A meta-analysis of cognitive functioning in nondemented adults with type 2 diabetes mellitus

Hyperglycemia and cognitive impairments anticipate the onset of an overt type 2 diabetes-like phenotype in TALLYHO/JngJ mice

Type 2 Diabetes mellitus (T2DM) is a metabolic disorder characterized by chronic hyperglycemia, resulting from deficits in insulin secretion, insulin action, or both. Whilst the role of insulin in the peripheral nervous system has been ascertained in countless studies, its role in the central nervous system (CNS) is emerging only recently. Brain insulin has been lately associated with brain disorders like Alzheimer's disease, obsessive compulsive disorder, and attention deficit hyperactivity disorder. Thus, understanding the role of insulin as a common risk factor for mental and somatic comorbidities may disclose novel preventative and therapeutic approaches. We evaluated general metabolism (glucose tolerance, insulin sensitivity, energy expenditure, lipid metabolism, and polydipsia) and cognitive capabilities (attention, cognitive flexibility, and memory), in adolescent, young adult, and adult male and female TALLYHO/JngJ mice (TH, previously reported to constitute a valid experimental model of T2DM due to impaired insulin signaling). Adult TH mice have also been studied for alterations in gut microbiota diversity and composition. While TH mice exhibited profound deficits in cognitive flexibility and altered glucose metabolism, we observed that these alterations emerged either much earlier (males) or independent of (females) a comprehensive constellation of symptoms, isomorphic to an overt T2DM-like phenotype (insulin resistance, polydipsia, higher energy expenditure, and altered lipid metabolism). We also observed significant sex-dependent alterations in gut microbiota alpha diversity and taxonomy in adult TH mice. Deficits in insulin signaling may represent a common risk factor for both T2DM and CNS-related deficits, which may stem from (partly) independent mechanisms.

Prediction model for mild cognitive impairment in patients with type 2 diabetes using the autonomic function test

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is a risk factor for cognitive impairment, and reduced heart rate variability (HRV) has been correlated with cognitive impairment in elderly individuals. This study investigated risk factors and validated a predictive model for mild cognitive impairment (MCI) in patients with T2DM using an autonomic function test.

METHODS

Patients with T2DM, 50-85 years of age, who attended the diabetes clinic at Gyeongsang National University Hospital between March 2018 and December 2019, were included. A total of 201 patients had been screened; we enrolled 124 patients according to the inclusion and exclusion criteria in this study. Cognitive function was assessed using the Montreal Cognitive Assessment-Korean version (MOCA-K); MCI was defined as a total MOCA-K score ≤ 23. Risk factors for MCI in patients with T2DM, including demographic- and diabetes-related factors, and autonomic function test results, were analyzed. Based on multivariate logistic regression, a nomogram was developed as a prediction model for MCI.

RESULTS

Thirty-nine of 124 patients were diagnosed with MCI. Age, education, and decreased cardiovagal function were associated with a high risk for MCI, with cardiovagal function exerting the greatest influence. However, diabetes-related factors, such as glycemic control, duration of diabetes, or medications, were not associated with the risk for MCI. The nomogram demonstrated excellent discrimination (area under the curve, 0.832) and was well calibrated.

CONCLUSION

Approximately one-third of patients had MCI; as such, carefully evaluating cognitive function in elderly T2DM patients with reduced HRV is important to prevent progression to dementia.

Health literacy and cognitive function in people with diabetic foot ulcer with focus on knowledge, attitude, and practice in relation to foot self-care

Introduction

Preventative foot self-care is vital for avoiding diabetic foot ulcer episodes and lowering the risk of amputations. Yet, it demands high levels of health literacy and cognitive function.

Objective

To investigate health literacy and cognitive function in persons presenting with a diabetic foot ulcer.

Methods

Participants with type 2 diabetes were recruited from the tertiary foot clinic at Steno Diabetes Center North Denmark. The European Health Literacy Survey Questionnaire and Addenbrooke's Cognitive Examination were applied. A semi-structured interview guide was developed to evaluate foot self-care knowledge, attitude, and practice. The qualitative data were analyzed with a deductive approach based on a qualitative thematic analysis model. Subsequently, an integrated analysis of the quantitative and qualitative results was conducted.

Results

The participants (n = 12) had a mean age of 62.6 ± 8.4 years, and 11 were males. The mean diabetes duration was 15.9 ± 8.9 years. Eight participants had a recurrent diabetic foot ulcer. The health literacy level was sufficient in nine participants, and cognitive function was normal in five participants. Three different profiles related to foot self-care (proactive, active, or passive, respectively) were constructed by the final integrated analysis: a proactive profile refers to taking preventative action in concordance with knowledge and attitude, an active profile to taking action in response to a situation, but challenged by conflicting levels of knowledge and attitude, and a passive profile to not taking action.

Conclusion

The study suggests that people presenting with a diabetic foot ulcer have different foot self-care profiles based on person-specific health literacy, cognitive function, and knowledge, attitude, and practice element characteristics, highlighting the need for individualized education and intervention strategy instead of a one-size-fits-all approach.

Association between pre-diabetes or diabetes and cognitive impairment in a community-dwelling older population: Bushehr Elderly Health (BEH) program

Background

Persistent uncontrolled hyperglycemia is recognized as one of the risk factors for cognitive disorders. Accordingly, both type 1 and type 2 diabetes may predispose individuals to cognitive impairment, particularly in cases where glycemic control is insufficient. The objective of this comprehensive study is to separately assess cognitive dysfunctions in diabetic and non-diabetic older adults.

Methods

This cross-sectional study is part of phase 2 of the Bushehr elderly health program (BEHP). Cognitive function was evaluated using the Mini-cog and categorical verbal fluency tests (CFTs). Patients were classified as non-diabetics, pre-diabetics, or diabetics based on the diagnostic criteria for diabetes mellitus (DM). To compare the means of the two groups, we utilized the t-test or the Mann-Whitney test. Additionally Multivariable logistic regression models were used to determine the association between pre-diabetes or DM and cognitive impairment.

Results

Out of 1533 participants, 693 (45.2%) were identified as having cognitive impairment. The average hemoglobin A1C was higher in participants with cognitive impairment compared to those without cognitive impairment. (5.8 ± 1.6% vs. 5.5 ± 1.4%, P = 0.004). Furthermore, the mean blood glucose levels were found to be more elevated in cases of cognitive impairment (108.0 ± 47.4 mg/dL vs. 102.1 ± 0.35 mg/dL, P = 0.002). After adjusting for age, gender, body mass index (BMI), waist circumference, amount of physical activity, and smoking, the multivariable logistic regression model, declared an association between diabetes and cognitive impairment (OR = 1.48, P = 0.003). In addition, older patients, females, widows, and individuals with elevated LDL-Cs and those with high blood pressure were found to be more vulnerable to cognitive impairment.

Conclusion

The Bushehr Elderly Health Program (BEHP) study revealed that individuals affected with cognitive impairment may exhibit higher levels of HbA1c. This suggests a positive correlation between elevated HbA1c and cognitive impairment.

Upregulation of Nrf2 signaling: A key molecular mechanism of Baicalin's neuroprotective action against diabetes-induced cognitive impairment

BACKGROUND AND AIM

Diabetes-associated cognitive impairment (DCI) is a prevalent complication of diabetes. However, there is a lack of viable strategies for preventing and treating DCI. This study aims to explore the efficacy of baicalin (Bai) in attenuating DCI and elucidating the underlying mechanisms.

EXPERIMENTAL PROCEDURE

GK rats fed a high-fat and high-glucose diet were utilized to investigate the therapeutic potential of Bai. Cognitive function was assessed using the Morris water maze and novel object recognition tests. To gain insight into the molecular mechanisms underlying Bai's neuro-protective effects, co-cultured BV2/HT22 cells were established under high-glucose (HG) stimulation. The modes of action of Bai were subsequently confirmed in vivo using the DCI model in db/db mice.

KEY RESULTS

Bai restored cognitive and spatial memory and attenuated neuron loss, along with reducing expressions of Aβ and phosphorylated Tau protein in diabetic GK rats. At the cellular level, Bai exhibited potent antioxidant and anti-inflammatory effects against HG stimulation. These effects were associated with the upregulation of Nrf2 and supressed Keap1 levels. Consistent with these in vitro findings, similar mechanisms were observed in db/db mice. The significant neuroprotective effects of Bai were abolished when co-administered with ATRA, a Nrf2 blocker, in db/db mice, confirming that KEAP1-Nrf2 signaling pathway was responsible for the observed effect.

CONCLUSIONS AND IMPLICATIONS

Bai demonstrates a great therapeutic potential for attenuating DCI. The antioxidant defense and anti-inflammatory actions of Bai were mediated through the KEAP1-Nrf2 axis. These findings advance our understanding of potential treatment approaches for DCI, a common complication associated with diabetes.

The Effects of Type 2 Diabetes on Cognitive Performance: A Review of Reviews

BACKGROUND

Multiple systematic reviews have found that type 2 diabetes is associated with cognitive decrements. However, these reviews are heterogeneous in terms of methodology, quality and results, making it difficult for researchers and clinicians to build an informed overall picture. We therefore conducted a review of systematic reviews on the association between type 2 diabetes and cognitive decrements in relation to healthy controls.

METHODS

Following a pre-registered research protocol, we searched four major databases. Nine systematic reviews met our inclusion criteria: seven were meta-analyses and two were narrative syntheses. We assessed the risk of bias in each review and reported all effect sizes and confidence intervals obtained.

RESULTS

Type 2 diabetes was associated with cognitive decrements in all reviews, with small or negligible effect sizes obtained in the largest meta-analyses. The most studied cognitive domains were attention, executive functions, memory, processing speed and working memory. All reviews had methodological issues and were rated as having a high or an unclear risk of bias.

CONCLUSIONS

Type 2 diabetes appears to be associated with lower cognitive performance in several cognitive domains and in different age groups. However, high-quality meta-analyses on the subject are still needed. Future reviews must follow the PRISMA guidelines and take into account the risk of bias of the original studies through sensitivity analyses and the heterogeneity of the studies by conducting subgroup analyses for example according to age group and disease duration. The meta-analyses that aim to study the entire type 2 diabetes population without excluding severe comorbidities, should assess concept formation and reasoning, construction and motor performance, perception, and verbal functions and language skills in addition to the cognitive domains that have been most frequently analysed in the reviews conducted so far.

The Effectiveness of Cognitive-Focused Interventions for Adults With Diabetes: A Systematic Review

BACKGROUND

Adults with diabetes and impaired memory and executive functions are more likely to experience difficulties in diabetes self-management and achieving glycemic targets. The purpose of this systematic review was to evaluate the evidence of the effects of cognitive-focused interventions on cognitive ability, diabetes self-management, and management of glycemic levels for middle-aged adults and older adults with diabetes.

METHODS

A systematic review of randomized controlled/clinical trials published in English between 2012 and 2022 was conducted. A search was performed using 5 databases (PubMed, CINAHL, Embase, Web of Science, and Scopus) in addition to hand-searching. The search terms included diabetes, adults, cognitive-focused intervention, cognition, self-management, and hemoglobin A1C (HbA1C).

RESULTS

Eleven studies met the inclusion criteria. Cognitive ability and diabetes self-management were assessed using different measurements, and glycemic levels were measured with HbA1C. Nine studies applied cognitive training, one provided working memory training, and one used occupational therapy. Eight studies combined cognitive training with a co-intervention, including self-efficacy, lifestyle management, physical training, chronic disease self-management program, square-stepping exercise, psychoeducational intervention, and empowerment. Eight studies showed statistically significant improvements in at least one cognitive domain.

CONCLUSIONS

Cognitive-focused interventions have a positive effect on improving memory and executive function. However, the evidence of cognitive-focused interventions on diabetes self-management and glycemic levels has not been established. Future studies to improve cognition using effective strategies to improve cognitive function enhancing diabetes self-management behaviors and managing glycemic levels are warranted.

Diabetes, antidiabetic medications and risk of dementia: A systematic umbrella review and meta-analysis

AIMS

The objective of this umbrella review and meta-analysis was to evaluate the effect of diabetes on risk of dementia, as well as the mitigating effect of antidiabetic treatments.

MATERIALS AND METHODS

We conducted a systematic umbrella review on diabetes and its treatment, and a meta-analysis focusing on treatment. We searched MEDLINE/PubMed, Embase, PsycINFO, CINAHL and the Cochrane Library for systematic reviews and meta-analyses assessing the risk of cognitive decline/dementia in individuals with diabetes until 2 July 2023. We conducted random-effects meta-analyses to obtain risk ratios and 95% confidence intervals estimating the association of metformin, thiazolidinediones, pioglitazone, dipeptidyl peptidase-4 inhibitors, α-glucosidase inhibitors, meglitinides, insulin, sulphonylureas, glucagon-like peptide-1 receptor agonists (GLP1RAs) and sodium-glucose cotransporter-2 inhibitors (SGLT2is) with risk of dementia from cohort/case-control studies. The subgroups analysed included country and world region. Risk of bias was assessed with the AMSTAR tool and Newcastle-Ottawa Scale.

RESULTS

We included 100 reviews and 27 cohort/case-control studies (N = 3 046 661). Metformin, thiazolidinediones, pioglitazone, GLP1RAs and SGLT2is were associated with significant reduction in risk of dementia. When studies examining metformin were divided by country, the only significant effect was for the United States. Moreover, the effect of metformin was significant in Western but not Eastern populations. No significant effect was observed for dipeptidyl peptidase-4 inhibitors, α-glucosidase inhibitors, or insulin, while meglitinides and sulphonylureas were associated with increased risk.

CONCLUSIONS

Metformin, thiazolidinediones, pioglitazone, GLP1RAs and SGLT2is were associated with reduced risk of dementia. More longitudinal studies aimed at determining their relative benefit in different populations should be conducted.

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.

Predicting three categories of Dementia Assessment Sheet for Community-based Integrated Care System 8-items score-based glycemic targets using the number of animal names recalled

AIMS/INTRODUCTION

The Dementia Assessment Sheet for Community-based Integrated Care System 8-items (DASC-8) assesses memory, orientation, instrumental activities of daily living and basic activities of daily living. Category I (DASC-8 score ≤10), category II (11 ≤ DASC-8 score ≤16) and category III (DASC-8 score ≥17) have been defined. Based on these categories, the glycemic targets in diabetes patients aged ≥65 years have been proposed by the Japan Diabetes Society and the Japan Geriatrics Society Joint Committee. DASC-8 is difficult to apply to patients without family members or supportive persons. We propose a verbal fluency test as the screening tool.

MATERIALS AND METHODS

We enrolled 69 inpatients aged ≥65 years with type 2 diabetes, who were administered the DASC-8 and VF tests, which included recalling animal names and common nouns starting with a specified letter in 1 min. The relationship between DASC-8 and verbal fluency test scores was investigated.

RESULTS

Animal fluency correlated with DASC-8 scores after adjustment for patient characteristics. Animal scores correlated with orientation, instrumental activities of daily living and basic activities of daily living scores of DASC-8, and tended to show a relationship with DASC-8 memory scores. An animal score ≥8 predicted category I with a sensitivity of 89% and a specificity of 57%. An animal score ≤6 predicted category III with a sensitivity of 85% and a specificity of 67%.

CONCLUSIONS

Animal scores would be useful in predicting the categories of DASC-8. Animal fluency could be a screening tool of DASC-8 when a patient's family member or supportive person is absent.

Hippocampal transcriptome analysis reveals mechanisms of cognitive impairment in beagle dogs with type 1 diabetes

Diabetic encephalopathy is a common complication of type 1 diabetes. However, there have been few studies on cognitive impairment and hippocampal damage in type 1 diabetes mellitus (T1DM) using dogs as experimental animals. To investigate the effects of diabetes on the CNS, 40 adult beagles were divided into streptozotocin/alloxan type 1 diabetes model and control groups. The duration of diabetes in the model group was 120 days. A cognitive dysfunction scale was used to assess cognitive function. Hematoxylin and eosin and Golgi-Cox staining methods were used to observe morphological damage to the hippocampus. Transcriptomics was used to investigate differential gene expression in the hippocampus. The results showed that the cognitive dysfunction score of the model group was significantly higher than that of the control group. In addition, the number of normal neurons, the complexity of dendritic morphology, and the density of dendritic spines were decreased in the hippocampus of diabetic dogs. A total of 672 differentially expressed genes (DEGs) were identified, 289 of which were upregulated, and 383 were downregulated. Modified genes included DBH, IGFBP2, AVPR1A, and DRAXIN. In conclusion, type 1 diabetic dogs exhibit cognitive dysfunction. The DEGs were mainly enriched in metabolic, PI3K-Akt signaling, and neuroactive ligand-receptor interaction pathways.

Cognitive dysfunction in diabetes: abnormal glucose metabolic regulation in the brain

Cognitive dysfunction is increasingly recognized as a complication and comorbidity of diabetes, supported by evidence of abnormal brain structure and function. Although few mechanistic metabolic studies have shown clear pathophysiological links between diabetes and cognitive dysfunction, there are several plausible ways in which this connection may occur. Since, brain functions require a constant supply of glucose as an energy source, the brain may be more susceptible to abnormalities in glucose metabolism. Glucose metabolic abnormalities under diabetic conditions may play an important role in cognitive dysfunction by affecting glucose transport and reducing glucose metabolism. These changes, along with oxidative stress, inflammation, mitochondrial dysfunction, and other factors, can affect synaptic transmission, neural plasticity, and ultimately lead to impaired neuronal and cognitive function. Insulin signal triggers intracellular signal transduction that regulates glucose transport and metabolism. Insulin resistance, one hallmark of diabetes, has also been linked with impaired cerebral glucose metabolism in the brain. In this review, we conclude that glucose metabolic abnormalities play a critical role in the pathophysiological alterations underlying diabetic cognitive dysfunction (DCD), which is associated with multiple pathogenic factors such as oxidative stress, mitochondrial dysfunction, inflammation, and others. Brain insulin resistance is highly emphasized and characterized as an important pathogenic mechanism in the DCD.

Type 2 diabetes and cognitive performance in middle age: a cross-sectional study

INTRODUCTION

Type 2 diabetes has been associated with cognitive decrements already in middle-age. However, the sample sizes of the studies have been small and the neuropsychological tests used have been heterogeneous. In addition, only a few studies have matched the groups in terms of age, education and gender. In this cross-sectional matched pairs study, we investigated the cognitive performance of Finnish middle-aged type 2 diabetes patients compared to healthy individuals.

METHOD

A neuropsychological test battery consisting of 16 tests and 21 outcome measures was applied to 28 patients and 28 age-, education- and gender-matched healthy individuals. Various exclusion criteria were applied to minimize the risk of cognitive dysfunction due to factors other than diabetes.

RESULTS

We did not find between-group differences in any of the neuropsychological tests measuring attention, concept formation and reasoning, construction and motor performance, executive functions, memory, processing speed or working memory. In addition, there were no group differences in the frequency or severity of subjective cognitive symptoms, or in anxiety, depression, burnout, fatigue or alcohol use disorder symptoms. The effect sizes in this study were mostly negligible or small, with the mean effect size being -0.12.

CONCLUSIONS

In a carefully matched sample of middle-aged type 2 diabetes patients and healthy individuals, we found no significant effects and no meaningful evidence of cognitive differences between the groups.

Changes in Cognition and Brain Function After 26 Weeks of Progressive Resistance Training in Older Adults at Risk for Diabetes: A Pilot Randomized Controlled Trial

OBJECTIVES

Type 2 diabetes is associated with deficits in cognition and brain health. Individuals with at least 1 risk factor for diabetes (i.e. obesity, prediabetes) already experience some neurocognitive impairment and are at risk for further decline. One way to combat these deficits is through exercise, but its is unknown whether resistance exercise can improve these functions in this at-risk group.

METHODS

This study was a pilot randomized controlled trial. Participants were 60 to 80 years of age and had prediabetes (fasting capillary glucose 6.1 to 6.9 mmol/L) and/or were overweight or obese (body mass index ≥25). Participants completed resistance training or balance and stretching exercise (control) thrice weekly for 6 months. Neuropsychological tests were used to assess cognitive ability, whereas functional magnetic resonance imaging was used to examine brain activation patterns.

RESULTS

Resistance training led to improvements in task-switching, attention and conflict resolution, as well as improved patterns of brain activation that may mimic healthy older adults.

CONCLUSIONS

Resistance exercise may serve as an effective behavioural strategy to improve neurocognition in older adults at risk for type 2 diabetes. A large-scale powered trial is needed to further explore these findings.

Depressive symptoms mediate the relationship between diabetes and cognitive performance in a community-based sample of older adults

AIMS

To evaluate whether diabetes and prediabetes are associated with impaired cognitive performance among older adults and examine depressive symptoms as a mediator.

METHODS

We used cross-sectional data from the Einstein Aging Study, a systematically recruited, community-based cohort study of diverse older adults (N = 794; Age Mean (SD) = 78.9 (5.3); 64.4% Non-Hispanic White, 28.7% Non-Hispanic Black, 5.7% Hispanic). Diabetes status was established via self-reported diagnosis, prescribed medications, and fasting blood glucose. Depressive symptoms were assessed using the Geriatric Depression Scale. Cognitive tests included Digit Symbol, Trails-B, Free Recall, Category Fluency, Boston Naming, and Block Design. Linear regression and mediation analyses were applied.

RESULTS

Compared to those without diabetes, diabetes was associated with worse performance on all cognitive tests (ps < 0.05), except Trails-B (p = 0.53), and increased depressive symptoms (p < 0.01). For diabetes, mediation via increased depressive symptoms was observed for Free Recall (p = 0.044), Category Fluency (p = 0.033), and Boston Naming (p = 0.048).

CONCLUSIONS

Diabetes was consistently associated with worse cognitive performance and increased depressive symptoms among this older cohort, while prediabetes was not. Mediation findings suggest depressive symptoms may be a biobehavioral pathway linking diabetes and cognition, though the temporal sequence is unclear. If causal, addressing both diabetes and depressive symptoms among older adults may protect cognitive function.

M, Michelle. H, Anna. D, Reuben. R, Greg. K, Andre. JJ, Leslie L, Thomas. M, GF. TK. Impact of HIV on Cognitive Performance in Professional Drivers

BACKGROUND

The intellectually demanding modern workplace is often dependent on good cognitive health, yet there is little understanding of how neurocognitive dysfunction related to HIV presents in employed individuals working in high-risk vocations such as driving. HIV-associated neurocognitive impairment is also associated with poorer long-term cognitive, health, and employment outcomes.

SETTING

This study, set in Cape Town, South Africa, assessed the effects of HIV on neuropsychological test performance in employed male professional drivers.

METHOD

We administered a neuropsychological test battery spanning 7 cognitive domains and obtained behavioral data, anthropometry, and medical biomarkers from 3 groups of professional drivers (68 men with HIV, 55 men with cardiovascular risk factors, and 81 controls). We compared the drivers' cognitive profiles and used multiple regression modeling to investigate whether between-group differences persisted after considering potentially confounding sociodemographic and clinical variables (ie, income, home language, depression, and the Framingham risk score).

RESULTS

Relative to other study participants, professional drivers with HIV performed significantly more poorly on tests assessing processing speed (P < 0.003) and attention and working memory (P = 0.018). Group membership remained a predictor of cognitive performance after controlling for potential confounders. The cognitive deficits observed in men with HIV were, however, largely characterized as being mild or asymptomatic. Consistent with this characterization, their relatively poor performance on neuropsychological testing did not generalize to self-reported impairment on activities of daily living.

CONCLUSION

Drivers with HIV may be at risk of poorer long-term health and employment outcomes. Programs that monitor and support their long-term cognitive health are needed.

The Relative Importance of Vascular Risk Factors on Early Cognitive Aging Varies Only Slightly Between Men and Women

Objective

To investigate the sex-specific course and impact of vascular risk factors on cognitive aging in a rather young and healthy community-dwelling cohort.

Methods

We used data from a population-based cohort study, collected three times during 6 years, comprising 1,911 examinations from 798 participants aged 35–66 years at baseline. Cognitive performance on the Color-Word-Interference-Test, the Trail Making Tests (TMT) A&B, the Word Fluency Test, a 12-item word list, the Purdue Pegboard Test and a principal component global score were used as outcomes in linear mixed models. We evaluated (1) sex differences in cognitive trajectories, (2) the mediating role of hypertension, diabetes, smoking and obesity [body mass index (BMI) > 30] on sex differences and (3) in sex-stratified analyses, potential sex-specific effects of these risk factors on cognition.

Results

For all cognitive tests, we observed cognitive decline with age. Rates of decline slightly differed across sexes, showing a later but steeper decline for women in tests of memory (word list) and word fluency, but a steeper decline for men in tests of psychomotor speed and mental set shifting (TMT A&B) in older age. Women generally scored better on cognitive tests, but the slightly higher prevalence of classical vascular risks factors in men in our cohort could not explain these sex differences. Sex-stratified analyses revealed a generally small, concordantly negative, but quantitatively slightly different impact of diabetes, smoking and obesity on cognitive functions but mixed effects for arterial hypertension, depending on the blood pressure values, the treatment status and the duration of arterial hypertension.

Conclusion

Cognitive sex differences in this rather young and healthy cohort could not be explained by a differing prevalence of vascular risks factors across sexes. The association of cardiovascular risk factors with cognition, however, slightly differed between men and women, whereby effects were generally small. Whereas longtime diabetes, obesity and smoking had a sex-specific, but concordantly negative impact on psychomotor speed, executive and motor functions, we found some opposing effects for arterial hypertension. Our results can help to identify sex-specific susceptibilities to modifiable risk factors, to attract attention to potential information bias and to stimulate further research into alternative causes and mechanism of sex differences in cognitive aging.

Associations between depression and cognition, mild cognitive impairment and dementia in persons with diabetes mellitus: A systematic review and meta-analysis

AIMS

This systematic review aimed to examine whether persons with diabetes and depression had poorer cognition and higher dementia risk than persons with diabetes only. Moreover, the impact of timing, frequency of depressive episodes throughout life, and antidepressant treatment were examined.

METHODS

PubMed, Embase and PsycINFO were searched to obtain observational studies between August 2015 and June 2021 that examined the association between depression and cognition, mild cognitive impairment or dementia in people with diabetes. Studies published before August 2015 were retrieved from a previous systematic review. Findings were pooled using meta-analyses.

RESULTS

10 out of 19 included articles were appropriate for the meta-analyses. Persons with diabetes and depression experienced greater declines in executive function (SMD = -0.39 (-0.69, -0.08)), language (SMD = -0.80 (-1.52, -0.09)), memory (SMD = -0.63 (-1.12, -0.14)) and overall cognition (SMD = -0.77 (-1.33, -0.20)), and greater dementia risk (HR = 1.82 (1.79, 1.85)) than persons with diabetes only. No significant differences were observed for complex attention. No studies examined the role of timing and frequency of depressive episodes and antidepressant treatment.

CONCLUSION

In persons with diabetes, depression is associated with worse cognition and higher dementia risk. The potential mitigating effect of antidepressant treatment remains unclear.

Cardiovascular Risk Associated with Poorer Memory in Middle-Aged Adults from the Healthy Brain Project

BACKGROUND

Midlife cardiovascular risk factors (CVRF) are associated with reduced cognition and an increased risk of dementia.

OBJECTIVE

To further investigate this association using remote unsupervised online assessment of cognition and cardiovascular risk in middle-aged adults; and to explore the extent to which the association is altered by carriage of the APOE ɛ4 allele.

METHODS

The Healthy Brain Project is an online cohort of middle-aged cognitively unimpaired adults (40-70 years) who have undergone cognitive assessment and provided self-reports of demographic and health history. Cardiovascular risk was determined by ascertaining history of hypertension, hypercholesterolemia, diabetes mellitus, overweight (body mass index≥25), and current cigarette smoking. Participants (n = 2,480) were then grouped based on the number of reported CVRF into no CVRF, 1, 2, and≥3 CVRF. Associations between the number of CVRF as a continuous variable, CVRF group, and each individual CVRF with composite measures of attention, memory and subjective cognitive function were investigated.

RESULTS

Higher number of CVRF was associated with poorer attention (β= -0.042, p = 0.039) and memory (β= -0.080, p <  0.001), but not with subjective cognitive function. When considered individually, current smoking (β= -0.400, p = 0.015), diabetes (β= -0.251, p = 0.023), and hypercholesterolemia (β= -0.109, p = 0.044) were independently associated with poorer memory performance. APOE ɛ4 carriers with≥1 CVRF performed worse on memory than ɛ4 carriers with no CVRFs (β(SE) = 0.259(0.077), p = 0.004). This was not observed in ɛ4 non-carriers.

CONCLUSION

In cognitively normal middle-aged adults, CVRF were associated with poorer cognition, particularly in the memory domain. These results support feasibility of online assessment of cardiovascular risk for cognitive impairment.

The additive impact of cardio-metabolic disorders and psychiatric illnesses on accelerated brain aging

Severe mental illnesses (SMI) including major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia spectrum disorder (SSD) elevate accelerated brain aging risks. Cardio‐metabolic disorders (CMD) are common comorbidities in SMI and negatively impact brain health. We validated a linear quantile regression index (QRI) approach against the machine learning “BrainAge” index in an independent SSD cohort (N = 206). We tested the direct and additive effects of SMI and CMD effects on accelerated brain aging in the N = 1,618 (604 M/1,014 F, average age = 63.53 ± 7.38) subjects with SMI and N = 11,849 (5,719 M/6,130 F; 64.42 ± 7.38) controls from the UK Biobank. Subjects were subdivided based on diagnostic status: SMI+/CMD+ (N = 665), SMI+/CMD− (N = 964), SMI−/CMD+ (N = 3,765), SMI−/CMD− (N = 8,083). SMI (F = 40.47, p = 2.06 × 10⁻¹⁰) and CMD (F = 24.69, p = 6.82 × 10⁻⁷) significantly, independently impacted whole‐brain QRI in SMI+. SSD had the largest effect (Cohen’s d = 1.42) then BD (d = 0.55), and MDD (d = 0.15). Hypertension had a significant effect on SMI+ (d = 0.19) and SMI− (d = 0.14). SMI effects were direct, independent of MD, and remained significant after correcting for effects of antipsychotic medications. Whole‐brain QRI was significantly (p < 10⁻¹⁶) associated with the volume of white matter hyperintensities (WMH). However, WMH did not show significant association with SMI and was driven by CMD, chiefly hypertension (p < 10⁻¹⁶). We used a simple and robust index, QRI, the demonstrate additive effect of SMI and CMD on accelerated brain aging. We showed a greater effect of psychiatric illnesses on QRI compared to cardio‐metabolic illness. Our findings suggest that subjects with SMI should be among the targets for interventions to protect against age‐related cognitive decline.

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.

Using health check data to investigate cognitive function in Aboriginal and Torres Strait Islanders living with diabetes in the Torres Strait, Australia

Background

Type 2 Diabetes (T2DM) has a subtle deleterious effect on cognition and imposes a higher lifetime risk of cognitive impairment and dementia. In populations where both T2DM and dementia are highly prevalent, understanding more about the early effects of T2DM on cognition may provide insights into the lifetime risks of this disease.

Methods

In 2016, 186 Australian Aboriginal and/or Torres Strait Islander residents of the Torres Strait (54% female, mean age =38.9 years, SD =15.9, range =15–74) participated in a community health check. The effect of diabetes (Type 1 or Type 2) on speed of thinking and working memory was assessed with the Cogstate Brief Battery (CBB) during the health check.

Results

One third of participants had diabetes (n = 56, 30.1%). After adjusting for age, education and previous iPad/Tablet experience, participants with diabetes had a small, yet significant reduction in accuracy on the One Back working memory task (β = −.076, p = .010, r² = .042). The effect was most pronounced among participants with diabetes aged 20–49 years (n = 20), who also had evidence of poorer diabetes control (eg HbA1c% ≥6.5, 76.6%), relative to participants with diabetes aged 50 years and over (n = 31) (HbA1c% ≥6.5, 32.0%, p = .005).

Conclusions

Early and subtle decrements in working memory may be a potential complication of diabetes among Aboriginal and Torres Strait Islander residents of the Torres Strait. Several potentially influential variables were not captured in this study (eg medication and diabetes duration). Greater preventative health resources are required for this population, particularly given the emerging elevated dementia rates linked to chronic disease.

Insulin resistance and NAFLD may influence memory performance in obese patients with prediabetes or newly-diagnosed type 2 diabetes

BACKGROUND AND AIMS

Diabetes has consistently been shown to increase risk for cognitive decline. Cognitive deficits may occur at the very earliest stages of diabetes. We sought to estimate the determinants of memory function in a group of middle-aged obese subjects with prediabetes or newly-diagnosed type 2 diabetes mellitus.

METHODS AND RESULTS

Sixty-two obese patients in treatment with metformin-with prediabetes (n = 41) or newly diagnosed T2DM (n = 21), were studied. Short- and long-term memory function was assessed through a neuropsychological assessment consisting of two tests and a composite domain z score was calculated. Cardiometabolic variables, such as abdominal MRI quantification of subcutaneous (SAT) and visceral (VAT) adipose tissue content, and of intra-hepatocellular lipid content, as well as insulin sensitivity (Matsuda Index, HOMA-IR) and beta cell performance (Beta Index), by multiple sampling, 8-point oral glucose tolerance test, were also evaluated. Age, non-alcoholic fatty liver disease (NAFLD), and lnHOMA-IR together explained 18% (R square) of the variance in memory domain. Including NAFLD increased the explained variance by 8% and including lnHOMA-IR by 9.1%, whereas the contribution of age and other factors was negligible.

CONCLUSION

Preventing and managing insulin resistance in precocious and possibly earlier stages of diabetes might provide benefit in slowering down future cognitive decline.

Treating cognitive impairment in schizophrenia with GLP-1RAs: an overview of their therapeutic potential

INTRODUCTION

Schizophrenia is a neuropsychiatric disorder that affects approximately 1% of individuals worldwide. There are no available medications to treat cognitive impairment in this patient population currently. Preclinical evidence suggests that glucagon-like peptide-1 receptor agonists (GLP-1 RAs) improve cognitive function. There is a need to evaluate how GLP-1 RAs alter specific domains of cognition and whether they will be of therapeutic benefit in individuals with schizophrenia.

AREAS COVERED

This paper summarizes the effects of GLP-1 RAs on metabolic processes in the brain and how these mechanisms relate to improved cognitive function. We provide an overview of preclinical studies that demonstrate GLP-1 RAs improve cognition and comment on their potential therapeutic benefit in individuals with schizophrenia.

EXPERT OPINION

To understand the benefits of GLP-1 RAs in individuals with schizophrenia, further preclinical research with rodent models relevant to schizophrenia symptomology are needed. Moreover, preclinical studies must focus on using a wider range of behavioral assays to understand whether important aspects of cognition such as executive function, attention, and goal-directed behavior are improved using GLP-1 RAs. Further research into the specific mechanisms of how GLP-1 RAs affect cognitive function and their interactions with antipsychotic medication commonly prescribed is necessary.

Mitochondrial Dysfunction and Mitophagy Closely Cooperate in Neurological Deficits Associated with Alzheimer's Disease and Type 2 Diabetes

Alzheimer's disease (AD) and type 2 diabetes (T2D) are known to be correlated in terms of their epidemiology, histopathology, and molecular and biochemical characteristics. The prevalence of T2D leading to AD is approximately 50-70%. Moreover, AD is often considered type III diabetes because of the common risk factors. Uncontrolled T2D may affect the brain, leading to memory and learning deficits in patients. In addition, metabolic disorders and impaired oxidative phosphorylation in AD and T2D patients suggest that mitochondrial dysfunction is involved in both diseases. The dysregulation of pathways involved in maintaining mitochondrial dynamics, biogenesis and mitophagy are responsible for exacerbating the impact of hyperglycemia on the brain and neurodegeneration under T2D conditions. The first section of this review describes the recent views on mitochondrial dysfunction that connect these two disease conditions, as the pathways are observed to overlap. The second section of the review highlights the importance of different mitochondrial miRNAs (mitomiRs) involved in the regulation of mitochondrial dynamics and their association with the pathogenesis of T2D and AD. Therefore, targeting mitochondrial biogenesis and mitophagy pathways, along with the use of mitomiRs, could be a potent therapeutic strategy for T2D-related AD. The last section of the review highlights the known drugs targeting mitochondrial function for the treatment of both disease conditions.

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.

Cognitive impairment among patients with diabetes in Saudi Arabia: a cross-sectional study

Background

The incidence of cognitive impairment (CI) is higher in patients with diabetes mellitus (DM). The association between DM and CI and the risk factors for CI need to be addressed to estimate the prevalence of cognitive impairment in patients with DM and to identify the potential risk factors. The study is a cross-sectional study using a convenient sample of 269 subjects. Sociodemographic diabetes-related variables including biochemical markers were collected. CI and diabetes-related distress (DRD) were assessed using the Arabic version of Montreal Cognitive Assessment scale (MoCA) and the Diabetes Distress Screening Scale respectively.

Results

Overall, 80.3% had cognitive impairment while 33.8% had severe impairment. Older age, female gender, low level of education, and low income were associated with CI; duration of diabetes and DRD were associated with CI while ophthalmic complications were associated with severe CI. Duration of diabetes was inversely associated with CI. Level of HbA1c was significantly higher in patients with severe CI, and the probability of CI increased as the level of HbA1c increased. Low level of education was associated with severe CI, and CI was two times more likely among patients with DRD.

Conclusion

CI was higher than worldwide figures. Elderly females with low educational level, long duration of DM, and low socioeconomic status are at more risk. The probability of severe CI increased with increased level of HbA1c. Screening for CI in patients with diabetes along with intervention programs while considering the DRD and the level of HbA1c is crucial.

Feasibility of a 26-Week Exercise Program to Improve Brain Health in Older Adults at Risk for Type 2 Diabetes: A Pilot Study

OBJECTIVES

Older adults at risk for type 2 diabetes (i.e. overweight individuals or those with prediabetes) experience accelerated cognitive and brain deficits. Aerobic training is known to improve these deficits, but the effects of resistance training are relatively unknown. Before conducting a large-scale, randomized, controlled trial to assess the effects of resistance training, we first conducted a pilot feasibility study to examine recruitment, attendance and retention rates in this population.

METHODS

Program participants (aged 60 to 80 years, mean age 68.7±5.7 years, 50% females) at risk for type 2 diabetes (body mass index of ≥25 or fasting blood glucose of 6.1 to <7 mmol/L) underwent 26 weeks of thrice-weekly progressive resistance training (n=13) or balance-and-tone exercises (control group, n=11). Recruitment, attendance and retention rates were recorded, and study feedback from program participants and research assistants was collected via questionnaires.

RESULTS

We recruited 72 older adults (total number enrolled = 24) over 17 months. Program retention and attendance were 95.8% and 84.4%, respectively. Program participants and research assistants expressed a high level of study enjoyment, and suggestions on how to improve study procedures were provided.

CONCLUSIONS

Based on our findings, a large-scale study in this at-risk group of older adults is feasible, and key strategies to improving future trials were identified.

Prevalence of Psychiatric Morbidity and Cognitive Impairment among Patients Attending the Rural Noncommunicable Disease Clinic

Objective  This study aimed to assess the prevalence of cognitive impairment and psychiatric morbidity among the patients attending the rural noncommunicable disease clinic after controlling for various confounders (i.e., psychological morbidity, obesity, gender, level of education, duration of the illness and age).

Materials and Methods  One-hundred twenty-four patients were evaluated on the Hindi Mental State Examination for the cognitive function, Physical Health Questionnaire-9 for depression, and Generalized Anxiety Disorder-7 for anxiety disorders.

Results  About one-fourth (26.6%) of the participants had cognitive impairment. The prevalence of cognitive impairment was more among patients with hypertension (35.5%) as compared with the diabetes mellitus (13.6%) and those with comorbid hypertension and diabetes mellitus (26.6%). About one of the participants had depression (35.5%) and 29% of the patients had anxiety disorder. No significant difference was found in the level of cognitive deficits between those with hypertension and diabetes mellitus, when the confounding factors were not taken into account in the analysis. However, after controlling for psychiatric morbidity, obesity, gender, level of education, duration of the illness and age, those with hypertension were found to have significantly higher level of cognitive impairment compared with those with diabetes mellitus. A higher level of dysfunction was seen in the domains of orientation, registration, attention, recall, language, and visuospatial domains.

Conclusion  Present study suggests that patients of hypertension have higher level of cognitive impairment, when compared with those with diabetes mellitus, even after controlling for various confounders. Lack of difference between the two groups can be accounted by the confounding variables.

Diabetes and dementia - the two faces of Janus

Patients with type 2 diabetes are at high risk for cognitive decline and dementia. Despite the limited data on the possible pathogenetic mechanisms, evidence suggests that cognitive decline, and thus dementia and Alzheimer’s disease, might arise from a complex interplay between type 2 diabetes and the aging brain, including decreased insulin signalling and glucose metabolism, mitochondrial dysfunction, neuroinflammation, and vascular disease. Furthermore, there is increasing interest on the effects of antidiabetic agents on cognitive decline. There are many studies showing that antidiabetic agents might have beneficial effects on the brain, mainly through inhibition of oxidative stress, inflammation, and apoptosis. In addition, experimental studies on patients with diabetes and Alzheimer’s disease have shown beneficial effects on synaptic plasticity, metabolism of amyloid-β, and microtubule-associated protein tau. Therefore, in the present review, we discuss the effects of antidiabetic agents in relation to cognitive decline, and in particular dementia and Alzheimer’s disease, in patients with type 2 diabetes.

Proteotoxicity and mitochondrial dynamics in aging diabetic brain

Impaired neuronal proteostasis is a salient feature of both aging and protein misfolding disorders. Amyloidosis, a consequence of this phenomena is observed in the brains of diabetic patients over the chronic time period. These toxic aggregates not only cause age-related decline in proteostasis, but also dwindle its ability to increase or restore the chaperones in response to any stressful condition. Mitochondria acts as the main source of energy regulation and many metabolic disorders such as diabetes have been associated with altered oxidative phosphorylation (OxPhos) and redox imbalance in the mitochondria. The mitochondrial unfolded protein response (UPR^mt) acts as a mediator for maintaining the mitochondrial protein homeostasis and quality control during such conditions. Over a long time period, these responses start shutting off leading to proteotoxic stress in the neurons. This reduces the buffering capacity of protein network signalling during aging, thereby increasing the risk of neurodegeneration in the brain. In this review, we focus on the proteotoxic stress that occurs as an amalgamation of diabetes and aging, as well as the impact of mitochondrial dysfunction on the neuronal survival affecting the diabetic brain and its long term consequences on the memory changes.

Effects of exercise, cognitive, and dual-task interventions on cognition in type 2 diabetes mellitus: A systematic review and meta-analysis

Introduction

Previous evidence has shown significant effects of exercise, cognitive and dual-task training for improving cognition in healthy cohorts. The effects of these types of interventions in type 2 diabetes mellitus is unclear. The aim of this research was to systematically review evidence, and estimate the effect, of exercise, cognitive, and dual-task interventions on cognition in type 2 diabetes mellitus.

Method

Electronic databases including PubMed, EMBASE, CINAHL, PsycINFO, SPORTDiscus, and MEDLINE were searched for ongoing and completed interventional trials investigating the effect of either an exercise, cognitive or dual-task intervention on cognition in type 2 diabetes mellitus.

Results

Nine trials met the inclusion criteria–one dual-task, two cognitive, and six exercise. Meta-analyses of exercise trials showed no significant effects of exercise on measures of executive function (Stroop task, SMD = -0.31, 95% CI -0.71–0.09, P = 0.13, trail making test part A SMD = 0.28, 95% CI -0.20–0.77 P = 0.25, trail making test part B SMD = -0.15, 95% CI -0.64–0.34 P = 0.54, digit symbol SMD = 0.09, 95% CI -0.39–0.57 P = 0.72), and memory (immediate memory SMD = 0.20, 95% CI -0.28–0.69, P = 0.41 and delayed memory SMD = -0.06, 95% CI -0.55–0.42, P = 0.80). A meta-analysis could not be conducted using cognitive or dual-task data, but individual trials did report a favourable effect of interventions on cognition. Risk of bias was considered moderate to high for the majority of included trials.

Conclusions

Meta-analyses of exercise trials identified a small effect size (0.31), which whilst not significant warrants further investigation. Larger and more robust trials are needed that report evidence using appropriate reporting guidelines (e.g. CONSORT) to increase confidence in the validity of results.

Trial registration

Protocol was registered (CRD42017058526) on the International Prospective Register of Systematic Reviews (http://www.crd.york.ac.uk/PROSPERO).

Neurocognitive impairment in type 2 diabetes: evidence for shared genetic aetiology

AIMS/HYPOTHESIS

Type 2 diabetes is associated with cognitive impairments, but it is unclear whether common genetic factors influence both type 2 diabetes risk and cognition.

METHODS

Using data from 1892 Mexican-American individuals from extended pedigrees, including 402 with type 2 diabetes, we examined possible pleiotropy between type 2 diabetes and cognitive functioning, as measured by a comprehensive neuropsychological test battery.

RESULTS

Negative phenotypic correlations (ρp) were observed between type 2 diabetes and measures of attention (Continuous Performance Test [CPT d']: ρp = -0.143, p = 0.001), verbal memory (California Verbal Learning Test [CVLT] recall: ρp = -0.111, p = 0.004) and face memory (Penn Face Memory Test [PFMT]: ρp = -0.127, p = 0.002; PFMT Delayed: ρp = -0.148, p = 2 × 10-4), replicating findings of cognitive impairment in type 2 diabetes. Negative genetic correlations (ρg) were also observed between type 2 diabetes and measures of attention (CPT d': ρg = -0.401, p = 0.001), working memory (digit span backward test: ρg = -0.380, p = 0.005), and face memory (PFMT: ρg = -0.476, p = 2 × 10-4; PFMT Delayed: ρg = -0.376, p = 0.005), suggesting that the same genetic factors underlying risk for type 2 diabetes also influence poor cognitive performance in these domains. Performance in these domains was also associated with type 2 diabetes risk using an endophenotype ranking value approach. Specifically, on measures of attention (CPT d': β = -0.219, p = 0.005), working memory (digit span backward: β = -0.326, p = 0.035), and face memory (PFMT: β = -0.171, p = 0.023; PFMT Delayed: β = -0.215, p = 0.005), individuals with type 2 diabetes showed the lowest performance, while unaffected/unrelated individuals showed the highest performance, and those related to an individual with type 2 diabetes performed at an intermediate level.

CONCLUSIONS/INTERPRETATION

These findings suggest that cognitive impairment may be a useful endophenotype of type 2 diabetes and, therefore, help to elucidate the pathophysiological underpinnings of this chronic disease.

DATA AVAILABILITY

The data analysed in this study is available in dbGaP: www.ncbi.nlm.nih.gov/projects/gap/cgi-bin/study.cgi?study_id=phs001215.v2.p2.

Comparison of neurocognitive changes among newly diagnosed tuberculosis patients with and without dysglycaemia

BACKGROUND

Diabetes often occurs together with tuberculosis (TB) and both may affect each other negatively. Diabetes may be associated with neurocognitive dysfunctioning in affected patients and may negatively impact treatment adherence and outcomes. This study compared the neurocognitive status between newly diagnosed smear positive tuberculosis patients with dysglycaemia and those with normoglycaemia.

METHODS

The current study was a cross-sectional study involving one hundred and forty-six (146) newly diagnosed smear positive TB patients. Oral glucose tolerance test (OGTT) was performed and the results were categorized as either normoglycaemia, impaired glucose tolerance (IGT), impaired fasting glucose (IFG) or diabetes. Neurocognitive functioning among study participants was assessed at the time of TB diagnosis using Cognitive Failure Questionnaire (CFQ), Montreal Cognitive Assessment tool (MoCA), California Verbal Learning Test (CVLT), Brief Symptom Inventory (BSI) and the Spitzer Quality of Life Index (QLI).

RESULTS

The mean age of the participants (n = 146) was 38.7 years with 78.8% being males and 21.2% females. Using the fasting blood glucose test, the prevalence of impaired fasting glucose and diabetes were 5.5 and 3.4% respectively, both representing a total of 13 out of the 146 participants; whilst the prevalence of impaired glucose tolerance and diabetes using 2-h post-glucose values were 28.8 and 11.6% respectively, both representing a total of 59 out of the 146 participants. There were no significant differences in the mean scores on the neurocognitive measures between the dysglaycaemia and normoglycamic groups using fasting plasma glucose (FPG). However, there were significant differences in the mean scores between the dysglycaemia and normal groups using 2-h postprandial (2HPP) glucose values on Phobic Anxiety (Normal, Mean = 0.38 ± 0.603; dysglycaemia, Mean = 0.23 ± 0.356; p = 0.045), and Montreal Cognitive Assessment (MoCA) scores (17.26 ± 5.981 vs. 15.04 ± 5.834, p = 0.037).

CONCLUSION

Newly diagnosed smear positive patients with dysglycaemia were associated with significantly lower mean cognitive scores and scores on phobic anxiety than those with normoglyacaemia. The latter finding must be further explored.

Impact of Diabetes on the Symptoms of Breast Cancer Survivors

OBJECTIVES

To examine the impact of diabetes on the symptoms of women with breast cancer.

SAMPLE & SETTING

121 women with breast cancer who self-identified as having a diabetes diagnosis and 1,006 women with breast cancer without diabetes from 97 sites across the United States.

METHODS & VARIABLES

Symptom scores for depression, anxiety, sexual function, peripheral neuropathy, physical function, attention function, sleep disturbance, and fatigue were compared between women with breast cancer and diabetes and women with breast cancer without diabetes, controlling for age, education, income, marital status, and body mass index (BMI).

RESULTS

Women with breast cancer and diabetes who were three to eight years postdiagnosis reported poorer physical and attention function, more sleep disturbance, and greater fatigue than women with breast cancer without diabetes. Age, education, income, and BMI were independent predictors of symptoms experienced by women with breast cancer.

IMPLICATIONS FOR NURSING

Oncology nurses can assess and monitor women with breast cancer and diabetes for increased post-treatment sequelae. If problematic symptoms are identified, implementing treatment plans can decrease symptom burden and increase quality of life for women with breast cancer and diabetes.

Computerized Cognitive Training for Older Adults at Higher Dementia Risk due to Diabetes: Findings From a Randomized Controlled Trial

BACKGROUND

To evaluate the effects of adaptive and tailored computerized cognitive training on cognition and disease self-management in older adults with diabetes.

METHODS

This was a single-blind trial. Eighty-four community-dwelling older adults with diabetes were randomized into a tailored and adaptive computerized cognitive training or a generic, non-tailored or adaptive computerized cognitive training condition. Both groups trained for 8 weeks on the commercially available CogniFit program and were supported by a range of behavior change techniques. Participants in each condition were further randomized into a global or cognition-specific self-efficacy intervention, or to a no self-efficacy condition. The primary outcome was global cognition immediately following the intervention. Secondary outcomes included diabetes self-management, meta-memory, mood, and self-efficacy. Assessments were conducted at baseline, immediately after the training, and at a 6-month follow-up.

RESULTS

Adherence and retention were lower in the generic computerized cognitive training condition, but the self-efficacy intervention was not associated with adherence. Moderate improvements in performance on a global cognitive composite at the posttreatment assessments were observed in both cognitive training conditions, with further small improvement observed at the 6-month follow-up. Results for diabetes self-management showed a modest improvement on self-rated diabetes care for both intervention conditions following the treatment, which was maintained at the 6-month follow-up.

CONCLUSIONS

Our findings suggest that older adults at higher dementia risk due to diabetes can show improvements in both cognition and disease self-management following home-based multidomain computerized cognitive training. These findings also suggest that adaptive difficulty and individual task tailoring may not be critical components of such interventions.

TRIAL REGISTRATION

NCT02709629.

Meta-analysis of comorbid diabetes and family history of diabetes in non-affective psychosis

OBJECTIVE

Schizophrenia and other non-affective psychoses (NAP) are associated with an increased prevalence of both type 2 diabetes (DM2) as well as a family history of DM2. We performed a systematic review and meta-analysis of the association between comorbid DM2 and a family history of DM2 in patients with NAP.

METHOD

We searched major electronic databases from inception until August 2018 for studies of comorbid DM2 in patients with non-affective psychosis and family history of DM2 status. Random effects meta-analysis calculating odds ratios (ORs) and 95% confidence intervals (CI) and meta-regression analyses were performed.

RESULTS

Ten studies met the inclusion criteria. Across these studies, there were 804 patients with non-affective psychosis and comorbid DM2, and 2976 patients with non-affective psychosis without this comorbidity. A family history of DM2 was associated with an over four-fold increased odds of comorbid DM2 in patients with NAP (OR = 4.3, 95% CI 2.9-6.4, p<0.001). In; meta-regression analyses older age, but not sex, BMI, geographic region, study quality, or year; of publication moderated the association between comorbid DM2 and family history of DM2.

CONCLUSION

We found that a family history of DM2 was associated with an over four-fold increased odds of comorbid DM2 in patients with NAP. This association may be due to shared environmental or genetic risk factors, or gene-environment interactions. Given the increased risk of incident diabetes with antipsychotic treatment, screening for a family history of DM2 is germane to the clinical care of patients with NAP.

A Brief Neuropsychological Battery for Measuring Cognitive Functions Associated with Obesity

OBJECTIVE

Although ample evidence links obesity to cognitive dysfunction, the trajectory of cognitive change, the underlying mechanisms, and the involvement of related factors, such as metabolic disease and diet, remain unclear. To support further investigations of BMI and cognition, this study aimed to create a concise test battery to be used in future trials.

METHODS

Twenty neurocognitive measures were regressed on BMI in the Human Connectome Project Healthy Young Adult S1200 data release by using linear mixed models and by adjusting for major confounders. Measures were then identified by using least absolute shrinkage and selection operator regression analysis to select tests most strongly associated with BMI. To guide further test selection, the explained variance for each variable was visualized in the final model.

RESULTS

BMI was negatively associated with seven neurocognitive measures. Variable selection yielded a model that included years of education and, in order of model weight, delay discounting, the relational task, the Penn Progressive Matrices test, the oral reading recognition test, the Variable Short Penn Line Orientation test, and the Penn Word Memory test.

CONCLUSIONS

This research resulted in an approximate 40-minute test battery for the BMI-cognition relationship in young adults that can be used in trials investigating the interrelationship between obesity and cognitive performance.

Diabetes mellitus and risks of cognitive impairment and dementia: A systematic review and meta-analysis of 144 prospective studies

BACKGROUND

Uncertainties persist about the associations of diabetes with risk of cognitive impairment and dementia. We aimed to illuminate these associations from various aspects.

METHODS

We identified relevant prospective studies by searching PubMed up to Jun 2019. Summary relative risks (RR) were estimated using random-effects models. Credibility of each meta-analysis was assessed. Meta-regression and subgroup analyses were conducted.

RESULTS

Of 28,082 identified literatures, 144 were eligible for inclusion in the systematic review, among which 122 were included in the meta-analysis. Diabetes conferred a 1.25- to 1.91-fold excess risk for cognitive disorders (cognitive impairment and dementia). Subjects with prediabetes also had higher risk for dementia. As for diabetes-related biochemical indicators, fasting plasma glucose (FPG) was non-linearly related to cognitive disorders; the elevated levels of 2 -h postload glucose (2h-PG), glycosylated hemoglobin (HbA1c), low and high levels of fasting plasma insulin (FPI) were associated with an increased risk of dementia. Encouragingly, the use of pioglitazone exhibited a 47% reduced risk of dementia in diabetic population.

CONCLUSIONS

Diabetes, even prediabetes and changes of diabetes-related biochemical indicators, predicted increased incidence of cognitive impairment and dementia. The protective effects of pioglitazone warrant further investigation in randomized trials.

Sugar in mind: Untangling a sweet and sour relationship beyond type 2 diabetes

It is widely recognised that type 2 diabetes (T2D) represents a major disease burden but it is only recently that its role in neurodegeneration has attracted more attention. This research has shown that T2D is associated with impaired cerebral health, cognitive decline and dementia. However, the impact on the brain of progressive metabolic changes associated with the pre-clinical development of the disease is less clear. The aim of this review is to comprehensively summarise how the emergence of risk factors and co-morbid conditions linked to the development of T2D impact cerebral health. Particular attention is directed at characterising how normal but elevated blood glucose levels in individuals without T2D contribute to neurodegenerative processes, and how the main risk factors for T2D including obesity, physical activity and diet modulate these effects. Where available, evidence from the animal and human literature is contrasted, and sex differences in risk and outcomes are highlighted.

Neurocognitive Deficits in a Cohort With Class 2 and Class 3 Obesity: Contributions of Type 2 Diabetes and Other Comorbidities

OBJECTIVE

This study examined the relationship between specific metabolic and vascular risk factors and cognition in adults with severe obesity.

METHODS

A total of 129 adults (with BMI ≥ 35 kg/m² ) underwent a baseline clinical evaluation and neuropsychological assessment. Regression analyses examined the relationship between cognition and medical factors (BMI, hemoglobin A1c, diabetes, hypertension, continuous positive airway pressure use, obstructive sleep apnea [OSA], and osteoarthritis).

RESULTS

Diabetes was associated with deficits in overall cognitive performance and with deficits in the executive processing speed and verbal fluency domains. Hemoglobin A1c was inversely related to overall cognitive performance and deficits in the attention domain. Participants using continuous positive airway pressure to treat OSA had stronger learning and memory performance, whereas OSA was associated with reduced total learning. Elevated BMI together with diabetes diagnosis was associated with reduced verbal fluency and greater variability in sustained attention.

CONCLUSIONS

Obesity-associated comorbidities most notably appeared to have a greater relative influence on cognitive performance than BMI itself in adults with severe obesity. This likely reflects the fact that a very elevated BMI was ubiquitous and thereby probably exerted a similar influence among all adults in the cohort. Accordingly, in the context of severe obesity, diabetes and other comorbidities may have greater sensitivity to cognitive deficits than BMI alone.

Type 2 diabetes and later cognitive function in older American Indians: The Strong Heart Study

OBJECTIVES

Insulin resistance is a substantial health issue for American Indians, with type 2 diabetes overrepresented in this population as compared with non-Hispanic whites. Insulin resistance and its related conditions in turn increase risk for dementia and cognitive impairment. The aim of the current study was to determine whether type 2 diabetes and insulin resistance at midlife was associated with later-life cognitive testing in a large sample of older American Indians, aged 65 and older.

METHODS

American Indian participants who underwent both fasting blood draw as part of the Strong Heart Study and had subsequent cognitive testing as part of the later adjunct Cerebrovascular Disease and its Consequences in American Indians study were included (n = 790). Regression models examined type 2 diabetes and impaired fasting glucose and subsequent cognitive test performance as part of a longitudinal study design. The relationship between a continuous measure of insulin resistance and later cognitive test performance was assessed using generalized estimating equations.

RESULTS

Controlling for demographic and clinical factors, verbal fluency and processing speed/working memory were significantly negatively associated with having type 2 diabetes and with insulin resistance, but not with impaired fasting glucose.

CONCLUSION

In this sample of American Indians, type 2 diabetes at midlife was associated with subsequent lower performance on measures of executive function. These results may have important implications for future implementation of diagnostic and intervention services in this population.

Effect of Milk and Other Dairy Products on the Risk of Frailty, Sarcopenia, and Cognitive Performance Decline in the Elderly: A Systematic Review

Nutrition is a modifiable factor potentially related to aging. Milk and other dairy products may contribute to the prevention of physical and cognitive impairment. We conducted a systematic review to investigate the effectiveness of dairy product intake for preventing cognitive decline, sarcopenia, and frailty in the elderly population. A systematic search for publications in electronic databases [MEDLINE via PubMed, Embase, Scopus, the Cochrane Central Register of Controlled Trials (CENTRAL), and the Cochrane Database of Systematic Reviews] from 2009 to 2018 identified observational and interventional studies in English and Spanish that tested the relation between dairy product consumption and cognitive decline, sarcopenia, and frailty in community-dwelling older people. We assessed the participants, the type of exposure or intervention, the outcomes, and the quality of evidence. We screened a total of 661 records and included 6 studies (5 observational prospective cohort studies and 1 randomized controlled trial). Regarding cognitive impairment, the relation cannot be firmly established. Consumption of milk at midlife may be negatively associated with verbal memory performance. In older women, high intakes of dairy desserts and ice cream were associated with cognitive decline. On the other hand, 1 study demonstrated a significant inverse relation between dairy intake and development of Alzheimer disease among older Japanese subjects. The consumption of dairy products by older people may reduce the risk of frailty, especially with high consumption of low-fat milk and yogurt, and may also reduce the risk of sarcopenia by improving skeletal muscle mass through the addition of nutrient-rich dairy proteins (ricotta cheese) to the habitual diet. Despite the scarcity of evidence on the topic, our systematic review shows that there are some positive effects of dairy products on frailty and sarcopenia, whereas studies concerning cognitive decline have contradictory findings.

Type 2 Diabetes and Cognitive Functions in Middle Age: A Meta-Analysis

Objectives: Type 2 diabetes mellitus has been linked with cognitive decrement and an increased risk of dementia in older people. Less is known about whether diabetes affects cognition at younger ages. The objective of this meta-analysis was to examine possible differences (effect sizes) in cognitive performance between middle-aged type 2 diabetic patients and healthy controls. Secondary aim was to examine whether age is related to the magnitude of effect sizes. Methods: Electronic databases and lists of references of selected articles were used to search for studies examining type 2 diabetes and cognition in patients under age 65 compared to healthy controls. Twelve studies met the inclusion criteria. Standardized mean differences (Hedges's g) were calculated for main cognitive domains and their subdomains. Association between age and effect sizes was evaluated with meta-regression analyses. Publication bias and methodological quality of the studies were assessed. Results: Patients performed worse than controls in several cognitive functions. The largest differences were found in information processing speed (g = -0.68), attention/concentration (g = -0.55), executive functions (g = -0.51), and working memory (g = -0.51). There was no significance difference in visual memory (g = -0.15). Age was significantly related to the effect size in information processing speed, language, verbal memory and visual memory. However, the direction of association varied across these cognitive domains. Conclusions: The results suggest that cognitive decrement in diabetes is not restricted to older people, but may begin to appear in middle age. More attention should be paid to early recognition and treatment of diabetes-related cognitive decrement in healthcare systems. (JINS, 2019, 25, 215-229).

Perspectives on the production of milk on small-holder dairy farms and its utilisation in developing countries

The profitability of milk production in the developing world varies widely among farming systems. This results from poor animal productivity and an inefficient marketing-chain structure in which farmers seldom profit from their dairying activities. The lack of chilling facilities for milk storage and the need to adulterate the raw product along the market chain to enhance profit margins means that consumers are not well catered for. Co-operative selling of milk, along with the acquisition of higher-quality feeds and veterinary medicines, has boosted the financial resilience of small-holder farming communities worldwide, although, in many regions, the co-operative model has not succeeded largely through a lack of trust between families even within the communities. Commercial reality dictates that farming communities work together to achieve financial sustainability, although the model adopted for each community may differ. Although milk has traditionally provided many consumers with their only source of animal protein, vitamin and minerals, we are now discovering its many other virtues, particularly in relation to cognitive development and memory retention and the provision of antioxidants. The impact of milk-processing technology on some of these remarkable properties requires further investigation to ensure that milk consumers worldwide benefit from these positive attributes.