Exploring effects of type 2 diabetes on cognitive functioning in older adults

Characterizing cognitive phenotypes and clinical correlates in type 2 diabetes using fuzzy clustering and decision tree analysis

Cognitive impairment is frequently seen in patients with type 2 diabetes (T2DM), ranging from mild impairment to dementia. However, our knowledge of the specific profiles and risk factors for these different levels of impairment is limited. In this study involving 152 patients with T2DM, cognitive function was assessed using the Montreal Cognitive Assessment test. The Fuzzy C-means clustering algorithm was utilized to group individuals with similar cognitive characteristics. The study evaluated how well clinical parameters could classify characteristics of clusters using the Classification and Regression Trees algorithm. ROC analysis was then used to assess the classification success. Three distinct cognitive clusters were identified. Cluster 1 had the poorest cognitive performance and was characterized by more women, lower education levels, and lower levels of iron, hemoglobin, and creatine. Cluster 3, the amnestic cluster, was distinguished by low TSH levels. The decision tree model highlighted several parameters, including education level, hemoglobin, duration of diabetes mellitus (DM), iron, TSH, gender, family history of diabetes, and microalbumin/creatinine ratio, as significantly affecting the distinction of cognitive clusters. Diabetes-associated cognitive impairment stems from multifaceted pathophysiological mechanisms influenced by complex risk factors, resulting in diverse types of cognitive deficits.

Event-Related Potential Changes Following 12-week Yoga Practice in T2DM Patients: A Randomized Controlled Trial

Introduction. Type 2 diabetes patients are more likely to experience cognitive decline (1.5%) and dementia (1.6%) than healthy individuals. Although cognitive impairment adversely affects Type 2 diabetes mellitus (T2DM) patients, it is the least addressed complication of T2DM patients. Objective. The present study attempts to examine the changes in cognitive performance of T2DM patients and the probable factors contributing to the changes following 12-week yoga practice. Methods. The current study is a parallel group randomized controlled trial that compared the outcomes of the participants randomized to a yoga group (YG) (n = 25) and to a wait-list control group (n = 29). The study assessed N200 and N450 event-related potential (ERP) components following the Stroop task, heart rate variability (HRV) and HbA1c before and after the intervention. Results. The mean amplitude of the N200 ERP component showed a significant group difference after the intervention, demonstrating an improved neural efficiency in the process of conflict monitoring and response inhibition. No differences were present for the N450 component. T2DM patients showed reduced heart rate and increased mean RR following yoga practice without any corresponding changes in other HRV parameters, demonstrating an overall improvement in cardiac activity. Along with that yoga practice also reduced HbA1c levels in T2DM patients, indicating improved glycemic control. Moreover, HbA1c levels were negatively correlated with reaction time after the intervention, indicating an impact of glycemic control on cognitive performance. Conclusion. The 12-week yoga practice improved cognitive performance by enhancing the processes of conflict monitoring and response inhibition. Further, improved cognitive performance postintervention was facilitated by improved glycemic control.

Feasibility and preliminary efficacy of different intensities of functional training in elderly type 2 diabetes patients with cognitive impairment: a pilot randomised controlled trial

BACKGROUND

Aging and type-2 diabetes (T2D) are the most important risk factors for cognitive impairment and Alzheimer's disease. Exercise training is an effective, safe, and practical intervention in improving glucose metabolism, physical function, and cognitive disorders. This pilot study investigated the feasibility and preliminary efficacy of high-intensity low-volume (HIFT) vs. low-intensity high-volume (LIFT) functional training in elderly T2D patients with cognitive impairment.

METHODS

Forty-eight elderly T2D patients (31 female, 17 male, age 67.5 ± 5.8 years, MMSE score 18.8 ± 2.6, FBG 209.5 ± 37.9) were randomly assigned to HIFT, LIFT and control groups. Cognitive impairment was diagnosed with MMSE ≤ 23 based Iranian society. The SDMT, CVLT-II, BVMT-R, and Stroop tests were used to evaluated processing speed, learning, memory and attention respectively. Physical fitness tests include: tandem stance and walk test; TUG; 6MWT, 10MWT; SSST; 5TSTS; and hand grip was used to evaluated static and dynamic balance, agility, walking endurance, gait speed, lower limb function and lower and upper body strength respectively. As well as, Biochemical (FBG, insulin, HOMA-IR, HbA1c) and physiological outcomes (SBP, and DBP) were assessed. The HIFT group performed six weeks of functional training (three sessions per week) with 120-125% of the lactate threshold. The LIFT group performed six weeks of functional training (five sessions per week) with a 70-75% lactate threshold. Feasibility, safety, and acceptability of exercise programs were assessed at the end of the study.

RESULT

HIFT showed a higher adherence rate (91% vs. 87.5%), safety, and acceptability compared to LIFT. MMSE and Stroop scores, 6MWT, FBG, insulin, HOMA-IR, HbA1c, SBP, and DBP significantly improved in HIFT (all, P ≤ 0.004) and LIFT (all, P ≤ 0.023). Changes in 6MWT, FBG, insulin, HOMA-IR, and HbA1c in HIFT (all, P ≤ 0.001) and LIFT (all, P ≤ 0.008) were significant compared to the control group. Changes in Stroop scores were significant only in the HIFT group compared to the control group (P = 0.013). SDMT, CVLT-II, BVMT-R, balance test, 10MWT, SSST, TUG and hang grip significantly improved only in HIFT (all, P ≤ 0.038).

CONCLUSION

HIFT vs. LIFT is a safe, feasible, and effective approach for improving some aspects of physical, biochemical, and cognitive function in elderly T2D patients with cognitive impairment. This pilot study provides initial proof-of-concept data for the design and implementation of an appropriately powered randomised controlled trial (RCT) of HIFT vs. LIFT in a larger sample of elderly T2D patients with cognitive impairment.

TRIAL REGISTRATION

Randomized controlled trial (RCT) (Iranian Registry of Clinical Trials, trial registration number: IRCT20230502058055N1. Date of registration: 11/06/2023.

Acute effects of different exercise forms on executive function and the mechanism of cerebral hemodynamics in hospitalized T2DM patients: a within-subject study

Objective

This study aimed to investigate the acute effects of aerobic exercise (AE), resistance exercise (RE), and integrated concurrent exercise (ICE; i.e., AE plus RE) on executive function among hospitalized type 2 diabetes mellitus (T2DM) inpatients, and the mechanism of cerebral hemodynamics.

Methods

A within-subject design was applied in 30 hospitalized patients with T2DM aged between 45 and 70 years in the Jiangsu Geriatric Hospital, China. The participants were asked to take AE, RE, and ICE for 3 days at 48-h intervals. Three executive function (EF) tests, namely, Stroop, More-odd shifting, and 2-back tests, were applied at baseline and after each exercise. The functional near-infrared spectroscopy brain function imaging system was used to collect cerebral hemodynamic data. The one-way repeated measurement ANOVA was used to explore training effects on each test indicator.

Results

Compared with the baseline data, the EF indicators have been improved after both ICE and RE (p < 0.05). Compared with the AE group, the ICE and RE groups have demonstrated significant improvements in inhibition (ICE: MD = - 162.92 ms; RE: MD = -106.86 ms) and conversion functions (ICE: MD = -111.79 ms; RE: MD = -86.95 ms). Based on the cerebral hemodynamic data, the beta values of brain activation in executive function related brain regions increased after three kinds of exercise, the EF improvements after the ICE showed synchronous activation of blood flow in the dorsolateral prefrontal cortex (DLPFC), the frontal polar (FPA) and orbitofrontal cortex (OFC), the improvement of inhibitory function after RE displayed synchronous activation of DLPFC and FPA, and AE mainly activates DLPFC. The HbO₂ concentration in the pars triangularis Broca's area increased significantly after AE, but the EF did not improve significantly.

Conclusion

The ICE is preferred for the improvements of executive function in T2DM patients, while AE is more conducive to the improvements of refresh function. Moreover, a synergistic mechanism exists between cognitive function and blood flow activation in specific brain regions.

Insulin resistance, age and depression's impact on cognition in middle-aged adults from the PREVENT cohort

BACKGROUND

Alzheimer's disease (AD), type 2 diabetes mellitus (characterised by insulin resistance) and depression are significant challenges facing public health. Research has demonstrated common comorbidities among these three conditions, typically focusing on two of them at a time.

OBJECTIVE

The goal of this study, however, was to assess the inter-relationships between the three conditions, focusing on mid-life (defined as age 40-59) risk before the emergence of dementia caused by AD.

METHODS

In the current study, we used cross-sectional data from 665 participants from the cohort study, PREVENT.

FINDINGS

Using structural equation modelling, we showed that (1) insulin resistance predicts executive dysfunction in older but not younger adults in mid-life, that (2) insulin resistance predicts self-reported depression in both older and younger middle-aged adults and that (3) depression predicts deficits in visuospatial memory in older but not younger adults in mid-life.

CONCLUSIONS

Together, we demonstrate the inter-relations between three common non-communicable diseases in middle-aged adults.

CLINICAL IMPLICATIONS

We emphasise the need for combined interventions and the use of resources to help adults in mid-life to modify risk factors for cognitive impairment, such as depression and diabetes.

Transdiagnostic Perspective of Impulsivity and Compulsivity in Obesity: From Cognitive Profile to Self-Reported Dimensions in Clinical Samples with and without Diabetes

Impulsive and compulsive behaviors have both been observed in individuals with obesity. The co-occurrence of obesity and type 2 diabetes (T2D) is more strongly associated with impulsivity, although there are no conclusive results yet. A multidimensional assessment of impulsivity and compulsivity was conducted in individuals with obesity in the absence or presence of T2D, compared with healthy, normal-weight individuals, with highly impulsive patients (gambling disorders), and with highly compulsive patients (anorexia nervosa). Decision making and novelty seeking were used to measure impulsivity, and cognitive flexibility and harm avoidance were used for compulsivity. For impulsivity, patients with obesity and T2D showed poorer decision-making ability compared with healthy individuals. For compulsivity, individuals with only obesity presented less cognitive flexibility and high harm avoidance; these dimensions were not associated with obesity with T2D. This study contributes to the knowledge of the mechanisms associated with diabetes and its association with impulsive–compulsive behaviors, confirming the hypothesis that patients with obesity and T2D would be characterized by higher levels of impulsivity.

Diabetes and Cognitive Impairment: A Role for Glucotoxicity and Dopaminergic Dysfunction

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia, responsible for the onset of several long-term complications. Recent evidence suggests that cognitive dysfunction represents an emerging complication of DM, but the underlying molecular mechanisms are still obscure. Dopamine (DA), a neurotransmitter essentially known for its relevance in the regulation of behavior and movement, modulates cognitive function, too. Interestingly, alterations of the dopaminergic system have been observed in DM. This review aims to offer a comprehensive overview of the most relevant experimental results assessing DA’s role in cognitive function, highlighting the presence of dopaminergic dysfunction in DM and supporting a role for glucotoxicity in DM-associated dopaminergic dysfunction and cognitive impairment. Several studies confirm a role for DA in cognition both in animal models and in humans. Similarly, significant alterations of the dopaminergic system have been observed in animal models of experimental diabetes and in diabetic patients, too. Evidence is accumulating that advanced glycation end products (AGEs) and their precursor methylglyoxal (MGO) are associated with cognitive impairment and alterations of the dopaminergic system. Further research is needed to clarify the molecular mechanisms linking DM-associated dopaminergic dysfunction and cognitive impairment and to assess the deleterious impact of glucotoxicity.

No Effects of Acute Psychosocial Stress on Working Memory in Older People With Type 2 Diabetes

Type 2 diabetes (T2D) has been considered a public health threat due to its growing prevalence, particularly in the older population. It is important to know the effects of psychosocial stress and its potential consequences for some basic cognitive processes that are important in daily life. Currently, there is very little information about how people with T2D face acute psychosocial stressors, and even less about how their response affects working memory (WM), which is essential for their functionality and independence. Our aim was to characterize the response to an acute laboratory psychosocial stressor and its effects on WM in older people with T2D. Fifty participants with T2D from 52 to 77 years old were randomly assigned to a stress (12 men and 12 women) or control (12 men and 14 women) condition. Mood and physiological (cortisol, C, and salivary alpha-amylase, sAA) responses to tasks were measured. In addition, participants completed a WM test before and after the stress or control task. Our results showed that the TSST elicited higher negative affect and greater C and sAA responses than the control task. No significant differences in WM were observed depending on the exposure to stress or the control task. Finally, participants who showed higher C and sAA responses to the stressor had lower WM performance. Our results indicate that medically treated older adults with T2D show clear, typical mood and physiological responses to an acute psychosocial stressor. Finally, the lack of acute psychosocial stress effects on WM suggests that it could be related to aging and not to this disease, at least when T2D is adequately treated.

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.

Mild Cognitive Impairment Subtypes and Type 2 Diabetes in Elderly Subjects

Background: Type 2 diabetes (T2D) is correlated to amnestic mild cognitive impairment (aMCI) and to non-amnestic mild cognitive impairment (naMCI). This study evaluated whether the T2D variable characterizes a peculiar cognitive profile in elderly patients. Moreover, it explores the association between glycated hemoglobin levels (HbA1c), T2D duration, insulin and oral hypoglycemic agent treatment, and cognition in elderly diabetic patients. Methods: Detailed neuropsychological battery was used to diagnose MCI subtypes. A total of 39 MCI subjects with T2D (T2D-MCI) and 37 MCI subjects without T2D (ND-MCI), matched for age, educational level, and Mini-Mental State Examination score, were included. Results: ND-MCI performed worse in memory and language domains than T2D-MCI. The amnestic subtype is more frequent among ND-MCI and non-amnestic subtype in T2D-MCI. In T2D-MCI, high HbA1c levels correlate with episodic memory (immediate recall) and T2D duration. Some indexes of episodic memory (immediate recall), attention, and visual-spatial ability correlate with insulin treatment. Conclusions: An association between T2D and non-amnestic MCI is suggested. In the T2D-MCI group, significant associations between insulin treatment and memory (immediate recall), complex figure copy, and attention were found.

Reliability of 30-s Chair Stand Test with and without Cognitive Task in People with Type-2 Diabetes Mellitus

Background: Reliability refers to the precision of an assessment, so it is a critical topic to take the right decisions related to health management. People usually perform several tasks at the same time in their daily life. The aim of this study was to examine the reliability of the 30-s chair stand test in people with type 2 Diabetes Mellitus (T2DM) with test–retest, with and without dual-task (motor + cognitive task). Methods: Twenty-six subjects with T2DM and 30 subjects without T2DM performed the 30-s Chair Stand Test (30sCST) in which they must sit and stand as many times as possible in 30 s. They performed the test in the usual way (30sCST) and also with an additional cognitive task (30sCST-DT). A retest was conducted 7–14 days later. Results: Relative reliability was excellent in both groups (intraclass correlation coefficient > 0.9). In 30sCST-DT, relative reliability was high in the T2DM group (intraclass correlation coefficient > 0.7) and excellent in subjects without T2DM (intraclass correlation coefficient > 0.9). Conclusions: The 30sCST and the 30sCST-DT tests are reliable tools for people with T2DM to measure changes after an intervention. The smallest real difference was 15% and 20% upper in the T2DM group in the 30sCST and 30sCST-DT tests, respectively.

Neuropsychological function in type 2 diabetes mellitus

Type 2 diabetes mellitus (DM) is a major and growing health problem. Brain-related effects of type 2 DM have been studied in several ways over the past few decades. Results have shown effects on brain structure, incidence of dementia, and impairment of various cognitive functions. The present study examined a sample of clinically-referred patients with type 2 DM and compared them with a sample of control patients who were matched on a pairwise basis on age, education, and gender. Each patient was tested using a comprehensive, integrated neuropsychological test battery. Results showed a pattern of generalized and specific neuropsychological dysfunction affecting a broad range of neurocognitive and sensorimotor abilities. However, no differences were found on measures of attention/concentration, memory, or abstract reasoning. Nevertheless, the DM group consistently performed worse on all measures. The DM group's score on a summary measure of neuropsychological function (GNDS) reflected moderate brain-related impairment. A neurocognitive profile is identified that may help clinicians understand their DM patients.

Greater Disease Burden, Greater Risk? Exploring Cognitive Change and Health Status Among Older Blacks

Objective: The objective of study is to examine the relationships between health status and changes in cognition over time among middle to older aged Blacks. Method: Data come from the Baltimore Study of Black Aging-Patterns of Cognitive Aging. At baseline, 602 Black participants, ranging from ages 48 to 95 years, were enrolled. At follow-up, approximately 3 years later, 450 participants were re-interviewed. Results: After accounting for baseline cognition, age, sex, and education, a greater number of health conditions was associated with slower perceptual speed (b = -5.099, p = .022). Average peak expiratory flow was also associated with improvements in working memory (b = 0.029, p = .019) and perceptual speed (b = 0.026, p = .026), controlling for model covariates. Discussion: Study findings demonstrate that greater disease burden is associated with declines in specific fluid cognitive abilities in middle to later life among Blacks. This finding highlights the importance of reducing health disparities that disproportionately affect Blacks.

Glucose regulation and face recognition deficits in older adults: the role of attention

The present study investigated the perceptual, attentional, and memory processes underlying face recognition deficits observed in older adults with impaired glucoregulation. Participants were categorized as good glucoregulators or poor glucoregulators on the basis of an oral glucose tolerance test. Using event-related potential (ERP) methodology, 23 participants (62-88 years) performed a 2-stimulus oddball task. Participants were asked to rate and memorize 10 "target" faces, which were then presented amongst 120 unfamiliar foils. Behavioral results indicated that good glucoregulators were significantly more accurate at recognizing target faces. ERP markers of early visual perception (P1 and N170 components) and memory formation (P3 component) were unaffected by glucoregulatory efficiency. The P2 component, an index of attentional processing, was larger and delayed in the poor glucoregulators. To the best of our knowledge, this study is the first to suggest that face recognition deficits in poor glucoregulators may be due to impairments in attentional processing.

Change in Cognitive Performance From Midlife Into Old Age: Findings from the Midlife in the United States (MIDUS) Study

OBJECTIVES

A substantial body of research has documented age-related declines in cognitive abilities among adults over 60, yet there is much less known about changes in cognitive abilities during midlife. The goal was to examine longitudinal changes in multiple cognitive domains from early midlife through old age in a large national sample, the Midlife in the United States (MIDUS) study.

METHODS

The Brief Test of Adult Cognition by Telephone (BTACT) was administered on two occasions (MIDUS 2, MIDUS 3), an average of 9 years apart. At MIDUS 3, those with the cognitive assessment (N=2518) ranged in age from 42 to 92 years (M=64.30; SD=11.20) and had a mean education of 14.68 years (SD=2.63). The BTACT includes assessment of key aging-sensitive cognitive domains: immediate and delayed free recall, number series, category fluency, backward digit span, processing speed, and reaction time for attention switching and inhibitory control, which comprise two factors: episodic memory and executive functioning.

RESULTS

As predicted, all cognitive subtests and factors showed very small but significant declines over 9 years, with differences in the timing and extent of change. Processing speed showed the earliest and steepest decrements. Those with higher educational attainment scored better on all tests except reaction time. Men had better executive functioning and women performed better on episodic memory.

CONCLUSIONS

Examining cognitive changes in midlife provides opportunities for early detection of cognitive impairments and possibilities for preventative interventions. (JINS, 2018, 24, 805-820).

Impact of glycemic status on longitudinal cognitive performance in men with and without HIV infection

OBJECTIVES

To determine the relationship between glycemic status and cognitive performance in men living with HIV (MLWH) and without HIV infection.

DESIGN

A prospective HIV/AIDS cohort study in four US cities between 1999 and 2016.

METHODS

Glycemic status was categorized as normal glucose, impaired fasting glucose, controlled diabetes mellitus and uncontrolled diabetes mellitus at each semiannual visit. Cognitive performance was evaluated using nine neuropsychological tests which measure attention, constructional ability, verbal learning, executive functioning, memory and psychomotor speed. Linear mixed models were used to assess the association between glycemic status and cognition.

RESULTS

Overall, 900 MLWH and 1149 men without HIV were included. MLWH had significantly more person-visits with impaired fasting glucose (52.1 vs. 47.9%) and controlled diabetes mellitus (58.2 vs. 41.8%) than men without HIV (P < 0.05). Compared with men with normal glucose, men with diabetes mellitus had significantly poorer performance on psychomotor speed, executive function and verbal learning (all P < 0.05). There was no difference in cognition by HIV serostatus. The largest effect was observed in individuals with uncontrolled diabetes mellitus throughout the study period, equivalent to 16.5 and 13.4 years of aging on psychomotor speed and executive function, respectively, the effect of which remained significant after adjusting for HIV-related risk factors. Lower CD4+ nadir was also associated with worse cognitive performance.

CONCLUSION

Abnormalities in glucose metabolism were more common among MLWH than men without HIV and were related to impaired cognitive performance. Metabolic status, along with advanced age and previous immunosuppression, may be important predictors of cognition in the modern antiretroviral therapy era.

Association of ApoE Genetic Polymorphism and Type 2 Diabetes with Cognition in Non-Demented Aging Chinese Adults: A Community Based Cross-Sectional Study

Apolipoprotein E (ApoE) gene polymorphism has been implicated in predisposition to diabetes and dementia in old population, but the results from the different studies were inconclusive. A cross-sectional study was carried out to explore the relationship among ApoE gene polymorphism, diabetes and cognition in non-demented aging Chinese adults. A total number of 1000 community dwellers aged 55 years and above were randomly recruited. Demographic information of the participants was collected using well designed self-administered questionnaires. The Montreal Cognitive Assessment (MoCA) test was employed to evaluate the cognitive status of the participants. Semi-quantitative food frequency questionnaire was used to obtain the dietary intake information. Fasting venous blood samples were taken for ApoE genotyping and serum lipid measurements. 238 participants were type 2 diabetes mellitus (T2DM) patients and 145 participants were ApoE4 carriers. ApoE 4-T2DM subjects had higher serum triglyceride (TG) concentration than E2 and E3 carriers (P < 0.05). T2DM subjects carrying ApoE4 had lower cognition than subjects with E2 or E3 carriers (P < 0.05). Comparing to non-type 2 diabetic mild cognitive impaired (nT2DM-MCI) subjects, the type 2 diabetic mild cognitive impaired (T2DM-MCI) subjects have higher serum glucose (Glu) level and lower high-density lipoprotein (HDL-C) level (P < 0.05). The T2DM-MCI subjects carrying ApoE4 have lower cognition than E2 and E3 carriers (P <0.05); and the interaction of ApoE genotype with T2DM was detected (P < 0.05). Our results indicated the association among ApoE gene polymorphism, T2DM and cognitive performance in non-demented aging population. The carrying of ApoE4 predisposed the T2DM subjects and the T2DM-MCI subjects to have poor cognitive performance. Additional experimental studies are required to explore the mechanism that ApoE genotype modifies the risk for cognitive impairment in aging subjects with T2DM.

Early Cognitive Deficits in Type 2 Diabetes: A Population-Based Study

Evidence links type 2 diabetes to dementia risk. However, our knowledge on the initial cognitive deficits in diabetic individuals and the factors that might promote such deficits is still limited. This study aimed to identify the cognitive domains initially impaired by diabetes and the factors that play a role in this first stage. Within the population-based Swedish National Study on Aging and Care–Kungsholmen, 2305 cognitively intact participants aged ≥60 y were identified. Attention/working memory, perceptual speed, category fluency, letter fluency, semantic memory, and episodic memory were assessed. Diabetes (controlled and uncontrolled) and prediabetes were ascertained by clinicians, who also collected information on vascular disorders (hypertension, heart diseases, and stroke) and vascular risk factors (VRFs, including smoking and overweight/obesity). Data were analyzed with linear regression models. Overall, 196 participants (8.5%) had diabetes, of which 144 (73.5%) had elevated glycaemia (uncontrolled diabetes); 571 (24.8%) persons had prediabetes. In addition, diabetes, mainly uncontrolled, was related to lower performance in perceptual speed (β – 1.10 [95% CI – 1.98, – 0.23]), category fluency (β – 1.27 [95% CI – 2.52, – 0.03]), and digit span forward (β – 0.35 [95% CI – 0.54, – 0.17]). Critically, these associations were present only among APOEɛ4 non–carriers. The associations of diabetes with perceptual speed and category fluency were present only among participants with VRFs or vascular disorders. Diabetes, especially uncontrolled diabetes, is associated with poorer performance in perceptual speed, category fluency, and attention/primary memory. VRFs, vascular disorders, and APOE status play a role in these associations.

Hypertension, diabetes and obesity are associated with lower cognitive performance in community-dwelling elderly: Data from the FIBRA study

Background

Systemic hypertension (SH), diabetes mellitus (DM) and abdominal obesity may negatively impact cognitive performance.

Objective

To evaluate the association between SH, DM and abdominal obesity and cognitive performance among cognitively unimpaired elderly.

Methods

A cross-sectional study of individuals aged 65+ from seven Brazilian cities was conducted. SH and DM diagnoses were self-reported and abdominal circumference was objectively measured. Individuals who scored below the education-adjusted cutoff scores on the Mini-Mental State Examination (MMSE) were excluded.

Results

Among 2,593 elderly, 321 (12.38%) had SH, DM and abdominal obesity concomitantly (Group I) and 421 (16.23%) had none of the three diseases (Group II). Group I had a higher proportion of individuals that were women, aged 70-74 years, illiterate and with lower income. Group I had a higher number of participants with low cognitive performance (28.04% vs. 17.58% in Group II). Variables associated with poor cognitive performance were: female gender (OR: 2.43, p < 0.001); and lower education (OR: 0.410, p < 0.001). The presence of the three diseases and age were not significant in the education-adjusted model.

Conclusion

There was an association between cognition and the presence of SH, DM and obesity. However, education seems to be decisive in determining cognitive performance in the presence of these three conditions.

Computerized cognitive training for older diabetic adults at risk of dementia: Study protocol for a randomized controlled trial

Introduction

Older adults with type 2 diabetes are at high risk of cognitive decline and dementia and form an important target group for dementia risk reduction studies. Despite evidence that computerized cognitive training (CCT) may benefit cognitive performance in cognitively healthy older adults and those with mild cognitive impairment, whether CCT may benefit cognitive performance or improve disease self-management in older diabetic adults has not been studied to date. In addition, whether adaptive difficulty levels and tailoring of interventions to individuals' cognitive profile are superior to generic training remains to be established.

Methods

Ninety community-dwelling older (age ≥ 65) diabetic adults are recruited and randomized into a tailored and adaptive computerized cognitive training condition or to a generic, nontailored, or adaptive CCT condition. Both groups complete an 8-week training program using the commercially available CogniFit program. The intervention is augmented by a range of behavior-change techniques, and participants in each condition are further randomized into a global or cognition-specific phone-based self-efficacy (SE) condition, or a no-SE condition. The primary outcome is global cognitive performance immediately after the intervention. Secondary outcomes include diabetes self-management, meta-memory, mood, and SE.

Discussion

This pilot study is the first trial evaluating the potential benefits of home-based tailored and adaptive CCT in relation to cognitive and disease self-management in older diabetic adults. Methodological strengths of this trial include the double-blind design, the clear identification of the proposed active ingredients of the intervention, and the use of evidence-based behavior-change techniques. Results from this study will indicate whether CCT has the potential to lower the risk of diabetes-related cognitive decline. The outcomes of the trial will also advance our understanding of essential intervention parameters required to improve or maintain cognitive function and enhance disease self-management in this at-risk group.

Cognitive effects of a 30-min aerobic exercise bout on adults with overweight/obesity and type 2 diabetes

BACKGROUND

Several studies document reliable brain health benefits of acute exercise bouts. However, no prior studies have explored such effects among those living with co-morbid overweight/obesity and type 2 diabetes (T2DM), both of which are conditions associated with cognitive performance decrements.

PURPOSE

To examine the impact of a 30-min bout of moderate-intensity aerobic exercise on executive function among adults with overweight/obesity and T2DM, employing a widely used experimental paradigm.

METHODS

Thirty adults with overweight/obesity and T2DM were randomly assigned to moderate (30% maximal heart rate reserve) and minimal (r.p.m. 30-50; work load 5) intensity aerobic exercise. Pre-exercise to post-exercise changes in Stroop interference and Go/No-Go scores were compared across conditions.

RESULTS

Primary analyses revealed no overall effect of exercise condition on changes in Stroop or Go/No-Go performance. Post-hoc moderation analyses indicated that Stroop interference scores were reduced, following moderate exercise among female participants and among those who were more physically active.

CONCLUSION

The current study revealed no reliable benefit of acute aerobic exercise for overweight and obese individuals living with T2DM overall. There may be limited benefits for women and more and active subgroups, but the precise nature of such benefits remains unclear.

Obese adolescents with type 2 diabetes perform worse than controls on cognitive and behavioral assessments

BACKGROUND

Children with type 1 diabetes demonstrate worse cognitive performance compared with their peers. Little is known regarding the cognitive and behavioral performance in obese adolescents with type 2 diabetes.

METHODS

Cross sectional evaluation of 20 obese adolescents with type 2 diabetes and 20 healthy adolescents was performed in Cincinnati, Ohio. Cognitive tests that included measures of processing speed, working memory, verbal and semantic fluency and parent reports of executive function and problem behavior were compared. Academic achievement and the relationship between cognitive/behavioral scores and diabetes duration and diabetes control (hemoglobin A1c) were assessed in the type 2 diabetes group only.

RESULTS

The type 2 diabetes group had mean duration of diabetes of 2.8 ± 2.2 yr and hemoglobin A1c of 7.9 ± 2.2%. Adolescents with type 2 diabetes scored lower than controls on tests of working and verbal memory and processing speed (all p < 0.05) and worse for Internalizing, Externalizing, and Total Problems behaviors on the Child Behavior Checklist (all p < 0.05). Adolescents with type 2 diabetes scored below the population mean in academic achievement, most notably calculation. Working memory and processing speed were negatively correlated with duration of diabetes (r = -0.50 and -0.47, respectively, p < 0.05).

CONCLUSIONS

Obese youth with type 2 diabetes score poorly compared with controls on multiple assessments of cognitive function and adaptive behavior. Further work is needed to determine if these effects are driven by obesity, diabetes or other demographic and socioeconomic risk factors.

Age and Semantic Inhibition Measured by the Hayling Task: A Meta-Analysis

Objective

Cognitive aging is commonly associated with a decrease in executive functioning (EF). A specific component of EF, semantic inhibition, is addressed in the present study, which presents a meta-analytic review of the literature that has evaluated the performance on the Hayling Sentence Completion test in young and older groups of individuals in order to assess the magnitude of the age effect.

Method

A systematic search involving Web of Science, PsyINFO, PsychARTICLE, and MedLine databases and Google Scholar was performed. A total of 11 studies were included in this meta-analysis, encompassing a total of 887 participants; 440 young and 447 older adults. The effect sizes for group differences on four measures of the Hayling test, latency responses and error scores on the Automatic and Inhibition sections of the test were calculated using the Comprehensive Meta-Analysis software package.

Results

The results revealed large age effects for response latencies in both the Automatic (Hedges' g = 0.81) and Inhibitory conditions (Hedges' g = 0.98), though the latter two effect sizes did not differ from each other. In contrast, analysis of errors revealed a significant difference between the small effect seen in the Automatic condition (Hedges' g = 0.13) relative to the moderate effect seen in the Inhibition condition (Hedges' g = 0.55).

Conclusions

These results may be important for a better understanding of the inhibitory functioning in elderly individuals, although they should be interpreted with caution because of the limited number of studies in the literature to date.

The role of insulin pump therapy for type 2 diabetes mellitus

Many patients with type 2 diabetes fail to achieve adequate glucose control despite escalation of treatment and combinations of multiple therapies including insulin. Patients with long-standing type 2 diabetes often suffer from the combination of severe insulin deficiency in addition to insulin resistance, thereby requiring high doses of insulin delivered in multiple injections to attain adequate glycemic control. Insulin-pump therapy was first introduced in the 1970s as an approach to mimic physiological insulin delivery and attain normal glucose in patients with type 1 diabetes. The recent years have seen an increase in the use of this technology for patients with type 2 diabetes. This article summarizes the clinical studies evaluating insulin pump use in patients with type 2 diabetes and discusses the benefits and shortcomings of pump therapy in this population. Copyright © 2016 John Wiley & Sons, Ltd.

Impaired Word and Face Recognition in Older Adults with Type 2 Diabetes

BACKGROUND AND AIMS

Older adults with type 2 diabetes mellitus (DM2) exhibit accelerated decline in some domains of cognition including verbal episodic memory. Few studies have investigated the influence of DM2 status in older adults on recognition memory for more complex stimuli such as faces. In the present study we sought to compare recognition memory performance for words, objects and faces under conditions of relatively low and high cognitive load.

METHODS

Healthy older adults with good glucoregulatory control (n = 13) and older adults with DM2 (n = 24) were administered recognition memory tasks in which stimuli (faces, objects and words) were presented under conditions of either i) low (stimulus presented without a background pattern) or ii) high (stimulus presented against a background pattern) cognitive load.

RESULTS

In a subsequent recognition phase, the DM2 group recognized fewer faces than healthy controls. Further, the DM2 group exhibited word recognition deficits in the low cognitive load condition.

CONCLUSIONS

The recognition memory impairment observed in patients with DM2 has clear implications for day-to-day functioning. Although these deficits were not amplified under conditions of increased cognitive load, the present study emphasizes that recognition memory impairment for both words and more complex stimuli such as face are a feature of DM2 in older adults.

The Utility of Brief Cognitive Tests for Patients With Type 2 Diabetes Mellitus: A Systematic Review

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with an increased risk for mild cognitive impairment and dementia in both middle-aged and older individuals. Brief cognitive tests can potentially serve as a reliable and cost effective approach to detect for cognitive decrements in clinical practice.

OBJECTIVE

This systematic review examined the utility of brief cognitive tests in studies with patients with T2DM.

METHOD

This systematic review was conducted according to guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. "PubMed," "PsychINFO," "ScienceDirect," and "ProQuest" electronic databases were searched to identify articles published from January 1, 2005 to December 31, 2015.

RESULTS

The search yielded 22 studies, with only 8 using brief tests as a cognitive screening tool, whereas the majority using these tests as a measure of global cognitive functions. In regard to cognitive screening studies, most had failed to fulfil the standard reporting of diagnostic test accuracy criteria such as Standards for Reporting of Diagnostic Accuracy for dementia and cognitive impairment. Moreover, few studies reported discriminant indices such as sensitivity, specificity, and positive and negative predictive values of brief cognitive tests in detecting cognitive impairment in patients with T2DM. Among studies which used brief cognitive tests as a measure of global cognitive function, patients with diabetes tended to perform worse than patients without diabetes. Processing speed appeared to be particularly impaired among patients with diabetes, therefore, measures of processing speed such as the Digit Symbol Substitution Test may add value to brief cognitive tests such as the Montreal Cognitive Assessment.

CONCLUSIONS

The Montreal Cognitive Assessment supplemented by the Digit Symbol Substitution Test indicate initial promise in screening for cognitive impairment in T2DM.

Acute Resveratrol Consumption Improves Neurovascular Coupling Capacity in Adults with Type 2 Diabetes Mellitus

Background: Poor cerebral perfusion may contribute to cognitive impairment in type 2 diabetes mellitus (T2DM). We conducted a randomized controlled trial to test the hypothesis that resveratrol can enhance cerebral vasodilator function and thereby alleviate the cognitive deficits in T2DM. We have already reported that acute resveratrol consumption improved cerebrovascular responsiveness (CVR) to hypercapnia. We now report the effects of resveratrol on neurovascular coupling capacity (CVR to cognitive stimuli), cognitive performance and correlations with plasma resveratrol concentrations. Methods: Thirty-six T2DM adults aged 40–80 years were randomized to consume single doses of resveratrol (0, 75, 150 and 300 mg) at weekly intervals. Transcranial Doppler ultrasound was used to monitor changes in blood flow velocity (BFV) during a cognitive test battery. The battery consisted of dual-tasking (finger tapping with both Trail Making task and Serial Subtraction 3 task) and a computerized multi-tasking test that required attending to four tasks simultaneously. CVR to cognitive tasks was calculated as the per cent increase in BFV from pre-test basal to peak mean blood flow velocity and also as the area under the curve for BFV. Results: Compared to placebo, 75 mg resveratrol significantly improved neurovascular coupling capacity, which correlated with plasma total resveratrol levels. Enhanced performance on the multi-tasking test battery was also evident following 75 mg and 300 mg of resveratrol. Conclusion: a single 75 mg dose of resveratrol was able to improve neurovascular coupling and cognitive performance in T2DM. Evaluation of benefits of chronic resveratrol supplementation is now warranted.

Predictors of Cognitive Decline in Older Adult Type 2 Diabetes from the Veterans Affairs Diabetes Trial

AIMS

Cognitive decline disproportionately affects older adult type 2 diabetes. We tested whether randomized intensive (INT) glucose-lowering reduces the rate(s) of cognitive decline in adults with advanced type 2 diabetes (mean: age, 60 years; diabetes duration, 11 years) from the Veterans Affairs Diabetes Trial.

METHODS

A battery of neuropsychological tests [digit span, digit symbol substitution (DSym), and Trails-making Test-Part B (TMT-B)] was administered at baseline in ~1700 participants and repeated at year 5. Thirty-seven risk factors were evaluated as predictors of cognitive decline in multivariable regression analyses.

RESULTS

The mean age-adjusted DSym or TMT-B declined significantly in all study participants (P < 0.001). Randomized INT glucose-lowering did not significantly alter the rate of cognitive decline. The final model of risk factors associated with 5-year decline in age-adjusted TMT-B included as significant predictors: longer baseline diabetes duration (beta = -0.028; P = 0.0057), lower baseline diastolic blood pressure (BP; beta = 0.028; P = 0.002), and baseline calcium channel blocker medication use (beta = -0.639; P < 0.001). Higher baseline pulse pressure was significantly associated with decline in age-adjusted TMT-B suggesting a role for both higher systolic and lower diastolic BPs. Baseline thiazide diuretic use (beta = -0.549; P = 0.015) was an additional significant predictor of 5-year decline in age-adjusted digit symbol score. Post-baseline systolic BP-lowering was significantly associated (P < 0.001) with decline in TMT-B performance. There was a significant inverse association between post-baseline plasma triglyceride-lowering (P = 0.045) and decline in digit symbol substitution task performance.

CONCLUSION

A 5-year period of randomized INT glucose-lowering did not significantly reduce the rate of cognitive decline in older-aged adults with type 2 diabetes. Systolic and diastolic BPs as well as plasma triglycerides appeared as modifiable risk factors of the rate of cognitive decline in older adult type 2 diabetes.

Factors associated with neurocognitive test performance at baseline: a substudy of the INSIGHT Strategic Timing of AntiRetroviral Treatment (START) trial

OBJECTIVES

We describe neuropsychological test performance (NP) in antiretroviral treatment (ART)-naïve HIV-positive individuals with CD4 cell counts above 500 cells/μL.

METHODS

In a neurology substudy of the International Network for Strategic Initiatives in Global HIV Trials (INSIGHT) Strategic Timing of AntiRetroviral Treatment (START) study, eight neurocognitive tests were administered. The primary measure of NP was the quantitative NP z-score (QNPZ-8), the average of the z-scores for the eight tests. Associations of baseline factors with QNPZ-8 scores were assessed by multiple regression. Mild neurocognitive impairment (NCI) was defined as z-scores < -1 in at least two of six cognitive domains.

RESULTS

A total of 608 participants had a median age of 34 years; 11% were women and 15% were black; the median time since HIV diagnosis was 0.9 years; the median CD4 cell count was 633 cells/μL; 19.9% had mild NCI. Better NP was independently associated with younger age, being white, higher body mass index (0.10 per 10 kg/m(2) higher), and higher haematocrit percentage (0.19 per 10% higher). Worse NP was associated with longer time since HIV diagnosis (-0.17 per 10 years), diabetes (-0.29) and higher Framingham risk score (-0.15 per 10 points higher). QNPZ-8 scores differed significantly between geographical locations, with the lowest scores in Brazil and Argentina/Chile.

CONCLUSIONS

This is the largest study of NP in ART-naïve HIV-positive adults with CD4 counts > 500 cells/μL. Demographic factors and diabetes were most strongly associated with NP. Unmeasured educational/sociocultural factors may explain geographical differences. Poorer NP was independently associated with longer time since HIV diagnosis, suggesting that untreated HIV infection might deleteriously affect NP, but the effect was small.

Alzheimer's Genetic Risk Intensifies Neurocognitive Slowing Associated with Diabetes in Non-Demented Older Adults

Introduction

We examine interactive and intensification effects of type 2 diabetes (T2D) with APOE and an Alzheimer's disease genetic risk score (GRS) on neurocognitive speed performance and change in nondemented older adults.

Methods

In an accelerated longitudinal design, we used latent growth modeling to test moderators of level and change in a neurocognitive speed latent variable for 628 adults (baseline median age = 69.0) followed over 9 years. The GRS was compiled using the cumulative risk of APOE, CLU, CR1, and PICALM.

Results

First, T2D predicted slower speed performance at centering age (75). Second, no predictive effects were associated with APOE or GRS. Third, a significant interaction showed that high risk from both T2D and GRS was selectively associated with steeper longitudinal slowing than all comparison cross-domain risk groups.

Discussion

Higher AD-related genetic risk intensified deleterious effects of diabetes on neurocognitive slowing in nondemented aging beyond the independent influence of APOE.

Executive Function in Adults With Type 2 Diabetes: A Meta-Analytic Review

OBJECTIVE

To examine the extent to which Type 2 diabetes mellitus (T2DM) is associated with impairments in executive function (EF).

METHODS

Medline, PsychoInfo, and Scopus databases and published references were used to identify articles examining the association between T2DM status (case versus control) and EF decrements. Results from studies were converted to standardized mean differences and compared using random-effects models. Moderator analysis was conducted for age, sex, and diabetes duration using maximum likelihood estimation.

RESULTS

Sixty studies (59 articles) including 9815 individuals with T2DM and 69,254 controls were included. Findings indicated a small but reliable association between T2DM status and EF decrements (d = -0.248, p < .001), observed across all aspects of EF examined: verbal fluency, mental flexibility, inhibition, working memory, and attention. Disease duration significantly moderated the effect of T2DM status on EF.

CONCLUSIONS

T2DM is associated with a mild-to-moderate EF decrements. Such decrements are stronger among those with shorter disease duration.

Correlation between cognitive impairment and depressive mood of Thai elderly with type 2 diabetes in a primary care setting

OBJECTIVE

The objective of this study was to evaluate the relationship between cognitive impairment and depressive mood in Thai elderly with type 2 diabetes at primary care centres.

MATERIALS AND METHODS

Two-hundred and eighty three (283) older people with type 2 diabetes were enrolled in this study. Mini-Cog and mini-mental state examination (MMSE) Thai 2002 were used to measure cognitive impairment while Thai geriatric screening test (TGDS) was used to measure depressive mood in all participants. Spearmen correlation was applied to determine the relationship between cognitive function and depressive mood.

RESULTS

There was a positive relationship between cognitive impairment and depressive mood in older people with type 2 diabetes. The scores from Mini-Cog and MMSE Thai 2002 were negatively correlated with TGDS scores while adjusting for the effects of age and years of education with rs = -0.1, p = 0.06 and rs = -0.2, p<0.01, respectively. Although it showed an inverse relationship of the scores between cognitive and depressive mood screening tests, the results between the tests were positive when interpreting the test scores. It means that the higher score in Mini-Cog and MMSE Thai 2002 (non-cognitive impairment) were associated with the lower score in TGDS (non-depressed mood).

CONCLUSION

The finding of this study showed that older people with type 2 diabetes who had cognitive impairment seemed to have depressive mood. Hence, these two co-morbidities should be considered in order to give an optimal care to older people with diabetes.

Cognitive functioning among patients with diabetic foot

AIMS

Using diabetic foot (DF) as an indicator of severe diabetes, we aimed to investigate the cognitive profile of DF patients and the relations between cognitive functioning and both diabetes complications and comorbidities.

METHODS

Dementia-free patients with DF aged 30-90 (n=153) were assessed through medical records and a cognitive battery. Information on diabetes complications and comorbidities was collected via interview; glycated hemoglobin (HbA1c) was tested. Data were analyzed using robust logistic or quantile regression adjusted for potential confounders.

RESULTS

The mean Mini-Mental Examination (MMSE) score of patients was 24.6 (SD=3.6), and 40% had global cognitive dysfunction (MMSE ≤24). Among elderly patients (aged ≥65), MMSE impairment was related to amputation (OR 3.59, 95% CI 1.07-12.11). Episodic memory impairment was associated with foot amputation (OR 4.13, 95% CI 1.11-15.28) and microvascular complications (OR 9.68, 95% CI 1.67-56.06). Further, elderly patients with HbA1c <7% had increased odds of psychomotor slowness (OR 7.75, 95% CI 1.55-38.73) and abstract reasoning impairment (OR 4.49, 95% CI: 1.15-17.46). However, such significant associations were not shown in adult patients aged <65.

CONCLUSION

Amputation, microvascular diseases and glycemic control were associated with impaired global cognitive function and its domains among patients aged ≥65.

Development of the Thai version of Mini-Cog, a brief cognitive screening test

AIMS

Cognitive impairment, such as dementia, has emerged as the leading public health problem among the elderly. Therefore, early detection of the disorder and providing appropriate healthcare and management is important, particularly, for the patients with comorbid diabetes who require long-term treatment strategies. In Thailand, because of a large number of elderly patients with diabetes, and time constraints in primary care settings, a short and effective cognitive screening test is required. The Mini-Cog is a short and valid cognitive screening test that was specifically designed for use in primary care settings. The present study translated the English language version into a Thai language version, and then measured the interrater reliability and concurrent validity.

METHODS

The processes of cross-language translation were carried out to develop a Thai language version of the Mini-Cog. A total of 21 Thai older adults with type 2 diabetes with a mean aged of 69 ± 7 years were recruited into a study investigating the interrater reliability and concurrent validity of the Mini-Cog Thai version in one primary care center in Thailand.

RESULTS

The Mini-Cog Thai version showed a good interrater reliability (K = 0.80, P < 0.001, 95% CI 0.50-1.00) and a positive concurrent validity (r = 0.47, P = 0.007, 95% CI 0.37,0.55) with the Mini-Mental State Examination Thai 2002.

CONCLUSIONS

The findings show that the Thai version of the Mini-Cog is a reliable, performance-based tool in the screening for cognitive function in primary care settings in Thailand. It is recommended that it could be used as a new cognitive screening test for the aging population in the Thai community.

A systematic review of type 2 diabetes mellitus and hypertension in imaging studies of cognitive aging: time to establish new norms

The rising prevalence of type 2 diabetes (T2DM) and hypertension in older adults, and the deleterious effect of these conditions on cerebrovascular and brain health, is creating a growing discrepancy between the "typical" cognitive aging trajectory and a "healthy" cognitive aging trajectory. These changing health demographics make T2DM and hypertension important topics of study in their own right, and warrant attention from the perspective of cognitive aging neuroimaging research. Specifically, interpretation of individual or group differences in blood oxygenation level dependent magnetic resonance imaging (BOLD MRI) or positron emission tomography (PET H2O(15)) signals as reflective of differences in neural activation underlying a cognitive operation of interest requires assumptions of intact vascular health amongst the study participants. Without adequate screening, inclusion of individuals with T2DM or hypertension in "healthy" samples may introduce unwanted variability and bias to brain and/or cognitive measures, and increase potential for error. We conducted a systematic review of the cognitive aging neuroimaging literature to document the extent to which researchers account for these conditions. Of the 232 studies selected for review, few explicitly excluded individuals with T2DM (9%) or hypertension (13%). A large portion had exclusion criteria that made it difficult to determine whether T2DM or hypertension were excluded (44 and 37%), and many did not mention any selection criteria related to T2DM or hypertension (34 and 22%). Of all the surveyed studies, only 29% acknowledged or addressed the potential influence of intersubject vascular variability on the measured BOLD or PET signals. To reinforce the notion that individuals with T2DM and hypertension should not be overlooked as a potential source of bias, we also provide an overview of metabolic and vascular changes associated with T2DM and hypertension, as they relate to cerebrovascular and brain health.

Autonomy of patients with type 2 diabetes with an insulin pump device: is it predictable?

BACKGROUND

Insulin pump therapy may be offered to patients with type 2 diabetes that is not controlled by multiple daily injections. Patients with type 2 diabetes may suffer from unrecognized cognitive disabilities, which may compromise the use of a pump device.

METHODS

To predict patient autonomy, we evaluated 39 patients with type 2 diabetes from our database (n = 143) after continuous subcutaneous insulin infusion (CSII) initiation using (1) an autonomy questionnaire evaluating the patient's cognitive and operative capacities for CSII utilization, (2) the Montreal Cognitive Assessment (MOCA) for the detection of mild cognitive disabilities, (3) the Hospital Anxiety and Depression Scale (HADS) for the detection of anxiety and depression, and (4) the Diabetes Treatment Satisfaction Questionnaire (DTSQ). Patients were selected to constitute 3 groups matched for age, with different degrees of autonomy at discharge after the initial training program: complete (n = 13), partial (n = 13), or no autonomy (n = 13).

RESULTS

The satisfaction level with the pump device was high. At the last follow-up visit, only 23% of patients did not reach complete autonomy. The autonomy score correlated fairly with the MOCA score (R = 0.771, P < .001). A receiver operating characteristic (ROC) analysis showed that at a cut-off score of 24, the MOCA identified autonomous versus dependent patients at long-term follow-up (area under the ROC curve [AUC], 0.893; sensitivity, 81%; specificity, 81%). The HADS correlated negatively with the autonomy score, and the sociocultural level also influenced autonomy with pump utilization.

CONCLUSION

Patients with type 2 diabetes with partial autonomy at discharge may progress to complete autonomy. The MOCA and HADS may help predict a patient's ability to manage with a pump device.

Functional Living in Older Adults With Type 2 Diabetes: Executive Functioning, Dual Task Performance, and the Impact on Postural Stability and Motor Control

OBJECTIVE

Older adults with type 2 diabetes mellitus (DM2) experience accelerated age-related decline in some domains of cognition. The present study sought to investigate executive functioning and dual tasking capacities in this group.

METHOD

Older adults with DM2 and age-matched controls completed self-report measures assessing everyday activities, a comprehensive cognitive battery and more specific tasks assessing executive functioning, dual tasking, postural stability, and motor control.

RESULTS

Executive abilities were particularly compromised in the participants with DM2. Furthermore, the DM2 group exhibited reduced postural stability under dual task conditions.

DISCUSSION

These findings suggest that deficits in more complex cognitive activities underlie the decline in everyday function in DM2.

IDE (rs6583817) polymorphism and pulse pressure are independently and interactively associated with level and change in executive function in older adults

OBJECTIVE

We report a gene × environment (health) study focusing on concurrent performance and longitudinal change in a latent-variable executive function (EF) phenotype. Specifically, we tested the independent and interactive effects of a recently identified insulin degrading enzyme genetic polymorphism (IDE rs6583817) and pulse pressure (PP; one prominent aging-related vascular health indicator) across up to 9 years of EF data in a sample of older adults from the Victoria Longitudinal Study. Both factors vary across a continuum of risk-elevating to risk-reducing and have been recently linked to normal and impaired cognitive aging.

METHOD

We assembled a genotyped and typically aging group of older adults (n = 599, M age = 66 years at baseline), following them for up to 3 longitudinal waves (M interval = 4.4 years). We used confirmatory factor analyses, latent growth modeling, and path analyses to pursue 3 main research goals.

RESULTS

First, the EF single factor model was confirmed comprising 4 executive function tasks and it demonstrated measurement invariance across the waves. Second, older adults with the major IDE G allele exhibited better EF outcomes than homozygotes for the minor A allele at the centering age of 75 years. Adults with higher PP performed more poorly on EF tasks at age 75 years and exhibited greater EF longitudinal decline. Third, gene × health interaction analyses showed that worsening vascular health (higher PP) differentially affected EF performance in older adults with the IDE G allele.

CONCLUSION

Genetic interaction analyses can reveal differential and magnifying effects on cognitive phenotypes in aging. In the present case, pulse pressure is confirmed as a risk factor for concurrent and changing cognitive health in aging, but the effects operate differently across the risk and protective allelic distribution of this IDE gene.

Characteristics of neuropsychological functions in inpatients with poorly-controlled type 2 diabetes mellitus

Aims/Introduction:  It has been suggested that type 2 diabetes is associated with cognitive impairment. We investigated the neuropsychological profile of inpatients with poorly controlled type 2 diabetes and assessed the effects of clinical factors on neuropsychological functions.

MATERIALS AND METHODS

  Forty-two patients with type 2 diabetes and 32 non diabetic control subjects were matched for age, sex ratio, and level of education. Attention & working memory, processing speed, verbal memory, visuospatial memory, visuoconstruction, and executive function were tested. Information about physical function, alcohol use, hypertension, dyslipidemia, and myocardial infarction was retrieved from personal interviews and medical records.

RESULTS

  Diabetic patients demonstrated mild cognitive deterioration in attention & working memory, processing speed, verbal memory, and executive function. In particular, neuropsychological decline became prominent when tasks related with speed and verbal stimuli became unstructured and complex. Age was significantly associated with the majority of neuropsychological tests, whereas tasks dealing with working memory and executive function were associated with age only in the diabetic group. Duration of diabetes was associated with Backward Digit Span.

CONCLUSIONS

  Accelerated aging had a major influence on cognitive decline in the diabetic group, whereas diminished performance in working memory and executive function might have been more related to diabetes-related cognitive impairment. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00170.x, 2011).

Diabetes, markers of brain pathology and cognitive function: the Age, Gene/Environment Susceptibility-Reykjavik Study

OBJECTIVE

We investigated whether, and the extent to which, vascular and degenerative lesions in the brain mediate the association of diabetes with poor cognitive performance.

METHODS

This cross-sectional study included 4,206 participants (age > 65 years; 57.8% women) of the Age, Gene/Environment Susceptibility-Reykjavik Study. Data were collected through interview, clinical examination, psychological testing, and laboratory tests. The composite scores on memory, information-processing speed, and executive function were derived from a cognitive test battery. Markers of cerebral macrovascular (cortical infarcts), microvascular (subcortical infarcts, cerebral microbleeds, and higher white matter lesion volume), and neurodegenerative (lower gray matter, normal white matter, and total brain tissue volumes) processes were assessed on magnetic resonance images. Mediation models were employed to test the mediating effect of brain lesions on the association of diabetes with cognitive performance controlling for potential confounders.

RESULTS

There were 462 (11.0%) persons with diabetes. Diabetes was significantly associated with lower scores on processing speed and executive function, but not with memory function. Diabetes was significantly associated with all markers of brain pathology. All of these markers were significantly associated with lower scores on memory, processing speed, and executive function. Formal mediation tests suggested that markers of cerebrovascular and degenerative pathology significantly mediated the associations of diabetes with processing speed and executive function.

INTERPRETATION

Diabetes is associated with poor performance on cognitive tests of information-processing speed and executive function. The association is largely mediated by markers of both neurodegeneration and cerebrovascular disease. Older people with diabetes should be monitored for cognitive problems and brain lesions.

Adults with diabetic peripheral neuropathy exhibit impairments in multitasking and other executive functions

BACKGROUND AND PURPOSE

Diabetic peripheral neuropathy (DPN) contributes to functional impairment, and there is growing evidence that neuropsychological factors also influence physical function. We compared cognitive and executive function in adults with DPN with an age-matched comparison group, and examined the relationships between DPN, executive function, and physical function.

METHODS

Twenty subjects with DPN and 20 comparison subjects were assessed. Diabetic peripheral neuropathy was quantified via the Michigan Neuropathy Screening Instrument and nerve conduction velocity testing. Subjects were administered Beck's Depression Inventory, the Mini-Mental Status Examination, and the Timed Up and Go (TUG) test. Each participant also completed a battery of 7 executive function tasks, including the Cognitive Timed Up and Go (cTUG) test, in which a concurrent mental subtraction task was added to the standard TUG test.

RESULTS

The DPN group demonstrated poorer letter fluency (34.2 ± 11.6 words vs 46.2 ± 12.2 words; P = 0.001), category fluency (47.0 ± 8.1 words vs 56.3 ± 8.5 words; P = 0.003), and Rey-Osterrieth scores (25.9 ± 4.3 points vs 31.7 ± 2.4 points; P < 0.001), and took longer to complete both the TUG (10.3 ± 2.8 seconds vs 5.9 ± 1.0 seconds; P < 0.001) and cTUG (13.0 ± 5.8 seconds vs 6.9 ± 1.6 seconds; P < 0.001). Poorer global cognitive performance and greater depression symptoms were significantly related to each other (r = -0.46; P = 0.04) and to slower TUG times (r = -0.53; P = 0.02; and r = 0.54; P = 0.02, respectively).

DISCUSSION AND CONCLUSIONS

Verbal, visuospatial, and multitasking measures of executive function may be impaired in adults with DPN. Future research should examine how these and other cognitive and psychological factors, such as depression, affect physical function in this population.

Assessing premorbid cognitive ability in adults with type 2 diabetes mellitus--a review with implications for future intervention studies

Associations between type 2 diabetes mellitus (T2DM) and accelerated cognitive decline are well established. However, the sensitivity of neuropsychological tests to detect early deficits in cognitively normal adults with T2DM is unknown. This review examined cognitive domains and specific neuropsychological tests that are impaired in T2DM, based on clinically significant differences (effect sizes >0.5) between T2DM and groups without T2DM. Nine cross-sectional studies were identified which reported means and standard deviations for individual tests. Tests of executive function, working memory and psychomotor and attentional functions were found to be impaired in T2DM. Impairments of executive function and choice reaction time may have consequences for everyday functioning, in particular the risk of falls in older adults. More research on cognitive deficits in dual-task situations and how they impact everyday functioning is needed; the Trail Making Task, Symbol Digit Modalities Test, Verbal Fluency Task and tests of reaction time and processing speed could be included as core components of test batteries in future intervention studies. They could also be assessed in newly diagnosed T2DM and used to monitor progressive deterioration of cognitive function and the efficacy of therapeutic interventions on cognitive function.

IDE (rs6583817) polymorphism and type 2 diabetes differentially modify executive function in older adults

We tested independent and interactive contributions of a recently noted and promising insulin degrading enzyme polymorphism (IDE; rs6583817) and type 2 diabetes (T2D) to executive function performance, concurrently and longitudinally. Regarding normal neurocognitive decline and Alzheimer's disease, T2D is a known risk factor and this IDE variant might contribute risk or risk reduction via the minor (A) or major (G) allele. We compared normal aging and T2D groups (baseline n = 574; ages 53-95 years) over 2 longitudinal waves (mean interval = 4.4 years). We used confirmatory factor analysis, latent growth curve modeling, and path analysis. A confirmed single-factor model of 4 executive function tasks established the cognitive phenotype. This IDE variant predicted concurrent group differences and differential change in cognitive performance. Furthermore, the IDE major allele reduced risk of cognitive decline. T2D predicted performance only concurrently. Both IDE and T2D are associated with executive function levels in older adults, but only IDE moderated 2-wave change. Previously linked to Alzheimer's disease, this IDE variant should be further explored for its potential influence on cognitive phenotypes of normal aging.

Continuous glucose monitoring and cognitive performance in type 2 diabetes

BACKGROUND

Type 2 diabetes is associated with reductions in cognitive function that are associated with glycated hemoglobin (HbA1c) levels, but there is no information on whether cognition is related to postmeal glucose spikes. We explored the relationship of cognition to glucose levels measured by a continuous glucose monitoring system (CGMS) both before and after a weight loss diet.

SUBJECTS AND METHODS

Forty-four white subjects with type 2 diabetes (59.0 ± 6.2 years old; body mass index, 32.8 ± 4.2 kg/m(2); HbA1c, 6.9 ± 1.0%) completed an 8-week energy-restricted (approximately 6-7 MJ, 30% deficit) diet. Cognitive functioning (short-term memory, working memory, speed of processing [inspection time], psychomotor speed, and executive function) was assessed during four practice sessions, baseline, and Week 8. Parallel glucose levels were attained using the CGMS in 27 subjects. Outcomes were assessed by fasting blood glucose (FBG), postprandial peak glucose (G(max)), time spent >12 mmol/L (T > 12), and 24-h area under the glucose curve (AUC(24)).

RESULTS

Despite a fall in FBG of 0.65 mmol/L after 8 weeks, digits backward results correlated with FBG at both Week 0 and Week 8 (r = -0.43, P < 0.01 and r = -0.32, P < 0.01, respectively). Digits forward results correlated with FBG (r = -0.39, P < 0.01), G(max) (r = -0.46, P < 0.05), and AUC(24) (r = -0.50, P < 0.01) at Week 0 and FBG (r = -0.59, P < 0.001), G(max) (r = 0.37, P = 0.01), AUC(24) (r = -0.41, P < 0.01), and percentage weight loss (r = 0.31, P < 0.01) at Week 8. Cognitive function was not altered by weight loss, gender, baseline lipid levels, or premorbid intelligence levels (National Adult Reading Test).

CONCLUSIONS

FBG, G(max,) and AUC(24) were related to cognitive function and an energy-restricted diet for 8 weeks did not alter this relationship.