Intensive glycaemic control and cognitive decline in patients with type 2 diabetes: a meta-analysis

Visit-to-Visit Glucose Variability, Cognition, and Global Cognitive Decline: The Multi-Ethnic Study of Atherosclerosis

CONTEXT

Higher visit-to-visit glucose variability (GV) is associated with dysglycemia and type 2 diabetes (T2D), key risk factors for cognitive decline.

OBJECTIVE

Evaluate the association of GV with cognitive performance and decline in racially/ethnically diverse older populations with and without T2D.

METHODS

We calculated the standard deviation of glucose (SDG), average real variability (ARV), and variability independent of the mean (VIM) among 4367 Multi-Ethnic Study of Atherosclerosis participants over 6 clinical examinations. Participants completed a cognitive assessment at the fifth examination, and a subset completed a second assessment 6 years later. We used multivariable linear regression to estimate the association of intraindividual GV with cognitive test scores after adjustments for cardiovascular risk factors and mean glucose level over the study period.

RESULTS

Two-fold increments in the VIM and SDG were associated with worse Cognitive Abilities Screening Instrument (CASI) performance, while two-fold increments in VIM and ARV were associated with worse Digit Symbol Coding test score. GV measures were not associated with change in CASI performance among 1834 participants with repeat CASI data 6 years later. However, among 229 participants with incident T2D, the SDG and VIM were associated with decline in CASI (-1.7 [95% CI: -3.1, -0.3] and -2.1 [-3.7, -0.5] points, respectively). In contrast, single-timepoint glucose and HbA1c were not associated with CASI decline among participants with or without incident T2D.

CONCLUSION

Higher visit-to-visit GV over 16 to 18 years is associated with worse cognitive performance in the general population, and with modest global cognitive decline in participants with T2D.

Circulating levels of endothelial progenitor cells are associated with better cognitive function in older adults with glucagon-like peptide 1 receptor agonist-treated type 2 diabetes

AIMS

To evaluate cognitive function in subjects with type 2 diabetes (T2D) treated with glucagon-like peptide 1 receptor agonist (GLP-1RA) plus metformin or metformin alone and its association with endothelial progenitor cells (EPCs).

METHODS

Adults with T2D treated with GLP-1RA plus metformin (GLP-1RA + MET) or MET alone for at least 12 months were included. Montreal Cognitive Assessment test (MoCA), Mini-Mental State Examination (MMSE), Mini Nutritional Assessment (MNA) and disability tests were administered. Circulating levels of seven EPCs phenotypes were measured by flow cytometry.

RESULTS

A total of 154 elderly patients were included, of whom 78 in GLP-1RA + MET group and 76 in MET group. The GLP-1RA + MET group showed better cognitive function as indicated by a significant higher MoCA and MMSE scores, and higher levels of CD34⁺ CD133⁺, CD133⁺ KDR⁺, and CD34⁺ CD133⁺ KDR⁺ as compared with MET group. The number of CD34⁺ CD133⁺ KDR⁺ cells was an independent predictor of higher MoCA, MMSE and MNA scores.

CONCLUSIONS

People with T2D on GLP-1RA + MET treatment had better cognitive function and higher circulating levels of EPCs as compared with those on MET alone warranting further studies to understand the interrelationship between EPCs, GLP-RA treatment and cognitive health.

Diabetes, Hypertension, and the Risk of Dementia

Background: Type 2 diabetes (T2D) and hypertension (HTN) are well-known modifiable risk factors for dementia, but their intricate attributes accounting for dementia development has not been clearly delineated. Objective: We conducted this study to investigate and compare the effects of T2D and HTN on dementia risk. Methods: We screened data of matched pairs of patients with T2D or HTN between January 1, 2000 and December 31, 2017 from Taiwan’s National Health Insurance Research Database. Fine and Gray’s subdistribution hazard models were used for calculating the risk of dementia. Results: Patients with T2D and subsequent HTN were associated with significantly higher risks of all-cause dementia (aHR 1.51, 95% CI 1.25–1.83) and vascular dementia (aHR 2.30, 95% CI 1.71–3.13) compared with those without subsequent HTN. Patients with HTN and subsequent T2D were associated with significantly higher risks of all-cause dementia (aHR 1.15, 95% CI 1.08–1.21), vascular dementia (aHR 1.25, 95% CI 1.62–1.34), and other dementia (aHR 1.31, 95% CI 1.03–1.66) compared with those without subsequent HTN. The subgroups of male and female patients, age of 50–69 and 70–90 years with subsequent comorbidity were associated with significantly higher risks of all-cause dementia and vascular dementia than those without subsequent comorbidity. Conclusion: This nationwide cohort study demonstrated that patients with T2D and subsequent HTN had association with higher risks of all-cause dementia and vascular dementia, and those with HTN and subsequent T2D were associated with higher risks of all-cause dementia, vascular dementia, and other dementia.

Diagnostic, Prognostic, and Mechanistic Biomarkers of Diabetes Mellitus-Associated Cognitive Decline

Cognitive dysfunctions such as mild cognitive impairment (MCI), Alzheimer’s disease (AD), and other forms of dementia are recognized as common comorbidities of type 2 diabetes mellitus (T2DM). Currently, there are no disease-modifying therapies or definitive clinical diagnostic and prognostic tools for dementia, and the mechanisms underpinning the link between T2DM and cognitive dysfunction remain equivocal. Some of the suggested pathophysiological mechanisms underlying cognitive decline in diabetes patients include hyperglycemia, insulin resistance and altered insulin signaling, neuroinflammation, cerebral microvascular injury, and buildup of cerebral amyloid and tau proteins. Given the skyrocketing global rates of diabetes and neurodegenerative disorders, there is an urgent need to discover novel biomarkers relevant to the co-morbidity of both conditions to guide future diagnostic approaches. This review aims to provide a comprehensive background of the potential risk factors, the identified biomarkers of diabetes-related cognitive decrements, and the underlying processes of diabetes-associated cognitive dysfunction. Aging, poor glycemic control, hypoglycemia and hyperglycemic episodes, depression, and vascular complications are associated with increased risk of dementia. Conclusive research studies that have attempted to find specific biomarkers are limited. However, the most frequent considerations in such investigations are related to C reactive protein, tau protein, brain-derived neurotrophic factor, advanced glycation end products, glycosylated hemoglobin, and adipokines.

Type 2 diabetes mellitus accelerates brain aging and cognitive decline: Complementary findings from UK Biobank and meta-analyses

Background

Type 2 diabetes mellitus (T2DM) is known to be associated with neurobiological and cognitive deficits; however, their extent, overlap with aging effects, and the effectiveness of existing treatments in the context of the brain are currently unknown.

Methods

We characterized neurocognitive effects independently associated with T2DM and age in a large cohort of human subjects from the UK Biobank with cross-sectional neuroimaging and cognitive data. We then proceeded to evaluate the extent of overlap between the effects related to T2DM and age by applying correlation measures to the separately characterized neurocognitive changes. Our findings were complemented by meta-analyses of published reports with cognitive or neuroimaging measures for T2DM and healthy controls (HCs). We also evaluated in a cohort of T2DM-diagnosed individuals using UK Biobank how disease chronicity and metformin treatment interact with the identified neurocognitive effects.

Results

The UK Biobank dataset included cognitive and neuroimaging data (N = 20,314), including 1012 T2DM and 19,302 HCs, aged between 50 and 80 years. Duration of T2DM ranged from 0 to 31 years (mean 8.5 ± 6.1 years); 498 were treated with metformin alone, while 352 were unmedicated. Our meta-analysis evaluated 34 cognitive studies (N = 22,231) and 60 neuroimaging studies: 30 of T2DM (N = 866) and 30 of aging (N = 1088). Compared to age, sex, education, and hypertension-matched HC, T2DM was associated with marked cognitive deficits, particularly in executive functioning and processing speed. Likewise, we found that the diagnosis of T2DM was significantly associated with gray matter atrophy, primarily within the ventral striatum, cerebellum, and putamen, with reorganization of brain activity (decreased in the caudate and premotor cortex and increased in the subgenual area, orbitofrontal cortex, brainstem, and posterior cingulate cortex). The structural and functional changes associated with T2DM show marked overlap with the effects correlating with age but appear earlier, with disease duration linked to more severe neurodegeneration. Metformin treatment status was not associated with improved neurocognitive outcomes.

Conclusions

The neurocognitive impact of T2DM suggests marked acceleration of normal brain aging. T2DM gray matter atrophy occurred approximately 26% ± 14% faster than seen with normal aging; disease duration was associated with increased neurodegeneration. Mechanistically, our results suggest a neurometabolic component to brain aging. Clinically, neuroimaging-based biomarkers may provide a valuable adjunctive measure of T2DM progression and treatment efficacy based on neurological effects.

Funding

The research described in this article was funded by the W. M. Keck Foundation (to LRMP), the White House Brain Research Through Advancing Innovative Technologies (BRAIN) Initiative (NSFNCS-FR 1926781 to LRMP), and the Baszucki Brain Research Fund (to LRMP). None of the funding sources played any role in the design of the experiments, data collection, analysis, interpretation of the results, the decision to publish, or any aspect relevant to the study. DJW reports serving on data monitoring committees for Novo Nordisk. None of the authors received funding or in-kind support from pharmaceutical and/or other companies to write this article.

New Horizons-Cognitive Dysfunction Associated With Type 2 Diabetes

The prevalence of type 2 diabetes (T2D) and cognitive dysfunction increases with age. As society ages, clinicians will be increasingly tasked with managing older people who have both T2D and cognitive dysfunction. T2D is associated with an increased risk of cognitive dysfunction and hence there is increasing interest in whether T2D is a causal factor in the pathogenesis of cognitive decline and dementia. Recent advances in the use of sensitive measures of in vivo brain dysfunction in life-course studies can help understand potential mechanistic pathways and also help guide recommendations for clinical practice. In this article we will describe new horizons in the understanding of cognitive dysfunction associated with T2D. Coming from a clinical perspective, we discuss potential mechanisms and pathways linking the 2 conditions and the contribution of multimodal neuroimaging and study designs to advancing understanding in the field. We also highlight the important issues on the horizon that will need addressing in clinical identification, management, and risk reduction for people with coexistent T2D and cognitive dysfunction.

Trials and Treatments for Vascular Brain Health: Risk Factor Modification and Cognitive Outcomes

There is robust evidence linking vascular health to brain health, cognition, and dementia. In this article, we present evidence from trials of vascular risk factor treatment on cognitive outcomes. We summarize findings from randomized controlled trials of antihypertensives, lipid-lowering medications, diabetes treatments (including antidiabetic drugs versus placebo, and intensive versus standard glycemic control), and multidomain interventions (that target several domains simultaneously such as control of vascular and metabolic factors, nutrition, physical activity, and cognitive stimulation etc). We report that evidence on the efficacy of vascular risk reduction interventions is promising, but not yet conclusive, and several methodological limitations hamper interpretation. Evidence mainly comes from high-income countries and, as cognition and dementia have not been the primary outcomes of many trials, evaluation of cognitive changes have often been limited. As the cognitive aging process occurs over decades, it is unclear whether treatment during the late-life window is optimal for dementia prevention, yet older individuals have been the target of most trials thus far. Further, many trials have not been powered to explore interactions with modifiers such as age, race, and apolipoprotein E, even though sub-analyses from some trials indicate that the success of interventions differs depending on patient characteristics. Due to the complex multifactorial etiology of dementia, and variations in risk factors between individuals, multidomain interventions targeting several risk factors and mechanisms are likely to be needed and the long-term sustainability of preventive interventions will require personalized approaches that could be facilitated by digital health tools. This is especially relevant during the coronavirus disease 2019 (COVID-19) pandemic, where intervention strategies will need to be adapted to the new normal, when face-to-face engagement with participants is limited and public health measures may create changes in lifestyle that affect individuals’ vascular risk profiles and subsequent risk of cognitive decline.

A Primary Care Agenda for Brain Health: A Scientific Statement From the American Heart Association

A healthy brain is critical for living a longer and fuller life. The projected aging of the population, however, raises new challenges in maintaining quality of life. As we age, there is increasing compromise of neuronal activity that affects functions such as cognition, also making the brain vulnerable to disease. Once pathology-induced decline begins, few therapeutic options are available. Prevention is therefore paramount, and primary care can play a critical role. The purpose of this American Heart Association scientific statement is to provide an up-to-date summary for primary care providers in the assessment and modification of risk factors at the individual level that maintain brain health and prevent cognitive impairment. Building on the 2017 American Heart Association/American Stroke Association presidential advisory on defining brain health that included "Life's Simple 7," we describe here modifiable risk factors for cognitive decline, including depression, hypertension, physical inactivity, diabetes, obesity, hyperlipidemia, poor diet, smoking, social isolation, excessive alcohol use, sleep disorders, and hearing loss. These risk factors include behaviors, conditions, and lifestyles that can emerge before adulthood and can be routinely identified and managed by primary care clinicians.

The relationship between heart disease and cognitive impairment

Neurodegenerative dementias, such as Alzheimer's disease, and vascular cognitive impairment were once considered unrelated processes. Emerging evidence, however, shows that both conditions often coexist and that vascular risk factors in midlife predispose to the development of cognitive decline later in older adults. In addition, recent advanced in basic science research have elucidated key underpinnings of this association. In this chapter, we review the clinical and basic science data that explain the relationship between vascular risk factors, heart disease, and cognitive decline.

Effect of poor glycemic control in cognitive performance in the elderly with type 2 diabetes mellitus: The Mexican Health and Aging Study

Background

Cognitive impairment is twice more frequent in elderly with type 2 diabetes mellitus (DM). This study was conducted to determine the association between glycemic control and cognitive performance among community-dwelling elderly persons in Mexico.

Methods

Cross-sectional study conducted in individuals aged 60 years or elderly participating in the 2012 Mexican Health and Aging Study. Type 2 DM participants were classified in 3 groups according to their glycated hemoglobin levels (Hb_A1c): < 7% (intensive control), 7–7.9% (standard control) or ≥ 8% (poor control), and cognitive performance: low (CCCE ≤44 points), intermediate (44.1–59.52 points), or high (≥59.53 points). Multinomial logistic regression models were constructed to determine this association.

Results

Two hundred sixteen community-dwelling adults aged 60 and older with type 2 diabetes were selected. Subjects in the low cognitive performance group were older (69.7 ± 6.6 vs 65.86 ± 5.18 years, p < .001) and had a lower educational level (2.5 ± 2.6 vs 7.44 ± 4.15 years, p < .000) when compared to the high cognitive performance participants. Hb_A1c ≥ 8% was associated with having low (Odds Ratio (OR) 3.17, 95% CI 1.17–8.60, p = .024), and intermediate (OR 3.23, 95% CI 1.27–8.20, p = .014) cognitive performance; this trend was not found for Hb_A1c 7.0–7.9% group.

The multinomial regression analysis showed that the presence of Hb_A1c ≥ 8% (poor glycemic control) was associated with low (OR 3.17, 95% CI = 1.17–8.60, p = .024), and intermediate (OR 3.23, 95% CI = 1.27–8.20, p = .014) cognitive performance. After adjusting for confounding variables.

Conclusions

Glycemic control with a Hb_A1c ≥ 8% was associated with worse cognitive performance.

Type 2 diabetes and cognitive dysfunction-towards effective management of both comorbidities

Type 2 diabetes and cognitive dysfunction are highly prevalent disorders worldwide. Although type 2 diabetes is associated with an increased risk of dementia, awareness of the link between the two conditions is poor, and few recommendations are available to guide clinicians about how to approach cognitive dysfunction in people with diabetes. Clinical guidelines in diabetes have only recently begun to emphasise the importance of cognitive impairment in diabetes and its management. This Series paper aims to synthesise knowledge about the link between diabetes and cognitive dysfunction, issues pertaining to screening and diagnosis of cognitive impairment and dementia in those with type 2 diabetes, management of diabetes in people with cognitive dysfunction (accounting for age and frailty), and emerging therapies for prevention. A conceptual framework for approaching screening and diagnosis is included, and future research directions to guide the field forward are suggested.

Neurocognitive impairment in type 2 diabetes mellitus

There is emerging evidence that cognitive impairment could be a diabetes mellitus-related complication. It has been suggested that diabetic people are at increased risk of cognitive decline, since the metabolic and vascular disturbances of the disease affect brain function. Additionally, prolonged exposure to olther potential detrimental factors leads to irreversible cognitive decrements over time due to the aging process. Neurocognitive impairment signifies decreased performance in cognitive domains such as verbal and nonverbal memory, both immediate and delayed memory, executive function, attention, visuospatial and psychomotor performance, information processing speed, semantic knowledge, and language abilities. The aim of the present article is to review the existing literature on the issue of the neurocognitive decline in type 2 diabetes. A literature search of databases was performed, using as keywords "diabetes" and "cognitive impairment," and the reference list of papers so identified were examined, with only English language papers being used. Understanding and preventing diabetes-associated cognitive deficits remains a key priority for future research. It is important to ascertain whether interventions to delay diabetes onset or better control of established disease could prevent some of its adverse effects on cognitive skills.

Factors influencing safe glucose-lowering in older adults with type 2 diabetes: A PeRsOn-centred ApproaCh To IndiVidualisEd (PROACTIVE) Glycemic Goals for older people: A position statement of Primary Care Diabetes Europe

Diabetes in later life is associated with a range of factors increasing the complexity of glycaemic management. This position statement, developed from an extensive literature review of the subject area, represents a consensus opinion of primary care clinicians and diabetes specialists. It highlights many challenges facing older people living with type 2 diabetes and aims to support primary care clinicians in advocating a comprehensive, holistic approach. It emphasises the importance of the wishes of the individual and their carers when determining glycaemic goals, as well as the need to balance intended benefits of treatment against the risk of adverse treatment effects. Its ultimate aim is to promote consistent high-quality care for older people with diabetes.

Characterizing, Assessing, and Treating Cognitive Dysfunction in Major Depressive Disorder

LEARNING OBJECTIVES

After participating in this activity, learners should be better able to:• Characterize cognitive dysfunction in patients with major depressive disorder.• Evaluate approaches to treating cognitive dysfunction in patients with major depressive disorder.

ABSTRACT

Cognitive dysfunction is a core psychopathological domain in major depressive disorder (MDD) and is no longer considered to be a pseudo-specific phenomenon. Cognitive dysfunction in MDD is a principal determinant of patient-reported outcomes, which, hitherto, have been insufficiently targeted with existing multimodal treatments for MDD. The neural structures and substructures subserving cognitive function in MDD overlap with, yet are discrete from, those subserving emotion processing and affect regulation. Several modifiable factors influence the presence and extent of cognitive dysfunction in MDD, including clinical features (e.g., episode frequency and illness duration), comorbidity (e.g., obesity and diabetes), and iatrogenic artefact. Screening and measurement tools that comport with the clinical ecosystem are available to detect and measure cognitive function in MDD. Notwithstanding the availability of select antidepressants capable of exerting procognitive effects, most have not been sufficiently studied or rigorously evaluated. Promising pharmacological avenues, as well as psychosocial, behavioral, chronotherapeutic, and complementary alternative approaches, are currently being investigated.

Cognitive impairment in patients with type 2 diabetes mellitus: prevalence, pathogenetic mechanisms, the effect of antidiabetic drugs

In recent years, a large amount of data has been accumulated on the relationship between cognitive impairment, dementia and diabetes mellitus. This article presents an overview of modern literature, including the definition of cognitive functions, the modern classification of cognitive impairment, pathogenetic mechanisms of diabetes mellitus influence on the development of cognitive impairment and dementia (neurogenesis, integrity of the blood-brain barrier, systemic inflammatory reactions, hyper- and hypoglycemia, insulin resistance, vascular dysfunction of the microvasculature and increase in glucocorticosteroids). The influence of anti-diabetic medications on cognitive functions has been examined in detail: insulin preparations, oral hypoglycemic agents of the biguanide group (metformin), thiazolidinediones (rosiglitazone and pioglitazone), sulfonylurea derivatives (glycazide, glipizide), a-glucosidase (acarbose) inhibitors, incretin-directed therapy (receptor agonists glucan-like peptide (exenatide and liraglutide) and inhibitors of dipeptidylpeptidase type 4 (sitagliptin, vildagliptin and alogliptin)), sodium glucose inhibitors cotransporter type 2. The data demonstrating a multidirectional effect on the cognitive functions of various antidiabetic drugs is presented, the possible influence on the rate of progression of cognitive impairment and the risk of dementia of intensive control of plasma glucose level in comparison with the standard decrease in patients with type 2 diabetes is analyzed.

Rationale and design of the CAROLINA® - cognition substudy: a randomised controlled trial on cognitive outcomes of linagliptin versus glimepiride in patients with type 2 diabetes mellitus

Background

Type 2 diabetes mellitus is associated with cognitive dysfunction and an increased risk of dementia. Linagliptin is a glucose-lowering agent of the dipeptidyl peptidase-IV (DPP-IV) inhibitor class that is of particular interest for the prevention of accelerated cognitive decline, because it may potentially benefit the brain through pleiotropic effects, beyond glucose lowering. This paper presents the design of a study that aims to establish if linagliptin is superior to the sulfonylurea glimepiride in the prevention of accelerated cognitive decline in patients with type 2 diabetes mellitus.

Methods

The cognition substudy is an integral part of the ongoing event-driven, randomised, double blind CARdiOvascular safety of LINAgliptin (CAROLINA®) trial, which evaluates the effect of treatment with linagliptin versus glimepiride on cardiovascular outcomes. CAROLINA® includes patients with type 2 diabetes mellitus with sub-optimal glycaemic control at elevated cardiovascular risk. The substudy will evaluate patients randomised and treated who have a baseline Mini Mental State Examination (MMSE) score ≥ 24, documented years of formal education with at least one valid cognitive assessment at baseline and during follow-up. The primary cognitive outcome is the occurrence of accelerated cognitive decline at the end of follow-up. The two treatment groups will be compared by using a logistic regression. Accelerated cognitive decline is defined as a rate of cognitive decline that falls at or below the 16th percentile of decline for the whole cohort on either the MMSE or a combined score of the trail making and verbal fluency test. Potential confounders are taken into account at an individual patient level, using a regression based index.

Discussion

Between December 2010 and December 2012, 6042 patients were randomised and treated with either linagliptin (5 mg) or glimepiride (1-4 mg) once daily in CAROLINA®. Cognitive tests were conducted in nearly 4500 participants at baseline and are scheduled for two subsequent assessments, after 160 weeks of follow-up and end of follow-up. This substudy of the ongoing CAROLINA® trial will establish if linagliptin is superior to glimepiride in the prevention of accelerated cognitive decline in patients with type 2 diabetes mellitus. Final results are expected in 2019.

Trial registration

ClinicalTrials.gov Identifier: NCT 01243424.

Electronic supplementary material

The online version of this article (10.1186/s12883-018-1014-7) contains supplementary material, which is available to authorized users.

Effect of the treatment of Type 2 diabetes mellitus on the development of cognitive impairment and dementia

BACKGROUND

Prevention of cognitive impairment and dementia is an important public health goal. Epidemiological evidence shows a relationship between cognitive impairment and Type 2 diabetes mellitus. The risk of dementia increases with duration of disease. This updated systematic review investigated the effect on cognitive function of the type of treatment and level of metabolic control in people with Type 2 diabetes.

OBJECTIVES

To assess the effects of different strategies for managing Type 2 diabetes mellitus on cognitive function and the incidence of dementia.

SEARCH METHODS

We searched ALOIS (the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG)), the Cochrane Library, MEDLINE, Embase, PsycINFO, CINAHL and LILACS on 15 October 2016. ALOIS contains records from all major health care databases, (CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS), as well as from many trials' registers and grey literature sources.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) which compared two or more different treatments for Type 2 diabetes mellitus and in which cognitive function was measured at baseline and after treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the quality of the included RCTs. We pooled data for comparable trials and estimated the effects of treatment by using risk ratios (RRs) and mean differences (MDs), according to the nature of the outcome. We assessed the quality of the evidence using GRADE methods.

MAIN RESULTS

We identified seven eligible studies but only four provided data we could include in efficacy analyses. Two of these studies compared intensive versus standard glycaemic control and two compared different pharmacological treatments. All studies were at unclear risk of bias in at least two domains and one large study was at high risk of performance and detection bias.(a) Two studies with 13,934 participants at high cardiovascular risk provided efficacy data on intensive versus standard glycaemic control. A third study with 1791 participants provided additional data on hypoglycaemic episodes and mortality. There is probably no difference between treatment groups in the number of participants who decline by at least 3 points on the Mini-Mental State Examination (MMSE) over five years (RR 0.98, 95% CI 0.88 to 1.08; 1 study; n = 11,140; moderate-quality evidence); and there may also be little or no difference in the incidence of dementia (RR 1.27, 95% CI 0.87 to 1.85; 1 study; n = 11,140; low-quality evidence). From another study, there was probably little or no difference in MMSE score after 40 months (MD -0.01, 95% CI -0.18 to 0.16; 1 study; n = 2794; moderate quality evidence). Participants exposed to the intensive glycaemic control strategy probably experience more episodes of severe hypoglycaemia than those who have standard treatment (RR 2.18, 95% CI 1.52 to 3.14; 2 studies; n = 12,827; moderate-quality evidence). The evidence from these trials suggests that the intensity of glycaemic control may have little or no effect on all-cause mortality (RR 0.99, 95% CI 0.87 to 1.13; 3 studies; n = 15,888; low-quality evidence).(b) One study with 156 participants compared glibenclamide (glyburide) with repaglinide. There may be a small advantage of glibenclamide on global cognitive function measured with the MMSE after 12 months (MD -0.90, 95% CI -1.68 to -0.12; low-quality evidence). No data were reported on the incidence of dementia, hypoglycaemic events or all-cause mortality.(c) One study with 145 participants compared rosiglitazone plus metformin to glibenclamide (glyburide) plus metformin over 24 weeks. It reported only on cognitive subdomains and not on global cognitive function, incidence of MCI or dementia, hypoglycaemic events or all causes of mortality.

AUTHORS' CONCLUSIONS

We found no good evidence that any specific treatment or treatment strategy for Type 2 diabetes can prevent or delay cognitive impairment. The best available evidence related to the comparison of intensive with standard glycaemic control strategies. Here there was moderate-quality evidence that the strategies do not differ in their effect on global cognitive functioning over 40 to 60 months.

Type 2 diabetes, depressive symptoms and trajectories of cognitive decline in a national sample of community-dwellers: A prospective cohort study

We examined the individual and synergistic effects of type 2 diabetes and elevated depressive symptoms on memory and executive function trajectories over 10 and eight years of follow-up, respectively. Our sample comprised 10,524 community-dwellers aged ≥50 years in 2002–03 from the English Longitudinal Study of Ageing. With respect to memory (word recall), participants with either diabetes or elevated depressive symptoms recalled significantly fewer words compared with those free of these conditions (reference category), but more words compared with those with both conditions. There was a significant acceleration in the rate of memory decline in participants aged 50–64 years with both conditions (-0.27, 95% CI, -0.45 to -0.08, per study wave), which was not observed in those with either condition or aged ≥65 years. With respect to executive function (animal naming), participants aged ≥65 years with diabetes or those with elevated depressive symptoms named significantly fewer animals compared with the reference category, while those with both conditions named fewer animals compared with any other category. The rate of executive function decline was significantly greater in participants with both conditions (-0.54, 95% CI, -0.99 to -0.10; and –0.71, 95% CI, -1.16 to -0.27, per study wave, for those aged 50–64 and ≥65 years, respectively), but not in participants with either condition. Diabetes and elevated depressive symptoms are inversely associated with memory and executive function, but, individually, do not accelerate cognitive decline. The co-occurrence of diabetes and elevated depressive symptoms significantly accelerates cognitive decline over time, especially among those aged 50–64 years.

Short residence duration was associated with asthma but not cognitive function in the elderly: USA NHANES, 2001-2002

There has been a growing interest in how the built environment affects health and well-being. Housing characteristics are associated with human health while environmental chemicals could have mediated the effects. However, it is unclear if and how residence duration might have a role in health and well-being. Therefore, the aim of the present study was to investigate the associations among residence duration, common chronic diseases, and cognitive function in older adults in a national and population-based setting. Data were extracted from the US National Health and Nutrition Examination Survey, 2001-2002, with assessment information on demographics, lifestyle factors, housing characteristics, self-reported common chronic diseases, and cognitive function by using the digit symbol substitution test from the Wechsler Adult Intelligence Scale (a measurement of attention and psychomotor speed). Statistical analyses including the chi-square test, t test, and survey-weighted general linear modeling and logistic regression modeling were performed. Residence duration was significantly associated with risk of asthma but not with other chronic disease, showing a longer stay in the same housing leading to lower risk of asthma (OR 0.43, 95%CI 0.27-0.69, P = 0.002) among the American older adults. However, having asthma was not associated with cognitive function decline. In conclusion, residence duration was found to be associated with risk of asthma but not cognitive function. Future research examining the relationship of residence duration and cognitive tests by other domains of cognitive function following asthma episodes would be suggested. For practice and policy implications, familiarity with the housing environment might help with lessening respiratory symptoms.

Potential effects of current drug therapies on cognitive impairment in patients with type 2 diabetes

Type 2 diabetes mellitus is a complex metabolic disease that can cause serious damage to various organs. Among the best-known complications, an important role is played by cognitive impairment. Impairment of cognitive functioning has been reported both in type 1 and 2 diabetes mellitus. While this comorbidity has long been known, no major advances have been achieved in clinical research; it is clear that appropriate control of blood glucose levels represents the best current (although unsatisfactory) approach in the prevention of cognitive impairment. We have focused our attention on the possible effect on the brain of antidiabetic drugs, despite their effects on blood glucose levels, giving a brief rationale on the mechanisms (e.g. GLP-1, BDNF, ghrelin) that might be involved. Indeed, GLP-1 agonists are currently clinically studied in other neurodegenerative diseases (i.e. Parkinson's and Alzheimer's disease); furthermore, also other antidiabetic drugs have proven efficacy in preclinical studies. Overall, promising results are already available and finding new intervention strategies represents a current need in this field of research.

Risk factors of gender for renal progression in patients with early chronic kidney disease

Risk factors for chronic kidney disease (CKD), such as hypertension, hyperglycemia, albuminuria, renal structure, and sex hormones, have been reported to have different effects on males and females. Thus, CKD progression may differ depending on sex. In addition to CKD management, treatment at earlier stages can reduce complications and prevent disease progression as well as high medical expenses at late stages. We examined the differences in predictive risk factors for renal progression between male and female patients with early CKD.This case-cohort study recruited patients aged 18 years or older treated in the outpatient departments of 8 hospitals in Taiwan between August 2008 and September 2014. In total, 1530 patients were included in the analysis. Renal progression was defined as ≥25% decline based on baseline estimated glomerular filtration rate. To examine the predictive risk factors for renal progression, we constructed a subset multivariate logistic model with stepwise variable selection by using P < 0.10 for variable retention.The numbers of male and female patients with CKD exhibiting renal progression were 100 (11.64%) and 84 (12.52%), respectively. After adjusting for all the potential confounders, stepwise logistic regression analysis showed that main independent predictive risk factors for the male patients- (C statistic = 0.72) were proteinuria (odds ratio [OR] 2.20; 95% confidence interval [CI] 1.26-3.84), age (OR 1.04; 95% CI 1.02-1.06), anemia (OR 2.75; 95% CI 1.20-6.30), and poor control of blood pressure (OR 1.84; 95% CI 1.05-3.22). However, the main independent predictive factors for the female patients were (C statistic = 0.75) poor glycemic control (OR 2.28; 95% CI 1.22-4.25), poor blood pressure control (OR 1.93; 95% CI 1.06-3.50), and family income (OR 2.51; 95% CI 1.01-6.20).In conclusion, this study demonstrated that proteinuria was the most crucial risk factor for male patients, whereas poor glycemic control was the main risk factor for female patients. Poor blood pressure control was a shared risk factor for male and female patients.

Potentials of incretin-based therapies in dementia and stroke in type 2 diabetes mellitus

Patients with type 2 diabetes mellitus are at risk for accelerated cognitive decline and dementia. Furthermore, their risk of stroke is increased and their outcome after stroke is worse than in those without diabetes. Incretin-based therapies are a class of antidiabetic agents that are of interest in relation to these cerebral complications of diabetes. Two classes of incretin-based therapies are currently available: the glucagon-like-peptide-1 agonists and the dipeptidyl peptidase-4 -inhibitors. Independent of their glucose-lowering effects, incretin-based therapies might also have direct or indirect beneficial effects on the brain. In the present review, we discuss the potential of incretin-based therapies in relation to dementia, in particular Alzheimer's disease, and stroke in patients with type 2 diabetes. Experimental studies on Alzheimer's disease have found beneficial effects of incretin-based therapies on cognition, synaptic plasticity and metabolism of amyloid-β and microtubule-associated protein tau. Preclinical studies on incretin-based therapies in stroke have shown an improved functional outcome, a reduction of infarct volume as well as neuroprotective and neurotrophic properties. Both with regard to the treatment of Alzheimer's disease, and with regard to prevention and treatment of stroke, randomized controlled trials in patients with or without diabetes are underway. In conclusion, experimental studies show promising results of incretin-based therapies at improving the outcome of Alzheimer's disease and stroke through glucose-independent pleiotropic effects on the brain. If these findings would indeed be confirmed in large clinical randomized controlled trials, this would have substantial impact.

The impact of diabetes on cognitive decline: potential vascular, metabolic, and psychosocial risk factors

Older people with type 2 diabetes are at increased risk of developing cognitive impairment, for which several potential risk factors have been proposed. The present article reviews evidence in people with type 2 diabetes for associations of cognitive impairment with a range of vascular, metabolic, and psychosocial risk factors, many of which have a higher prevalence in people with type 2 diabetes than in non-diabetic adults of a similar age. Definitive research studies in this field are few in number. The risk factors may be involved in causal pathways or may act as useful markers of cerebrovascular damage (or both), and for which relatively consistent evidence is available, include poor glycemic control, hypoglycemia, microvascular disease, inflammation, and depression. For macrovascular disease, the strength of the association with cognitive impairment appears to depend on which vascular system has been examined. A role for pre-morbid ability in young adulthood as influencing the risk of both diabetes and cognitive impairment has also been suggested. The importance of considering inter-relationships between risk factors when investigating their potential contribution to cognitive impairment in future investigations is discussed.

Self-Care Behaviors and Glycemic Control in Low-Income Adults in México With Type 2 Diabetes Mellitus May Have Implications for Patients of Mexican Heritage Living in the United States

This study examined self-care behaviors and their relationship to glycemic control in low-income Mexican adults with type 2 diabetes in Southeastern Tamaulipas, México. A total of 135 patients were enrolled from 17 community health centers. The most frequent self-care behavior was medication management (80%), and the least frequent self-care behavior was self blood glucose monitoring (7%). All the patients demonstrated poor glycemic control, with glycated hemoglobin > 7%. Self-care behaviors were associated with fasting blood glucose (rs = .223, p = .005). Medication management was influenced by cognitive performance, F(1, 130) = 4.49, p = .036, and depression, F(1, 130) = 8.22, p = .005. Dietary behaviors were influenced by previous diabetes education, F(1, 130) = 6.73, p = .011. These findings indicate that education and cognitive behavioral interventions in Spanish for Mexican adults with type 2 diabetes are urgently needed.