Diabetes as a risk factor for dementia and mild cognitive impairment: a meta-analysis of longitudinal studies

Optimal therapy of type 2 diabetes: a controversial challenge

Type 2 diabetes mellitus (T2DM) is one of the most common chronic disorders in older adults and the number of elderly diabetic subjects is growing worldwide. Nonetheless, the diagnosis of T2DM in elderly population is often missed or delayed until an acute metabolic emergency occurs. Accumulating evidence suggests that both aging and environmental factors contribute to the high prevalence of diabetes in the elderly. Clinical management of T2DM in elderly subjects presents unique challenges because of the multifaceted geriatric scenario. Diabetes significantly lowers the chances of "successful" aging, notably it increases functional limitations and impairs quality of life. In this regard, older diabetic patients have a high burden of comorbidities, diabetes-related complications, physical disability, cognitive impairment and malnutrition, and they are more susceptible to the complications of dysglycemia and polypharmacy. Several national and international organizations have delivered guidelines to implement optimal therapy in older diabetic patients based on individualized treatment goals. This means appreciation of the heterogeneity of the disease as generated by life expectancy, functional reserve, social support, as well as personal preference. This paper will review current treatments for achieving glycemic targets in elderly diabetic patients, and discuss the potential role of emerging treatments in this patient population.

Dementia and cognitive decline in type 2 diabetes and prediabetic stages: towards targeted interventions

Type 2 diabetes is associated with dementia, and also with more slight cognitive decrements. In this Review we discuss trajectories from normal cognition to dementia in people with type 2 diabetes, and explore opportunities for treatment. Slight diabetes-associated cognitive decrements and dementia affect different age groups and show a different evolution. These cognitive entities should therefore not be regarded as a continuum, although their effects might be additive. Vascular damage is a key underlying process in both entities. Glucose-mediated processes and other metabolic disturbances might also have a role. No treatment has been established, but management of vascular risk factors and optimisation of glycaemic control could have therapeutic benefit. We identify possible opportunities for intervention to improve cognitive outcomes in people with type 2 diabetes, and suggest how treatment can be tailored to individual risk profiles and comorbidities.

Dietary Mineral Intake and Risk of Mild Cognitive Impairment: The PATH through Life Project

BACKGROUND

Higher dietary intake of potassium, calcium, and magnesium is protective against ischemic strokes while also being associated with a decreased risk of all-cause dementia. The effect of dietary iron intake on cerebral function is less clear but iron is also implicated in Alzheimer neuropathology. The aim of this study was to investigate whether dietary intake of these minerals was also associated with increased risk of mild cognitive impairment (MCI, amnestic) and other mild cognitive disorders (MCD).

METHODS

Associations between dietary mineral intake and risk of MCI/MCD were assessed in cognitively healthy individuals (n = 1406, 52% female, mean age 62.5 years) living in the community, who were followed up over 8 years. Relative risk was assessed with Cox hazard ratios (HRs) after controlling for health and socio-demographic covariates.

RESULTS

Higher magnesium intake was associated with a reduced risk of developing MCI/MCD (MCI: HR 0.07, 95% confidence interval (CI) 0.01-0.56, p = 0.013; MCD: HR 0.47, 95% CI 0.22-0.99, p = 0.046) in multivariate analyses. Higher intake of potassium (MCI: HR 1.09, 95% CI 1.01-1.17, p = 0.028; MCD: HR 1.05, 95% CI 0.99-1.10, p = 0.107) and iron (MCI: HR 1.54, 95% CI 1.03-2.29, p = 0.034) was associated with an increased risk of developing MCI/MCD.

CONCLUSION

These findings suggest that dietary intake of minerals known to be implicated in biological processes associated with vascular and Alzheimer's pathology may contribute to disease progression earlier in the disease process and require further attention.

Diabetes Mellitus and Blood-Brain Barrier Dysfunction: An Overview

A host of diabetes-related insults to the central nervous system (CNS) have been clearly documented in type-1 and -2 diabetic patients as well as experimental animal models. These host of neurological disorders encompass hemodynamic impairments (e.g., stroke), vascular dementia, cognitive deficits (mild to moderate), as well as a number of neurochemical, electrophysiological and behavioral alterations. The underlying causes of diabetes-induced CNS complications are multifactorial and are relatively little understood although it is now evident that blood-brain barrier (BBB) damage plays a significant role in diabetes-dependent CNS disorders. Changes in plasma glucose levels (hyper- or hypoglycemia) have been associated with altered BBB transport functions (e.g., glucose, insulin, choline, amino acids, etc.), integrity (tight junction disruption), and oxidative stress in the CNS microcapillaries. Last two implicating a potential causal role for upregulation and activation of the receptor for advanced glycation end products (RAGE). This type I membrane-protein also transports amyloid-beta (Aβ) from the blood into the brain across the BBB thus, establishing a link between type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD, also referred to as "type 3 diabetes"). Hyperglycemia has been associated with progression of cerebral ischemia and the consequent enhancement of secondary brain injury. Difficulty in detecting vascular impairments in the large, heterogeneous brain microvascular bed and dissecting out the impact of hyper- and hypoglycemia in vivo has led to controversial results especially with regard to the effects of diabetes on BBB. In this article, we review the major findings and current knowledge with regard to the impact of diabetes on BBB integrity and function as well as specific brain microvascular effects of hyper- and hypoglycemia.

Mild cognitive impairment and depressive symptoms in elderly patients with diabetes: prevalence, risk factors, and comorbidity

The aim of the study was to estimate the prevalence of mild cognitive impairment (MCI), depressive syndrome cases, and its comorbidity, and to identify predictors of these conditions. Methods. 276 diabetics elders were screened for MCI and depressive symptoms. Detailed information of history of diabetes, and data of BMI, HbA1c, and blood lipids were collected. Results. The prevalence of MCI was 31.5%, depressive syndrome was 29.7%, and MCI with coexisting depressive mood was 9.1%. The logistic regression analysis revealed that variables which increased the likelihood of having been diagnosed with MCI were: higher HbA1c level, previous CVD, hypertension, retinopathy, increased number of comorbidities, and less years of formal education. Significant predictors of having a depressive mood included female gender, single marital status, current and past smoking status, lack of physical activity, higher BMI and total cholesterol level, increased number of comorbidities, history of hypoglycemia, and insulin treatment. Factors associated with both MCI and depressive syndrome were female gender, single marital status, past smoking status, retinopathy, previous CVD or stroke, increased number of comorbidities, and insulin treatment. Conclusions. Depressive symptoms, MCI, and its comorbidity are common in elderly subjects with type 2 diabetes. Systematic screening could result in the identification of high-risk patients.

[A case of an elderly diabetic patient with dementia effectively treated with weekly exenatide]

A 74-year-old man with diabetes mellitus since 64 years of age had been treated with glimepiride, metformin and alogliptin; however, his glycemic control remained poor, i.e., a casual blood glucose level of 318 mg/dl, HbA1c level of 10.6% and glycated albumin level of 24.9%. Although his blood glucose level improved with intensive insulin therapy, he exhibited dementia with an MMSE score of 9/30 and was unable to continue insulin injections by himself, thus rejecting his family's help. The extended-release form of the GLP-1 agonist exenatide (Bydureon(®)) was recently introduced in Japan. This new anti-diabetic agent enables the administration of once-weekly type 2 diabetes treatment that delivers a continuous dose of exenatide in a single weekly injection. We employed weekly exenatide therapy in combination with oral hypoglycemic agents in this case. The patient visited our outpatient clinic for injections every week, showing a remarkable improvement in his HbA1c level, from 10.7% to 7.1% in five months. Subcutaneous induration was the only side effect of weekly exenatide injection. Weekly exenatide therapy can be easily managed by other caregivers and is expected to be a useful treatment approach in elderly diabetic patients with dementia.

Advanced BrainAGE in older adults with type 2 diabetes mellitus

Aging alters brain structure and function and diabetes mellitus (DM) may accelerate this process. This study investigated the effects of type 2 DM on individual brain aging as well as the relationships between individual brain aging, risk factors, and functional measures. To differentiate a pattern of brain atrophy that deviates from normal brain aging, we used the novel BrainAGE approach, which determines the complex multidimensional aging pattern within the whole brain by applying established kernel regression methods to anatomical brain magnetic resonance images (MRI). The “Brain Age Gap Estimation” (BrainAGE) score was then calculated as the difference between chronological age and estimated brain age. 185 subjects (98 with type 2 DM) completed an MRI at 3Tesla, laboratory and clinical assessments. Twenty-five subjects (12 with type 2 DM) also completed a follow-up visit after 3.8 ± 1.5 years. The estimated brain age of DM subjects was 4.6 ± 7.2 years greater than their chronological age (p = 0.0001), whereas within the control group, estimated brain age was similar to chronological age. As compared to baseline, the average BrainAGE scores of DM subjects increased by 0.2 years per follow-up year (p = 0.034), whereas the BrainAGE scores of controls did not change between baseline and follow-up. At baseline, across all subjects, higher BrainAGE scores were associated with greater smoking and alcohol consumption, higher tumor necrosis factor alpha (TNFα) levels, lower verbal fluency scores and more severe deprepession. Within the DM group, higher BrainAGE scores were associated with longer diabetes duration (r = 0.31, p = 0.019) and increased fasting blood glucose levels (r = 0.34, p = 0.025). In conclusion, type 2 DM is independently associated with structural changes in the brain that reflect advanced aging. The BrainAGE approach may thus serve as a clinically relevant biomarker for the detection of abnormal patterns of brain aging associated with type 2 DM.

Physical disability in the elderly with diabetes: epidemiology and mechanisms

Diabetes mellitus is a common chronic condition worldwide, especially in the elderly population. Several epidemiologic studies in the last 2 years have consistently associated diabetes with physical disability, a condition that may profoundly affect the quality of life of older people. Although in older people with diabetes, the pathogenesis of functional limitation and disability has not been completely elucidated, it is certainly complex and involves multiple potential pathways. In this narrative review, we described the most recent epidemiologic and clinical evidence supporting the association between diabetes and impaired physical function in older persons focusing on emerging biological mechanisms explaining the excess risk of disability associated with diabetes.

In silico cross seeding of Aβ and amylin fibril-like oligomers

Recent epidemiological data have shown that patients suffering from Type 2 Diabetes Mellitus have an increased risk to develop Alzheimer's disease and vice versa. A possible explanation is the cross-sequence interaction between Aβ and amylin. Because the resulting amyloid oligomers are difficult to probe in experiments, we investigate stability and conformational changes of Aβ-amylin heteroassemblies through molecular dynamics simulations. We find that Aβ is a good template for the growth of amylin and vice versa. We see water molecules permeate the β-strand-turn-β-strand motif pore of the oligomers, supporting a commonly accepted mechanism for toxicity of β-rich amyloid oligomers. Aiming for a better understanding of the physical mechanisms of cross-seeding and cell toxicity of amylin and Aβ aggregates, our simulations also allow us to identify targets for the rational design of inhibitors against toxic fibril-like oligomers of Aβ and amylin oligomers.

Apolipoprotein E gene, environmental risk factors, and their interactions in dementia among seniors

OBJECTIVES

Little research has been conducted to explore the joint effect of apolipoprotein E (ApoE) genotypes and environmental risk factors on dementia. In this study, we examined the roles of ApoE alleles and genotypes in dementia and cognitively impaired not demented (CIND), assessed the risk of co-existing or prior health conditions (i.e. depression), family history of diseases, and lifestyle factors on dementia, and explored the interactions between genetic and environmental risk factors and their joint effects on dementia and cognitive impairment.

METHODS

This is a genetic association study. A total of 1185 seniors (391 dementia, 389 CIND, and 405 cognitively intact, matched for age and gender) were selected from the Canadian Study of Health and Aging clinical assessment datasets. Multivariate logistic regression was used to explore the association between ApoE, environment risk factors, and outcomes.

RESULTS

Participants with ApoE ε4 alleles or ε3/ε4 genotypes were at risk of dementia. More education reduced the risk of dementia or CIND. Previous health conditions (e.g. stroke) increased the risk of dementia or CIND. Regular exercise decreased the risk of CIND. ApoE ε3/ε4 genotype and baseline depression had a 7.97-fold greater risk of incident dementia after adjusting for other significant risk factors. No interactions were found in any dementia and CIND models.

CONCLUSIONS

More attention should be paid to assess and treat depressed older people, especially for those with ApoE ε3/ε4 genotypes. Further replication studies in different populations are warranted.

Non-high-density lipoprotein cholesterol and other risk factors of mild cognitive impairment among Chinese type 2 diabetic patients

OBJECTIVE

To identify some risk factors of MCI among patients with type 2 diabetes(T2DM) and to find if there is any correlation between these factors and the degree of cognitive decline.

METHODS

A total of 155 patients with T2DM referred to the Department of Endocrinology at First Hospital of Qinhuangdao were enrolled. To assess MCI the Montreal Cognitive Assessment (MoCA) scoring system was used. There were 66 patients with MCI and 89 patients without MCI (control). HbAlc, blood lipid, liver and renal functions were measured in all subjects.

RESULTS

Compared with the control group, type 2 diabetic patients with MCI had a longer duration of diabetes; higher non-high-density lipoprotein cholesterol (non-HDL-C), triglycerides, total cholesterol, HbA1c, and BMI; and lower high-density lipoprotein cholesterol (HDL-C) (P<0.05). The rates of patients with a history of habitual light-to-moderate alcohol consumption, a high proportion of Mediterranean-type diet, and regular physical activity were lower; and the rate of current smoking was higher in type 2 diabetic patients with MCI than the control group (P<0.05). Among patients with MCI, the results indicated that MoCA score was negatively correlated with non-HDL-C (r=-0.761 P<0.001).

CONCLUSIONS

Our results suggest that non-HDL-C can act as a readily available method for estimating risk of MCI in Chinese type 2 diabetic patient in routine clinical practice. Good lifestyle likely reduces MCI risk in diabetic patients.

Sweet memories: 20 years of progress in research on cognitive functioning in diabetes

This paper appears in a special issue of the European Journal of Pharmacology that commemorates the retirement of Professor Willem Hendrik Gispen as distinguished professor of Utrecht University and as editor of the European Journal of Pharmacology. The paper provides an overview of a research line on the impact of diabetes on cognition that we started together 20 years ago, and that continues to this day. I will report how we more or less stumbled upon this topic, that was understudied, but proved to be of definite clinical relevance. I will discuss how we tried to establish animal models, how developments from clinical and experimental studies from around the world led us to reconsider our concepts, and how findings from research on diabetic neuropathy, insulin signaling in the brain, Alzheimer's disease and dementia, and vascular disease and stroke converged and helped to create new ideas and refute others. This voyage has not ended yet, because the ultimate goal is to offer patients with diabetes treatment that can protect them against accelerated cognitive decline. Although this could take another 20 years, the research from Willem Hendrik and his group brought us an important step in the right direction.

Montreal Cognitive Assessment is superior to Standardized Mini-Mental Status Exam in detecting mild cognitive impairment in the middle-aged and elderly patients with type 2 diabetes mellitus

Aim. This study compares the usefulness of Montreal Cognitive Assessment (MoCA) to Standardized Mini-Mental Status Exam (SMMSE) for diagnosing mild cognitive impairment (MCI) in Type 2 diabetes mellitus (DM) population. Methods. This prospective pilot study enrolled 30 community dwelling adults with Type 2 DM aged 50 years and above. Subjects were assessed using both the SMMSE and MoCA for MCI. In all subjects, depression and dementia were ruled out using the DSM IV criteria, and a functional assessment was done. MCI was diagnosed using the standard test, the European consortium criteria. Sensitivity and specificity analysis, positive and negative predictive values, likelihood ratios and Kappa statistic were calculated. Results. In comparison to consortium criteria, the sensitivity and specificity of MoCA were 67% and 93% in identifying individuals with MCI, and SMMSE were 13% and 93%, respectively. The positive and negative predictive values for MoCA were 84% and 56%, and for SMMSE were 66% and 51%, respectively. Kappa statistics showed moderate agreement between MoCA and consortium criteria (kappa = 0.4) and a low agreement between SMMSE and consortium criteria (kappa = 0.07). Conclusion. In this pilot study, MoCA appears to be a better screening tool than SMMSE for MCI in the diabetic population.

Management of type 2 diabetes in older people

The prevalence of diabetes is increasing due to aging of the population and increasing obesity. In the developed world, there is an epidemiologic shift from diabetes being a disease of middle age to being a disease of older people due to increased life expectancy. In old age, diabetes is associated with high comorbidity burden and increased prevalence of geriatric syndromes in addition to the traditional vascular complications. Therefore, comprehensive geriatric assessment should be performed on initial diagnosis of diabetes. Due to the heterogeneous nature of older people with diabetes and variations in their functional status, comorbidities, and life expectancy, therapeutic interventions, and glycemic targets should be individualized taking into consideration patients' preferences and putting quality of life at the heart of their care plans.

Risk factors for mild cognitive impairment among Mexican Americans

BACKGROUND

Although a great deal of literature has focused on risk factors for mild cognitive impairment (MCI), little published work examines risk for MCI among Mexican Americans.

METHODS

Data from 1628 participants (non-Hispanic n = 1002; Mexican American n = 626) were analyzed from two ongoing studies of cognitive aging and Alzheimer's disease, Project FRONTIER (Facing Rural Obstacles to health Now Through Intervention, Education & Research) and TARCC (Texas Alzheimer's Research & Care Consortium).

RESULTS

When looking at the full cohorts (non-Hispanic and Mexican American), age, education, Apolipoprotein E (APOE) ε4 status and gender were consistently related to MCI diagnosis across the two cohorts. However, when split by ethnicity, advancing age was the only significant risk factor for MCI among Mexican Americans across both cohorts.

CONCLUSIONS

The current data suggest that many of the previously established risk factors for MCI among non-Hispanic cohorts may not be predictive of MCI among Mexican Americans and point to the need for additional work aimed at understanding factors related to cognitive aging among this underserved segment of the population.

Diabetes mellitus and risk of dementia: A meta-analysis of prospective observational studies

AIMS/INTRODUCTION

The aim of the present study was to investigate the association between diabetes and the risk of all type dementia (ATD), Alzheimer's disease (AD) and vascular dementia (VaD).

MATERIALS AND METHODS

Prospective observational studies describing the incidence of ATD, AD and VaD in patients with diabetes mellitus were extracted from PubMed, EMBASE and other databases up to January 2012. Pooled relative risk (RR) estimates and 95% confidence intervals (CIs) were calculated using the random-effects model. Subgroup analyses and sensitivity analysis were also carried out.

RESULTS

A total of 28 studies contributed to the analysis. Pooled RR of developing ATD (n = 20) was 1.73 (1.65-1.82, I (2) = 71.2%), AD (n = 20) was 1.56 (1.41-1.73, I (2) = 9.8%) and VaD (n = 13) was 2.27 (1.94-2.66, I (2) = 0%) in patients with diabetes mellitus. Higher and medium quality studies did not show any significant difference for pooled RR for ATD, AD or VaD. Sensitivity analyses showed robustness of pooled RR among ATD, AD and VaD, showing no single study had a major impact on pooled RR.

CONCLUSIONS

The results showed a 73% increased risk of ATD, 56% increase of AD and 127% increase of VaD in diabetes patients.

Body mass index, lifestyles, physical performance and cognitive decline: the "Treviso Longeva (TRELONG)" study

OBJECTIVES

The relative contributions of risk factors, as body mass index (BMI), depression, chronic diseases, smoking, and lifestyles (as physical and performance activity, social contacts and reading habit) to cognitive decline in the elderly are unclear. We explored these variables in relation to 7-year cognitive decline in long-lived Italian elderly.

DESIGN

Secondary data analysis of a longitudinal study of a representative, age-stratified, population sample.

SETTING

The TREVISO LONGEVA (TRELONG) Study, in Treviso, Italy.

PARTICIPANTS

120 men and 189 women, age 77 years and older (mean age 80.2 ± 6.9 years) survivors after seven years of follow up.

MEASUREMENTS

Cognitive decline measured as difference between Mini-Mental State Examination (MMSE) score in 2003 and in 2010; Body mass index (BMI), handgrip, Short Physical Performance Battery (SPPB) score, social contacts, reading habit, sight, hearing, schooling, mediterranean diet and multiple clinical and survey data recorded at baseline in 2003.

RESULTS

In separate univariate analyses, age, SPPB score < 5, depressive symptoms (GDS) and more comorbidities (CCI) were associated with greater cognitive decline. Otherwise higher BMI, higher handgrip, reading habit, non-deteriorated sight and hearing, and schooling were protective. In a final multivariate model, age and higher BMI were associated with greater cognitive decline while reading habits was protective. SPPB score < 5 tends, though weakly, to be associated with greater cognitive decline. These associations remained with multivariate adjustment for gender, schooling, Charlson co-morbidity index (CCI) and baseline MMSE.

CONCLUSION

Age and higher baseline BMI, independent of gender, and other confounding factors, are risk factors for cognitive decline. Reading habit plays a protective role seven years later among northern Italian adults aged 70 years or older. Low physical performance tends, though weakly, to be associated with greater cognitive decline.

Non-cognitive symptoms and related conditions in the Alzheimer's disease: a literature review

The Alzheimer's disease is considered a progressive cognitive disorder; however, several non-cognitive symptoms accompany all stages of the disease, appearing at times before the cognitive symptoms become manifest. This article reviews the literature on non-cognitive symptoms normally related to the Alzheimer's disease, including gait and balance dysfunction, olfactory dysfunction, diabetes, pain, and psychiatric symptoms.

Efficacy of cognitive rehabilitation therapies for mild cognitive impairment (MCI) in older adults: working toward a theoretical model and evidence-based interventions

To evaluate the efficacy of cognitive rehabilitation therapies (CRTs) for mild cognitive impairment (MCI). Our review revealed a need for evidence-based treatments for MCI and a lack of a theoretical rehabilitation model to guide the development and evaluation of these interventions. We have thus proposed a theoretical rehabilitation model of MCI that yields key intervention targets-cognitive compromise, functional compromise, neuropsychiatric symptoms, and modifiable risk and protective factors known to be associated with MCI and dementia. Our model additionally defines specific cognitive rehabilitation approaches that may directly or indirectly target key outcomes-restorative cognitive training, compensatory cognitive training, lifestyle interventions, and psychotherapeutic techniques. Fourteen randomized controlled trials met inclusion criteria and were reviewed. Studies markedly varied in terms of intervention approaches and selected outcome measures and were frequently hampered by design limitations. The bulk of the evidence suggested that CRTs can change targeted behaviors in individuals with MCI and that CRTs are associated with improvements in objective cognitive performance, but the pattern of effects on specific cognitive domains was inconsistent across studies. Other important outcomes (i.e., daily functioning, quality of life, neuropsychiatric symptom severity) were infrequently assessed across studies. Few studies evaluated long-term outcomes or the impact of CRTs on conversion rates from MCI to dementia or normal cognition. Overall, results from trials are promising but inconclusive. Additional well-designed and adequately powered trials are warranted and required before CRTs for MCI can be considered evidence-based.

Cognitive impairment associated with atrial fibrillation: a meta-analysis

BACKGROUND

Atrial fibrillation (AF) has been linked with an increased risk for cognitive impairment and dementia.

PURPOSE

To complete a meta-analysis of studies examining the association between AF and cognitive impairment.

DATA SOURCES

Search of MEDLINE, PsycINFO, Cochrane Library, CINAHL, and EMBASE databases and hand search of article references.

STUDY SELECTION

Prospective and nonprospective studies reporting adjusted risk estimates for the association between AF and cognitive impairment.

DATA EXTRACTION

Two abstracters independently extracted data on study characteristics, risk estimates, methods of AF and outcome ascertainment, and methodological quality.

DATA SYNTHESIS

Twenty-one studies were included in the meta-analysis. Atrial fibrillation was significantly associated with a higher risk for cognitive impairment in patients with first-ever or recurrent stroke (relative risk [RR], 2.70 [95% CI, 1.82 to 4.00]) and in a broader population including patients with or without a history of stroke (RR, 1.40 [CI, 1.19 to 1.64]). The association in the latter group remained significant independent proof of clinical stroke history (RR, 1.34 [CI, 1.13 to 1.58]). However, there was significant heterogeneity among studies of the broader population (I2 = 69.4%). Limiting the analysis to prospective studies yielded similar results (RR, 1.36 [CI, 1.12 to 1.65]). Restricting the analysis to studies of dementia eliminated the significant heterogeneity (P = 0.137) but did not alter the pooled estimate substantially (RR, 1.38 [CI, 1.22 to 1.56]).

LIMITATIONS

There is an inherent bias because of confounding variables in observational studies. There was significant heterogeneity among included studies.

CONCLUSION

Evidence suggests that AF is associated with a higher risk for cognitive impairment and dementia, with or without a history of clinical stroke. Further studies are required to elucidate the association between AF and subtypes of dementia as well as the cause of cognitive impairment.

Physical activity, cognitive function, and brain health: what is the role of exercise training in the prevention of dementia?

Tor preventive measures are necessary to attenuate the increased economic and social burden of dementia. This review will focus on the potential for physical activity and exercise training to promote brain health and improve cognitive function via neurophysiological changes. We will review pertinent animal and human research examining the effects of physical activity on cognitive function and neurophysiology. We will discuss cross-sectional and longitudinal studies addressing the relationship between neurocognitive health and cardiorespiratory fitness or habitual activity level. We will then present and discuss longitudinal investigations examining the effects of exercise training on cognitive function and neurophysiology. We will conclude by summarizing our current understanding of the relationship between physical activity and brain health, and present areas for future research given the current gaps in our understanding of this issue.

Neural stem cells in the diabetic brain

Experimental diabetes in rodents rapidly affects the neurogenic niches of the adult brain. Moreover, behavioral disorders suggest that a similar dysfunction of the neurogenic niches most likely affects diabetic and prediabetic patients. Here, we review our present knowledge about adult neural stem cells, the methods used for their study in diabetic models, and the effects of experimental diabetes. Variations in diet and even a short hyperglycemia profoundly change the structure and the proliferative dynamics of the neurogenic niches. Moreover, alterations of diabetic neurogenic niches appear to be associated with diabetic cognitive disorders. Available evidence supports the hypothesis that, in the adult, early changes of the neurogenic niches might enhance development of the diabetic disease.

Management of type 2 diabetes mellitus in older adults

In the near future, the majority of patients with diabetes will be adults aged 65 or older. Unlike young adults with diabetes, elderly diabetic people may be affected by a variety of comorbid conditions such as depression, cognitive impairment, muscle weakness (sarcopenia), falls and fractures, and physical frailty. These geriatric syndromes should be considered in the establishment of treatment goals in older adults with diabetes. Although there are several guidelines for the management of diabetes, only a few are specifically designed for the elderly with diabetes. In this review, we present specific conditions of elderly diabetes which should be taken into account in the management of diabetes in older adults. We also present advantages and disadvantages of various glucose-lowering agents that should be considered when choosing a proper regimen for older adults with diabetes.

An update on type 2 diabetes, vascular dementia and Alzheimer's disease

The risk of dementia is increased in people with type 2 diabetes mellitus (T2DM). This review gives an update on the relation between T2DM and specific dementia subtypes - i.e. Alzheimer's disease and vascular dementia - and underlying pathologies. We will show that while epidemiological studies link T2DM to Alzheimer's disease as well as vascular dementia, neuropathological studies attribute the increased dementia risk in T2DM patients primarily to vascular lesions in the brain. Risk factors for dementia among patients with T2DM are also addressed. Currently, there is evidence that microvascular complications, atherosclerosis and severe hypoglycemic events increase dementia risk. However, for a more complete understanding of risk factors for dementia in T2DM a life time perspective is needed. This should identify which individuals are at increased risk, what are vulnerable periods in life, and what are windows of opportunity for treatment. Currently, there are no DM specific treatments for dementia, but we will review observations from clinical trials that tried to prevent cognitive decline through intensified glycemic control and address other clinical implications of the association between T2DM and dementia.