Relationship between the diagnostic components of metabolic syndrome (MS) and cognition by ApoE genotype in the elderly

The role of microRNA-34 family in Alzheimer's disease: A potential molecular link between neurodegeneration and metabolic disorders

Growing evidence indicates that overexpression of the microRNA-34 (miR-34) family in the brain may play a crucial role in Alzheimer's disease (AD) pathogenesis by targeting and downregulating genes associated with neuronal survival, synapse formation and plasticity, Aβ clearance, mitochondrial function, antioxidant defense system, and energy metabolism. Additionally, elevated levels of the miR-34 family in the liver and pancreas promote the development of metabolic syndromes (MetS), such as diabetes and obesity. Importantly, MetS represent a well-documented risk factor for sporadic AD. This review focuses on the recent findings regarding the role of the miR-34 family in the pathogenesis of AD and MetS, and proposes miR-34 as a potential molecular link between both disorders. A comprehensive understanding of the functional roles of miR-34 family in the molecular and cellular pathogenesis of AD brains may lead to the discovery of a breakthrough treatment strategy for this disease.

A systematic review of existing peripheral biomarkers of cognitive aging: Is there enough evidence for biomarker proxies in behavioral modification interventions?: An initiative in association with the nutrition, exercise and lifestyle team of the Canadian Consortium on Neurodegeneration in Aging

Peripheral biomarkers have shown significant value in predicting brain health and may serve as a useful proxy measurement in the assessment of evidence-based lifestyle behavior modification programs, including physical activity and nutrition programs, that aim to maintain cognitive function in late life. The aim of this systematic review was to elucidate which peripheral biomarkers are robustly associated with cognitive function among relatively healthy non-demented older adults. Following the standards for systematic reviews (PICO, PRIMSA), and employing MEDLINE and Scopus search engines, 222 articles were included in the review. Based on the review of biomarker proxies of cognitive health, it is recommended that a comprehensive biomarker panel, or biomarker signature, be developed as a clinical end point for behavior modification trials aimed at enhancing cognitive function in late life. The biomarker signature should take a multisystemic approach, including lipid, immune/inflammatory, and metabolic biomarkers in the biological signature index of cognitive health.

Metabolic Syndrome and cognitive decline in the elderly: A systematic review

Background

Metabolic Syndrome (MetS) refers to a cluster of metabolic disturbances which is associated with increased risk for vascular and degenerative conditions in general population. Although the relationship between vascular risk factors and dementia is undisputable, additional hazard for cognitive decline in older population with concurrent metabolic disorders still waits to be demonstrated. The present review aims to analyze data on MetS and risk for cognitive decline in elderly persons.

Methods

Database searches were performed in Medline, ISI and PsycINFO for articles assessing cognitive performances of older subjects with MetS.

Results

Of a total of 505 studies, 25 were selected for the review. Risk of selection biases was identified in all the studies. Although all articles followed recognized diagnostic recommendations for MetS, minor criteria modifications were detected in most of them. Hyperglycemia was consistently associated with impaired cognitive performances in older individuals, but the role of MetS for cognitive decline and for the onset of dementia showed heterogeneous results.

Discussion

Current available data in the literature concerning the impact of MetS on the cognition of older population is inconclusive and based on inconsistent evidence. Differential effects of individual MetS components and factors associated with the age of the sample may have accounted for divergent findings among articles, but larger and higher quality studies in this field are still needed.

Metabolic Syndrome and Mild Cognitive Impairment: A Case-Control Study among Elderly in a Shanghai Suburb

BACKGROUND

Metabolic syndrome (MetS) maybe associated with mild cognitive impairment (MCI).

OBJECTIVE

To investigate the relationship between MetS, with its individual or combined components, and MCI among elderly.

METHODS

A case-control study was conducted among the elderly aged 65 years and over in a community located in the southwestern suburb of Shanghai, China. The Chinese version of the Mini-Mental Status Examination (C-MMSE) was used to screen subjects with MCI. Associations of MetS with its individual or combined components and MCI were analyzed using conditional regression analyses with or without adjustment for gender, education, current smoking, current drinking, and physical activities.

RESULTS

There were 379 subjects with MCI and 379 gender- and age-matched healthy controls in the study. Compared with healthy controls in univariate analyses, subjects with MCI were more likely to have less time spent on physical activity, lower C-MMSE score, heavier weight, larger waistline and hipline, higher diastolic blood pressure, higher body mass index, higher abdominal obesity index, higher serum glycated hemoglobin, higher serum triglycerides, higher serum cholesterol, higher serum uric acid, and higher serum alanine aminotransferase. After multivariable adjustment, MetS was significantly associated with an increased risk of MCI (OR = 2.277; 95% CI: 1.086-4.773). Among MetS components, abdominal obesity (OR = 2.101; 95% CI: 1.224-3.608) and hypertension (OR = 2.075; 95% CI: 1.170-3.678) showed a significant association with MCI, respectively; while these two components were combined, the association was stronger (OR = 2.459; 95% CI: 1.360-4.447).

CONCLUSION

MetS and its components, particularly abdominal obesity and hypertension, were found to be significantly associated with the risk of MCI.

What Metabolic Syndrome Contributes to Brain Outcomes in African American & Caucasian Cohorts

Metabolic syndrome (MetS), i.e., meeting criteria for any three of the following: hyperglycemia, hypertension, hypertriglyceridemia, low high-density lipoprotein and/or abdominal obesity, is associated with negative health outcomes. For example, MetS negatively impacts cognition; however, less is known about incremental MetS risk, i.e., meeting 1 or 2 as opposed to 3 or more criteria. We hypothesized incremental MetS risk would negatively contribute to cognition and relevant neuroanatomy, e.g., memory and hippocampal volumes, and that this risk extends to affective functioning. 119 non-demented/non-depressed participants (age=60.1+12.9;~50% African American) grouped by incremental MetS risk-no (0 criteria met), low (1-2 criteria met), or high (3+ criteria met)-were compared across cognition, affect and relevant neuroanatomy using multivariable linear regressions. Exploratory analyses, stratified by race, consider the role of health disparities in disease severity of individual MetS component (e.g., actual blood pressure readings) on significant results from primary analyses. Incremental MetS risk contributed to depressive symptomatology (no<low<high), learning and memory performance (no>low=high) after controlling for age, race (n.s.) and IQ. Different indices of disease severity contributed to different aspects of brain structure and function by race providing empirical support for future studies of the impact distinct health disparities in vascular risk have on brain aging. MetS compromised mood, cognition and hippocampal structure with incremental risk applying to some but not all of these outcomes. Care providers may wish to monitor a broader spectrum of risk including components of MetS like blood pressure and cholesterol levels when considering brain-behavior relationships in adults from diverse populations.

Metabolic syndrome is associated with poor memory and executive performance in elderly community residents: the PROOF study

OBJECTIVE

Aging is associated with a loss of cognitive performance and an increasing occurrence of cardiovascular events. Moreover, cardiovascular risk factors are linked to cognitive impairment and dementia. Whereas individual components of metabolic syndrome (Met S) have been reported to be linked to cognitive decline and dementia, there are very few studies on Met S as a whole. The present study aims to assess the relationship between Met S and its components and cognitive functioning in a cohort of elderly non-demented community residents.

DESIGN

Population-based cohort study (PROOF study). Cross-sectional analysis.

PARTICIPANTS

Dementia-free community-dwellers aged 65.

MEASURES

The PROOF participants underwent an extensive neuropsychological battery at baseline. Summary cognitive measures including memory, attention, and executive performance were created by converting the individual test results to Z scores and computing the average scores within each domain. Each of the three cognitive scores was individually compared between groups as a function of Met S. The cognitive scores and the covariates which were significant in univariate analyses were then included in logistic regression models.

RESULTS

A significant association was observed between the presence of metabolic syndrome, poor memory, and executive function even after adjusting for confounding factors (memory: odds ratio: 1.77, p = 0.008; executive functions: odds ratio: 1.91, p = 0.002).

CONCLUSIONS

Our study showed that in a sample of elderly community dwellers, Met S was associated with poor memory and executive performance. These results underline the importance of detecting and managing metabolic syndrome components to prevent cognitive impairment and dementia.

Genetic variants of apolipoprotein A5 T-1131C and apolipoprotein E common polymorphisms and their relationship to features of metabolic syndrome in adult dyslipidemic patients

OBJECTIVES

The aim was to evaluate the relationships of the T-1131C (rs662799) polymorphism variants of apolipoprotein A5 (Apo A5) gene and variants of apolipoprotein E (Apo E) gene common polymorphism (rs429358, rs7412) to signs of metabolic syndrome (MetS).

DESIGN AND METHODS

We examined 590 asymptomatic dyslipidemic patients divided into MetS+ (n=146) and MetS- (n=444) groups according to criteria of NCEP ATPIII Panel. We evaluated genotype frequencies and differences in MetS features between individual groups. Logistic regression analysis was used for the evaluation of Apo A5/Apo E variants as possible risk factors for MetS.

RESULTS

We found no statistical differences between genotype and allele frequencies for both Apo A5 and Apo E polymorphisms between MetS+ and MetS- groups. In all subjects and MetS- group, we confirmed well-known association of the -1131C Apo A5 minor allele with elevated triglycerides (TG, p<0.001). The Apo E gene E2 and E4 variants were associated with higher levels of TG (p<0.01) in comparison to E33 common variant. However, no statistical differences were observed in MetS+ subjects, regardless of significantly higher TG levels in this group. Apo A5/Apo E variant analysis in all dyslipidemic patients revealed significant increase of TG levels in all subgroups in comparison to common -1131T/E3 variant carriers, the most in -1131C/E4 variant subgroup. Logistic regression analysis models showed no association of Apo A5, Apo E and all Apo A5/Apo E variants with metabolic syndrome, even after adjustment for age and sex.

CONCLUSION

Our study refined the role of Apo A5 and Apo E genetic variants in the group of adult dyslipidemic patients. We demonstrate that except of TG, Apo A5 T-1131C (rs662799) and Apo E (rs429358, rs7412) polymorphisms have no remarkable effect on MetS characteristics.

Screening cognition in the elderly with metabolic syndrome

BACKGROUND

Metabolic syndrome reaches its highest prevalence in the elderly, and evidence suggests that metabolic syndrome could be an independent risk factor for cognitive impairment. The aims of this study were to detect whether patients with metabolic syndrome have lower cognition and to investigate whether there is a relationship with cognition and single metabolic syndrome components.

METHODS

We assessed fasting blood glucose (FBG), high-density lipoprotein cholesterol (HDL-C), triglycerides, high-sensitivity C-reactive protein (hsCRP), and anthropometric measurements. Metabolic syndrome was diagnosed according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. The population sample was divided into two groups according to the presence of metabolic syndrome. Cognitive function was investigated through the Mini-Mental State Examination (MMSE).

RESULTS

We enrolled 159 elderly subjects (mean age, 69.8±4.8 years). Seventy had metabolic syndrome. Metabolic syndrome subjects had higher hsCRP values (P<0.0001) and lower MMSE scores (P<0.0001) than those without metabolic syndrome. MMSE scores were significantly correlated with body mass index (BMI), hsCRP, metabolic syndrome, the number of metabolic syndrome components, and each of them. However, at multivariate regression analysis, only fasting blood glucose [FBG; B=-0.046; 95% confidence interval (CI) -0.066 to -0.028; P<0.0001] and the number of metabolic syndrome components (B=-0.317; 95% CI -0.572 to -0.010; P=0.042) were found to be independent predictors of lower MMSE scores.

CONCLUSION

We found that subjects with metabolic syndrome have lower MMSE scores than those without, even without symptomatic cognitive impairment, and that the number of metabolic abnormalities is independently associated to lower MMSE scores. We suggest that these patients should always undergo cognitive screening to prevent more severe outcomes.

Different associations of apolipoprotein E polymorphism with metabolic syndrome by sex in an elderly Chinese population

The metabolic syndrome (MetS) is characterized by a cluster of metabolic disorders including abnormal lipid and lipoprotein metabolism. Apolipoprotein E (ApoE) is involved in the regulation of the metabolism of cholesterol, lipoproteins, and triglycerides. The common ApoE polymorphism has been found to be associated with cardiovascular disease and diabetes. This study evaluated the ApoE genetic polymorphism and its relation to MetS defined by the modified National Cholesterol Education Program and International Diabetes Federation criteria in a population-based cross-sectional survey of an elderly Chinese population in Beijing, China. Genotypes of 937 men and 1385 women were included in the study. All participants were measured for blood pressure, anthropometric measurements, and fasting concentrations of glucose, triglycerides, cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. We applied a logistic regression model to derive adjusted odds ratios (ORs) and their 95% confidence intervals. In this Chinese population, the ɛ2, ɛ3, and ɛ4 allele frequencies were 8.3%, 83.4%, and 8.3% for men and 8.7%, 82.9%, and 8.4% for women, respectively. In men, concentrations of fasting triglycerides were higher among the APOE2 and E4 subjects; and a lower level of high-density lipoprotein cholesterol was observed in the APOE4 group. There were approximately linear associations of low-density lipoprotein cholesterol levels with APOE genotype groups in both men and women. We observed that the ɛ4 allele was associated with a significantly increased OR of MetS defined by the modified National Cholesterol Education Program criteria in men (OR, 1.75; 95% confidence interval, 1.17-2.63). In summary, our data show that common polymorphism of ApoE gene is associated with the presence of MetS in an elderly Chinese population.

Association between metabolic syndrome and cognitive decline: a systematic review of prospective population-based studies

OBJECTIVE

The association between metabolic syndrome (MS) and the risk of cognitive impairment or dementia remains unclear. In this article, we systematically review studies on the risk of cognitive disorders in patients with MS to determine the strength of the association between MS and cognitive decline.

METHODS

Electronic databases through December 2009 were searched to identify prospective population-based studies that examined the association between MS and risk of cognitive disorders. Two reviewers used a standardised form to collect data and assess eligibility. The quality of study was assessed by the Newcastle-Ottawa Scale.

RESULTS

We found nine eligible studies that involve 19 876 participants. All studies but two indicate that MS is associated with cognitive decline (from one-fold to more than two-fold increase in risk). It seems that MS may be associated with cognitive impairment (positive results in three of five) and vascular dementia (positive results in two of three), whereas three studies involving patients with Alzheimer's disease (AD) did not find the association between MS and AD. When examining the association of the individual risk factors of the MS and cognition in seven eligible studies, glucose (three studies) and hypertension (three studies) showed positive results associated with cognitive decline.

CONCLUSION

The MS may be associated with cognitive impairment and vascular dementia but not for AD, which need to be further investigated with high-quality studies.

Role of lipoproteins and inflammation in cognitive decline: do they interact?

The aim of this study was to examine the associations between high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, triglycerides, and cognition and focus on the modifying effect of inflammation. Data were collected in the population-based Longitudinal Aging Study Amsterdam and analyzed with mixed linear models. The sample comprised 1003 persons ≥ 65 years with cognitive data on at least 2 occasions over 6 years of follow-up. Cognition was measured with the Mini-Mental State Examination (general cognition), Auditory Verbal Learning Test (memory), and Coding Task (information processing speed). We found an independent association between high HDL cholesterol and better memory performance. In addition, low LDL cholesterol was predictive of worse general cognitive performance and faster decline on information processing speed. Furthermore, a significant modifying effect of inflammation (C-reactive protein, α-antichymotrypsin) was found. A negative additive effect of low LDL cholesterol and high inflammation was found on general cognition and memory performance. Also, high triglycerides were associated with lower memory performance in those with high inflammation. Thus, a combination of these factors may be used as markers of prolonged lower cognitive functioning.

Insulin resistance, diabetes and cognitive function: consequences for preventative strategies

Cognitive decline and dementia both place a heavy burden on patients and their relatives, and any means of preventing such age-related changes are worthy of consideration. Those who have the metabolic syndrome with or without diabetes suffer more often from dysexecutive problems and slower psychomotor speed than do other patients. In epidemiological studies, diabetes has appeared to be a risk factor for all types of dementia, including vascular dementia, although the role of the metabolic syndrome in the risk of Alzheimer's disease is still a matter of debate. The possible mechanisms of cognitive alterations are multiple, and may differ according to age group and duration of diabetes or the metabolic syndrome. Drug interventional trials addressing the prevention of cognitive decline through action on the metabolic syndrome are disappointing-albeit scarce at this time. Lifestyle interventions in middle-aged or younger-elderly subjects should also be implemented in the general population.