Cholesterol as a Risk Factor for Dementia and Cognitive Decline: A Systematic Review of Prospective Studies With Meta-Analysis

Impact of metabolic dysfunction on cognition in humans

PURPOSE OF REVIEW

The current review evaluates the recent literature on the impact of metabolic dysfunction in human cognition, focusing on epidemiological studies and meta-analyses of these.

RECENT FINDINGS

Worldwide around 50 million people live with dementia, a number projected to triple by 2050. Recent reports from the Lancet Commission suggest that 40% of dementia cases may be preventable primarily by focusing on well established metabolic dysfunction components and cardiovascular risk factors.

SUMMARY

There is robust evidence that type 2 diabetes and midlife hypertension increase risk of dementia in late life. Obesity and elevated levels of LDL cholesterol in midlife probably increase risk of dementia, but further research is needed in these areas. Physical activity, diet, alcohol, and smoking might also influence the risk of dementia through their effect on metabolic dysfunction. A key recommendation is to be ambitious about prevention, focusing on interventions to promote healthier lifestyles combating metabolic dysfunction. Only comprehensive multidomain and staff-requiring interventions are however efficient to maintain or improve cognition in at-risk individuals and will be unrealistic economic burdens for most societies to implement. Therefore, a risk score that identifies high-risk individuals will enable a targeted early intensive intervention toward those high-risk individuals that will benefit the most from a prevention against cardiovascular risk factors and metabolic dysfunction.

Untargeted GC/TOFMS unravel metabolic profiles in cerebrospinal fluid of Chinese people living with HIV

Background

Metabolic syndrome becomes a focus of clinical cares to people living with HIV (PLHIV) globally. This study aimed to explore the metabolic profiles in cerebrospinal fluid (CSF) of Chinese people living with HIV (PLHIV).

Methods

Cerebrospinal fluid samples from PLHIV and healthy controls were collected from our hospital. Then, the metabolic profiles of CSFs were analyzed PLHIV with healthy individual as the normal controls using the untargeted GC/TOFMS. Following this, kyoto encyclopedia of genes and genomes annotation and pathway analysis were performed to further explore the underlying mechanism of these metabolic alterations in cognitive impairment of PLHIV.

Results

Both PCA analysis and OPLS‐DA had presented that most samples were localized in 95% CI and the gap between control and HIV could significantly separate from each other. Upon this quality control, a total of 82 known metabolites were identified in CSF between PLHIV and healthy controls. Clustering of these metabolites presented that these differentially expressed metabolites could markedly distinguish HIV from healthy controls. Further pathway analyses showed that TCA cycle (citric acid, fumaric acid, lactate, et al.), amino acid (arginine, proline, alanine, aspartate, glutamine, et al.), lipid (cholesterol, butyrate, et al.) metabolisms were significantly changed in CSF of PLHIV, which might affect the cognitive status of PLHIV via affecting neuron energy support, signaling transduction, and neuroinflammation.

Conclusion

Metabolic profiles were significantly altered in CSF and might play key roles in the etiology of cognitive impairment of PHLIV. Further explore the exact mechanism for these metabolic changes might be useful for cognitive impairment management of PHLIV.

Role of plant-based diet in late-life cognitive decline: results from the Salus in Apulia Study

OBJECTIVES

Consistency among population-based studies investigating the relationship between diet and cognition in older inhabitants in the Mediterranean area is poor. The present study investigated whether diet changes over 12 years were associated with cognitive function in older people in Southern-Italy.

METHODS

From the 'Salus in Apulia Study', that includes the MICOL and GreatAGE Studies, 584 participants were selected, firstly enrolled in MICOL3 (M3) and later in the GreatAGE Study (MICOL4, M4). Foods and micronutrients intake were recorded in both studies, and global cognitive function in M4, assessed with the Mini Mental State Examination.

RESULTS

Plant-based foods, particularly coffee and vegetables, as well as vitamin A sources, were inversely associated to age-related cognitive impairment. Alcohol consumption showed a detrimental role on cognition, while red meat appeared to be beneficial in the present study, although its role is traditionally considered harmful for cognitive function.

DISCUSSION

Our study confirmed that a traditional Mediterranean dietary pattern based on agricultural products and low alcohol consumption may help to prevent/delay age-related cognitive impairment.

Are serum cholesterol levels associated with cognitive impairment and depression in elderly individuals without dementia?: A retrospective cohort study in South Korea

OBJECTIVES

As aging progresses, older adults experience several health changes, including changes in cholesterol levels, which increases their risk for other diseases. Older adults are particularly vulnerable to cognitive impairment and depression, which may be due to several factors. The aim of this study was to evaluate the association between serum cholesterol level and cognitive impairment and depression in older adults.

METHODS

This study used senior cohort data from the National Health Insurance Service of South Korea. A total of 128 371 participants contributed repeated measures to this dataset. Cognitive impairment was measured via a self-reported questionnaire and depression was measured using claim data. Generalized estimating equations were used to identify associations between serum cholesterol level and cognitive impairment and depression, including subgroup analyses by sex.

RESULTS

There was no significant association between low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), or triglycerides (TG) with cognitive impairment. Low high-density lipoprotein cholesterol (HDL-C) was significantly associated with a higher risk of cognitive impairment, whereas high HDL-C was associated with lower cognitive impairment. Higher LDL-C was significantly associated with lower depression. Higher TC also was significantly associated with depression.

CONCLUSION

HDL-C is associated with depressive symptoms, and may be a key factor in predicting psychiatric symptoms or cognitive decline. Our study suggest that routine health screenings may aid in the early detection of high-risk individuals.

Promoting Successful Cognitive Aging: A Ten-Year Update

A decade has passed since we published a comprehensive review in this journal addressing the topic of promoting successful cognitive aging, making this a good time to take stock of the field. Because there have been limited large-scale, randomized controlled trials, especially following individuals from middle age to late life, some experts have questioned whether recommendations can be legitimately offered about reducing the risk of cognitive decline and dementia. Despite uncertainties, clinicians often need to at least make provisional recommendations to patients based on the highest quality data available. Converging lines of evidence from epidemiological/cohort studies, animal/basic science studies, human proof-of-concept studies, and human intervention studies can provide guidance, highlighting strategies for enhancing cognitive reserve and preventing loss of cognitive capacity. Many of the suggestions made in 2010 have been supported by additional research. Importantly, there is a growing consensus among major health organizations about recommendations to mitigate cognitive decline and promote healthy cognitive aging. Regular physical activity and treatment of cardiovascular risk factors have been supported by all of these organizations. Most organizations have also embraced cognitively stimulating activities, a heart-healthy diet, smoking cessation, and countering metabolic syndrome. Other behaviors like regular social engagement, limiting alcohol use, stress management, getting adequate sleep, avoiding anticholinergic medications, addressing sensory deficits, and protecting the brain against physical and toxic damage also have been endorsed, although less consistently. In this update, we review the evidence for each of these recommendations and offer practical advice about behavior-change techniques to help patients adopt brain-healthy behaviors.

Cholesterol metabolites and plant sterols in cerebrospinal fluid are associated with Alzheimer's cerebral pathology and clinical disease progression

BACKGROUND AND PURPOSE

Altered cholesterol metabolism is associated with increased risk of neurodegeneration and in particular with the development of Alzheimer's disease (AD). Here, we investigate whether non-cholesterol sterols and oxysterols in the central nervous system are associated with (i) the presence of cerebral AD pathology, (ii) distinct aspects of AD pathology, i.e. amyloid pathology, neuronal injury, and tau pathology, and (iii) cognitive decline over time.

EXPERIMENTAL APPROACH

One hundred forty-two elder subjects with normal cognition, mild cognitive impairment, or mild dementia participating in a cohort study on cognitive decline and AD were included. Clinical and neuropsychological assessments were performed at inclusion and repeated at follow-up visits at 18 and 36 months. Concentrations of cholesterol, non-cholesterol sterols, and cholesterol metabolites were measured in cerebrospinal fluid (CSF), along with CSF beta-amyloid (Aβ)_1-42; Aβ_1-42/Aβ_1-40 ratio, total-tau (tau), and tau phosphorylated at threonine 181 (p-tau) as markers of amyloid pathology, neuronal injury and tau pathology, respectively. Cognitive decline was assessed by changes in Mini-Mental State Examination and Clinical Dementia Rating sum of boxes at follow-up visits.

KEY RESULTS

CSF 24S-hydroxycholesterol (24S-OHC) and the 24S-OHC/27-OHC ratio were higher in subjects with AD pathology. CSF desmosterol correlated with Aβ_1-42 levels. The 24S-OHC levels, the 24S-OHC/27-OHC ratio and the plant sterols campesterol and sitosterol were associated with the tau and p-tau levels. Both plant sterol concentrations along with the 24S-OHC/27-OHC ratio at baseline predicted cognitive decline at follow-up visits.

CONCLUSIONS AND IMPLICATIONS

We show the importance of CSF levels of several non-cholesterol sterols and oxysterols to AD and core AD biomarkers. The plant sterols campesterol and sitosterol appear to be involved in tau pathology and neurodegeneration. CSF desmosterol level indicates CNS cholesterol synthesis and might be of relevance for clinical disease severity. Therefore these non-cholesterol sterols may represent intervention targets to slow down disease progression.

From beta amyloid to altered proteostasis in Alzheimer's disease

Alzheimer's disease (AD) is an age related neurodegenerative disorder causing severe disability and important socio-economic burden, but with no cure available to date. To disentangle this puzzling disease genetic studies represented an important way for the comprehension of pathogenic mechanisms. Abnormal processing and accumulation of amyloid-β peptide (Aβ) has been considered the main cause and trigger factor of the disease. The amyloid cascade theory has fallen into crisis because the failure of several anti-amyloid drugs trials and because of the simple equation AD = abnormal Aβ deposition is not always the case. We now know that multiple neurodegenerative diseases share common pathogenic mechanisms leading to accumulation of misfolded protein species. Genome Wide Association studies (GWAS) led to the identification of large numbers of DNA common variants (SNPs) distributed on different chromosomes and modulating the Alzheimer's risk. GWAS genes fall into several common pathways such as immune system and neuroinflammation, lipid metabolism, synaptic dysfunction and endocytosis, all of them addressing to novel routes for different pathogenic mechanisms. Other hints could be derived from epidemiological and experimental studies showing some lifestyles may have a major role in the pathogenesis of many age-associated diseases by modifying cell metabolism, proteostasis and microglia mediated neuroinflammation.

Cardiovascular health metrics from mid- to late-life and risk of dementia: A population-based cohort study in Finland

BACKGROUND

Very few studies have explored the patterns of cardiovascular health (CVH) metrics in midlife and late life in relation to risk of dementia. We examined the associations of composite CVH metrics from midlife to late life with risk of incident dementia.

METHODS AND FINDINGS

This cohort study included 1,449 participants from the Finnish Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study, who were followed from midlife (baseline from1972 to 1987; mean age 50.4 years; 62.1% female) to late life (1998), and then 744 dementia-free survivors were followed further into late life (2005 to 2008). We defined and scored global CVH metrics based on 6 of the 7 components (i.e., smoking, physical activity, and body mass index [BMI] as behavioral CVH metrics; fasting plasma glucose, total cholesterol, and blood pressure as biological CVH metrics) following the modified American Heart Association (AHA)'s recommendations. Then, the composite global, behavioral, and biological CVH metrics were categorized into poor, intermediate, and ideal levels. Dementia was diagnosed following the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria. Data were analyzed with Cox proportional hazards and the Fine and Gray competing risk regression models. During the follow-up examinations, dementia was diagnosed in 61 persons in 1998 and additional 47 persons in 2005 to 2008. The fully adjusted hazard ratio (HR) of dementia was 0.71 (95% confidence interval [CI]: 0.43, 1.16; p = 0.174) and 0.52 (0.29, 0.93; p = 0.027) for midlife intermediate and ideal levels (versus poor level) of global CVH metrics, respectively; the corresponding figures for late-life global CVH metrics were 0.60 (0.22, 1.69; p = 0.338) and 0.91 (0.34, 2.41; p = 0.850). Compared with poor global CVH metrics in both midlife and late life, the fully adjusted HR of dementia was 0.25 (95% CI: 0.08, 0.86; p = 0.028) for people with intermediate global CVH metrics in both midlife and late life and 0.14 (0.02, 0.76; p = 0.024) for those with midlife ideal and late-life intermediate global CVH metrics. Having an intermediate or ideal level of behavioral CVH in both midlife and late life (versus poor level in both midlife and late life) was significantly associated with a lower dementia risk (HR range: 0.03 to 0.26; p < 0.05), whereas people with midlife intermediate and late-life ideal biological CVH metrics had a significantly increased risk of dementia (p = 0.031). Major limitations of this study include the lack of data on diet and midlife plasma glucose, high rate of attrition, as well as the limited power for certain subgroup analyses.

CONCLUSIONS

In this study, we observed that having the ideal CVH metrics, and ideal behavioral CVH metrics in particular, from midlife onwards is associated with a reduced risk of dementia as compared with people having poor CVH metrics. Maintaining life-long health behaviors may be crucial to reduce late-life risk of dementia.

Can Healthy Diets, Regular Exercise, and Better Lifestyle Delay the Progression of Dementia in Elderly Individuals?

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss and multiple cognitive impairments. Current healthcare costs for over 50 million people afflicted with AD are about $818 million and are projected to be $2 billion by 2050. Unfortunately, there are no drugs currently available that can delay and/or prevent the progression of disease in elderly individuals and in AD patients. Loss of synapses and synaptic damage are largely correlated with cognitive decline in AD patients. Women are at a higher lifetime risk of developing AD encompassing two-thirds of the total AD afflicted population. Only about 1-2% of total AD patients can be explained by genetic mutations in APP, PS1, and PS2 genes. Several risk factors have been identified, such as Apolipoprotein E4 genotype, type 2 diabetes, traumatic brain injury, depression, and hormonal imbalance, are reported to be associated with late-onset AD. Strong evidence reveals that antioxidant enriched diets and regular exercise reduces toxic radicals, enhances mitochondrial function and synaptic activity, and improves cognitive function in elderly populations. Current available data on the use of antioxidants in mouse models of AD and antioxidant(s) supplements in diets of elderly individuals were investigated. The use of antioxidants in randomized clinical trials in AD patients was also critically assessed. Based on our survey of current literature and findings, we cautiously conclude that healthy diets, regular exercise, and improved lifestyle can delay dementia progression and reduce the risk of AD in elderly individuals and reverse subjects with mild cognitive impairment to a non-demented state.

Association of Circulating Cholesterol Level with Cognitive Function and Mild Cognitive Impairment in the Elderly: A Community-based Population Study

Background:

The present study was designed to examine the association of circulating cholesterol with cognitive function in non-demented community aging adults.

Methods:

This was a cross-sectional study including 1754 Chinese adults aged 55-80 years. The association between serum cholesterol levels and cognitive function was examined. Participants were categorized into four groups according to the quartile of circulating TC (total cholesterol), High Density Lipoprotein Cholesterol (HDL-c), Low Density Lipoprotein Cholesterol (LDL-c) levels and HDLc/ LDL-c ratio. The difference in cognitive performance among the groups was compared. Logistic regression model was used to determine the association of circulating cholesterol level with the risk of Mild Cognitive Impairment (MCI).

Results:

Mild increase of serum LDL-c level correlated with better visual and executive, language, memory and delayed recall abilities. Higher circulating TC and HDL-c levels were found to be associated with poorer cognitive function, especially in aging female subjects. Higher circulating TC, HDL-c and HDL/LDL ratio indicated an increased risk of MCI, especially in female subjects.

Conclusion:

Slight increase in circulating LDL-c level might benefit cognitive function in aging adults. However, higher circulating TC and HDL-c levels might indicate a decline of cognitive function, especially in aging female subjects.

Novel therapeutic strategies for Alzheimer's disease targeting brain cholesterol homeostasis

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia. Aβ plaques and tauopathy are two major concerns associated with AD. Moreover, excessive Aβ accumulation can lead to other nonspecific metabolic brain abnormalities. There are various genetic, environmental, and other risk factors associated with AD. Identification of risk factors and its mechanisms by which these factors impart role in AD pathology would be helpful for the prevention of AD progression. Altered cholesterol homeostasis could be considered as a risk factor for AD progression. Brain cholesterol dysmetabolism is recognized as one of the crucial attributes for AD that affect major hallmarks of AD including neurodegeneration. To fill the gap between altered cholesterol levels in the brain and AD, the researchers started focusing on statins as re-purposing drugs for AD treatment. The various other hypothesis has been suggested due to a lack of beneficial results of statins in clinical trials, such as reduced brain cholesterol could underlie poor cognition. Unfortunately, it is still unclear, whether an increase or decrease in brain cholesterol levels responsible for Alzheimer's disease or not. Presently, scientists believed that managing the level of cholesterol in the brain may help as an alternative treatment strategy for AD. In this review, we focused on the therapeutic strategies for AD by targeting brain cholesterol levels.

Sex differences in exercise efficacy: Is midlife a critical window for promoting healthy cognitive aging?

Dementia is one of the most pressing health care issues of this century. As no curative treatment for dementia exists, research efforts are growing to identify effective lifestyle interventions to prevent or delay onset. One such promising strategy that promotes cognitive and brain health is engaging in physical exercise. However, current exercise recommendations are imprecise. To advance the potential of exercise as a preventative and treatment strategy, important questions regarding moderators (ie, biological sex and age) are being addressed in the literature. Biological sex is recognized as an important variable to consider in exercise efficacy on brain health, with females showing greater cognitive gains. This may be related to sex differences in underlying mechanisms. Here, we argue to better understand the sex differences in exercise efficacy, the timing of exercise intervention should also be considered. Specifically, we present the hypothesis that midlife in females is a critical window for the implementation of exercise as an early intervention to promote brain health and prevent dementia. Further, we speculate that exercise interventions targeting midlife will be of critical importance for the female brain, as females exit this period of the lifespan at greater risk for cognitive impairment. Given the potential sex differences in dementia risk and prevalence, it is imperative to assess potential sex differences in exercise efficacy as an early intervention during midlife.

Hemodynamic latency is associated with reduced intelligence across the lifespan: an fMRI DCM study of aging, cerebrovascular integrity, and cognitive ability

Changes in neurovascular coupling are associated with both Alzheimer's disease and vascular dementia in later life, but this may be confounded by cerebrovascular risk. We hypothesized that hemodynamic latency would be associated with reduced cognitive functioning across the lifespan, holding constant demographic and cerebrovascular risk. In 387 adults aged 18-85 (mean = 48.82), dynamic causal modeling was used to estimate the hemodynamic response function in the left and right V1 and V3-ventral regions of the visual cortex in response to a simple checkerboard block design stimulus with minimal cognitive demands. The hemodynamic latency (transit time) in the visual cortex was used to predict general cognitive ability (Full-Scale IQ), controlling for demographic variables (age, race, education, socioeconomic status) and cerebrovascular risk factors (hypertension, alcohol use, smoking, high cholesterol, BMI, type 2 diabetes, cardiac disorders). Increased hemodynamic latency in the visual cortex predicted reduced cognitive function (p < 0.05), holding constant demographic and cerebrovascular risk. Increased alcohol use was associated with reduced overall cognitive function (Full Scale IQ 2.8 pts, p < 0.05), while cardiac disorders (Full Scale IQ 3.3 IQ pts; p < 0.05), high cholesterol (Full Scale IQ 3.9 pts; p < 0.05), and years of education (2 IQ pts/year; p < 0.001) were associated with higher general cognitive ability. Increased hemodynamic latency was associated with reduced executive functioning (p < 0.05) as well as reductions in verbal concept formation (p < 0.05) and the ability to synthesize and analyze abstract visual information (p < 0.01). Hemodynamic latency is associated with reduced cognitive ability across the lifespan, independently of other demographic and cerebrovascular risk factors. Vascular health may predict cognitive ability long before the onset of dementias.

Effects of LDL Cholesterol and Statin Use on Verbal Learning and Memory in Older Adults at Genetic Risk for Alzheimer's Disease

BACKGROUND

The apolipoprotein epsilon 4 (APOE4) allele is a well-established genetic risk factor for Alzheimer's disease (AD). However, there are mixed findings as to how the APOE4 allele modifies the effects of both higher low-density lipoprotein cholesterol (LDL) and statin use on cognitive functioning.

OBJECTIVE

This study sought to examine the effects of LDL levels and statin use on verbal learning and memory, as modified by the presence of the APOE4 allele, in a sample of cognitively unimpaired, older adults at risk for AD.

METHODS

Neuropsychological, LDL, statin use, and APOE4 data were extracted from an ongoing longitudinal study at the Banner Alzheimer's Institute in Arizona. Participants were cognitively unimpaired based on Mini-Mental State Examination scores within a normal range, aged 47-75, with a family history of probable AD in at least one first-degree relative.

RESULTS

In the whole sample, higher LDL was associated with worse immediate verbal memory in APOE4 non-carriers, but did not have an effect on immediate verbal memory in APOE4 carriers. In APOE4 non-carriers, statin use was associated with better verbal learning, but did not have an effect on verbal learning in APOE4 carriers. Among women, higher LDL in APOE4 carriers was associated with worse verbal learning than in APOE4 non-carriers, and statin use in APOE4 non-carriers was associated with better verbal learning and immediate and delayed verbal memory but worse performances on these tasks in APOE4 carriers.

CONCLUSION

LDL and statin use may have differential effects on verbal learning and/or memory depending on genetic risk for AD. Women appear to be particularly vulnerable to statin use depending on their APOE4 status.

Brain proteomics links oxidative stress with metabolic and cellular stress response proteins in behavioural alteration of Alzheimer's disease model rats

Alzheimer's disease (AD) impairs memory and learning related behavioural performances of the affected person. Compared with the controls, memory and learning related behavioural performances of the AD model rats followed by hippocampal proteomics had been observed in the present study. In the eight armed radial maze, altered performance of the AD rats had been observed. Using liquid chromatography coupled tandem mass spectrometry (LC-MS/MS), 822 proteins had been identified with protein threshold at 95.0%, minimum peptide of 2 and peptide threshold at 0.1% FDR. Among them, 329 proteins were differentially expressed with statistical significance (P < 0.05). Among the significantly regulated (P < 0.05) 329 proteins, 289 met the criteria of fold change (LogFC of 1.5) cut off value. Number of proteins linked with AD, oxidative stress (OS) and hypercholesterolemia was 59, 20 and 12, respectively. Number of commonly expressed proteins was 361. The highest amount of proteins differentially expressed in the AD rats were those involved in metabolic processes followed by those linked with OS. Most notable was the perturbed state of the cholesterol metabolizing proteins in the AD group. Current findings suggest that proteins associated with oxidative stress, glucose and cholesterol metabolism and cellular stress response are among the mostly affected proteins in AD subjects. Thus, novel therapeutic approaches targeting these proteins could be strategized to withstand the ever increasing global AD burden.

Evaluation of the relationship between cognitive impairment and suboptimal health status in a northern Chinese population: a cross-sectional study

Background

Suboptimal health status (SHS) is an intermediate health status between ideal health and illness. As a determinant of cardiovascular disease and stroke, SHS is hypothesized to be associated with the development of cognitive impairment and dementia. This study aimed to investigate whether individuals with SHS have poor cognitive ability based on a community-based cohort in northern Chinese population.

Methods

3524 participants who were enrolled in Jidong cohort 2015 in Tangshan City were investigated in this study. Cognitive function was measured with the Mini-Mental State Examination (MMSE). SHS level was evaluated using a self-reporting Suboptimal Health Status Questionnaire-25 (SHSQ-25). The relationship between SHS and cognitive function was analyzed with logistic regression analysis, by which odds ratio (OR) and 95% confidence interval (CI) were calculated.

Results

The prevalence of cognitive impairment was 3.4% (121/3524) in our study, with the prevalence rates of 1.9% (34/1750) among men and 4.9% (87/1774) in women. The medians of total score of MMSE were 28 (interquartile range (IQR) = 27-29) in the SHS group, and 29 (IQR = 27-30) in the ideal health group. Logistic regression analysis showed that SHS was significantly correlated with cognitive impairment (adjusted OR = 2.936, 95% CI = 1.428-6.033). With regard to gender, the OR was 5.067 (95% CI = 1.346-19.068) in men, which was higher than that in women (OR = 2.324, 95% CI = 1.130-4.779).

Conclusions

SHS might be a risk factor for cognitive function in northern Chinese population. Early screening of SHS individuals, as well as urgent treatment of SHS might contribute to the prevention of cognitive impairment.

The Cognitive Effects of Statins are Modified by Age

To reveal new insights into statin cognitive effects, we performed an observational study on a population-based sample of 245,731 control and 55,114 statin-taking individuals from the UK Biobank. Cognitive performance in terms of reaction time, working memory and fluid intelligence was analysed at baseline and two follow-ups (within 5-10 years). Subjects were classified depending on age (up to 65 and over 65 years) and treatment duration (1-4 years, 5-10 years and over 10 years). Data were adjusted for health- and cognition-related covariates. Subjects generally improved in test performance with repeated assessment and middle-aged persons performed better than older persons. The effect of statin use differed considerably between the two age groups, with a beneficial effect on reaction time in older persons and fluid intelligence in both age groups, and a negative effect on working memory in younger subjects. Our analysis suggests a modulatory impact of age on the cognitive side effects of statins, revealing a possible reason for profoundly inconsistent findings on statin-related cognitive effects in the literature. The study highlights the importance of characterising modifiers of statin effects to improve knowledge and shape guidelines for clinicians when prescribing statins and evaluating their side effects in patients.

Incidence of and Risk factors for Mild Cognitive Impairment in Chinese Older Adults with Multimorbidity in Hong Kong

The aim of our study was to identify the incidence rate of and the risk factors for mild cognitive impairment (MCI) among Chinese older adults with multimorbidity in primary care in Hong Kong. Older adults aged 60 years and above with multimorbidity were recruited from the public primary care clinics in Hong Kong. Incidence rates were calculated with the person-years. Cox proportional hazard regression models were used to predict the risk factors for MCI. Sensitivity analysis was performed using multiple imputation. Among 462 participants included in the main analysis, 45 progressed from normal to MCI with an incidence rate of 80.9 cases per 1000 person-years. Older age (HR 2.82, 95% CI 1.26-6.28) and being single (HR 2.15, 95% CI 1.11-4.19) were risk factors for developing MCI in the multivariable regression model. A total of 660 participants were included in the sensitivity analysis, with an MCI incidence of 114.4 cases per 1000 person-years. Older age and being single remained to be risk factors for MCI among older adults with multimorbidity. There may be a high incidence of MCI among Chinese older adults with multimorbidity in primary care in Hong Kong. Future larger studies need to confirm the prevalence and incidence of MCI among primary care Chinese patients.

Neuropsychological Deficit Profiles, Vascular Risk Factors, and Neuropathological Findings in Hispanic Older Adults with Autopsy-Confirmed Alzheimer's Disease

This study aimed to determine if patterns of neuropsychological deficits, vascular risk factors, and neuropathology differ in Hispanic and Non-Hispanic patients with autopsy-confirmed Alzheimer's disease (AD). Participants were enrolled in a longitudinal study at the Shiley-Marcos AD Research Center at the University of California, San Diego. Hispanic (n = 14) and Non-Hispanic (n = 20) patients with autopsy-confirmed AD who scored ≥95 on the Dementia Rating Scale (DRS) were included. Patient groups were matched on age, education, global mental status, and severity of functional decline; they were compared to Hispanic (n = 14) or Non-Hispanic (n = 20) cognitively-normal controls of similar age and education. Ethnicity (Hispanic, Non-Hispanic) by disease state (autopsy-confirmed AD or cognitively normal) comparisons were made for cognitive test performance and vascular risk factors. Patient groups were further compared on measures of AD (Braak stage, neuritic plaques, neurofibrillary tangles), vascular neuropathology, and performance across cognitive domains of memory, language, attention, executive functions, and visuospatial abilities after scores were z-transformed based on respective culturally-appropriate control groups. Patient groups had similar overall AD pathology burden, whereas Hispanics with AD had more small parenchymal arteriolar disease and amyloid angiopathy than Non-Hispanics with AD. Despite largely similar pathology, Hispanics with AD were less cognitively impaired (relative to respective NC groups) than Non-Hispanics with AD, and exhibited a different pattern of deficits across cognitive domains. Findings suggest that cognitive deficits that are usually prominent in AD may be less salient in Hispanic patients and this may adversely impact the ability to clinically detect the disease in mild to moderate stages.

Associations of Lipid Levels and Cognition: Findings from the Hispanic Community Health Study/Study of Latinos

OBJECTIVE

Hispanics/Latinos in the United States are less aware of their cholesterol levels and have a higher burden of associated adverse cardiovascular and cerebrovascular outcomes than non-Latino whites. Investigations of the associations between cholesterol levels and cognition in this population have often occurred within the context of metabolic syndrome and are limited to select lipids despite the fact that triglycerides (TGs) may be more relevant to the health of Hispanics/Latinos.

METHODS

Baseline data from the Hispanic Community Health Study/Study of Latinos, collected from 2008 to 2011, was used to investigate the associations of lipid levels (i.e., TG, total cholesterol, TC; low-density and high-density lipoprotein cholesterol, LDL-C and HDL-C) with cognition (i.e., learning, memory, verbal fluency, and digit symbol substitution, DSS), adjusting for relevant confounders.

RESULTS

In 7413 participants ages 45 to 74 years from Central American, Cuban, Dominican, Mexican, Puerto Rican, and South American backgrounds, separate, fully adjusted linear regression models revealed that TG levels were inversely associated with DSS performance; however, this relationship was no longer significant once additional cardiovascular disease risk factors were added to the model (p = .06). TC and LDL-C levels (separately) were positively associated with learning and verbal fluency regardless of adjustments (p-values < .05). Separate analyses investigating the effect modification by background and sex revealed a particularly robust association between TC levels and DSS performance for Puerto Ricans and Central Americans (albeit in opposite directions) and an inverse relationship between TG levels and DSS performance for women (p-values < .02).

CONCLUSIONS

It is important to consider individual lipid levels and demographic characteristics when investigating associations between cholesterol levels and cognition in Hispanics/Latinos.

Atrial Fibrillation and Cognitive Function: JACC Review Topic of the Week

Numerous vascular risk factors and vascular diseases contribute to cognitive impairment and dementia. Many studies and registries show an association of atrial fibrillation (AF) with cognitive impairment, cognitive decline, and dementia. This is true for vascular dementia and Alzheimer's disease. The assumed multifactorial mechanisms include ischemic stroke, both apparent and silent, cerebral microinfarcts, cerebral hemorrhage, and reduced cerebral blood flow. A number of retrospective observational and prospective studies support that anticoagulation in patients with AF may reduce the risk of cognitive decline and dementia. This holds for both vitamin K antagonists (e.g., warfarin) and direct oral anticoagulants. However, it still remains unproven if anticoagulation reduces cognitive decline and dementia in AF patients based on randomized trials.

Associations between heart failure and risk of dementia: A PRISMA-compliant meta-analysis

BACKGROUND

There are differences among the outcomes regarding cognitive impairment in heart failure (HF) because the evidence is fragmented and sample size is small. Therefore we aimed to systematically review and analyze the available evidence about the association between HF and dementia.

METHODS

In the present study, we searched for articles published until August 2019 in the following databases: PubMed, Web of Science, EMBASE, Medline and Google Scholar. The pooled multivariate odds ratio (OR) or relative risk (RR) and 95% confidence intervals (CI) were obtained by the use of STATA 12.0 software.

RESULTS

The meta-analysis showed a positive association between HF and risk of all-cause dementia (OR/RR = 1.28, 95% CI 1.15 to 1.43, I = 70.0%, P < 0.001). Additionally, the study showed no significant association between HF and risk of Alzheimer's disease (AD) (OR/RR = 1.38, 95% CI 0.90 to 2.13, I = 74.8%, P = 0.008).

CONCLUSION

In conclusion, HF was associated with an increased risk of developing dementia. In addition, large scale prospective studies are essential to explore the associations between HF and risk of AD.

Association of blood lipids, atherosclerosis and statin use with dementia and cognitive impairment after stroke: A systematic review and meta-analysis

BACKGROUND

Trial and observational evidence is conflicting in terms of the association of blood lipids, atherosclerosis and statin use with dementia and cognitive impairment in the general population. It is uncertain whether the associations occur in stroke patients, who are at known higher risk of cognitive decline. This systematic review was to synthesize the evidence for these associations among stroke patients.

METHODS

MEDLINE, EMBASE, the Cochrane Library and trial registries were searched. We included randomized controlled trials (RCTs) or observational cohort studies conducted among patients with stroke and reported on the association of blood lipids, atherosclerosis or statin use with dementia or cognitive impairment. Meta-analysis was conducted separately for crude and maximally adjusted odds ratios (ORs) and hazard ratios (HRs).

RESULTS

Of 18,026 records retrieved, 56 studies (one RCT and 55 cohort studies) comprising 38,423 stroke patients were included. For coronary heart disease, the pooled OR of dementia and cognitive impairment was 1.32 (95%CI 1.10-1.58, n = 15 studies, I² = 0%) and 1.23 (95%CI 0.99-1.54, n = 14, I² = 26.9%), respectively. Peripheral artery disease was associated with dementia (OR 3.59, 95%CI 1.47-8.76, n = 2, I² = 0%) and cognitive impairment (OR 2.70, 95%CI 1.09-6.69, n = 1). For carotid stenosis, the pooled OR of dementia and cognitive impairment was 2.67 (95%CI 0.83-8.62, n = 3, I² = 77.9%) and 3.34 (95%CI 0.79-14.1, n = 4, I² = 96.6%), respectively. For post-stroke statin use, the pooled OR of dementia and cognitive impairment was 0.89 (95%CI 0.65-1.21, n = 1) and 0.56 (95%CI 0.46-0.69, n = 3, I² = 0%), respectively. No association was observed for hypercholesterolemia. These results were mostly consistent with adjusted ORs or HRs, which were reported from limited evidence.

CONCLUSION

Atherosclerosis was associated with an increased risk of post-stroke dementia. Post-stroke statin use was associated with decreased risk of cognitive impairment. To confirm whether or not statins confer advantages in the post-stroke population in terms of preventing cognitive decline over and above their known effectiveness in reducing risk of further vascular events, further stroke trials including cognitive assessment and observational analyses adjusted for key confounders, focusing on key subgroups or statin use patterns are required.

Dementia risk by combinations of metabolic diseases and body mass index: Japan Gerontological Evaluation Study Cohort Study

AIMS/INTRODUCTION

To compare the dementia risk associated with pre-existing diabetes, hypertension, dyslipidemia, obesity (body mass index [BMI] ≥25 kg/m2 ) and underweight (BMI <18.5 kg/m2 ) among older adults. We also explored the dementia risk associated with combinations of metabolic diseases and BMI.

MATERIALS AND METHODS

We used data from the Japan Gerontological Evaluation Study. Participants completed a health checkup in 2010 and were followed for 5.8 years on average. Dementia was measured by municipal long-term care insurance registration. Diabetes, hypertension, dyslipidemia, obesity and underweight were diagnosed by medication use or health examination results. We calculated the incidence of dementia and adjusted hazard ratios (HRs).

RESULTS

Among 3,696 participating older adults, 338 developed dementia. Adjusted HRs (95% confidence intervals) in men and women (reference: those without corresponding disease of normal weight) were as follows: 2.22 (1.26-3.90) and 2.00 (1.07-3.74) for diabetes; 0.56 (0.29-1.10) and 1.05 (0.64-1.71) for hypertension; 1.30 (0.87-1.94) and 0.73 (0.49-1.08) for dyslipidemia; 0.73 (0.42-1.28) and 0.82 (0.49-1.37) for BMI of 25-29.9 kg/m2 ; and 1.04 (0.51-2.10) and 1.72 (1.05-2.81) for underweight. Dementia risk was significantly higher in underweight men with dyslipidemia (HR 4.15, 95% CI 1.79-9.63) compared with normal-weight men without dyslipidemia, and in underweight women with hypertension (HR 3.79, 1.55-9.28) compared with normal-weight women without hypertension. Dementia incidence was highest among underweight older adults with hypertension followed by dyslipidemia.

CONCLUSIONS

Among Japanese older adults, underweight and prevalent diabetes are risk factors for developing dementia. Lower BMI is also associated with a higher incidence of dementia.

Associations Between Midlife (but Not Late-Life) Elevated Coronary Heart Disease Risk and Lower Cognitive Performance: Results From the Framingham Offspring Study

It is unclear how coronary heart disease (CHD) risk across the adult life span affects late-life cognition. We estimated associations of midlife and late-life elevated CHD risk with cognitive trajectories (general cognitive performance, processing speed/executive function, memory) in later life (after age 55 years or age 70 years) among 2,892 Framingham Offspring Study participants who had completed CHD risk assessments approximately every 4 years since 1971 and had undergone neuropsychological testing between 1999 and 2014. We stratified analyses by apolipoprotein E gene (APOE) Ɛ4 allele carrier status. Using linear mixed-effects models, elevated CHD risk in midlife (age 55 years) was associated with lower levels of general cognitive performance (β = -0.560 standard deviation (SD) units, 95% confidence interval (CI): -0.874, -0.246), executive function (β = -0.624 SD units, 95% CI: -0.916, -0.332), and memory (β = -0.560 SD units, 95% CI: -0.907, -0.213) at age 70 years but not with rates of cognitive change. Late-life (age 70 years) elevated CHD risk, however, was associated with somewhat better levels of general cognitive performance and memory. There were associations between duration of elevated CHD risk during midlife and levels (but not trajectories) of later-life cognitive outcomes. Associations were not modified by APOE-ɛ4 status. These findings suggest that midlife elevated CHD risk is associated with lower cognition, independently of APOE-ɛ4 status, suggesting that risk of vascular disease may not contribute a "second hit" to AD risk.

Cognitive resilience among APOE ε4 carriers in the oldest old

OBJECTIVES

Relatively few APOE ε4+ carriers survive to old age (age 80+) without cognitive impairment (CI); thus, little is known about distinguishing characteristics of resilient APOE ε4+ carriers. Herein, we describe the sociodemographic characteristics of a large sample of resilient APOE ε4+ women from the Women's Health Initiative Memory Study (WHIMS) and compare them to noncarriers and APOE ε4+ women who developed CI before age 80.

METHODS

Women were recruited for clinical trials evaluating postmenopausal hormone therapy and incidence of dementia. During posttrial follow-up, cognitive status was adjudicated annually. Among 5716 women, we compared groups by APOE ε4 status using logistic regression, covarying for treatment, demographics, lifestyle, cardiovascular and physical function, well-being, and self-rated general health.

RESULTS

Among 557 APOE ε4+ women, those who survived to age 80+ without CI had higher baseline self-rated general health (odds ratio [OR]: 1.02; 95% confidence interval [CI], 1.01-1.04) and cognitive scores (OR: 1.18; 95% CI, 1.12-1.25) than those who did not reach age 80 without CI. Baseline high total cholesterol and low-density lipoprotein (LDL) levels were similar across APOE ε4+ groups but were higher compared with APOE ε4- women. Among women who survived to 80+ without CI, more APOE ε4+ women had a history of high total cholesterol (P = .003) and LDL cholesterol (OR: 1.01; 95% CI, 1.00-1.01). There were no differences in hypertension, diabetes, or other vascular risk factors in APOE ε4+ women compared with noncarriers.

CONCLUSIONS

Results highlight the importance of baseline cognitive function and general health for late-life cognition among ε4+ women.

Association between air pollution and risk of vascular dementia: A multipollutant analysis in Taiwan

Evidence regarding the association of specific air pollutants with vascular dementia (VaD) risk is limited. In this nested case-control study, we enrolled 831 adults aged >65 years with VaD (International Classification of Diseases, Ninth Revision, Clinical Modification code 290.4x) newly diagnosed during 2005-2013; 3324 controls were age-, sex-, and VaD diagnosis year-matched with the study patients. Both patients with VaD and controls were selected from among a cohort of one million beneficiaries of Taiwan's National Health Insurance program, all of whom were registered in 2005. Exposure to the mean daily air pollutant concentration, derived from 76 fixed air quality monitoring stations, in 3, 5, and 7 years before VaD diagnosis was assessed using the spatial analysis method (i.e., ordinary kriging) on ArcGIS. A logistic regression model was used to calculate covariate-adjusted odds ratios (ORs) of VaD in relation to specific air pollutants. After potential confounders and other air pollutants were controlled for, high concentrations of coarse particulate matter (10 µm or less in diameter) and carbon monoxide (CO) were sporadically associated with higher OR of VaD. The most prominent association was observed for nitrogen dioxide (NO₂) exposure within 5 and 7 years before diagnosis. Compared with the <25th percentile of NO₂ exposure, the 25th-50th, 50th-75th, and >75th percentiles of NO₂ exposure significantly increased ORs (95% confidence intervals): 1.62 (1.28-2.23), 1.61 (1.11-2.33), and 2.22 (1.35-3.65) within 5 years before diagnosis, respectively, and 1.59 (1.20-2.11), 1.65 (1.15-2.37), and 2.05 (1.28-3.28) within 7 years before diagnosis, respectively. We found that higher NO₂ exposure in the past was significantly associated with an elevated risk of VaD. Although less consistent, higher exposure to CO was also associated with a higher risk of VaD. Most NO₂ in cities originates from motor vehicle exhaust; other sources of NO₂ are petrol and metal refining, electricity generation from coal-fired power stations, other manufacturing industries, and food processing. Future studies should investigate associations of VaD with specific sources of NO₂.

Comparative benefits of simvastatin and exercise in a mouse model of vascular cognitive impairment and dementia

Aerobic physical exercise (EX) and controlling cardiovascular risk factors in midlife can improve and protect cognitive function in healthy individuals and are considered to be effective at reducing late-onset dementia incidence. By investigating commonalities between these preventative approaches, we sought to identify possible targets for effective interventions. We compared the efficacy of EX and simvastatin (SV) pharmacotherapy to counteract cognitive deficits induced by a high-cholesterol diet (2%, HCD) in mice overexpressing TGF-β1 (TGF mice), a model of vascular cognitive impairment and dementia. Cognitive deficits were found in hypercholesterolemic mice for object recognition memory, and both SV and EX prevented this decline. EX improved stimulus-evoked cerebral blood flow responses and was as effective as SV in normalizing endothelium-dependent vasodilatory responses in cerebral arteries. The up-regulation of galectin-3-positive microglial cells in white matter (WM) of HCD-fed TGF mice with cognitive deficits was significantly reduced by both SV and EX concurrently with cognitive recovery. Altered hippocampal neurogenesis, gray matter astrogliosis, or microgliosis did not correlate with cognitive deficits or benefits. Overall, results indicate that SV and EX prevented cognitive decline in hypercholesterolemic mice and that they share common sites of action in preventing endothelial cell dysfunction and reducing WM inflammation.-Trigiani, L. J., Royea, J., Tong, X.-K., Hamel, E. Comparative benefits of simvastatin and exercise in a mouse model of vascular cognitive impairment and dementia.

Green tea and coffee intake and risk of cognitive decline in older adults: the National Institute for Longevity Sciences, Longitudinal Study of Aging

OBJECTIVE

To examine the association between green tea and coffee intake and cognitive decline in older adults.

DESIGN

A prospective cohort study. The average intake of green tea and coffee in the previous year was assessed through a dietitian interview using a dietary questionnaire. A Mini-Mental State Examination (MMSE) was conducted up to six times biennially. Cognitive decline was screened using the MMSE; its incidence was defined as the first time a score of <27 points was obtained in a biennial test from the baseline. Hazard ratios for incidence of cognitive decline were estimated according to the intake of the two beverages using multivariable Cox proportional hazard regression, controlling for sociodemographic and lifestyle factors.

SETTING

The National Institute for Longevity Sciences, Longitudinal Study of Aging (NILS-LSA) in Japan.

PARTICIPANTS

Men (n 620) and women (n 685), aged 60-85 years, from the NILS-LSA.

RESULTS

During a mean of 5·3 (sd 2·9) years of follow-up, 432 incident cases of cognitive decline were observed. Compared with participants who consumed green tea <once/d, the multivariable hazard ratio (95 % CI) was 0·70 (0·45, 1·06), 0·71 (0·52, 0·97) and 0·72 (0·54, 0·98) among those who consumed green tea once/d, 2-3 times/d and ≥4 times/d, respectively (Ptrend < 0·05). No significant association was found between coffee intake and cognitive decline.

CONCLUSIONS

The intake of green tea, but not coffee, was shown to reduce the risk of cognitive decline in older adults.

Different Exposures to Risk Factors Do Not Explain the Inverse Relationship of Occurrence Between Cancer and Neurodegenerative Diseases: An Italian Nested Case-control Study

Several studies reported that cancer is less frequent in persons with Alzheimer's and Parkinson's Diseases (AD/PD) and vice-versa. We evaluated whether a different distribution of known nongenetic risk factors for cancer and AD/PD, might explain their inverse relationship of occurrence. We nested 2 case-control studies in a subsample of a large cohort of 1,000,000 resident in Lombardy Region in Italy (n=1515), followed-up for cancer and AD/PD occurrence since 1991 until 2012. Conditional logistic regression was performed to determine the odds ratios (OR) and 95% confidence intervals (CI) of AD/PD in subjects with and without cancer and the risk of cancer in those with and without AD/PD. A total of 54 incident cases of AD/PD and 347 cancer cases were matched with 216 and 667 controls, respectively. After controlling for low education, obesity, history of hypertension, diabetes, dyslipidemia, physical activity, smoking habit, alcohol consumption, and dietary habit, cancer was found inversely associated with the risk of AD/PD (OR, 0.66; 95% CI, 0.32-1.38), and the risk of cancer in AD/PD was similarly reduced (OR, 0.42; 95% CI, 0.20-0.91). Different exposures to nongenetic risk factors of both diseases do not explain their competitive relationship of occurrence.

Different treatment forms of type II diabetes and the risk of dementia in German health claims data

AIMS

The association between type II diabetes (T2D) and increased all-cause dementia risk is well established. However, to date, there is no definite proof that a specific therapy for diabetes can halt a progress of cognitive decline. Therefore, we analyzed a large longitudinal random sample of German health claims data to focus on associations between T2D and dementia and to elucidate the role of different treatment forms of T2D on the risk for dementia.

METHODS

We used a longitudinal random sample (n = 250,000) of claims data of the largest public sickness fund in Germany, the Allgemeine Ortskrankenkasse (AOK). Dementia was defined as ICD-10 codes G31.0, G31.82, G23.1, F00, F01, F02, F03, and F05, and T2D was defined as E11-E14. We performed Cox proportional hazard models to explore the transition into dementia and to calculate the relative risk of dementia dependent on T2D and different T2D treatment forms.

RESULTS

All models were adjusted for sex, age, and each patient's history of depression, renal insufficiency, and cardiovascular comorbidities. Non-pharmacologic-treated diabetics showed a 23% increased dementia risk (p < 0.001) and oral ADM-treated diabetics showed a 16% increased risk (p < 0.001). Insulin-dependent diabetics is still the highest dementia risk (40%; p < 0.001) and obesity additionally attenuated this risk (75%; p < 0.001) increased risk.

CONCLUSIONS

We found that diabetes is an independent risk factor for all-cause dementia. An increased risk for dementia in insulin-dependent and obese subjects with diabetes was evident. Longitudinal studies on the effect of different forms of therapy and weight reduction are needed to verify the results of this study.

Cardiometabolic Risk and Body Composition in Youth With Down Syndrome

BACKGROUND AND OBJECTIVES

Whether BMI captures adiposity and cardiometabolic risk in Down syndrome (DS), a condition associated with obesity, short stature, and altered body proportions, is not known. We compared cardiometabolic risk measures in youth with DS and typically developing matched controls.

METHODS

Youth with (n = 150) and without (n = 103) DS of comparable age (10-20 years), sex, race, ethnicity, and BMI percentile underwent whole-body dual-energy X-ray absorptiometry, fasting glucose, insulin, lipids, lipoprotein particles, inflammatory factors, and when BMI percentile ≥85, an oral glucose tolerance test.

RESULTS

Sixty-four percent of youth with DS had BMI percentile ≥85. Among these, no difference in glucose, insulin, or insulin resistance was detected, but prediabetes was more prevalent with DS (26.4% vs 10.3%; P = .025) after adjustment for demographics, pubertal status, and BMI z score (odds ratio = 3.2; P = .026). Among all participants, those with DS had higher low-density lipoprotein cholesterol (median 107 [interquartile range 89-128] vs 88.5 [79-103] mg/dL; P < .00005), triglycerides (89.5 [73-133] vs 71.5 [56-104] mg/dL; P < .00005), non-high-density lipoprotein cholesterol (non-HDL-C; 128 [104-153] vs 107 [92-123] mg/dL; P < .00005), and triglycerides/HDL-C (2.2 [1.6-3.4] vs 1.7 [1.1-2.5] mg/dL; P = .0003) and lower levels of HDL-C (41 [36.5-47] vs 45 [37-53] mg/dL; P = .012). DS youth had higher high-sensitivity C-reactive protein, interleukin-6, small low-density lipoprotein particles (LDL-P), and total LDL-P, but similar LDL-P size. Youth with DS had less visceral fat (VFAT), fat mass, and lean mass for BMI z score, but greater VFAT at higher fat mass. However, VFAT did not fully explain the increased prevalence of dyslipidemia or prediabetes in youth with DS.

CONCLUSIONS

Despite similar insulin resistance, youth with DS had greater prevalence of dyslipidemia and prediabetes than typically developing youth, which was not fully explained by VFAT.

Restoring synaptic function through multimodal therapeutics

Alzheimer's disease (AD) is the major form of dementia and a growing epidemic for which no disease-modifying treatments exist. AD is characterized by the early loss of synapses in the brain and, at later stages, neuronal death accompanied with progressive loss of cognitive functions. Here we focus on the mechanisms involved in the maintenance of the synapse and how their perturbation leads to synaptic loss. We suggest treatment strategies that particularly target energy metabolism in terms of cholesterol and glucose biochemistry in neurons and astrocytes We also discuss the potential of restoring impaired protein homeostasis through autophagy. These pathways are analyzed from a basic science perspective and suggest new avenues for discovery. We also propose several targets for both basic and translational therapeutics in these pathways and provide perspective on future AD treatment.

Alterations in cholesterol metabolism as a risk factor for developing Alzheimer's disease: Potential novel targets for treatment

Alzheimer's disease (AD) is the most common form of dementia and it is characterized by the deposition of amyloid-β (Aβ) plaques and neurofibrillary tangles in the brain. However, the complete pathogenesis of the disease is still unknown. High level of serum cholesterol has been found to positively correlate with an increased risk of dementia and some studies have reported a decreased prevalence of AD in patients taking cholesterol-lowering drugs. Years of research have shown a strong correlation between blood hypercholesterolemia and AD, however cholesterol is not able to cross the Blood Brain Barrier (BBB) into the brain. Cholesterol lowering therapies have shown mixed results in cognitive performance in AD patients, raising questions of whether brain cholesterol metabolism in the brain should be studied separately from peripheral cholesterol metabolism and what their relationship is. Unlike cholesterol, oxidized cholesterol metabolites known as oxysterols are able to cross the BBB from the circulation into the brain and vice-versa. The main oxysterols present in the circulation are 24S-hydroxycholesterol and 27-hydroxycholesterol. These oxysterols and their catalysing enzymes have been found to be altered in AD brains and there is evidence indicating their influence in the progression of the disease. This review gives a broad perspective on the relationship between hypercholesterolemia and AD, cholesterol lowering therapies for AD patients and the role of oxysterols in pathological and non-pathological conditions. Also, we propose cholesterol metabolites as valuable targets for prevention and alternative AD treatments.

The association of vascular disorders with incident dementia in different age groups

Background

There is increasing evidence that dementia risk associated with vascular disorders is age dependent. Large population-based studies of incident dementia are necessary to further elucidate this effect. Therefore, the aim of the present study was to determine the association of vascular disorders with incident dementia in different age groups in a large primary care database.

Methods

We included 442,428 individuals without dementia aged ≥ 65 years from the longitudinal primary care Integrated Primary Care Information (IPCI) database. We determined in 6 age groups (from 65–70 to ≥ 90 years) the risk of hypertension, diabetes mellitus, dyslipidemia, stroke, myocardial infarction, heart failure, and atrial fibrillation for all-cause dementia using incidence rate ratios, Cox regression, and Fine and Gray regression models.

Results

The mean age at inclusion of the total study sample was 72.4 years, 45.7% of the participants were male, and median follow-up was 3.6 years. During 1.4 million person-years of follow-up, 13,511 individuals were diagnosed with dementia. The risk for dementia decreased with increasing age for all risk factors and was no longer significant in individuals aged ≥ 90 years. Adjusting for mortality as a competing risk did not change the results.

Conclusions

We conclude that vascular disorders are no longer a risk factor for dementia at high age. Possible explanations include selective survival of individuals who are less susceptible to the negative consequences of vascular disorders and differences in follow-up time between individuals with and without a vascular disorder. Future research should focus on the identification of other risk factors than vascular disorders, for example, genetic or inflammatory processes, that can potentially explain the strong age-related increase in dementia risk.

Electronic supplementary material

The online version of this article (10.1186/s13195-019-0496-x) contains supplementary material, which is available to authorized users.

ApoE4: an emerging therapeutic target for Alzheimer's disease

BACKGROUND

The growing body of evidence indicating the heterogeneity of Alzheimer's disease (AD), coupled with disappointing clinical studies directed at a fit-for-all therapy, suggest that the development of a single magic cure suitable for all cases may not be possible. This calls for a shift in paradigm where targeted treatment is developed for specific AD subpopulations that share distinct genetic or pathological properties. Apolipoprotein E4 (apoE4), the most prevalent genetic risk factor of AD, is expressed in more than half of AD patients and is thus an important possible AD therapeutic target.

REVIEW

This review focuses initially on the pathological effects of apoE4 in AD, as well as on the corresponding cellular and animal models and the suggested cellular and molecular mechanisms which mediate them. The second part of the review focuses on recent apoE4-targeted (from the APOE gene to the apoE protein and its interactors) therapeutic approaches that have been developed in animal models and are ready to be translated to human. Further, the issue of whether the pathological effects of apoE4 are due to loss of protective function or due to gain of toxic function is discussed herein. It is possible that both mechanisms coexist, with certain constituents of the apoE4 molecule and/or its downstream signaling mediating a toxic effect, while others are associated with a loss of protective function.

CONCLUSION

ApoE4 is a promising AD therapeutic target that remains understudied. Recent studies are now paving the way for effective apoE4-directed AD treatment approaches.

Increased Serum Acylated Ghrelin Levels in Patients with Mild Cognitive Impairment

Ghrelin is a stomach-derived circulating hormone. In addition to its function as an orexigenic stimulant, the role of ghrelin in the consolidation of learning and memory has been implicated in recent years. However, the status of circulating acylated ghrelin (AG, that is, the functional form of ghrelin) in the symptomatic predementia stage of Alzheimer's disease (AD) has rarely been investigated. In the current study, we examined the serum levels of acylated and total ghrelin in 22 patients with mild cognitive impairment (MCI) and 30 cognitively normal controls. We have found that patients with MCI had significantly increased serum AG levels, which were inversely associated with defected short- and long-term memory as well as language skills. Of note, the levels of total circulating ghrelin were similar between the two groups. Intriguingly, serum AG but not total ghrelin was associated with AD risk factors including the age, hypertension, and hyperlipidemia. Therefore, circulating AG may serve as a potential early systemic biomarker for AD-related cognitive impairments. Nevertheless, the simplest interpretation of the results is that the levels of circulating AG are associated with cognitive impairments in patients with MCI, thereby forming the groundwork for our future studies on the systemic mechanisms of AD pertaining to the ghrelin system.

Global, regional, and national burden of Alzheimer's disease and other dementias, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016

BACKGROUND

The number of individuals living with dementia is increasing, negatively affecting families, communities, and health-care systems around the world. A successful response to these challenges requires an accurate understanding of the dementia disease burden. We aimed to present the first detailed analysis of the global prevalence, mortality, and overall burden of dementia as captured by the Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2016, and highlight the most important messages for clinicians and neurologists.

METHODS

GBD 2016 obtained data on dementia from vital registration systems, published scientific literature and surveys, and data from health-service encounters on deaths, excess mortality, prevalence, and incidence from 195 countries and territories from 1990 to 2016, through systematic review and additional data-seeking efforts. To correct for differences in cause of death coding across time and locations, we modelled mortality due to dementia using prevalence data and estimates of excess mortality derived from countries that were most likely to code deaths to dementia relative to prevalence. Data were analysed by standardised methods to estimate deaths, prevalence, years of life lost (YLLs), years of life lived with disability (YLDs), and disability-adjusted life-years (DALYs; computed as the sum of YLLs and YLDs), and the fractions of these metrics that were attributable to four risk factors that met GBD criteria for assessment (high body-mass index [BMI], high fasting plasma glucose, smoking, and a diet high in sugar-sweetened beverages).

FINDINGS

In 2016, the global number of individuals who lived with dementia was 43·8 million (95% uncertainty interval [UI] 37·8-51·0), increased from 20.2 million (17·4-23·5) in 1990. This increase of 117% (95% UI 114-121) contrasted with a minor increase in age-standardised prevalence of 1·7% (1·0-2·4), from 701 cases (95% UI 602-815) per 100 000 population in 1990 to 712 cases (614-828) per 100 000 population in 2016. More women than men had dementia in 2016 (27·0 million, 95% UI 23·3-31·4, vs 16.8 million, 14.4-19.6), and dementia was the fifth leading cause of death globally, accounting for 2·4 million (95% UI 2·1-2·8) deaths. Overall, 28·8 million (95% UI 24·5-34·0) DALYs were attributed to dementia; 6·4 million (95% UI 3·4-10·5) of these could be attributed to the modifiable GBD risk factors of high BMI, high fasting plasma glucose, smoking, and a high intake of sugar-sweetened beverages.

INTERPRETATION

The global number of people living with dementia more than doubled from 1990 to 2016, mainly due to increases in population ageing and growth. Although differences in coding for causes of death and the heterogeneity in case-ascertainment methods constitute major challenges to the estimation of the burden of dementia, future analyses should improve on the methods for the correction of these biases. Until breakthroughs are made in prevention or curative treatment, dementia will constitute an increasing challenge to health-care systems worldwide.

FUNDING

Bill & Melinda Gates Foundation.

Low Phytanic Acid-Concentrated DHA Prevents Cognitive Deficit and Regulates Alzheimer Disease Mediators in an ApoE-/- Mice Experimental Model

Alzheimer’s disease (AD) is the main cause of dementia and cognitive impairment. It has been associated with a significant diminution of omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) levels in the brain. Clinical trials with DHA as a treatment in neurological diseases have shown inconsistent results. Previously, we reported that the presence of phytanic acid (PhA) in standard DHA compositions could be blunting DHA’s beneficial effects. Therefore, we aimed to analyze the effects of a low PhA-concentrated DHA and a standard PhA-concentrated DHA in Apolipoprotein E knockout (ApoE^−/−) mice. Behavioral tests and protein expression of pro-inflammatory, pro-oxidant, antioxidant factors, and AD-related mediators were evaluated. Low PhA-concentrated DHA decreased Aβ, ß-amyloid precursor protein (APP), p-tau, Ca²⁺/calmodulin-dependent protein kinase II (CAMKII), caspase 3, and catalase, and increased brain derived neurotrophic factor (BDNF) when compared to standard PhA-concentrated DHA. Low PhA-concentrated DHA decreased interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) protein expression in ApoE^−/− mice when compared to standard PhA-concentrated DHA. No significant differences were found in p22phox, inducible nitric oxide synthase (iNOS), glutathione peroxidase (GPx), superoxide dismutase 1 (SOD-1), and tau protein expression. The positive actions of a low PhA-concentrated DHA were functionally reflected by improving the cognitive deficit in the AD experimental model. Therefore, reduction of PhA content in DHA compositions could highlight a novel pathway for the neurodegeneration processes related to AD.

Perfluoroalkyl acids in serum of Korean children: Occurrences, related sources, and associated health outcomes

Perfluoroalkyl acids (PFAAs) have been widely used in human environment, and their exposure among general population has been frequently reported. However, extent of PFAAs exposure and their potential effects among children are not well characterized. In this study, children of between 3 and 18 years of age (n = 150) were recruited in Seoul and Gyeonggi, Korea, and the serum levels of 16 PFAAs along with lipids and thyroid hormones were measured. Questionnaire survey was conducted for dietary and behavioral characteristics of the children. Among the measured PFAAs, PFOA, PFNA, PFHxS, and PFOS were detected in all the samples, and PFUnDA and PFDA were detected in over 75% of the samples. PFOS was detected at the highest concentration with a median of 5.68 ng/mL. PFUnDA was detected at higher levels (median of 0.652 ng/mL) compared to those reported for children in USA. Serum PFAA levels were not different by sex among the children of <10 years of age, but in older children, those of boys are significantly higher than girls. Physiological characteristics like menstruation may explain lower PFAAs levels of the girls. In addition, breastmilk consumption, fish/shellfish consumption, non-stick frying pan use, and waterproof cloth use were identified as potential sources of PFAAs exposure. Serum PFUnDA level was positively associated with total cholesterol and low-density lipoprotein level of the children. PFNA was positively associated with free T4 level. High levels of PFUnDA among children and its association with serum lipids warrant replication and confirmation in other populations and/or supports by experimental studies.

Prospective Associations of Erythrocyte Composition and Dietary Intake of n-3 and n-6 PUFA with Measures of Cognitive Function

Polyunsaturated fatty acid (PUFA) consumption is recommended as part of a healthy diet, but evidence of the impact of individual species and biological concentrations on cognitive function is limited. We examined prospective associations of PUFA erythrocyte composition and dietary intake with measures of cognitive function among participants of the Boston Puerto Rican Health Study (aged 57 years). Erythrocyte and dietary PUFA composition were ascertained at baseline and associated with 2-year scores on the Mini-Mental State Exam (MMSE) (n = 1032) and cognitive domain patterns derived from a battery of tests (n = 865), as well as with incidence of cognitive impairment. Erythrocyte and dietary n-3 PUFA were not significantly associated with MMSE score. However, total erythrocyte and dietary n-3 very-long-chain fatty acids (VLCFA), and intake of individual species, were associated with better executive function (P-trend < 0.05, for all). There was evidence that greater erythrocyte n-6 eicosadienoic acid concentration was associated with lower MMSE and executive function scores (P-trend = 0.02). Only erythrocyte arachidonic acid (ARA) concentration predicted cognitive impairment (Odds Ratio = 1.26; P = 0.01). Among Puerto Rican adults, we found that n-3 VLCFA consumption may beneficially impact executive function. Further, these findings provide some evidence that n-6 metabolism favoring greater ARA tissue incorporation, but not necessarily dietary intake, could increase the risk of cognitive impairment.

Age dependency of risk factors for cognitive decline

Background

Risk factors for cognitive decline might depend on chronological age. The aim of the study was to explore the age dependency of risk factors for cognitive decline in cognitively healthy subjects aged 55–85 years at baseline.

Methods

We included 2527 cognitively healthy subjects from the Longitudinal Aging Study Amsterdam (LASA). Median follow-up was 9.1 (IQR: 3.2–19.0) years. The association of genetic and cardiovascular risk factors, depressive symptoms, inflammation markers and lifestyle risk factors with decline in MMSE and memory function was tested using spline regression analyses.

Results

Subjects were on average 70.1 (SD 8.8) years old at baseline. Based on a spline regression model, we divided our sample in three age groups: ≤70 years (young-old), > 70–80 years (old) and > 80 years (oldest-old). The association of LDL cholesterol, homocysteine, hypertension, history of stroke, depressive symptoms, interleukin-6, a1-antichymotrypsin, alcohol use and smoking with cognitive decline significantly differed between the age groups. In general, the presence of these risk factors was associated with less cognitive decline in the oldest-old group compared to the young-old and old group.

Conclusions

The negative effect of various risk factors on cognitive decline decreases with higher age. A combination of epidemiological factors, such as the selection towards healthier subjects during follow-up, but also risk factor specific features, for example ensuring the cerebral blood flow in case of hypertension, explain this diminished association at higher age. It is important to take these age differences into account when applying preventive strategies to avert cognitive decline.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0876-2) contains supplementary material, which is available to authorized users.

Environmental and behavioural modifications for improving food and fluid intake in people with dementia

BACKGROUND

Weight loss, malnutrition and dehydration are common problems for people with dementia. Environmental modifications such as, change of routine, context or ambience at mealtimes, or behavioural modifications, such as education or training of people with dementia or caregivers, may be considered to try to improve food and fluid intake and nutritional status of people with dementia.

OBJECTIVES

Primary: To assess the effects of environmental or behavioural modifications on food and fluid intake and nutritional status in people with dementia. Secondary: To assess the effects of environmental or behavioural modifications in connection with nutrition on mealtime behaviour, cognitive and functional outcomes and quality of life, in specific settings (i.e. home care, residential care and nursing home care) for different stages of dementia. To assess the adverse consequences or effects of the included interventions.

SEARCH METHODS

We searched the Specialized Register of Cochrane Dementia and Cognitive Improvement (ALOIS), MEDLINE, Eembase, PsycINFO, CINAHL, ClinicalTrials.gov and the World Health Organization (WHO) portal/ICTRP on 17 January 2018. We scanned reference lists of other reviews and of included articles.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) investigating interventions designed to modify the mealtime environment of people with dementia, to modify the mealtime behaviour of people with dementia or their caregivers, or both, with the intention of improving food and fluid intake. We included people with any common dementia subtype.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, extracted data and assessed the risk of bias of included trials. We assessed the quality of evidence for each outcome using the GRADE approach.

MAIN RESULTS

We included nine studies, investigating 1502 people. Three studies explicitly investigated participants with Alzheimer's disease; six did not specify the type of dementia. Five studies provided clear measures to identify the severity of dementia at baseline, and overall very mild to severe stages were covered. The interventions and outcome measures were diverse. The overall quality of evidence was mainly low to very low.One study implemented environmental as well as behavioural modifications by providing additional food items between meals and personal encouragement to consume them. The control group received no intervention. Differences between groups were very small and the quality of the evidence from this study was very low, so we are very uncertain of any effect of this intervention.The remaining eight studies implemented behavioural modifications.Three studies provided nutritional education and nutrition promotion programmes. Control groups did not receive these programmes. After 12 months, the intervention group showed slightly higher protein intake per day (mean difference (MD) 0.11 g/kg, 95% confidence interval (CI) -0.01 to 0.23; n = 78, 1 study; low-quality evidence), but there was no clear evidence of a difference in nutritional status assessed with body mass index (BMI) (MD -0.26 kg/m² favouring control, 95% CI -0.70 to 0.19; n = 734, 2 studies; moderate-quality evidence), body weight (MD -1.60 kg favouring control, 95% CI -3.47 to 0.27; n = 656, 1 study; moderate-quality evidence), or score on Mini Nutritional Assessment (MNA) (MD -0.10 favouring control, 95% CI -0.67 to 0.47; n = 656, 1 study; low-quality evidence). After six months, the intervention group in one study had slightly lower BMI (MD -1.79 kg/m² favouring control, 95% CI -1.28 to -2.30; n = 52, 1 study; moderate-quality evidence) and body weight (MD -8.11 kg favouring control, 95% CI -2.06 to -12.56; n = 52, 1 study; moderate-quality evidence). This type of intervention may have a small positive effect on food intake, but little or no effect, or a negative effect, on nutritional status.Two studies compared self-feeding skills training programmes. In one study, the control group received no training and in the other study the control group received a different self-feeding skills training programme. For both comparisons the quality of the evidence was very low and we are very uncertain whether these interventions have any effect.One study investigated general training of nurses to impart knowledge on how to feed people with dementia and improve attitudes towards people with dementia. Again, the quality of the evidence was very low so that we cannot be certain of any effect.Two studies investigated vocal or tactile positive feedback provided by caregivers while feeding participants. After three weeks, the intervention group showed an increase in calories consumed per meal (MD 200 kcal, 95% CI 119.81 to 280.19; n = 42, 1 study; low-quality evidence) and protein consumed per meal (MD 15g, 95% CI 7.74 to 22.26; n = 42, 1 study; low-quality evidence). This intervention may increase the intake of food and liquids slightly; nutritional status was not assessed.

AUTHORS' CONCLUSIONS

Due to the quantity and quality of the evidence currently available, we cannot identify any specific environmental or behavioural modifications for improving food and fluid intake in people with dementia.

Associations between waist circumference, metabolic risk and executive function in adolescents: A cross-sectional mediation analysis

The main objective of this study was to investigate the associations between waist circumference, metabolic risk factors, and executive function in adolescents. Methods: The study was cross-sectional and included 558 adolescents (mean age 14.2 years). Anthropometrics and systolic blood pressure (sysBP) were measured and fasting blood samples were analyzed for metabolic risk factors. A metabolic risk factor cluster score (MetS-cluster score) was computed from the sum of standardized sysBP, triglycerides (TG), inverse high-density lipid cholesterol (HDLc) and insulin resistance (homeostasis model assessment). Cognitive control was measured with a modified flanker task. Results: Regression analyses indicated that after controlling for demographic variables, HDLc exhibited a negative and TG a positive association with flanker reaction time (RT). Waist circumference did not demonstrate a statistically significant total association with the cognitive outcomes. In structural equation modeling, waist circumference displayed an indirect positive association with incongruent RT through a higher MetS-cluster score and through lower HDLc. The only statistically significant direct association between waist circumference and the cognitive outcomes was for incongruent RT in the model including HDLc as mediator. Conclusions: These findings are consonant with the previous literature reporting an adverse association between certain metabolic risk factors and cognitive control. Accordingly, these results suggest specificity between metabolic risk factors and cognitive control outcomes. Further, results of the present study, although cross-sectional, provide new evidence that specific metabolic risk factors may mediate an indirect association between adiposity and cognitive control in adolescents, even though a direct association between these variables was not observed. However, taking the cross-sectional study design into consideration, these results should be interpreted with caution and future longitudinal or experimental studies should verify the findings of this study.