Metabolic cardiovascular syndrome and risk of dementia in Japanese-American elderly men. The Honolulu-Asia aging study

Combining modifiable risk factors and risk of dementia: a systematic review and meta-analysis

OBJECTIVE

To systematically review the literature relating to the impact of multiple co-occurring modifiable risk factors for cognitive decline and dementia.

DESIGN

A systematic review and meta-analysis of the literature relating to the impact of co-occurring key risk factors for incident cognitive decline and dementia. All abstracts and full text were screened independently by two reviewers and each article assessed for bias using a standard checklist. A fixed effects meta-analysis was undertaken.

DATA SOURCES

Databases Medline, Embase and PsycINFO were searched from 1999 to 2017.

ELIGIBILITY CRITERIA

For inclusion articles were required to report longitudinal data from participants free of cognitive decline at baseline, with formal assessment of cognitive function or dementia during follow-up, and an aim to examine the impact of additive or clustered comorbid risk factor burden in with two or more core modifiable risk factors.

RESULTS

Seventy-nine full-text articles were examined. Twenty-two articles (18 studies) were included reporting data on >40 000 participants. Included studies consistently reported an increased risk associated with greater numbers of intraindividual risk factors or unhealthy behaviours and the opposite for healthy or protective behaviours. A meta-analysis of studies with dementia outcomes resulted in a pooled relative risk for dementia of 1.20 (95% CI 1.04 to 1.39) for one risk factor, 1.65 (95% CI 1.40 to 1.94) for two and 2.21 (95% CI 1.78 to 2.73) for three or more, relative to no risk factors. Limitations include dependence on published results and variations in study outcome, cognitive assessment, length of follow-up and definition of risk factor exposure.

CONCLUSIONS

The strength of the reported associations, the consistency across studies and the suggestion of a dose response supports a need to keep modifiable risk factor exposure to a minimum and to avoid exposure to additional modifiable risks. Further research is needed to establish whether particular combinations of risk factors confer greater risk than others.

PROSPERO REGISTRATION NUMBER

42016052914.

MRI-based evaluation of structural degeneration in the ageing brain: Pathophysiology and assessment

Advances in MRI technology have significantly contributed to our ability to understand the process of brain ageing, allowing us to track and assess changes that occur during normal ageing and neurological conditions. This paper focuses on reviewing structural changes of the ageing brain that are commonly seen using MRI, summarizing the pathophysiology, prevalence, and neuroanatomical distribution of changes including atrophy, lacunes, white matter lesions, and dilated perivascular spaces. We also review the clinically accessible methodology for assessing these MRI-based changes, covering visual rating scales, as well computer-aided and fully automated methods. Subsequently, we consider novel assessment methods designed to evaluate changes across the whole brain, and finally discuss new directions in this field of research.

Pathophysiological Mechanisms Linking Type 2 Diabetes and Dementia: Review of Evidence from Clinical, Translational and Epidemiological Research

BACKGROUND

Type 2 diabetes represents an increasing health burden world-wide and its prevalence in particularly higher in elderly population. Consistent epidemiological evidence suggests an increased risk of dementia associated to type 2 diabetes; the mechanisms underlying these associations, however, remain unclear.

OBJECTIVE

The study aims to review epidemiological, clinical and pre-clinical data that weigh on pathophysiological links, mechanisms of disease and associations between type 2 diabetes and dementia to identify areas of opportunity for future research.

METHODS

We searched the following electronic bibliographic databases: PUBMED, EMBASE, SCIELO, MEDLINE and OVID for clinical, translational and epidemiological research literature that summarize diabetes-related risk factors for dementia, metabolic and neurological changes associated to T2D, evidence of therapeutic approaches in type 2 diabetes and its pathophysiological implications for dementia.

RESULTS

Type 2 diabetes mellitus increases risk for all-cause dementia, vascular dementia and Alzheimer's disease. The most evaluated mechanisms linking both disorders in pre-clinical studies include an increase in neuronal insulin resistance, impaired insulin signaling, pro-inflammatory state, mitochondrial dysfunction and vascular damage which increase deposition of β-amyloid, tau proteins and GSK3β, leading to an earlier onset of dementia in individuals with impairment in the glucose metabolism. Neuroimaging and neuropathology evidence linking cerebrovascular lesions, neurodegeneration and particularly small-vessel disease in the onset of dementia is consistent with the increased risk of incident dementia in type 2 diabetes, but consistent evidence of AD-related pathology is scarce. Epidemiological data shows increased risk of dementia related to hypoglycemic episodes, glycemic control, metabolic syndrome, insulin resistance and genetic predisposition, but the evidence is not consistent and statistical analysis might be affected by inconsistent covariate controlling. Therapeutic approaches for T2D have shown inconsistent result in relation to dementia prevention and delay of cognitive decline; lifestyle intervention, particularly physical activity, is a promising alternative to ameliorate the impact of disability and frailty on T2D-related dementia.

CONCLUSION

Vascular disease, inflammation and impaired brain insulin signaling might occur in T2D and contribute to dementia risk. Evidence from epidemiological studies has not consistently reported associations that could integrate a unified mechanism of disease in humans. Evaluation of the effect of antidiabetic medications and non-pharmacological interventions in dementia prevention in type 2 diabetes is promising but has thus far offered inconsistent results.

Physical activity can improve cognition in patients with Alzheimer's disease: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND/OBJECTIVE

Alzheimer's disease (AD) is mainly characterized by decline of cognitive functions such as memory and learning, which has a high prevalence and poor drug efficacy in treatment regimes. A systematic review and meta-analysis of randomized controlled trials (RCTs) were conducted to evaluate the effectiveness of exercise on cognitive function in patients diagnosed with AD.

METHODS

The bibliographic databases (PubMed, Cochrane Library and Embase, and Web of Science) and four Chinese databases (Wanfang data, CBM, CNKI, and VIP) were searched to identify RCTs published in any language between January 1, 1960, and January 1, 2018. Only peer-reviewed articles and RCTs were included. The collected data were analyzed by Review Manager (5.3).

RESULTS

Overall, 869 patients diagnosed with AD were included from 13 RCTs. Patients in the intervention group received pure exercise interventions and a cognitive test. Although there was heterogeneity in intervention methods and cognitive measures among studies, meta-analysis (seven studies) supports positive effects of physical activity on cognitive function of patients with AD (mean difference [MD] =2.53, the 95% CI=0.84 to 4.22, test for overall effect: Z=2.93 [P=0.003]). Eight studies demonstrated that exercise improves cognitive function for individuals with AD. However, the remaining five studies did not display a beneficial effect of exercise on cognitive function in patients with AD.

CONCLUSION

This meta-analysis and systematic review indicated that exercise intervention might improve the cognitive function of AD or slow down the decline of cognition; however, this relationship was not always true across studies. RCTs with clear intervention criteria, large samples, and long-term follow-up are needed in the future to demonstrate the benefits of exercise for cognitive function in AD patients.

Metabolomic characterization of hypertension and dyslipidemia

BACKGROUND

Hypertension and dyslipidemia are two main risk factors for cardiovascular diseases (CVD). Moreover, their coexistence predisposes individuals to a considerably increased risk of CVD. However, the regulatory mechanisms involved in hypertension and dyslipidemia as well as their interactions are incompletely understood.

OBJECTIVES

The aims of our study were to identify metabolic biomarkers and pathways for hypertension and dyslipidemia, and compare the metabolic patterns between hypertension and dyslipidemia.

METHODS

In this study, we performed metabolomic investigations into hypertension and dyslipidemia based on a "healthy" UK population. Metabolomic data from the Husermet project were acquired by gas chromatography-mass spectrometry and ultra-performance liquid chromatography-mass spectrometry. Both univariate and multivariate statistical methods were used to facilitate biomarker selection and pathway analysis.

RESULTS

Serum metabolic signatures between individuals with and without hypertension or dyslipidemia exhibited considerable differences. Using rigorous selection criteria, 26 and 46 metabolites were identified as potential biomarkers of hypertension and dyslipidemia respectively. These metabolites, mainly involved in fatty acid metabolism, glycerophospholipid metabolism, alanine, aspartate and glutamate metabolism, are implicated in insulin resistance, vascular remodeling, macrophage activation and oxidised LDL formation. Remarkably, hypertension and dyslipidemia exhibit both common and distinct metabolic patterns, revealing their independent and synergetic biological implications.

CONCLUSION

This study identified valuable biomarkers and pathways for hypertension and dyslipidemia, and revealed common and different metabolic patterns between hypertension and dyslipidemia. The information provided in this study could shed new light on the pathologic mechanisms and offer potential intervention targets for hypertension and dyslipidemia as well as their related diseases.

The role of metabolic syndrome factors on cognition using latent variable modeling: The neurocognitive study on aging

OBJECTIVE

Although metabolic syndrome (MetS) has been shown to increase the risk of cognitive decline, it still remains unclear whether the risk is related to MetS as a whole or its individual factors. The aim of the present study was to explore whether MetS or its individual factors are associated with a lower cognitive function in older adults in a Mediterranean population using latent variable modeling.

METHOD

Neurocognitive data from 640 Greek-Cypriot community dwellers (female 59.1%), aged ≥55 years, in good general health, were analyzed. Assessments of anthropometric, blood pressure, fasting blood glucose, total cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, and triglyceride concentrations were carried out to investigate the relationship between MetS factors and cognitive-linguistic outcomes of language, executive function, and verbal episodic memory.

RESULTS

When the MetS factors were modeled as a single latent variable, they had small negative effects on language and executive functions. Significance was not retained after age and education were controlled for. When individual MetS factors along with age and education were modeled as predictors, there were moderate negative age effects, whereas education yielded strong positive effects on all three cognitive outcomes. Weak significant negative coefficients of body mass index (BMI) and blood glucose were found for executive functions, and a weak significant positive effect of BMI was found for memory. Separate analysis by sex resulted in minor but significant differences.

CONCLUSION

BMI and blood glucose predicted cognitive performance after controlling for age and education, and thus their proper management should be taken into account for maintaining cognitive health in aging. Findings also demonstrate the importance of education and age in studies investigating cardiometabolic risk factors and cognitive function, as well as the need for further research on the effects of sex.

Number of Teeth, Oral Self-care, Eating Speed, and Metabolic Syndrome in an Aged Japanese Population

BACKGROUND

Many studies have reported that oral health status is associated with various systemic health issues. This study examined the correlations among oral health, lifestyle factors, and metabolic syndrome (MetS) in aged participants.

METHODS

We analyzed cross-sectional oral and medical health checkup data from 2,379 participants aged 75 and 80 years. MetS was diagnosed according to the Harmonization criteria, with the exception of the criterion for central obesity, and body mass index was used instead of waist circumference. Logistic regression analyses were performed to evaluate the correlation between oral health status and lifestyle factors and MetS in both sexes and by sex.

RESULTS

In both sexes, the odds ratio (OR) for MetS was 1.54 (95% confidence interval [CI], 1.10-2.17) among those who had 0-9 teeth compared with those with 20-28 teeth. MetS was significantly more likely for those eating quickly than those eating slowly (OR 2.06; 95% CI, 1.35-3.16). Participants using secondary oral hygiene products every day had a significantly lower OR (0.71; 95% CI, 0.55-0.92) for MetS than did those who did not. Participants with 0-9 teeth who ate quickly had a significantly higher OR (2.48; 95% CI, 1.06-5.78) for MetS compared with those with 20-28 teeth who ate slowly.

CONCLUSION

These results suggest that maintaining teeth, eating slowly, and using secondary oral hygiene products every day are associated with a lower likelihood of MetS in the aged population.

Relationship of Lipids and Lipid-Lowering Medications With Cognitive Function: The Multi-Ethnic Study of Atherosclerosis

Studies on the relationship of cholesterol concentrations and lipid-lowering medications with dementia risk have yielded inconsistent findings. Therefore, we investigated the association of lipid concentrations and lipid-lowering medications with cognitive function in the Multi-Ethnic Study of Atherosclerosis across 3 different cognitive domains assessed by means of the Cognitive Abilities Screening Instrument (CASI; version 2), the Digit Symbol Coding (DSC) Test, and the Digit Span (DS) Test in 2010-2012. After adjustment for sociodemographic and confounding factors, including concentrations of other lipids and use of lipid-lowering medication, higher total cholesterol, low-density lipoprotein cholesterol, and non-high-density-lipoprotein cholesterol concentrations were modestly associated with higher DS Test scores. None of the lipid parameters were associated with CASI or DSC Test scores. Similarly, changes in lipid concentrations were not associated with any cognitive function test score. Using treatment effects model analysis and after adjusting for confounding factors, including lipid concentrations, the use of any lipid-lowering medication, especially statins, was associated with higher scores on the CASI and backward DS tests but not on the DSC and forward DS tests. Our study does not support a robust association between lipid concentrations and cognitive function or between the use of lipid-lowering medication, especially statins, and worse cognitive function.

Do flavanols-rich natural products relieve obesity-related insulin resistance?

Growing evidence support that insulin resistance may occur as a severe problem due to chronic energetic overfeeding and subsequent obesity. When an abundance of glucose and saturated fat enter the cell, impaired blood flow, hypoxia, inflammation and macrophage infiltration in obese adipose tissue may induce oxidative stress and insulin resistance. Excessive circulating saturated fatty acids ectopically accumulate in insulin-sensitive tissues and impair insulin action. In this context, excessive hepatic lipid accumulation may play a central, pathogenic role in insulin resistance. It is thought that dietary polyphenols may ameliorate obesity-related insulin resistance by attenuating inflammatory responses and oxidative stress. The most often occurring natural polyphenolic compounds are flavonoids. In this review, the possible mechanistic effect of flavonoid-rich natural products on insulin resistance-related metabolic pathways is discussed. Polyphenol intake can prevent high-fat-diet-induced insulin resistance via cell surface G protein-coupled estrogen receptors by upregulating the expression of related genes, and their pathways, which are responsible for the insulin sensitivity.

Nutritional Factors Affecting Adult Neurogenesis and Cognitive Function

Adult neurogenesis, a complex process by which stem cells in the hippocampal brain region differentiate and proliferate into new neurons and other resident brain cells, is known to be affected by many intrinsic and extrinsic factors, including diet. Neurogenesis plays a critical role in neural plasticity, brain homeostasis, and maintenance in the central nervous system and is a crucial factor in preserving the cognitive function and repair of damaged brain cells affected by aging and brain disorders. Intrinsic factors such as aging, neuroinflammation, oxidative stress, and brain injury, as well as lifestyle factors such as high-fat and high-sugar diets and alcohol and opioid addiction, negatively affect adult neurogenesis. Conversely, many dietary components such as curcumin, resveratrol, blueberry polyphenols, sulforaphane, salvionic acid, polyunsaturated fatty acids (PUFAs), and diets enriched with polyphenols and PUFAs, as well as caloric restriction, physical exercise, and learning, have been shown to induce neurogenesis in adult brains. Although many of the underlying mechanisms by which nutrients and dietary factors affect adult neurogenesis have yet to be determined, nutritional approaches provide promising prospects to stimulate adult neurogenesis and combat neurodegenerative diseases and cognitive decline. In this review, we summarize the evidence supporting the role of nutritional factors in modifying adult neurogenesis and their potential to preserve cognitive function during aging.

Defining Optimal Brain Health in Adults: A Presidential Advisory From the American Heart Association/American Stroke Association

Cognitive function is an important component of aging and predicts quality of life, functional independence, and risk of institutionalization. Advances in our understanding of the role of cardiovascular risks have shown them to be closely associated with cognitive impairment and dementia. Because many cardiovascular risks are modifiable, it may be possible to maintain brain health and to prevent dementia in later life. The purpose of this American Heart Association (AHA)/American Stroke Association presidential advisory is to provide an initial definition of optimal brain health in adults and guidance on how to maintain brain health. We identify metrics to define optimal brain health in adults based on inclusion of factors that could be measured, monitored, and modified. From these practical considerations, we identified 7 metrics to define optimal brain health in adults that originated from AHA's Life's Simple 7: 4 ideal health behaviors (nonsmoking, physical activity at goal levels, healthy diet consistent with current guideline levels, and body mass index <25 kg/m2) and 3 ideal health factors (untreated blood pressure <120/<80 mm Hg, untreated total cholesterol <200 mg/dL, and fasting blood glucose <100 mg/dL). In addition, in relation to maintenance of cognitive health, we recommend following previously published guidance from the AHA/American Stroke Association, Institute of Medicine, and Alzheimer's Association that incorporates control of cardiovascular risks and suggest social engagement and other related strategies. We define optimal brain health but recognize that the truly ideal circumstance may be uncommon because there is a continuum of brain health as demonstrated by AHA's Life's Simple 7. Therefore, there is opportunity to improve brain health through primordial prevention and other interventions. Furthermore, although cardiovascular risks align well with brain health, we acknowledge that other factors differing from those related to cardiovascular health may drive cognitive health. Defining optimal brain health in adults and its maintenance is consistent with the AHA's Strategic Impact Goal to improve cardiovascular health of all Americans by 20% and to reduce deaths resulting from cardiovascular disease and stroke by 20% by the year 2020. This work in defining optimal brain health in adults serves to provide the AHA/American Stroke Association with a foundation for a new strategic direction going forward in cardiovascular health promotion and disease prevention.

Association of midlife lipids with 20-year cognitive change: A cohort study

INTRODUCTION

Existing studies predominantly consider the association of late-life lipid levels and subsequent cognitive change. However, midlife rather than late-life risk factors are often most relevant to cognitive health.

METHODS

We quantified the association between measured serum lipids in midlife and subsequent 20-year change in performance on three cognitive tests in 13,997 participants of the Atherosclerosis Risk in Communities study.

RESULTS

Elevated total cholesterol, low-density lipoprotein cholesterol, and triglycerides were associated with greater 20-year decline on a test of executive function, sustained attention, and processing speed. Higher total cholesterol and triglycerides were also associated with greater 20-year decline in memory scores and a measure summarizing performance on all three tests. High-density lipoprotein cholesterol was not associated with cognitive change. Results were materially unchanged in sensitivity analyses addressing informative missingness.

DISCUSSION

Elevated total cholesterol, low-density lipoprotein cholesterol, and triglycerides in midlife were associated with greater 20-year cognitive decline.

Melatonin prevents memory impairment induced by high-fat diet: Role of oxidative stress

Consumption of high-fat diet (HFD) induces oxidative stress in the hippocampus that leads to memory impairment. Melatonin has antioxidant and neuroprotective effects. In this study, we hypothesized that chronic administration of melatonin can prevent memory impairment induced by consumption of HFD. Melatonin was administered to rats via oral gavage (100mg/kg/day) for 4 weeks. HFD was also instituted for the same duration. Behavioral studies were conducted to test spatial memory using the radial arm water maze. Additionally, oxidative stress biomarkers were assessed in the hippocampus. Results showed that HFD impaired both short- and long- term memory (P<0.05), while melatonin treatment prevented such effects. Furthermore, melatonin prevented HFD-induced reduction in levels of GSH, and ratio of GSH/GSSG, and increase in GSSG in the hippocampus. Melatonin also prevented reduction in the catalase activity in hippocampus of animals on HFD. In conclusion, HFD induced memory impairment and melatonin prevented this impairment probably by preventing alteration of oxidative stress in the hippocampus.

Hypercholesterolaemia and vascular dementia

Vascular dementia (VaD) is the second commonest cause of dementia. Stroke is the leading cause of disability in adults in developed countries, the second major cause of dementia and the third commonest cause of death. Traditional vascular risk factors-diabetes, hypercholesterolaemia, hypertension and smoking-are implicated as risk factors for VaD. The associations between cholesterol and small vessel disease (SVD), stroke, cognitive impairment and subsequent dementia are complex and as yet not fully understood. Similarly, the effects of lipids and lipid-lowering therapy on preventing or treating dementia remain unclear; the few trials that have assessed lipid-lowering therapy for preventing (two trials) or treating (four trials) dementia found no evidence to support the use of lipid-lowering therapy for these indications. It is appropriate to treat those patients with vascular risk factors that meet criteria for lipid-lowering therapy for the primary and secondary prevention of cardiovascular and cerebrovascular events, and in line with current guidelines. Managing the individual patient in a holistic manner according to his or her own vascular risk profile is recommended. Although the paucity of randomized controlled evidence makes for challenging clinical decision making, it provides multiple opportunities for on-going and future research, as discussed here.

Body mass index in midlife and dementia: Systematic review and meta-regression analysis of 589,649 men and women followed in longitudinal studies

INTRODUCTION

We conducted a meta-analysis of the conflicting epidemiologic evidence on the association between midlife body mass index (BMI) and dementia.

METHODS

We searched standard databases to identify prospective, population-based studies of dementia risk by midlife underweight, overweight, and obesity. We performed random-effects meta-analyses and meta-regressions of adjusted relative risk (RR) estimates and formally explored between-study heterogeneity.

RESULTS

We included 19 studies on 589,649 participants (2040 incident dementia cases) followed up for up to 42 years. Midlife (age 35 to 65 years) obesity (BMI ≥ 30) (RR, 1.33; 95% confidence interval [CI], 1.08-1.63), but not overweight (25 < BMI < 30) (RR, 1.07; 95% CI, 0.96-1.20), was associated with dementia in late life. The association with midlife underweight (RR, 1.39; 95% CI, 1.13-1.70) was potentially driven by residual confounding (P from meta-regression = .004), selection (P = .046), and information bias (P = .007).

DISCUSSION

Obesity in midlife increases the risk of dementia. The association between underweight and dementia remains controversial.

Glycemia but not the Metabolic Syndrome is Associated with Cognitive Decline: Findings from the European Male Ageing Study

OBJECTIVE

Previous research has indicated that components of the metabolic syndrome (MetS), such as hyperglycemia and hypertension, are negatively associated with cognition. However, evidence that MetS itself is related to cognitive performance has been inconsistent. This longitudinal study investigates whether MetS or its components affect cognitive decline in aging men and whether any interaction with inflammation exists.

METHODS

Over a mean of 4.4 years (SD ± 0.3), men aged 40-79 years from the multicenter European Male Ageing Study were recruited. Cognitive functioning was assessed using the Rey-Osterrieth Complex Figure (ROCF), the Camden Topographical Recognition Memory (CTRM) task, and the Digit Symbol Substitution Test (DSST). High-sensitivity C-reactive protein (hs-CRP) levels were measured using a chemiluminescent immunometric assay.

RESULTS

Overall, 1,913 participants contributed data to the ROCF analyses and 1,965 subjects contributed to the CTRM and DSST analyses. In multiple regression models the presence of baseline MetS was not associated with cognitive decline over time (p > 0.05). However, logistic ordinal regressions indicated that high glucose levels were related to a greater risk of decline on the ROCF Copy (β = -0.42, p < 0.05) and the DSST (β = -0.39, p < 0.001). There was neither a main effect of hs-CRP levels nor an interaction effect of hs-CRP and MetS at baseline on cognitive decline.

CONCLUSION

No evidence was found for a relationship between MetS or inflammation and cognitive decline in this sample of aging men. However, glycemia was negatively associated with visuoconstructional abilities and processing speed.

Differential associations of plasma lipids with incident dementia and dementia subtypes in the 3C Study: A longitudinal, population-based prospective cohort study

BACKGROUND

Vascular risk factors have been proposed as important targets for the prevention of dementia. As lipid fractions represent easily modifiable targets, we examined the longitudinal relationship of baseline lipid fractions with 13-y incident dementia and its subtypes (Alzheimer disease [AD] and mixed or vascular dementia) in older community-dwelling persons.

METHODS AND FINDINGS

Non-institutionalized persons aged 65+ y (n = 9,294) were recruited for the Three-City Study (3C Study), a population-based cohort study from the electoral rolls of the cities of Dijon, Bordeaux, and Montpellier, France, between March 1999 and March 2001. Follow-up examinations were performed every 2 y after the baseline assessment. The final study sample comprised 7,470 participants from the 3C Study (mean age ± standard deviation [SD] 73.8 ± 5.3 y, 61.0% women) who were prospectively followed up for up to 13 y. Fasting lipid fractions (triglycerides [TGs], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], total cholesterol [TC]) were studied as continuous variables, and results are reported per SD increase of each lipid fraction. Incident dementia and its subtypes were studied as censored variables using Cox models with age as time scale. Analyses were adjusted for sex, study center, and educational level, as well as vascular risk factors and apolipoprotein E (APOE) ε4 genotype. We corrected for multiple testing, yielding a significance threshold of 0.0169. p-Values above the significance threshold but less than 0.05 were considered nominally significant. During a mean (± SD) follow-up period of 7.9 ± 3.6 y, 779 participants developed incident dementia (n = 532 AD and n = 154 mixed or vascular dementia). Higher LDL-C and TC concentrations at baseline were associated with an increased risk of AD (hazard ratio [HR] per SD increase = 1.13 [95% CI 1.04-1.22], p = 0.0045, and HR = 1.12 [1.03-1.22], p = 0.0072, respectively). These associations were largely unchanged after adjustment for vascular risk factors and were attenuated after adjustment for APOEε4 (HR per SD increase = 1.12 [1.03-1.23], p = 0.0110, and HR = 1.12 [1.02-1.23], p = 0.0171, respectively). Higher TG concentrations at baseline were associated with an increased risk of all dementia (HR per SD increase = 1.11 [1.03-1.19], p = 0.0044) and mixed or vascular dementia (HR = 1.21 [1.04-1.41], p = 0.0163). However, these associations disappeared after adjusting for vascular risk factors (HR = 1.07 [0.98-1.17], p = 0.1374, and HR = 1.17 [0.96-1.42], p = 0.1206, respectively). Main limitations of the study include interval censoring of incident dementia cases, potential selective survival bias, and the fact that variation in lipid concentrations during follow-up could not be accounted for in the analyses.

CONCLUSIONS

In a large population-based sample of older community-dwelling persons with up to 13 y of follow-up, we observed that higher LDL-C and TC concentrations were associated with an increased risk of AD. This result was independent of vascular risk factors and was attenuated after adjustment for APOEε4 carrier status. TG and HDL-C concentrations were not associated with risk of incident dementia or its subtypes after accounting for vascular risk factors.

Association of dementia in patients with benign paroxysmal positional vertigo

OBJECTIVE

We conducted a cohort study to investigate whether benign paroxysmal positional vertigo (BPPV) is correlated with an increased risk of dementia.

METHODS

We established a case cohort comprising 7818 patients aged over 20 years who were diagnosed with BPPV from 2000 to 2010. In addition, we formed a control cohort by randomly selecting 31,272 people without BPPV and matched them with the BPPV patients according to gender, age, and index year. Cox proportional hazard regressions were performed to compute the hazard ratio (HR) of dementia after we adjusted for demographic characteristics and comorbidity.

RESULTS

The prevalence of comorbidity was higher among patients with BPPV than among those without BPPV. In addition, patients with BPPV exhibited a 1.24-fold (95% confidence interval, CI 1.09-1.40; P < 0.001) higher risk of dementia than those without BPPV after we adjusted for age, gender, and comorbidity. An analysis stratified according to demographic factors revealed that women with BPPV exhibited a 1.36-fold (95% CI 1.16-1.59; P < 0.001) higher risk of dementia. Patients with BPPV aged over 65 years exhibited a significantly higher risk of dementia (adjusted HR: 1.26; 95% CI 1.10-1.43; P < 0.001) than those without BPPV.

CONCLUSIONS

Patients with BPPV exhibited a higher risk of dementia than those without BPPV.

Reduced neurotrophic factor level is the early event before the functional neuronal deficiency in high-fat diet induced obese mice

Neurodegeneration is considered one of the possible complications of high fat diet (HFD) induced obesity. Much evidence has shown the close relationship between HFD and dementia at comparatively later stage of neuronal injury. It is so far not clear that the initial events of neuronal injury resulting from HFD and obesity. In the present research, obese mouse model achieved by 3-month HFD was applied for the investigation of the possible neuronal deficiency before the obvious cognitive decline. We found that 3-month HFD has already increased the average level of body weight of mice. But almost no obvious cognitive defect was observed. At such time point, we detected the cleavage of amyloid precursor protein (APP), including the expression and maturation level of α- and β-secretase and proteolytic fragment soluble APP. Results showed similar readout between HFD and normal diet (ND) mice. Besides, neuronal inflammation and brain-blood barrier permeability were also detected. No obvious changes could be observed between HFD and ND mice. Surprisingly, the first detectable neuronal changes was showed to be the downregulation of some neurotrpic factors, like neuronal growth factor β and brain derived neurotrophic factor, together with the activity of specific receptors, like Trk receptor phosphorylation. All the data piled up indicated that the early neuronal change in HFD induced obese mice was the downregulation of some neurotrophic factors. The results may provide the potential clue to therapeutic and preventive strategy for HFD induced cognitive decline.

Metabolic syndrome, hypertension, and nervous system injury: Epidemiological correlates

Metabolic syndrome (MetS) is a common and complex disorder combining hypertension, obesity, dyslipidemia, and insulin resistance. MetS represents a risk factor for changes in cognitive functions in older age, and several studies have suggested that MetS may be linked to dementia. This article reviews the main evidences about the relationship between MetS and neurodegenerative disease. Starting from an epidemiological point of view, the article analyzes medico-social aspects related to MetS, considering the reduction of work capacity and the condition of disability that it involves. Some authors affirm that on the basis of current Italian legislation, it is possible to consider the syndrome as a disability. This is because all the diseases that make up MetS are high-risk clinical pathological conditions. For these reasons, a joint action is required to contain the incidence of MetS, the high social costs, and the loss of productivity related to the syndrome. In conclusion, healthcare initiatives could be adopted in order to increase the understanding of the pathogenic contributions of each element on MetS and how they can be modified. These actions will be useful to reduce healthcare costs and can lead to more effective prevention of metabolic disease, thus promoting good health.

ABBREVIATIONS

MetS: Metabolic syndrome; WHO: World Health Organization; CVD: cerebrovascular diseases; AD: Alzheimer's Disease; VaD: Vascular Dementia; IDF: International Diabetes Federation; T2DM: type 2 diabetes mellitus; CAD: coronary artery disease; MCI: mild cognitive impairment; NCDs: Non Communicable Diseases; BMI: Body Mass Index; ICIDH: International classification of impairments, disabilities and handicaps.

Age-Related Changes in Gustatory, Homeostatic, Reward, and Memory Processing of Sweet Taste in the Metabolic Syndrome: An fMRI Study

Age affects the human taste system at peripheral and central levels. Metabolic syndrome is a constellation of risk factors (e.g., abdominal obesity and hypertension) that co-occur, increase with age, and heighten risk for cardiovascular disease, diabetes, and cognitive decline. Little is known about how age, metabolic syndrome, and hunger state interact to influence how the brain processes information about taste. We investigated brain activation during the hedonic evaluation of a pleasant, nutritive stimulus (sucrose) within regions critical for taste, homeostatic energy regulation, and reward, as a function of the interactions among age, metabolic syndrome, and hunger condition. We scanned young and elderly adults, half with risk factors associated with metabolic syndrome twice: Once fasted overnight and once after a preload. Functional magnetic resonance imaging data indicated significant effects of age as well as interactive effects with metabolic syndrome and hunger condition. Age-related differences in activation were dependent on the hunger state in regions critical for homoeostatic energy regulation and basic as well as higher order sensory processing and integration. The effects of age and metabolic syndrome on activation in the insula, orbital frontal cortex, caudate, and the hypothalamus may have particularly important implications for taste processing, energy regulation, and dietary choices.

Association between Metabolic Syndrome and Cognitive Impairment after Acute Ischemic Stroke: A Cross-Sectional Study in a Chinese Population

BACKGROUND AND OBJECTIVES

Metabolic syndrome (MetS), a risk factor for many vascular conditions, is associated with vascular cognitive disorders. The objective of the present study was to explore the associations of MetS and its individual components with the risks of cognitive impairment and neurological dysfunction in patients after acute stroke.

METHODS

This cross-sectional study enrolled 840 patients ranging in age from 53 to 89 years from the Tianjin area of North China. Cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination. Neuropsychiatric behavior was assessed using the Neuropsychiatric Inventory Questionnaire. Emotional state was examined according to the Hamilton Depression Rating Scale, and neuromotor function was evaluated using the National Institutes of Health Stroke Scale, Barthel index, and the Activity of Daily Living test. After overnight fasting, blood samples were obtained to measure biochemistry indicators.

RESULTS

MetS and its individual components were closely correlated with MoCA score. MetS patients had high levels of inflammation and a 3.542-fold increased odds ratio (OR) for cognitive impairment [95% confidence interval (CI): 1.972-6.361]. Of the individual MetS components, central obesity (OR 3.039; 95% CI: 1.839-5.023), high fasting plasma glucose (OR 1.915; 95% CI: 1.016-3.607), and type 2 diabetes (OR 2.241; 95% CI: 1.630-3.081) were associated with an increased incidence of cognitive impairment. Consistent and significant worsening in different neurological domains was observed with greater numbers of MetS components.

CONCLUSIONS

MetS was associated with worse cognitive function, neuromotor dysfunction, and neuropsychological symptoms among Chinese acute stroke patients.

Relationship between plasma lipids and mild cognitive impairment in the elderly Chinese: a case-control study

Background

High lipid levels may constitute a more important risk factor for cognitive health in previous studies. However, the association of plasma lipids with mild cognitive impairment (MCI) among elderly people had not been studied exactly. This study aims to explore the relationship between plasma lipids/lipoproteins and the risk of MCI in elderly Chinese individuals.

Methods

CSI-MCI study was a preliminary case-control study of the association of plasma lipids/lipoproteins with MCI in 112 MCI cases and 115 cognitively normal controls. Plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG) levels were measured in fasting blood samples. Multivariable logistic regression was used to evaluate the potential association between MCI and these factors. Statistical models were adjusted for multiple demographic and biological covariates.

Results

The subjects with MCI were significantly older, higher percentage of females and less educated than controls (P <0.05). As expected, subjects with MCI had lower MMSE score compared with controls (P <0.05). Multivariate logistic regression analysis showed that higher plasma TC level was associated with the risk of MCI in models adjusting for age, sex and education. However, This association was attenuated after adjusting for BMI, Type 2 diabetes mellitus, heart disease and hypertension. Plasma TG level was negatively associated with the risk of MCI. The adjusted odds ratio (OR) of MCI was significantly reduced for the highest quartile of plasma TG level (OR: 0.76, 95 % CI: 0.48–0.97), but not for the second or third quartile, compared with the lowest quartile (adjusted models). Plasma HDL level was significantly negatively associated with the risk of MCI. There was no association between plasma LDL level and the risk of MCI, adjustment for demographics, vascular disorders did not change this relation.

Conclusions

Plasma TC was significantly higher in MCI subjects compared to cognitively normal controls, Elevated plasma HDL and triglyceride were associated with the occurrence of MCI. These findings need to be confirmed in further longitudinal studies.

Cognitive disorders in diabetic patients

This chapter gives an overview of the literature on cognitive dysfunction in adults with type 1 or type 2 diabetes. First, methods to evaluate cognitive functioning and the pattern and severity of cognitive dysfunction in relation to diabetes will be discussed. The reader will note that diabetes is associated with worse cognitive functioning and an increased dementia risk. Next, diabetes-associated abnormalities on brain MRI, including reductions in brain volume - i.e., cerebral atrophy - and vascular lesions, will be addressed. At the group level there are clear relations between these imaging abnormalities and cognitive dysfunction, but at the level of the individual patient these relations are often less clear. Subsequently, risk factors for cognitive performance will be discussed. Evidently, these risk factors are related to diabetes type and the age of the patients involved. For type 1 diabetes, an early age at diabetes onset is the most consistent risk factor, whereas in type 2 diabetes, vascular risk factors and vascular comorbidities are consistent indicators of increased risk. The final section of the chapter addresses possible preventive and treatment measures and implications for daily care.

Diabetes and neurodegeneration in the brain

Although an association between diabetes mellitus (DM) and cognitive dysfunction has been recognized for a century, it is often not considered as a complication of DM and remains under-recognized. Cognitive dysfunction, usually present as mild cognitive impairment, can occur with either type 1 or type 2 DM. Both forms of DM contribute to accelerated cerebral atrophy and to the presence of heightened white matter abnormalities. These effects are noted most at the two extremes of life, in childhood and in the advanced years. The cognitive spheres most affected include attention and executive function, processing speed, perception, and memory. Although DM is unlikely to lead to frank dementia, its ability to exacerbate existing neurodegenerative processes, such as Alzheimer disease, will impact tremendously upon our society in the upcoming decades as our population ages. This chapter describes the clinical impact of DM upon the brain, along with discussion of the potential therapeutic avenues to be discovered in the coming decades. We need to prepare for better preventative and therapeutic management of this cerebral neurodegenerative condition.

Simvastatin inhibits protein isoprenylation in the brain

Evidence suggests that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, may reduce the risk of Alzheimer's disease (AD). Statin action in patients with AD, as in those with heart disease, is likely to be at least partly independent of the effects of statins on cholesterol. Statins can alter cellular signaling and protein trafficking through inhibition of isoprenylation of Rho, Cdc42, and Rab family GTPases. The effects of statins on protein isoprenylation in vivo, particularly in the central nervous system, are poorly studied. We utilized two-dimensional gel electrophoresis approaches to directly monitor the levels of isoprenylated and non-isoprenylated forms of Rho and Rab family GTPases. We report that simvastatin significantly inhibits RhoA and Rab4, and Rab6 isoprenylation at doses as low as 50nM in vitro. We also provide the first in vivo evidence that statins inhibit the isoprenylation of RhoA in the brains of rats and RhoA, Cdc42, and H-Ras in the brains of mice treated with clinically relevant doses of simvastatin.

Epigenetic modifications by inhibiting histone deacetylases reverse memory impairment in insulin resistance induced cognitive deficit in mice

Insulin resistance has been reported as a strong risk factor for Alzheimer's disease. However the molecular mechanisms of association between these still remain elusive. Various studies have highlighted the involvement of histone deacetylases (HDACs) in insulin resistance and cognitive deficits. Thus, the present study was designed to investigate the possible neuroprotective role of HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA) in insulin resistance induced cognitive impairment in mice. Mice were subjected to either normal pellet diet (NPD) or high fat diet (HFD) for 8 weeks. HFD fed mice were treated with SAHA at 25 and 50 mg/kg i.p. once daily for 2 weeks. Serum insulin, glucose, triglycerides, total cholesterol and HDL-cholesterol levels were measured. A battery of behavioral parameters was performed to assess cognitive functions. Level of tumour necrosis factor (TNF-α) was measured in hippocampus to assess neuroinflammation. To further explore the molecular mechanisms we measured the histone H3 acetylation and brain derived neurotrophic factor (BDNF) level. HFD fed mice exhibit characteristic features of insulin resistance. These mice also showed a severe deficit in learning and memory along with reduced histone H3 acetylation and BDNF levels. In contrast, the mice treated with SAHA showed significant and dose dependent improvement in insulin resistant condition. These mice also showed improved learning and memory performance. SAHA treatment ameliorates the HFD induced reduction in histone H3 acetylation and BDNF levels. Based upon these results, it could be suggested that HDAC inhibitors exert neuroprotective effects by increasing H3 acetylation and subsequently BDNF level.

Statins for the prevention of dementia

BACKGROUND

This is an update of a Cochrane review first published in 2001 and then updated in 2009. Vascular risk factors including high cholesterol levels increase the risk of dementia due to Alzheimer's disease and of vascular dementia. Some observational studies have suggested an association between statin use and lowered incidence of dementia.

OBJECTIVES

To evaluate the efficacy and safety of statins for the prevention of dementia in people at risk of dementia due to their age and to determine whether the efficacy and safety of statins for this purpose depends on cholesterol level, apolipoprotein E (ApoE) genotype or cognitive level.

SEARCH METHODS

We searched ALOIS (the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group), The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS, ClinicalTrials.gov and the World Health Organization (WHO) Portal on 11 November 2015.

SELECTION CRITERIA

We included double-blind, randomised, placebo-controlled trials in which statins were administered for at least 12 months to people at risk of dementia.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included two trials with 26,340 participants aged 40 to 82 years of whom 11,610 were aged 70 or older. All participants had a history of, or risk factors for, vascular disease. The studies used different statins (simvastatin and pravastatin). Mean follow-up was 3.2 years in one study and five years in one study. The risk of bias was low. Only one study reported on the incidence of dementia (20,536 participants, 31 cases in each group; odds ratio (OR) 1.00, 95% confidence interval (CI) 0.61 to 1.65, moderate quality evidence, downgraded due to imprecision). Both studies assessed cognitive function, but at different times using different scales, so we judged the results unsuitable for a meta-analysis. There were no differences between statin and placebo groups on five different cognitive tests (high quality evidence). Rates of treatment discontinuation due to non-fatal adverse events were less than 5% in both studies and there was no difference between statin and placebo groups in the risk of withdrawal due to adverse events (26,340 participants, 2 studies, OR 0.94, 95% CI 0.83 to 1.05).

AUTHORS' CONCLUSIONS

There is good evidence that statins given in late life to people at risk of vascular disease do not prevent cognitive decline or dementia. Biologically, it seems feasible that statins could prevent dementia due to their role in cholesterol reduction and initial evidence from observational studies was very promising. However, indication bias may have been a factor in these studies and the evidence from subsequent RCTs has been negative. There were limitations in the included studies involving the cognitive assessments used and the inclusion of participants at moderate to high vascular risk only.

Metabolic syndrome increases oxidative stress but does not influence disability and short-time outcome in acute ischemic stroke patients

Oxidative stress has been implicated in the pathophysiology of cardiovascular disease and MetS and it may be one of molecular mechanisms involved in stroke. The aims of the present study were to verify differences in oxidative stress markers in acute ischemic stroke patients with and without MetS and to verify whether MetS influences disability and short time outcome of the patients. 148 patients with acute ischemic stroke were divided in two groups: with MetS (n = 92) and without MetS (n = 56). The modified Rankin Scale (mRS) was used for measuring the functional disability after 3-month follow-up. The study assessed the metabolic profile and oxidative stress markers. Stroke patients with MetS had higher levels of lipid hydroperoxides (p < 0.0001) and advanced oxidation protein products (AOPP, p = 0.0302) than those without MetS. Hydroperoxides were directly and independently associated with MetS (OR: 1.000, 95 % IC = 1.000-1.000, p = 0.005). Linear regression demonstrated that AOPP levels (R(2) = 0.281, p < 0.0001) and oxidative stress index (OSI, R(2) = 0.223, p < 0.0001) were directly associated with triglycerides levels and hydroperoxides levels was also directly associated with glucose levels (R(2) = 0.080, p = 0.013. The mRS and short-come outcome did not differ after 3 months in both groups. In conclusion, an increase in oxidative stress markers was shown in acute ischemic stroke patients with MetS and this elevation seems to be involved mainly with changes in lipid profile, but the presence of MetS did not influence short-time disability and survival of the acute ischemic stroke patients.

Clinical and Sociodemographic Factors Associated with Cognitive Impairment and Neuroprotection in Diabetes Patients

The aim of this study is to analyze the potential impact of factors (clinical and demographic variables and comorbidities) associated with Diabetes Mellitus (DM) on certain mental processes related to cognitive impairment, with special attention to the analysis of parameters that define processing speed and executive function. Neuropsychological examination of elderly Spanish patients (N = 59, 33 females, Mage 70.98 years) diagnosed with DM, in addition to application of an ad hoc questionnaire to collect information on comorbidities and other relevant demographic variables. Based on a cross-sectional design, correlational analysis was carried out. Cognitive performance showed an inverse relationship to age and cardiopathology while years of schooling and regular physical activity appeared as neuroprotective factors. DM is an illness which, linked to other variables, can be regarded as a risk factor for the development of cognitive impairment. Certain factors (physical activity and cognitive stimulation) have the potential to mitigate this tendency. There is a need to further our understanding of the neurobiological mechanisms involved.

Vascular disease burden in Indian subjects with vascular dementia

BACKGROUND

Vascular disease factors like hypertension, diabetes mellitus, dyslipidaemia, and ischaemic heart disease contribute to the development of vascular dementia. As comorbidity of vascular disease factors in vascular dementia is common, we investigated the vascular disease burden in subjects with vascular dementia.

AIMS

To investigate the vascular disease burden due to four vascular disease factors: hypertension, diabetes mellitus, dyslipidaemia, and ischaemic heart disease in Indian subjects with vascular dementia.

METHODS

In this study, 159 subjects with probable vascular dementia (as per NINDS-AIREN criteria) attending the memory clinic at a tertiary care hospital were assessed for the presence of hypertension, diabetes mellitus, dyslipidaemia, and ischaemic heart disease using standardised operational definitions and for severity of dementia on the Clinical Dementia Rating (CDR) scale. The data obtained was subjected to appropriate statistical analysis.

RESULTS

Dyslipidaemia (79.25 per cent) was the most common vascular disease factor followed by hypertension (73.58 per cent), ischaemic heart disease (58.49 per cent), and diabetes mellitus (40.80 per cent). Most subjects (81.1 per cent) had two or more vascular disease factors. Subjects with more severe dementia had more vascular disease factors (sig 0.001).

CONCLUSION

People with moderate to severe dementia have a significantly higher vascular disease burden; therefore, higher vascular disease burden may be considered as a poor prognostic marker in vascular dementia. Subjects with vascular dementia and their caregivers must manage cognitive impairment and ADL alongside managing serious comorbid vascular diseases that may worsen the dementia.

Obesity and Insulin Resistance Are the Central Issues in Prevention of and Care for Comorbidities

For a long time the assumption has been that, although weight reduction was necessary and desirable, comorbidities were far more important and needed treatment even if weight loss was not a treatment goal, preferably with medication. This controversy leads to postponement of treatment, and later on causes very intensive medical treatment, thus, raising the health care costs to unacceptable levels, leading to the medicalization of individuals, and a declining of the responsibility of patients for their health, leaving the question of when to regard their own weight as a problem that should be dealt with up to individuals. The central problem is insulin resistance, which leads to a cascade of health problems. This condition should be diagnosed in primary practice and obesity clinics to ensure a better, tailor-made treatment for patients. Treatment should start at the earliest stage possible, when comorbidities are still reversible and includes a personalized dietary advice and counseling, preferably by a dietitian, to tackle insulin resistance. An exercise program is part of the treatment.

Neural correlates of taste and pleasantness evaluation in the metabolic syndrome

Metabolic syndrome (MetS) is a constellation of cardiometabolic abnormalities that commonly occur together and increase risk for cardiovascular disease and type II diabetes. Having MetS, especially during middle-age, increases the risk for dementia in later life. Abdominal obesity is a central feature of MetS; therefore, increased efforts to prevent obesity and identify predictors of weight gain are of extreme importance. Altered processing of food reward in the brain of obese individuals has been suggested to be a possible mechanism related to overeating. We scanned fifteen healthy middle-aged controls (aged 44-54) and sixteen middle-aged adults with MetS after a fast (hungry) and after a preload (sated), while they rated the pleasantness of sucrose (sweet) and caffeine (bitter) solutions. Data were analyzed using voxelwise linear mixed-effects modeling, and a region of interest analysis to examine associations between hypothalamic activation to sweet taste and BMI during hunger and satiety. The results indicate that middle-aged individuals with MetS respond with significantly less brain activation than controls without MetS during pleasantness evaluation of sweet and bitter tastes in regions involved in sensory and higher-level taste processing. Participants with higher BMI had greater hypothalamic response during pleasantness evaluation of sucrose in the sated condition. Importantly, this study is the first to document differential brain circuitry in middle-aged adults with MetS, a population at risk for poor physical and cognitive outcomes. Future research aimed at better understanding relationships among MetS, obesity, and brain function is warranted to better conceptualize and develop interventions for overeating in these disorders.

Link between type 2 diabetes and Alzheimer's disease: from epidemiology to mechanism and treatment

The aim of this paper is to provide a comprehensive review of the epidemiological evidence linking type 2 diabetes mellitus and its related conditions, including obesity, hyperinsulinemia, and metabolic syndrome, to Alzheimer’s disease (AD). Several mechanisms could help to explain this proposed link; however, our focus is on insulin resistance and deficiency. Studies have shown that insulin resistance and deficiency can interact with amyloid-β protein and tau protein phosphorylation, each leading to the onset and development of AD. Based on those epidemiological data and basic research, it was recently proposed that AD can be considered as “type 3 diabetes”. Special attention has been paid to determining whether antidiabetic agents might be effective in treating AD. There has been much research both experimental and clinical on this topic. We mainly discuss the clinical trials on insulin, metformin, thiazolidinediones, glucagon-like peptide-1 receptor agonists, and dipeptidyl peptidase-4 inhibitors in the treatment of AD. Although the results of these trials seem to be contradictory, this approach is also full of promise. It is worth mentioning that the therapeutic effects of these drugs are influenced by the apolipoprotein E (APOE)-ε4 genotype. Patients without the APOE-ε4 allele showed better treatment effects than those with this allele.

Cellular and metabolic alterations in the hippocampus caused by insulin signalling dysfunction and its association with cognitive impairment during aging and Alzheimer's disease: studies in animal models

A growing body of animal and epidemiological studies suggest that metabolic diseases such as obesity, insulin resistance, metabolic syndrome and type 2 diabetes mellitus are associated with the development of cognitive impairment, dementia and Alzheimer's disease, particularly in aging. Several lines of evidence suggest that insulin signalling dysfunction produces these metabolic alterations and underlie the development of these neurodegenerative diseases. In this article, we address normal insulin function in the synapse; we review and discuss the physiopathological hallmarks of synaptic insulin signalling dysfunction associated with metabolic alterations. Additionally, we describe and review the major animal models of obesity, insulin resistance, metabolic syndrome and type 2 diabetes mellitus. The comprehensive knowledge of the molecular mechanisms behind the association of metabolic alterations and cognitive impairment could facilitate the early detection of neurodegenerative diseases in patients with metabolic alterations, with treatment that focus on neuroprotection. It could also help in the development of metabolic-based therapies and drugs for using in dementia and Alzheimer's disease patients to alleviate their symptoms in a more efficient and comprehensive way.

Relationship between cognitive impairment and echocardiographic parameters: a review

With >24 million people affected worldwide, dementia is one of the main public health challenges modern medicine has to face. The path leading to dementia is often long, with a wide spectrum of clinical presentations, and preceded by a long preclinical phase. Previous studies have demonstrated that clinical strokes and covert vascular lesions of the brain contribute to the risk for developing dementia. Although it is not yet known whether preventing such lesions reduces the risk for dementia, it is likely that starting preventive measures early in the course of the disease may be beneficial. Echocardiography is a widely available, relatively inexpensive, noninvasive imaging modality whereby morphologically or hemodynamically derived parameters may be integrated easily into a risk assessment model for dementia. The aim of this review is to analyze the information that has accumulated over the past two decades on the prognostic value of echocardiographic factors in cognitive impairment. The associations between cognitive impairment and echocardiographic parameters, including left ventricular systolic and diastolic indices, left atrial morphologic parameters, cardiac output, left ventricular mass, and aortic root diameter, have previously been reported. In the light of these studies, it appears that echocardiography may help further improve currently used risk assessment models by allowing detection of subclinical cardiac abnormalities associated with future cognitive impairment. However, many limitations, including methodologic heterogeneity and the observational designs of these studies, restrict the scope of these results. Further prospective studies are required before integrating echocardiography into a preventive strategy.

Neurocognitive functioning in overweight and obese patients with bipolar disorder: data from the Systematic Treatment Optimization Program for Early Mania (STOP-EM)

OBJECTIVE

Obesity is frequent in people with bipolar I disorder (BD I) and has a major impact on the course of the illness. Although obesity negatively influences cognitive function in patients with BD, its impact in the early phase of the disorder is unknown. We investigated the impact of overweight and obesity on cognitive functioning in clinically stable patients with BD recently recovered from their first manic episode.

METHOD

Sixty-five patients with BD (25 overweight or obese and 40 normal weight) recently remitted from a first episode of mania and 37 age- and sex-matched healthy control. subjects (9 overweight or obese and 28 normal weight) were included in this analysis from the Systematic Treatment Optimization Program for Early Mania (commonly referred to as STOP-EM). All subjects had their cognitive function assessed using a standard neurocognitive battery. We compared cognitive function between normal weight patients, overweight-obese patients, and normal weight healthy control subjects.

RESULTS

There was a negative affect of BD diagnosis on the domains of attention, verbal memory, nonverbal memory, working memory, and executive function, but we were unable to find an additional effect of weight on cognitive functioning in patients. There was a trend for a negative correlation between body mass index and nonverbal memory in the patient group.

CONCLUSIONS

These data suggest that overweight-obesity does not negatively influence cognitive function early in the course of BD. Given that there is evidence for a negative impact of obesity later in the course of illness, there may be an opportunity to address obesity early in the course of BD.

The association of metabolic syndrome and aging with cognition in Asian men

BACKGROUND

The present cross-sectional study examined the associations of individual metabolic factors and age with the short-term memory and perceptual capacity in 472 healthy Asian men.

METHODS

The symbol digit and digit span tests from the Swedish Performance Evaluation System were used to assess the perceptual capacity and memory cognitive domains. Linear regression with the stepwise method, and multivariate analyses of the General Linear Model with the Bonferroni correction for multiple comparisons were carried out with the SPSS 21.0 package.

RESULTS

High blood pressure and HDL were not significantly associated with either short-term memory or perceptual capacity. Age and glucose level were negatively associated but regular physical exercise was positively associated with perceptual capacity. On the other hand, high triglyceride level (TG) was positively associated but high waist/height ratio was negatively associated with short-term memory. When men without any component of the metabolic syndrome (MetS) were compared with men with one, two or three or more components of MetS, no significant differences in cognitive performance were noted.

CONCLUSION

Not all the metabolic factors were significantly associated with short-term memory or the perceptual capacity domains. Those that were did not show a sufficiently consistent pattern of association to support a role for MetS as a whole in cognitive decline with aging. It may not be meaningful to evaluate the association of MetS as a whole with cognition.

The relationship between cholesterol and cognitive function is homocysteine-dependent

Introduction

Previous studies have identified hyperlipidemia as a potential risk factor for dementia and Alzheimer’s disease. However, studies on cholesterol measured in late-life and cognitive function have been inconsistent. Few studies have explored nonlinear relationships or considered interactions with other biomarker measures.

Methods

A cross-sectional sample of 1,889 participants from four rural counties in the People’s Republic of China was included in this analysis. Serum total cholesterol, high-density lipoprotein, triglycerides, and homocysteine levels were measured in fasting blood samples. A composite cognitive score was derived based on nine standardized cognitive test scores. Analysis of covariance models were used to investigate the association between biomarker measures and the composite cognitive scores.

Results

There was a significant interaction between the homocysteine quartile group and the cholesterol quartile group on cognitive scores (P=0.0478). In participants with normal homocysteine levels, an inverse U-shaped relationship between total cholesterol level and cognitive score was found, indicating that both low and high cholesterol levels were associated with lower cognitive scores. In participants with high homocysteine levels, no significant association between cholesterol and cognition was found.

Conclusion

The relationship between cholesterol levels and cognitive function depends upon homocysteine levels, suggesting an interactive role between cholesterol and homocysteine on cognitive function in the elderly population. Additional research is required to confirm our findings in other populations, and to explore potential mechanisms underlying the lipid–homocysteine interaction.

Role of dietary and endogenous antioxidants in diabetes

Diabetes affects different people of all ages, race, and sex. This is a condition characterized by a state of chronic hyperglycaemia that leads to an increase of intracellular oxidative stress linked to the overproduction of free radicals. In the present review, we focus our attention on the molecular mechanisms leading to oxidative stress-mediates complications with particular regard to central nervous system (CNS). Furthermore, the present review reports the effects of different kind of antioxidants with enzymatic and nonenzymatic action that may significantly decrease the intracellular free radicals' overproduction and prevents the hyperglycaemia-mediated complications.

Aspartic acid in the hippocampus: a biomarker for postoperative cognitive dysfunction

This study established an aged rat model of cognitive dysfunction using anesthesia with 2% isoflurane and 80% oxygen for 2 hours. Twenty-four hours later, Y-maze test results showed that isoflurane significantly impaired cognitive function in aged rats. Gas chromatography-mass spectrometry results showed that isoflurane also significantly increased the levels of N,N-diethylacetamide, n-ethylacetamide, aspartic acid, malic acid and arabinonic acid in the hippocampus of isoflurane-treated rats. Moreover, aspartic acid, N,N-diethylacetamide, n-ethylacetamide and malic acid concentration was positively correlated with the degree of cognitive dysfunction in the isoflurane-treated rats. It is evident that hippocampal metabolite changes are involved in the formation of cognitive dysfunction after isoflurane anesthesia. To further verify these results, this study cultured hippocampal neurons in vitro, which were then treated with aspartic acid (100 μmol/L). Results suggested that aspartic acid concentration in the hippocampus may be a biomarker for predicting the occurrence and disease progress of cognitive dysfunction.

Metabolic syndrome, prediabetes, and brain abnormalities on mri in patients with manifest arterial disease: the SMART-MR study

OBJECTIVE

Metabolic syndrome (MetS) is a cluster of cardiovascular risk factors leading to atherosclerosis and diabetes. Diabetes is associated with both structural and functional abnormalities of the brain. MetS, even before diabetes is diagnosed, may also predispose to cerebral changes, probably through shared mechanisms. We examined the association of MetS with cerebral changes in patients with manifest arterial disease.

RESEARCH DESIGN AND METHODS

Cross-sectional data on MetS and brain MRI were available in 1,232 participants with manifest arterial disease (age 58.6 ± 10.1 years; 37% MetS). Volumes of brain tissue, ventricles, and white matter hyperintensities (WMH) were obtained by automated segmentation and expressed relative to intracranial volume. Infarcts were distinguished into lacunar and nonlacunar infarcts.

RESULTS

The presence of MetS (n = 451) was associated with smaller brain tissue volume (B -0.72% [95% CI -0.97, -0.47]), even in the subgroup of patients without diabetes (B -0.42% [95% CI -0.71, -0.13]). MetS was not associated with an increased occurrence of WMH or cerebral infarcts. Impaired glucose metabolism, abdominal obesity, and elevated triglycerides were individual components associated with smaller brain volume. Obesity and hypertriglyceridemia remained associated with smaller brain volume when patients with diabetes were excluded. Hypertension was associated with an increased occurrence of WMH and infarcts.

CONCLUSIONS

In patients with manifest arterial disease, presence of MetS is associated with smaller brain volume, even in patients without diabetes. Screening for MetS and treatment of its individual components, in particular, hyperglycemia, hypertriglyceridemia, and obesity, may prevent progression of cognitive aging in patients with MetS, even in a prediabetic stage.