Serum cholesterol, APOE genotype, and the risk of Alzheimer's disease: a population-based study of African Americans

The role of thyroid-stimulating hormone in regulating lipid metabolism: Implications for body-brain communication

Thyroid-stimulating hormone (TSH) is a pituitary hormone that stimulates the thyroid gland to produce and release thyroid hormones, primarily thyroxine and triiodothyronine. These hormones are key players in body-brain communication, influencing various physiological processes, including the regulation of metabolism (both peripheral and central effects), feedback mechanisms, and lipid metabolism. Recently, the increasing incidence of abnormal lipid metabolism has highlighted the link between thyroid function and lipid metabolism. Evidence suggests that TSH can affect all bodily systems through body-brain communication, playing a crucial role in growth, development, and the regulation of various physiological systems. Lipids serve dual purposes: they are involved in energy storage and metabolism, and they act as vital signaling molecules in numerous cellular activities, maintaining overall human health or contributing to various diseases. This article reviews the role of TSH in regulating lipid metabolism via body-brain crosstalk, focusing on its implications for common lipid metabolism disorders such as obesity, atherosclerosis, nonalcoholic fatty liver disease, neuropsychiatric disorders (including Alzheimer's disease, Parkinson's disease, multiple sclerosis, epilepsy, and depression), and cerebrovascular disorders such as stroke.

A randomized feasibility trial of the modified Atkins diet in older adults with mild cognitive impairment due to Alzheimer's disease

Background

Alzheimer's disease (AD) is increasing in prevalence, but effective treatments for its cognitive impairment remain severely limited. This study investigates the impact of ketone body production through dietary manipulation on memory in persons with mild cognitive impairment due to early AD and explores potential mechanisms of action.

Methods

We conducted a 12-week, parallel-group, controlled feasibility trial of a ketogenic diet, the modified Atkins diet (MAD), compared to a control diet in patients with cognitive impairments attributed to AD. We administered neuropsychological assessments, including memory tests, and collected blood samples at baseline and after 12 weeks of intervention. We performed untargeted lipidomic and targeted metabolomic analyses on plasma samples to detect changes over time.

Results

A total of 839 individuals were screened to yield 38 randomized participants, with 20 assigned to receive MAD and 18 assigned to receive a control diet. Due to attrition, only 13 in the MAD arm and nine in the control arm were assessed for the primary endpoint, with two participants meeting ketosis levels used to define MAD adherence criteria. The average change from baseline in the Memory Composite Score was 1.37 (95% CI: -0.87, 4.90) points higher in the MAD group compared to the control group. The effect size of the intervention on baseline MAD change was moderate (Cohen's D = 0.57, 95% CI: -0.67, 1.33). In the 15 participants (nine MAD, six control) assessed for lipidomic and metabolomic-lipidomics and metabolomics, 13 metabolites and 10 lipids showed significant changes from baseline to 12 weeks, including triacylglycerols (TAGs, 50:5, 52:5, and 52:6), sphingomyelins (SM, 44:3, 46:0, 46:3, and 48:1), acetoacetate, fatty acylcarnitines, glycerol-3-phosphate, and hydroxy fatty acids.

Conclusions

Attrition was greatest between baseline and week 6. All participants retained at week 6 completed the study. Despite low rates of adherence by criteria defined a priori, lipidomic and metabolomic analyses indicate significant changes from baseline in circulating lipids and metabolites between MAD and control participants at 12-week postrandomization, and MAD participants showed greater, albeit nonsignificant, improvement in memory.

Differential effects of cholesterol levels on cognition according to body mass index in Parkinson's disease

BACKGROUND

Cholesterol is an essential component of the neuronal cell membrane and is crucial for neuronal function; however, the role of cholesterol levels in Parkinson's disease (PD) is debatable. This study investigated the complex relationship between total cholesterol (TC) levels, body mass index (BMI), and cognition in patients with PD.

METHODS

This study included 321 drug-naïve patients with PD who underwent dopamine transporter (DAT) imaging and baseline neuropsychological tests. Multivariate linear regression and Cox regression models were used to investigate the effect of TC levels on the composite score of each cognitive domain and dementia conversion after adjusting for covariates, respectively. Interaction analyses were performed to examine the interaction effect between TC levels and BMI on baseline cognition and dementia conversion.

RESULTS

TC levels and cognition showed no significant relationship after adjusting for potential confounders. A significant interaction effect between TC levels and BMI was observed in frontal/executive function and dementia conversion. Further analyses showed that TC levels were positively associated with frontal/executive function in the under-/normal weight group (β = 0.205, p = 0.013), whereas a negative relationship existed between TC levels and frontal/executive function in the obese group (β =  - 0.213, p = 0.017). Cox regression analyses also showed the differential effects of TC levels on dementia conversion according to BMI (under-/normal weight group: hazard ratio [HR] = 0.550, p = 0.013; obese group: HR = 2.085, p = 0.014).

CONCLUSIONS

This study suggests a cross-over interaction between TC levels and BMI on cognitive symptoms in PD.

Do cerebral microbleeds increase the risk of dementia? A systematic review and meta-analysis

Background

Dementia is a neurological disorder that commonly affects the elderly. Cerebral microbleeds (CMBs) are small, tiny lesions of the cerebral blood vessels and have been suggested as a possible risk factor for dementia. However, data about the association between CMBs and dementia risk are inconsistent and inconclusive. Therefore, we conducted this systematic review and meta-analysis to investigate the association between CMBs and dementia and highlight the possible explanations.

Methods

We followed the standard PRISMA statement and the Cochrane Handbook guidelines to conduct this study. First, we searched medical electronic databases for relevant articles. Then, we screened the retrieved articles for eligibility, extracted the relevant data, and appraised the methodological quality using the Newcastle-Ottawa Scale. Finally, the extracted data were pooled as risk ratios (RR) and hazard ratios (HR) in the random-effects meta-analysis model using the Review Manager software.

Results

We included nine studies with 14,221 participants and follow-up periods > 18 months. Overall, CMBs significantly increased the risk of developing dementia (RR 1.84, 95% CI [1.27-2.65]). This association was significant in the subgroups of studies on high-risk populations (RR 2.00, 95% CI [1.41-2.83], n = 1657 participants) and those in the general population (RR 2.30, 95% CI [1.25-4.26], n = 12,087 participants) but not in the memory clinic patients. Further, CMBs increased the risk of progressing to incident dementia over time (HR 2, 95% CI [1.54-2.61]).

Conclusion

Individuals with CMBs have twice the risk of developing dementia or progressing to MCI than those without CMBs. The detection of CMBs will help identify the population at higher risk of developing dementia. Physicians should educate individuals with CMBs and their families on the possibility of progressing to dementia or MCI. Regular cognitive assessments, cognitive training, lifestyle modifications, and controlling other dementia risk factors are recommended for individuals with CMBs to decrease the risk of cognitive decline and dementia development.

Cholesterol twists the transmembrane Di-Gly region of amyloid-precursor protein

Nearly 95% of Alzheimer's disease (AD) occurs sporadically without genetic linkage. Aging, hypertension, high cholesterol content, and diabetes are known nongenomic risk factors of AD. Aggregation of Aβ peptides is an initial event of AD pathogenesis. Aβ peptides are catabolic products of a type I membrane protein called amyloid precursor protein (APP). Aβ40 is the major product, whereas the 2-residue-longer version, Aβ42, induces amyloid plaque formation in the AD brain. Since cholesterol content is one risk factor for sporadic AD, we aimed to explore whether cholesterol in the membrane affects the structure of the APP transmembrane region, thereby modulating the γ-secretase cutting behavior. Here, we synthesized several peptides containing the APP transmembrane region (sequence 693-726, corresponding to the Aβ_22-55 sequence) with one or two Cys mutations for spin labeling. We performed three electron spin resonance experiments to examine the structural changes of the peptides in liposomes composed of dioleoyl phosphatidylcholine and different cholesterol content. Our results show that cholesterol increases membrane thickness by 10% and peptide length accordingly. We identified that the di-glycine region of Aβ_36-40 (sequence VGGVV) exhibits the most profound change in response to cholesterol compared with other segments, explaining how the presence of cholesterol affects the γ-secretase cutting site. This study provides spectroscopic evidence showing how cholesterol modulates the structure of the APP transmembrane region in a lipid bilayer.

Medical comorbidities and ethnicity impact plasma Alzheimer's disease biomarkers: Important considerations for clinical trials and practice

INTRODUCTION

Despite the clinical implementation, there remain significant gaps in our knowledge regarding the impact of race/ethnicity or common medical comorbidity on plasma Alzheimer's disease (AD) biomarkers.

METHODS

Plasma biomarkers of amyloid beta (Aβ)_40, Aβ₄₂ , total tau, and neurofilament light chain (NfL) were measured across cognitively normal Mexican Americans (n = 445) and non-Hispanic Whites (n = 520).

RESULTS

Dyslipidemia was associated with elevated Aβ₄₀ (P = .01) and Aβ₄₂ (P = .001) while hypertension was associated with elevated Aβ₄₀ (P = .003), Aβ₄₂ (P < .001), and total tau (P = .002) levels. Diabetes was associated with higher Aβ₄₀ (P < .001), Aβ₄₂ (P < .001), total tau (P < .001), and NfL (P < .001) levels. Chronic kidney disease (CKD) was associated with elevations in Aβ₄₀ (P < .001), Aβ₄₂ (P < .001), total tau (P < .001), and NfL (P < .001) levels. Mexican Americans had significantly lower Aβ₄₀ (P < .001) and higher total tau (P = .005) levels.

DISCUSSION

Plasma AD biomarkers vary significantly in association with common medical comorbidities as well as ethnicity. These findings are important for those using these biomarkers in clinical practice and clinical trials.

ARMADA: Assessing reliable measurement in Alzheimer's disease and cognitive aging project methods

INTRODUCTION

Early detection of cognitive decline in older adults is a public health priority. Advancing Reliable Measurement in Alzheimer's Disease and Cognitive Aging (ARMADA), a multisite study, is validating cognition, emotion, motor, and sensory modules of the National Institutes of Health Toolbox for Assessment of Neurological and Behavioral Function (NIHTB) in the aging spectrum from cognitively normal to dementia of the Alzheimer's type (DAT).

METHODS

Participants 65 to 85 years old, in demographic groups racially proportional to the general US population, are recruited in one of three groups to validate the NIHTB: cognitively normal, amnestic mild cognitive impairment (aMCI), or mild DAT. Additional special emphasis cohorts include (1) Blacks in the three clinical groups; (2) Spanish-speakers in the three clinical groups; (3) cognitively normal, population-proportional, over age 85.

DISCUSSION

Longitudinal study will determine whether NIHTB can predict cognitive decline and is associated with Alzheimer's disease biomarkers. Here, we detail the methods for the ARMADA study.

Hypothyroidism and Diabetes-Related Dementia: Focused on Neuronal Dysfunction, Insulin Resistance, and Dyslipidemia

The incidence of dementia is steadily increasing worldwide. The risk factors for dementia are diverse, and include genetic background, environmental factors, sex differences, and vascular abnormalities. Among the subtypes of dementia, diabetes-related dementia is emerging as a complex type of dementia related to metabolic imbalance, due to the increase in the number of patients with metabolic syndrome and dementia worldwide. Thyroid hormones are considered metabolic regulatory hormones and affect various diseases, such as liver failure, obesity, and dementia. Thyroid dysregulation affects various cellular mechanisms and is linked to multiple disease pathologies. In particular, hypothyroidism is considered a critical cause for various neurological problems-such as metabolic disease, depressive symptoms, and dementia-in the central nervous system. Recent studies have demonstrated the relationship between hypothyroidism and brain insulin resistance and dyslipidemia, leading to diabetes-related dementia. Therefore, we reviewed the relationship between hypothyroidism and diabetes-related dementia, with a focus on major features of diabetes-related dementia such as insulin resistance, neuronal dysfunction, and dyslipidemia.

Association of cardiovascular risk burden with risk of dementia and brain pathologies: A population-based cohort study

INTRODUCTION

The impact of cardiovascular risk burden on brain pathologies remains unclear. We aimed to examine the association of the Framingham General Cardiovascular Risk Score (FGCRS) with dementia risk, and brain pathologies.

METHODS

Within the Rush Memory and Aging Project, 1588 dementia-free participants were assessed on FGCRS at baseline and followed up to 21 years. During the follow-up, 621 participants died and underwent autopsies.

RESULTS

The multi-adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) of FGCRS were 1.03 (1.00-1.07) for dementia and 1.04 (1.01-1.07) for Alzheimer's disease (AD) dementia. Further, a higher FGCRS was associated with higher gross chronic cerebral infarctions (odds ratio [OR] 1.08, 95% CI 1.02-1.14), cerebral atherosclerosis (OR 1.10, 95% CI 1.03-1.17), and global AD pathology (OR 1.06, 95% CI 1.01-1.12).

CONCLUSIONS

A higher FGCRS is associated with an increased risk of dementia and AD dementia. Both vascular and AD pathologies in the brain may underlie this association.

A multitude of signaling pathways associated with Alzheimer's disease and their roles in AD pathogenesis and therapy

The exact molecular mechanisms associated with Alzheimer's disease (AD) pathology continue to represent a mystery. In the past decades, comprehensive data were generated on the involvement of different signaling pathways in the AD pathogenesis. However, the utilization of signaling pathways as potential targets for the development of drugs against AD is rather limited due to the immense complexity of the brain and intricate molecular links between these pathways. Therefore, finding a correlation and cross-talk between these signaling pathways and establishing different therapeutic targets within and between those pathways are needed for better understanding of the biological events responsible for the AD-related neurodegeneration. For example, autophagy is a conservative cellular process that shows link with many other AD-related pathways and is crucial for maintenance of the correct cellular balance by degrading AD-associated pathogenic proteins. Considering the central role of autophagy in AD and its interplay with many other pathways, the finest therapeutic strategy to fight against AD is the use of autophagy as a target. As an essential step in this direction, this comprehensive review represents recent findings on the individual AD-related signaling pathways, describes key features of these pathways and their cross-talk with autophagy, represents current drug development, and introduces some of the multitarget beneficial approaches and strategies for the therapeutic intervention of AD.

Apolipoprotein E Induced Cognitive Dysfunction: Mediation Analysis of Lipids and Glucose Biomarkers in an Elderly Cohort Study

INTRODUCTION

Prior evidence suggested Apolipoprotein E (APOE), lipids, and glucose metabolism may act through the same pathways on the pathogenesis of Alzheimer's disease (AD).

METHODS

This prospective study used data from the Chinese Longitudinal Healthy Longevity Study. We tested the associations of APOE genotype (ε2ε2, ε2ε3, ε2ε4, ε3ε3, ε3ε4, and ε4ε4) and cognitive function using generalized estimating equations (GEE). We examined for possible mediation and effect modification by lipids and glucose level in this association.

RESULTS

APOE ε2 showed significant direct protective effect and indirect harmful effect through TC on cognitive function. Abnormal lipids or glucose levels were not consistently associated with cognitive dysfunction in our study. We did not detect significant indirect effects through lipids for APOE ε4 or any indirect effects through glucose.

DISCUSSION

These findings suggested complicated relationships among APOE, lipids, glucose, and cognitive function. Further study can make validations in other populations.

Association between statin use and Alzheimer's disease with dose response relationship

This study aimed to determine the dose-response relationship between the levels of statin exposure and the incidence of Alzheimer's disease (AD). We included 119,013 Korean adults (≥ 60 years old) using a database from the Korean National Health Insurance Service (2002-2013). Statin exposure was treated as a time-varying variable. Incidence of AD was defined by the first claim code for AD with anti-Alzheimer drugs. AD occurred in 9467 cases during a median 7.2 years of follow-up. Overall, statin use was not associated with an increased risk of AD incidence [adjusted hazard ratio (aHR) = 1.04; 95% confidence interval (CI) = 0.99-1.10]. When examined by level of statin exposure, statin prescription < 540 days during a 2-year window time was associated with a higher risk for incidence of AD compared to statin non-use. However, days of prescription ≥ 540 and cumulative defined daily dose ≥ 540 of statin were associated with decreased risk of AD [aHR (95% CI) = 0.87 (0.80-0.95) and 0.79 (0.68-0.92), respectively]. Our findings indicate that less persistent statin use is associated with increased risk of AD, whereas persistent and adherent statin use is associated with decreased risk of AD.

Hypertension and Hypercholesterolemia Modify Dementia Risk in Relation to APOEɛ4 Status

BACKGROUND

There is significant interest in understanding the role of modifiable vascular risk factors contributing to dementia risk across age groups.

OBJECTIVE

Risk of dementia onset was assessed in relation to vascular risk factors of hypertension and hypercholesterolemia among cognitively normal APOEɛ4 carriers and non-carriers.

METHODS

In a sample of prospectively characterized longitudinal cohort from the National Alzheimer's Coordinating Center database, 9,349 participants met criteria for normal cognition at baseline, had a CDR-Global (CDR-G) score of zero, and had concomitant data on APOEɛ4 status and medical co-morbidities including histories of hypertension and hypercholesterolemia. Multivariable Cox proportional hazards models adjusted for well-known potential confounders were used to compare dementia onset among APOEɛ4 carriers and non-carriers by young (≤65 years) and old (> 65 year) age groups.

RESULTS

519 participants converted to dementia within an average follow up of 5.97 years. Among older APOEɛ4 carriers, hypercholesterolemia was related to lower risk of dementia (HR (95% CI), 0.68 (0.49-0.94), p = 0.02). Among older APOEɛ4 non-carriers, hypertension was related to higher risk of dementia (HR (95% CI), 1.44 (1.13-1.82), p = 0.003). These results were corroborated among a subset with autopsy data characterizing underlying neuropathology. Among younger participants, vascular risk factors did not impact dementia risk, likely from a lower frequency of vascular and Alzheimer's as etiologies of dementia among this cohort.

CONCLUSION

A history of hypercholesterolemia related to a lower risk of dementia among older APOEɛ4 carriers, while hypertension related to a higher risk of dementia among older APOEɛ4 non-carriers.

Association of mid-life serum lipid levels with late-life brain volumes: The atherosclerosis risk in communities neurocognitive study (ARICNCS)

BACKGROUND

Limited information exists regarding the association between midlife lipid levels and late-life total and regional brain volumes.

METHODS

We studied 1872 participants in the longitudinal community-based Atherosclerosis Risk in Communities Neurocognitive Study. Serum lipid levels were measured in 1987-1989 (mean age, 53 ± 5 years). Participants underwent 3T brain MRI scans in 2011-2013. Brain volumes were measured using FreeSurfer image analysis software. Linear regression models were used to assess the associations between serum lipids and brain volumes modeled in standard deviation (SD) units, adjusting for potential confounders.

RESULTS

In adjusted analyses, one SD higher low-density lipoprotein cholesterol (LDL) levels were associated with larger total brain volumes (β 0.033, 95% CI 0.006-0.060) as well as larger volumes of the temporal (β 0.038, 95% CI 0.003-0.074) and parietal lobes (β 0.044, 95% CI 0.009-0.07) and Alzheimer disease-related region (β 0.048, 95% CI 0.048-0.085). Higher triglyceride levels were associated with smaller total brain volumes (β -0.033, 95% CI -0.060, -0.007). The associations between LDL levels and brain volumes were modified by age (P for interaction <0.001), with higher LDL levels associated with larger total and regional brain volumes only among adults >53 years at baseline, and were attenuated after application of weights to account for informative attrition, although associations with the parietal and Alzheimer's disease-related region remained significant. High-density lipoprotein cholesterol was not associated with brain volumes.

CONCLUSION

Higher LDL levels in late midlife were associated with larger brain volumes later in life, while higher triglyceride levels were associated with smaller brain volumes. These associations were driven by adults >53 years at baseline.

Blood Lipids and Cognitive Performance of Aging Polish Adults: A Case-Control Study Based on the PolSenior Project

Background: The demand for effective strategies for maintaining cognitive capableness and establishing early dementia diagnosis has been tremendous, especially in the context of population aging. However, studies on the elderly population and neurocognitive impairment had provided ambiguous results throughout, while potential blood biomarkers of cognitive decline are yet to be clearly understood.

Objectives: The present study is aimed at assessing the relationship between blood lipids—especially in the context of their usefulness as biomarkers of an early cognitive decline—and cognitive functioning of aging adults.

Materials and Methods: The study sample consisted of 230 participants—(109 women, 121 men) aged 65+ years. Plasma 24(S)-hydroxycholesterol [24(S)-OHC], serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL) were assessed. The analyses were conducted in three groups of cognitive performance: cognitively normal, mild cognitive impairment (MCI), and mild dementia, of which the subjects were divided with the Mini-Mental State Examination (MMSE).

Results: No significant differences in 24(S)-OHC plasma concentrations for different levels of cognitive performance were found. Significant differences were found in serum TC (p = 0.026) and LDL (p = 0.007) concentrations for different levels of cognitive performance. Concentrations of both parameters were highest in the MCI group and lowest in mild dementia and cognitive norm, respectively. No significant differences between serum HDL concentrations and cognitive performance were found.

Conclusions: To fully assess the potential of research on blood lipids in regards to a cognitive decline, cross-sectional or epidemiological studies aimed at further exploring blood lipid roles in both the early and advanced MCI and dementia, are needed.

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.

Preliminary Report on the Feasibility and Efficacy of the Modified Atkins Diet for Treatment of Mild Cognitive Impairment and Early Alzheimer's Disease

Ketone bodies, the products of fat metabolism, are a source of energy for the brain and are available even when glucose supplies are inadequate (such as with severe carbohydrate deprivation) or its metabolism is faulty (as it is in Alzheimer's disease). This phase I/II randomized clinical trial examined the feasibility of using a modified Atkins diet (MAD) to induce ketogenesis in persons with mild cognitive impairment (MCI) or early AD, and the effect of this diet on memory and other clinical outcomes. In the first 2.5 years of active recruitment, only 27 eligible and willing patients enrolled. After extensive assessment and education, they and their study partners were randomly assigned for 12 weeks to either the MAD or the National Institute on Aging (NIA) recommended diet for seniors. As of April 2018, 9 patients in the MAD arm and 5 in the NIA arm have completed the trial. In spite of extensive teaching, coaching, and monitoring, adherence to both diets was only fair. Among those in the MAD arm who generated at least trace amounts of urinary ketones, there was a large (effect size = 0.53) and statistically significant (p = 0.03) increase in Memory Composite Score between the baseline and week-6 assessment. MAD participants also reported increased energy between baseline and week-6 assessment. Despite challenges to implementing this trial, resulting in a small sample, our preliminary data suggest that the generation of even trace ketones might enhance episodic memory and patient-reported vitality in very early AD.

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.

Effects of Cholesterol in Stress-Related Neuronal Death-A Statistical Analysis Perspective

The association between plasma cholesterol levels and the development of dementia continues to be an important topic of discussion in the scientific community, while the results in the literature vary significantly. We study the effect of reducing oxidized neuronal cholesterol on the lipid raft structure of plasma membrane. The levels of plasma membrane cholesterol were reduced by treating the intact cells with methyl-ß-cyclodextrin (MßCD). The relationship between the cell viability with varying levels of MßCD was then examined. The viability curves are well described by a modified form of the empirical Gompertz law of mortality. A detailed statistical analysis is performed on the fitting results, showing that increasing MßCD concentration has a minor, rather than significant, effect on the cellular viability. In particular, the dependence of viability on MßCD concentration was found to be characterized by a ~25% increase per 1 μM of MßCD concentration.

Prevention of dementia presents a potentially critical platform for improvement of long-term public health

With the aging of the population, Alzheimer disease (AD) has become an epidemic and a major public health threat. Hundreds of molecules tested in clinical trials in the last decade to treat AD have failed, moving the field to examine the clinical and neurobiological value of prevention of cognitive decline and AD. This short review describes recently finished or currently ongoing clinical trials for prevention of AD, both their main outcomes and secondary outcomes. In addition, the potential modifying effects of age and of genetics as important factors that may affect the design of future clinical trials is discussed. Finally, we discuss the development of new molecular imaging and of digital technologies as a means to disclosure of dementia-related risk and disease progress, and their potential importance as contributors to adherence to healthy lifestyle for the prevention or delay of AD onset.

Clinical Application of APOE in Alzheimer's Prevention: A Precision Medicine Approach

Population-attributable risk models estimate that up to one-third of Alzheimer's disease (AD) cases may be preventable through risk factor modification. The field of AD prevention has largely focused on addressing these factors through universal risk reduction strategies for the general population. However, targeting these strategies in a clinical precision medicine fashion, including the use of genetic risk factors, allows for potentially greater impact on AD risk reduction. Apolipoprotein E (APOE), and specifically the APOE ε4 variant, is one of the most well-established genetic influencers on late-onset AD risk. In this review, we evaluate the impact of APOE ε4 carrier status on AD prevention interventions, including lifestyle, nutrigenomic, pharmacogenomic, AD comorbidities, and other biological and behavioral considerations. Using a clinical precision medicine strategy that incorporates APOE ε4 carrier status may provide a highly targeted and distinct approach to AD prevention with greater potential for success.

Metabolic Syndrome, Mild Cognitive Impairment, and Dementia: A Meta-Analysis of Longitudinal Studies

OBJECTIVE

A systematic review and a meta-analysis of both clinical and population-based studies was undertaken according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement to clarify whether Metabolic Syndrome (MetS) is a risk or a protective factor for incident dementia, Alzheimer disease (AD), and vascular dementia (VaD), and whether it's involved in progression to dementia in patients affected by mild cognitive impairment (MCI).

METHODS

Search terms included ("metabolic syndrome" OR "syndrome x" OR "plurimetabolic syndrome") AND ("dementia" OR "Alzheimer disease" OR "vascular dementia" OR "mild cognitive impairment" OR "MCI"). Research was restricted to articles published in English between January 1, 2000 and August 31, 2018. No age limit was set.

RESULTS

At the end of the selection procedure, nine longitudinal studies were selected for the meta-analysis: six studies enrolled cognitively well-functioning participants and three studies involved MCI patients. A total of 18,313 participants aged older than 40 years with mean MetS prevalence of 22.7% were followed on average for 9.41years. A fixed model was used to estimate pooled hazard ratios and 95% confidence intervals.

CONCLUSION

No statistically significant pooled association emerged between MetS and incident dementia and AD. MetS increased the incidence of pure VaD. MetS increased the risk of progression from MCI to dementia. Follow-up length might be a key factor in investigating these associations further. Because MetS is constituted by a set of potentially modifiable factors, further studies with longer follow-up and repeated assessment of both MetS and cognitive status are desirable to draw definite conclusions.

Predictors of neurodegeneration differ between cognitively normal and subsequently impaired older adults

Effects of Alzheimer's disease (AD) risk factors on brain volume changes may partly explain what happens during the preclinical AD stage in people who develop subsequent cognitive impairment (SI). We investigated predictors of neurodegeneration, measured by MRI-based volume loss, in older adults before diagnosis of cognitive impairment. There were 623 cognitively normal and 65 SI Baltimore Longitudinal Study of Aging participants (age 55-92 years) enrolled in the neuroimaging substudy from 1994 to 2015. Mixed-effects regression was used to assess the associations of AD risk factors (age, APOE e4 carrier status, diabetes, hypertension, obesity, current smoking, and elevated cholesterol) with brain regional volume change among the overall sample and by diagnostic status. Older age, APOE e4 carrier status, hypertension, and HDL cholesterol were predictors of volumetric change. Among SI participants only, hypertension, obesity, and APOE e4 carrier status were associated with greater declines in selected brain regions. SI individuals in the preclinical AD stage are vulnerable to risk factors that have either a protective or null effect in cognitively normal individuals.

The SNP43 (G/A) polymorphism in CAPN10 gene confers an increased risk of cognitive impairment in cerebral small vessel disease

BACKGROUND

Cognitive impairment, significantly reducing processing speed and executive function, is the critical consequence of cerebral small vessel disease (SVD), in which genetic variations have been studied. In this study, we explore the role of SNP43 (G/A) and SNP63 (C/T) polymorphism in the CAPN10 on cognitive impairment process in cerebral SVD.

METHODS

Cerebral SVD patients (n = 224) and healthy controls (n = 187) were recruited. The relationship between frequency distribution of SNP43 (G/A) and SNP63 (T/C) genotype and allele in CAPN10 gene, and cognitive impairment was examined. The independent risk factors for cognitive impairment in SVD were determined by logistic regression analysis.

RESULTS

Accordingly, the frequency distribution of genotype and allele at SNP43 (G/A) was significantly different between cerebral SVD patients and healthy controls. Cerebral SVD patients with GG genotype were more susceptible for cognitive impairment, whereas cerebral SVD patients with GA + AA genotype were less possible to suffer from cognitive impairment, compared with those with GG genotype. And also, cerebral SVD does not include SNP63 (C/T) to associate with cognitive impairment, and SNP43 (G/A), total cholesterol, triglyceride, low-density lipoprotein, and high-density lipoprotein were independent risk factors for cognitive impairment in SVD.

CONCLUSION

Our study provides evidence that SNP43 (G/A) in the CAPN10 gene increases the risk of cognitive impairment in SVD patients. Besides it is proven that, patients with G allele are more susceptible to suffer from cerebral SVD with worse cognitive impairment.

Lipidomic Profiles in Diabetes and Dementia

Lipids are a diverse class of hydrophobic and amphiphilic molecules which make up the bulk of most biological systems and are essential for human life. The role of lipids in health and disease has been recognized for many decades, as evidenced by the early identification of cholesterol as an important risk factor of heart disease and the development and introduction of statins as a one of the most successful therapeutic interventions to date. While several studies have demonstrated an increased risk of dementia, including Alzheimer's disease (AD), in those with diabetes mellitus, the nature of this risk is not well understood. Recent developments in the field of lipidomics, driven primarily by technological advances in high pressure liquid chromatography and particularly mass spectrometry, have enabled the detailed characterization of the many hundreds of individual lipid species in mammalian systems and their association with disease states. Diabetes mellitus and AD have received particular attention due to their prominence in Western societies as a result of the ongoing obesity epidemic and the aging populations. In this review, we examine how these lipidomic studies are informing on the relationship between lipid metabolism with diabetes and AD and how this may inform on the common pathological pathways that link diabetes risk with dementia.

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.

Alzheimer's Disease: From Genetic Variants to the Distinct Pathological Mechanisms

Being the most common cause of dementia, AD is a polygenic and neurodegenerative disease. Complex and multiple factors have been shown to be involved in its pathogenesis, of which the genetics play an indispensable role. It is widely accepted that discovery of potential genes related to the pathogenesis of AD would be of great help for the understanding of neurodegeneration and thus further promote molecular diagnosis in clinic settings. Generally, AD could be clarified into two types according to the onset age, the early-onset AD (EOAD) and the late-onset AD (LOAD). Progresses made by genetic studies on both EOAD and LOAD are believed to be essential not only for the revolution of conventional ideas but also for the revelation of new pathological mechanisms underlying AD pathogenesis. Currently, albeit the genetics of LOAD is much less well-understood compared to EOAD due to its complicated and multifactorial essence, Genome-wide association studies (GWASs) and next generation sequencing (NGS) approaches have identified dozens of novel genes that may provide insight mechanism of LOAD. In this review, we analyze functions of the genes and summarize the distinct pathological mechanisms of how these genes would be involved in the pathogenesis of AD.

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.

Current status of biomarker research in neurology

Neurology is one of the typical disciplines where personalized medicine has been recently becoming an important part of clinical practice. In this article, the brief overview and a number of examples of the use of biomarkers and personalized medicine in neurology are described. The various issues in neurology are described in relation to the personalized medicine and diagnostic, prognostic as well as predictive blood and cerebrospinal fluid biomarkers. Such neurological domains discussed in this work are neuro-oncology and primary brain tumors glioblastoma and oligodendroglioma, cerebrovascular diseases focusing on stroke, neurodegenerative disorders especially Alzheimer's and Parkinson's diseases and demyelinating diseases such as multiple sclerosis. Actual state of the art and future perspectives in diagnostics and personalized treatment in diverse domains of neurology are given.

Exploration of Environmental and Genetic Risk Factors for Alzheimer's Disease: The Value of Cross-Cultural Studies

Advances in molecular genetics have revolutionized epidemiological research. It is now possible to combine the techniques of population genetics with research on risk factors to construct genetic-environmental interactive models that explain geographic-ethnic variations in disease rates. Cross-cultural studies involving populations from developing and developed countries offer a unique opportunity for constructing these models by providing a wide diversity of environmental exposures. Results from a comparative Indianapolis-Ibadan study suggest that Alzheimer's disease incidence rates are lower in Yoruba than in African Americans and that these lower rates may be due to a combination of genetic and environmental, primarily dietary, influences.

Genetics, Dementia, and the Elderly

Whether or not an individual develops dementia is powerfully influenced by genes. For Alzheimer's disease, the most common type of dementia, one susceptibility gene with major effects has been identified, but progress finding other susceptibility genes has stalled. Twin studies have revealed that nongenetic risk also plays an important role, as there are many monozygotic twin pairs in which only one individual has dementia. Scientists have argued that gene-by-environment interactions will be key to understanding vulnerability to Alzheimer's disease; but to date, few substantial gene-by-environment interactions have been replicated. Often, too, the nongenetic or lifestyle factor appears to have a protective effect only for those individuals not carrying the risky version of the gene, not for those individuals who are at genetic risk.

Endocrine Risk Factors for Cognitive Impairment

Cognitive impairment, including Alzheimer's disease and other kinds of dementia, is a major health problem in older adults worldwide. Although numerous investigators have attempted to develop effective treatment modalities or drugs, there is no reasonably efficacious strategy for preventing or recovering from cognitive impairment. Therefore, modifiable risk factors for cognitive impairment have received attention, and the growing literature of metabolic risk factors for cognitive impairment has expanded from epidemiology to molecular pathogenesis and therapeutic management. This review focuses on the epidemiological evidence for the association between cognitive impairment and several endocrine risk factors, including insulin resistance, dyslipidemia, thyroid dysfunction, vitamin D deficiency, and subclinical atherosclerosis. Researches suggesting possible mechanisms for this association are reviewed. The research investigating modifiable endocrine risk factors for cognitive impairment provides clues for understanding the pathogenesis of cognitive impairment and developing novel treatment modalities. However, so far, interventional studies investigating the beneficial effect of the "modification" of these "modifiable risk factors" on cognitive impairment have reported variable results. Therefore, well-designed, randomized prospective interventional studies are needed.

Influence of antihypertensive therapy on cerebral perfusion in patients with metabolic syndrome: relationship with cognitive function and 24-h arterial blood pressure monitoring

AIMS

To investigate the regional cerebral blood flow, cognitive function, and parameters of 24-h arterial blood pressure monitoring in patients with metabolic syndrome before and after combination antihypertensive therapy.

METHODS

The study involved 54 patients with metabolic syndrome (MetS) investigated by brain single-photon emission computed tomography, 24-h blood pressure monitoring (ABPM), and comprehensive neuropsychological testing before and after 24 weeks of combination antihypertensive therapy.

RESULTS

Patients with metabolic syndrome had significantly poorer regional cerebral blood flow compared with control group: by 7% (P = 0.003) in right anterior parietal cortex, by 6% (P = 0.028) in left anterior parietal cortex, by 8% (P = 0.007) in right superior frontal lobe, and by 10% (P = 0.00002) and 7% (P = 0.006) in right and left temporal brain regions, correspondingly. The results of neuropsychological testing showed 11% decrease in mentation (P = 0.002), and 19% (P = 0.011) and 20% (P = 0.009) decrease in immediate verbal and visual memory in patients with MetS as compared with control group. Relationships between the indices of ABPM, cerebral perfusion, and cognitive function were found. Data showed an improvement of regional cerebral blood flow, ABPM parameters, and indicators of cognitive functions after 6 months of antihypertensive therapy in patients with MetS.

CONCLUSION

The study showed the presence of diffuse disturbances in cerebral perfusion is associated with cognitive disorders in patients with metabolic syndrome. Combination antihypertensive treatment exerts beneficial effects on the 24-h blood pressure profile, increases cerebral blood flow, and improves cognitive function in patients with MetS.

Bile Acid Modifications at the Microbe-Host Interface: Potential for Nutraceutical and Pharmaceutical Interventions in Host Health

Bile acids have emerged as important signaling molecules in the host, as they interact either locally or systemically with specific cellular receptors, in particular the farnesoid X receptor (FXR) and TGR5. These signaling functions influence systemic lipid and cholesterol metabolism, energy metabolism, immune homeostasis, and intestinal electrolyte balance. Through defined enzymatic activities, the gut microbiota can significantly modify the signaling properties of bile acids and therefore can have an impact upon host health. Alterations to the gut microbiota that influence bile acid metabolism are associated with metabolic disease, obesity, diarrhea, inflammatory bowel disease (IBD), Clostridium difficile infection, colorectal cancer, and hepatocellular carcinoma. Here, we examine the regulation of this gut-microbiota-liver axis in the context of bile acid metabolism and indicate how this pathway represents an important target for the development of new nutraceutical (diet and/or probiotics) and targeted pharmaceutical interventions.

Danggui-Shaoyao-San: New Hope for Alzheimer's Disease

Danggui-Shaoyao-San (DSS), also called Toki-shakuyaku-san (TJ-23) or Dangguijakyak-san (DJS), is a well-known herbal formula (Angelica sinensis (Oliv.) Diels., Ligusticum chuanxiong Hort., Paeonia lactiflora pall., Poria cocos (Schw.) Wolf, Alisma orientalis (Sam.) Juzep., Atractylodes macrocephala Koidz.), which has been widely used in oriental countries for the treatment of various gynecological diseases. Recent studies show that DSS has an effect on free radical-mediated neurological diseases and exhibits anti-inflammatory and antioxidant activities and reduces cell apoptosis in the hippocampus. In addition, DSS mediates the modulation of central monoamine neurotransmitter systems and ameliorates dysfunction of the central cholinergic nervous system and scopolamine-induced decrease in ACh levels. DSS improves the function of the dopaminergic, adrenergic, and serotonergic nervous systems. Interestingly, DSS can alleviate cognitive dysfunction of Alzheimer's disease (AD) patients, suggesting that it is a useful therapeutic agent for AD. This paper reviews the mechanism of DSS for the treatment of AD.

Serum Levels of ApoA1 and ApoA2 Are Associated with Cognitive Status in Older Men

Background. Advancing age, chronic inflammation, oxidative damage, and disorders of lipid metabolism are positively linked to the late-life cognitive impairment. Serum biomarkers may be associated with the cognitive status in older men. Methods. 440 old male subjects with different cognitive functions were recruited to investigate probable serum markers. Pearson Chi-Squared test, univariate analysis, and multivariate logistic regression analysis were performed to evaluate biomarkers which may be associated with cognitive status. Results. Levels of fundus atherosclerosis (AS) (P < 0.001), age (P < 0.001), serum biomarkers peroxidase (POD) (P = 0.026) and interleukin-6 (IL-6) (P = 0.001), serum levels of high-density lipoprotein cholesterol (HDL-C) (P < 0.001), apolipoprotein A2 (ApoA2) (P = 0.001), and ApoC2 (P = 0.005) showed significant differences. Compared to group 3, ApoA1 in group 1 (OR = 1.30, 95% CI 1.01–1.67) and group 2 (OR = 1.47, 95% CI 1.11–1.94) were higher, while ApoA2 were lower (group 1: OR = 0.43, 95% CI 0.18–1.02; group 2: OR = 0.21, 95% CI 0.08–0.54) after adjusting for control variables. Conclusion. The results demonstrated that age, AS levels, POD, IL-6, HDL-C, ApoA2, and ApoC2 were significantly related to cognitive status. Moreover, ApoA1 and ApoA2 were independently associated with cognitive impairment and late-life dementia.

Effect of apolipoprotein E (APO E) polymorphism on leptin in Alzheimer's disease

Background:

Leptin, a 16 kDa peptide hormone synthesized and secreted specifically from white adipose cells protects neurons against amyloid β-induced toxicity, by increasing Apolipoprotein E (APO E)-dependent uptake of β amyloid into the cells, thereby, protect individuals from developing Alzheimer's disease (AD). The APO E ε4 allele is a known genetic risk factor for AD by accelerating onset. It is estimated that the lifetime risk of developing AD increases to 29% for carriers with one ε4 allele and 9% for those with no ε4 allele.

Objectives:

To determine the levels of serum leptin, cholesterol, low density lipoprotein (LDL-C), and high density lipoprotein (HDL-C) in the diagnosed cases of AD and the association of them with cognitive decline and Apolipoprotein E (APO E) genotypes in AD.

Materials and Methods:

Serum levels of serum leptin, cholesterol, LDL-C, and HDL-C along with APO E polymorphism were studied in 39 subjects with probable AD and 42 cognitive normal individuals.

Results:

AD group showed significantly lower levels of leptin (P = 0.00) as compared to control group. However, there was no significant difference in cholesterol, triglycerides, LDL-C, and HDL-C levels in AD and control groups. The frequency of ε4 allele in AD (38.5%) was found to be significantly higher than in control (10.3%). ε3 allele was more frequent than ε4 allele in AD and control group.

Metabolic Risk Factors of Sporadic Alzheimer's Disease: Implications in the Pathology, Pathogenesis and Treatment

Alzheimer's disease (AD), the major cause of dementia among the elderly world-wide, manifests in familial and sporadic forms, and the latter variety accounts for the majority of the patients affected by this disease. The etiopathogenesis of sporadic AD is complex and uncertain. The autopsy studies of AD brain have provided limited understanding of the antemortem pathogenesis of the disease. Experimental AD research with transgenic animal or various cell based models has so far failed to explain the complex and varied spectrum of AD dementia. The review, therefore, emphasizes the importance of AD related risk factors, especially those with metabolic implications, identified from various epidemiological studies, in providing clues to the pathogenesis of this complex disorder. Several metabolic risk factors of AD like hypercholesterolemia, hyperhomocysteinemia and type 2 diabetes have been studied extensively both in epidemiology and experimental research, while much less is known about the role of adipokines, pro-inflammatory cytokines and vitamin D in this context. Moreover, the results from many of these studies have shown a degree of variability which has hindered our understanding of the role of AD related risk factors in the disease progression. The review also encompasses the recent recommendations regarding clinical and neuropathological diagnosis of AD and brings out the inherent uncertainty and ambiguity in this area which may have a distinct impact on the outcome of various population-based studies on AD-related risk factors.

Association of apolipoprotein E genetic variation in Alzheimer's disease in Indian population: a meta-analysis

BACKGROUND

Dementia is an age-related disorder associated with elderly population, resulting from interaction of lifestyle risk factors with genetic, vascular, and other risk factors to affect risk of disease. Alzheimer's disease (AD) is the most common form of dementia, estimated to be affecting 4.4% of the population older than 65 years of age. Apolipoprotein E (ApoE) ε4 allele is a known genetic risk factor for AD, which not only predisposes and influences the severity of pathological changes in the brain, thereby modifying the age at onset, but also promotes cognitive decline early in nondemented older people.

OBJECTIVES

To review the published evidence on ApoE polymorphism with the susceptibility to AD and frequency of ApoE ε4 genotype (ε4/-) and homozygotes (ε4/4) among patients diagnosed with AD as compared to controls in Indian Population.

MATERIALS AND METHODS

In the present study, MEDLINE was reviewed for articles published till June 2013 supplemented by citation analysis from retrieved articles to select case-control studies. A meta-analysis was performed to demonstrate the association of ApoE gene with vascular dementia by random effects to demonstrate models. The association was assessed by odds ratio (OR) with 95% confidence intervals (CIs).

STUDY SELECTION

Case-control studies, using clinical criteria for AD with ApoE polymorphism determined for allele and genotype in both cases and controls.

STATISTICAL ANALYSIS

A meta-analysis was performed to demonstrate the association of ApoE gene with AD by random effects to demonstrate models. The association was assessed by OR with 95% CIs. We also looked for publication bias and performed sensitivity analysis to investigate the influence of each individual study.

RESULTS

A total of 7 studies representing data from 417 patients with AD and 651 controls in the Indian population were eligible. The ApoE ε2/4, ε3/4, and ε4/4 genotypes (OR = 3.93, 95% CI: 1.60-9.68; OR = 4.18, 95% CI: 2.54-6.87; OR = 4.81, 95% CI: 1.95-11.86, respectively) as well as ApoE ε4 allele (OR = 5.90, 95% CI: 3.44-10.13) were associated with an increased risk of AD, whereas ApoE ε2/3, ε3/3 genotypes (OR = 0.52, 95% CI: 0.32-0.83; OR = 0.28, 95% CI: 0.19-0.42), and ApoE ε3 allele (OR = 0.29, 95% CI: 0.17-0.50) were found to be marginally significant protective factors for AD. There was no significant difference in ApoE ε2/2 genotype and ApoE ε2 allele frequency (OR = 0.42; 95% CI: 0.11-1.68; OR = 0.69, 95% CI: 0.37-1.31, respectively) in patients with AD and controls.

CONCLUSIONS

These results indicate that all genotypes of ApoE ε4 allele, that is, ε2/4, ε3/4, and ε4/4, are associated with an increased risk of AD, whereas ApoE ε2/2, ε2/3, and ε3/3 are protective for AD.

Metabolic and hormonal signatures in pre-manifest and manifest Huntington's disease patients

Huntington's disease (HD) is an inherited neurodegenerative disorder typified by involuntary body movements, and psychiatric and cognitive abnormalities. Many HD patients also exhibit metabolic changes including progressive weight loss and appetite dysfunction. Here we have investigated metabolic function in pre-manifest and manifest HD subjects to establish an HD subject metabolic hormonal plasma signature. Individuals at risk for HD who have had predictive genetic testing showing the cytosine-adenine-guanine (CAG) expansion causative of HD, but who do not yet present signs and symptoms sufficient for the diagnosis of manifest HD are said to be “pre-manifest.” Pre-manifest and manifest HD patients, as well as both familial and non-familial controls, were evaluated for multiple peripheral metabolism signals including circulating levels of hormones, growth factors, lipids, and cytokines. Both pre-manifest and manifest HD subjects exhibited significantly reduced levels of circulating growth factors, including growth hormone and prolactin. HD-related changes in the levels of metabolic hormones such as ghrelin, glucagon, and amylin were also observed. Total cholesterol, HDL-C, and LDL-C were significantly decreased in HD subjects. C-reactive protein was significantly elevated in pre-manifest HD subjects. The observation of metabolic alterations, even in subjects considered to be in the pre-manifest stage of HD, suggests that in addition, and prior, to overt neuronal damage, HD affects metabolic hormone secretion and energy regulation, which may shed light on pathogenesis, and provide opportunities for biomarker development.

APOE ε4 and the risk for Alzheimer disease and cognitive decline in African Americans and Yoruba

BACKGROUND

There is little information on the association of the APOEe4 allele and AD risk in African populations. In previous analyses from the Indianapolis-Ibadan dementia project, we have reported that APOE ε4 increased the risk for Alzheimer's disease (AD) in African Americans but not in Yoruba. This study represents a replication of this earlier work using enriched cohorts and extending the analysis to include cognitive decline.

METHODS

In this longitudinal study of two community dwelling cohorts of elderly Yoruba and African Americans, APOE genotyping was conducted from blood samples taken on or before 2001 (1,871 African Americans & 2,200 Yoruba). Mean follow up time was 8.5 years for African Americans and 8.8 years for Yoruba. The effects of heterozygosity or homozygosity of ε4 and of the possession of e4 on time to incident AD and on cognitive decline were determined using Cox's proportional hazards regression and mixed effects models.

RESULTS

After adjusting for covariates, one or two copies of the APOE ε4 allele were significant risk factors for incident AD (p < 0.0001) and cognitive decline in the African-American population (p < 0001). In the Yoruba, only homozygosity for APOE ε4 was a significant risk factor for AD (p = 0.0002) but not for cognitive decline (p = 0.2346), however, possession of an e4 allele was significant for both incident AD (p = 0.0489) and cognitive decline (p = 0.0425).

CONCLUSIONS

In this large longitudinal comparative study, APOE ε4 had a significant, but weaker, effect on incident AD and on cognitive decline in Yoruba than in African Americans. The reasons for these differences remain unclear.

Possible modification of Alzheimer's disease by statins in midlife: interactions with genetic and non-genetic risk factors

The benefits of statins, commonly prescribed for hypercholesterolemia, in treating Alzheimer's disease (AD) have not yet been fully established. A recent randomized clinical trial did not show any therapeutic effects of two statins on cognitive function in AD. Interestingly, however, the results of the Rotterdam study, one of the largest prospective cohort studies, showed reduced risk of AD in statin users. Based on the current understanding of statin actions and AD pathogenesis, it is still worth exploring whether statins can prevent AD when administered decades before the onset of AD or from midlife. This review discusses the possible beneficial effects of statins, drawn from previous clinical observations, pathogenic mechanisms, which include β-amyloid (Aβ) and tau metabolism, genetic and non-genetic risk factors (apolipoprotein E, cholesterol, sex, hypertension, and diabetes), and other clinical features (vascular dysfunction and oxidative and inflammatory stress) of AD. These findings suggest that administration of statins in midlife might prevent AD in late life by modifying genetic and non-genetic risk factors for AD. It should be clarified whether statins inhibit Aβ accumulation, tau pathological features, and brain atrophy in humans. To answer this question, a randomized controlled study using amyloid positron emission tomography (PET), tau-PET, and magnetic resonance imaging would be useful. This clinical evaluation could help us to overcome this devastating disease.

Influence of cognitive impairment on the management of ischaemic stroke

BACKGROUND

Because of ageing of the population, it is more and more frequent to treat ischaemic stroke patients with pre-stroke cognitive impairment (PSCI). Currently, there is no specific recommendation on ischaemic stroke management in these patients, both at the acute stage and in secondary prevention. However, these patients are less likely to receive treatments proven effective in randomised controlled trials, even in the absence of contra-indication.

OBJECTIVE

To review the literature to assess efficacy and safety of validated therapies for acute ischaemic stroke and secondary prevention in PSCI patients.

RESULTS

Most randomised trials did not take into account the pre-stroke cognitive status. The few observational studies conducted at the acute stage or in secondary prevention, did not provide any information that the benefit could be either lost or replaced by harm in the presence of PSCI.

CONCLUSIONS

There is no reason not to treat ischaemic stroke patients with PSCI according to the currently available recommendations for acute management and secondary prevention. Further observational studies are needed and pre-stroke cognition should be taken into account in future stroke trials.