A cross-sectional study of lipids and ApoC levels in Alzheimer's patients with and without cardiovascular disease

Higher Apolipoprotein C-III Levels in Cerebrospinal Fluid are Associated with Slower Cognitive Decline in Mild Cognitive Impairment

BACKGROUND

Although a growing body of evidence shows an important role of apolipoproteins in the pathogenesis of Alzheimer's disease (AD), the association of apolipoprotein C-III (APOC-III) with cognitive decline is not clear.

OBJECTIVE

To examine whether higher cerebrospinal fluid (CSF) and plasma APOC-III levels were associated with better cognitive performance over time in the early stage of AD.

METHODS

Baseline CSF and plasma APOC-III levels were analyzed in relation to cross-sectionally and longitudinally cognitive performance over a 12-year period. Data were extracted from the Alzheimer's Disease Neuroimaging Initiative database, and 234 subjects (89 subjects with normal cognition (NC) and 145 subjects with mild cognitive impairment (MCI)) with CSF APOC-III measurements and 454 subjects (58 subjects with NC and 396 subjects with MCI) with plasma APOC-III measurements were included.

RESULTS

In the cross-sectional study, we did not find a significant relationship between CSF APOC-III and cognitive performance in pooled individuals with MCI and NC. However, longitudinal analysis found that higher baseline CSF APOC-III was significantly associated with slower cognitive decline over a 12-year period in individuals with MCI, but not the healthy controls, after controlling for several covariates and Alzheimer biomarkers. Plasma APOC-III levels showed a mild correlation with CSF APOC-III levels, but were not associated with longitudinal cognitive changes in the pooled sample or in diagnosis-stratified analyses.

CONCLUSIONS

Higher CSF APOC-III levels are significantly associated with slower cognitive decline over a 12-year period among individuals with MCI.

A core transcriptional signature of human microglia: Derivation and utility in describing region-dependent alterations associated with Alzheimer's disease

Growing recognition of the pivotal role microglia play in neurodegenerative and neuroinflammatory disorders has accentuated the need to characterize their function in health and disease. Studies in mouse have applied transcriptome-wide profiling of microglia to reveal key features of microglial ontogeny, functional profile, and phenotypic diversity. While similar, human microglia exhibit clear differences to their mouse counterparts, underlining the need to develop a better understanding of the human microglial profile. On examining published microglia gene signatures, limited consistency was observed between studies. Hence, we sought to derive a core microglia signature of the human central nervous system (CNS), through a comprehensive analysis of existing transcriptomic datasets. Nine datasets derived from cells and tissues, isolated from various regions of the CNS across numerous donors, were subjected independently to an unbiased correlation network analysis. From each dataset, a list of coexpressing genes corresponding to microglia was identified, with 249 genes highly conserved between them. This core signature included known microglial markers, and compared with other signatures provides a gene set specific to microglia in the context of the CNS. The utility of this signature was demonstrated by its use in detecting qualitative and quantitative region-specific alterations in aging and Alzheimer's disease. These analyses highlighted the reactive response of microglia in vulnerable brain regions such as the entorhinal cortex and hippocampus, additionally implicating pathways associated with disease progression. We believe this resource and the analyses described here, will support further investigations to the contribution of human microglia in CNS health and disease.

Cloning and characterization of an apolipoprotein C2 promoter in the mouse central nervous system

Apolipoprotein C2 is an important member of the apolipoprotein C family, and is a potent activator of lipoprotein lipase. In the central nervous system, apolipoprotein C2 plays an important role in the catabolism of triglyceride-rich lipoproteins. Studies into the exact regulatory mechanism of mouse apolipoprotein C2 expression have not been reported. In this study, seven luciferase expression vectors, which contained potential mouse apolipoprotein C2 gene promoters, were constructed and co-transfected with pRL-TK into HEK293T cells to investigate apolipoprotein C2 promoter activity. Luciferase assays indicated that the apolipoprotein C2 promoter region was mainly located in the +104 bp to +470 bp region. The activity of the different lengths of apolipoprotein C2 promoter region varied. This staggered negative-positive-negative arrangement indicates the complex regulation of apolipoprotein C2 expression and provides important clues for elucidating the regulatory mechanism of apolipoprotein C2 gene transcription.

Metabolic-cognitive syndrome: a cross-talk between metabolic syndrome and Alzheimer's disease

A growing body of epidemiological evidence suggested that metabolic syndrome (MetS) and Mets components (impaired glucose tolerance, abdominal or central obesity, hypertension, hypertriglyceridemia, and reduced high-density lipoprotein cholesterol) may be important in the development of age-related cognitive decline (ARCD), mild cognitive impairment (MCI), vascular dementia, and Alzheimer's disease (AD). These suggestions proposed in these patients the presence of a "metabolic-cognitive syndrome", i.e. a MetS plus cognitive impairment of degenerative or vascular origin. This could represent a pathophysiological model in which to study in depth the mechanisms linking MetS and MetS components with dementia, particularly AD, and predementia syndromes (ARCD or MCI), suggesting a possible integrating view of the MetS components and their influence on cognitive decline. In the present article, we discussed the role of these factors in the development of cognitive decline and dementia, including underlying mechanisms, supporting their influence on β-amyloid peptide metabolism and tau protein hyperphosphorylation, the principal neuropathological hallmarks of AD. In the next future, trials could then be undertaken to determine if modifications of these MetS components including inflammation, another factor probably related to MetS, could lower risk of developing cognitive decline. Future research aimed at identifying mechanisms that underlie comorbid associations of MetS components will not only provide important insights into the causes and interdependencies of predementia and dementia syndromes, but will also inspire novel strategies for treating and preventing cognitive disorders.

Cholesterol metabolism and transport in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder, affecting millions of people worldwide. Apart from age, the major risk factor identified so far for the sporadic form of AD is possession of the epsilon4 allele of apolipoprotein E (APOE), which is also a risk factor for coronary artery disease (CAD). Other apolipoproteins known to play an important role in CAD such as apolipoprotein B are now gaining attention for their role in AD as well. AD and CAD share other risk factors, such as altered cholesterol levels, particularly high levels of low density lipoproteins together with low levels of high density lipoproteins. Statins--drugs that have been used to lower cholesterol levels in CAD, have been shown to protect against AD, although the protective mechanism(s) involved are still under debate. Enzymatic production of the beta amyloid peptide, the peptide thought to play a major role in AD pathogenesis, is affected by membrane cholesterol levels. In addition, polymorphisms in several proteins and enzymes involved in cholesterol and lipoprotein transport and metabolism have been linked to risk of AD. Taken together, these findings provide strong evidence that changes in cholesterol metabolism are intimately involved in AD pathogenic processes. This paper reviews cholesterol metabolism and transport, as well as those aspects of cholesterol metabolism that have been linked with AD.

Cognitive function in drinkers compared to abstainers in the New Mexico elder health survey

BACKGROUND

Recent epidemiological studies have shown that individuals who ingest alcohol regularly have a higher level of cognitive function and are less likely to develop dementia than those who abstain. The purpose of this study was to compare nine measures of cognitive function in drinkers compared to abstainers.

METHODS

A cross-sectional community survey was conducted of 883 randomly selected Hispanic and non-Hispanic white men and women, age >or=65 years of age, undergoing a paid home interview and 4-hour interview/examination in a senior health clinic (The New Mexico Elder Health Survey). The interviews included questions on frequency and quantity of alcohol ingested.

RESULTS

Participants who consumed alcohol had significantly better mean scores on 7 of 9 cognitive function tests and less frequently had scores below selected "cut points" compared to those who abstained from all alcohol intake. Scoring used multivariate linear and logistic regression models adjusted for sex, ethnicity, age, level of education, and evidence of depression.

CONCLUSIONS

Participants in the New Mexico Elder Health Survey (nearly equal numbers of Hispanic and non-Hispanic white men and women) who consumed alcohol had better scores on their cognitive tests than did those participants who abstained.

Cholesterol at the crossroads: Alzheimer's disease and lipid metabolism

Alzheimer's Disease (AD) is a devastating disease that affects millions of elderly persons. Despite years of intense investigations, genetic risk factors that affect the majority of AD cases have yet to be determined. Recent studies suggest that cholesterol metabolism has integral part in AD pathogenesis, suggesting that genes that regulate lipid metabolism may also play roles in AD. This review will first describe emerging evidence that links cholesterol to the mechanisms thought to underlie AD. Based on this rationale, candidate genes located in regions implicated in AD that have roles in lipid metabolism will then be discussed.