentially connected to hub or nonhub nodes. Over half of the original hubs were reproducible when networks were thresholded to a density ≥10%. Furthermore, the between-group differences in graph measures observed in the unthresholded network remained present after thresholding, irrespective of the chosen density. We therefore conclude that moderate fixed-density thresholds can successfully be applied to control for the effects of density in structural brain network analysis.

Studying the neuropsychological sequelae of SARS-CoV-2: lessons learned from 35 years of neuroHIV research

The virology of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and the human immune response to the virus are under vigorous investigation. There are now several reports describing neurological symptoms in individuals who develop coronavirus disease 2019 (COVID-19), the syndrome associated with SARS-CoV-2 infection. The prevalence, incidence, and clinical course of these symptoms will become clearer in the coming months and years through epidemiological studies. However, the long-term neurological and cognitive consequence of SARS-CoV-2 infection will remain conjectural for some time and will likely require the creation of cohort studies that include uninfected individuals. Considering the early evidence for neurological involvement in COVID-19 it may prove helpful to compare SARS-CoV-2 with another endemic and neurovirulent virus, human immunodeficiency virus-1 (HIV-1), when designing such cohort studies and when making predictions about neuropsychological outcomes. In this paper, similarities and differences between SARS-CoV-2 and HIV-1 are reviewed, including routes of neuroinvasion, putative mechanisms of neurovirulence, and factors involved in possible long-term neuropsychological sequelae. Application of the knowledge gained from over three decades of neuroHIV research is discussed, with a focus on alerting researchers and clinicians to the challenges in determining the cause of neurocognitive deficits among long-term survivors.

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

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

Association between diabetes and mood disorders and the potential use of anti-hyperglycemic agents as antidepressants

Epidemiological and mechanistic studies support the association between Diabetes Mellitus and mood disorders, such as Major Depressive Disorder and Bipolar Disorder. This association is especially relevant in specific domains of depressive psychopathology, such as disturbances in reward systems and cognitive functions. Several anti-hyperglycemic agents have demonstrated effects on depressive symptoms and cognitive decline and this efficacy is probably the result of an action in shared brain targets between these two groups of conditions. These medications include subcutaneous insulin, intranasal insulin, metformin, and liraglutide. The study of the mechanisms involved in the relationship between Diabetes Mellitus and mood disorders offers a new avenue of investigation, and this understanding can be applied when examining whether antidiabetic agents can be repurposed as antidepressants and mood stabilizers. The objective of this narrative review is to critically appraise the literature surrounding drugs commonly used as anti-hyperglycemic agents and their effects on the brain, while discussing their potential as a new treatment for mental illnesses, and specifically, mood disorders.

DL-3-n-butylphthalide (NBP) ameliorates cognitive deficits and CaMKII-mediated long-term potentiation impairment in the hippocampus of diabetic db/db mice

Objective: Diabetes-associated cognitive deficits is characterized by long-term potentiation (LTP) decline in the hippocampus. DL-3-n-butylphthalide (NBP) is a novel agent exerting protective effect against ischemic brain. However, the effects of NBP on diabetes-associated cognitive deficits and underlying mechanisms are not fully clear. This study was designed to evaluate the effects of NBP on the cognitive deficits through activating CaMKII-mediated LTP process and protecting neuron structure of hippocampus in diabetic db/db mice. Methods: Male db/db mice were randomly divided into db/db group (n = 8) and db/db+NBP group (n = 8, 120mg/Kg NBP by gavage). Male db/m mice (n = 8) were included as control group. All animals were treated for 6 weeks. Morris Water Maze test was carried out to evaluate cognitive function. Electrophysiological recordings were performed to test LTP level. HE-staining and electron microscopy of hippocampus were used to observe structure change of neurons and synapse. RT-PCR and Western blot were used to assess the expression of CaMKII, NR2B, and GluR1. Results: Type 2 diabetes mellitus caused LTP decline, and significantly decreased NR2B, CaMKII, and GluR1 expression. Histological analysis showed that disorganized pyramidal cells, as well as degraded neuron and synapse ultrastructure in db/db mice. NBP treatment restored LTP and its associated proteins in db/db mice. The structure changes of hippocampal cells were partly reversed by NBP intervention. Conclusion: These results suggest that NBP ameliorates cognitive deficits induced by type 2 diabetes mellitus through improving CaMKII-mediated LTP and cell ultrastructure in the hippocampus. NBP is a potential therapeutic agent for diabetes-associated cognitive deficits. Abbreviations: NBP: DL-3-n-butylphthalide; LTP: long-term potentiation; CaMKII: calcium/calmodulin-dependent protein kinase II; NR2B: N-methyl-D-aspartic acid receptor subtype 2B; GluR1: α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subtype 1.

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

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