Inflammatory markers in younger vs elderly normal volunteers and in patients with Alzheimer's disease

Cytokine dysregulation in amnestic mild cognitive impairment

The pathophysiology of amnestic Mild Cognitive Impairment (aMCI) is largely unknown, although some papers found signs of immune activation. To assess the cytokine network in aMCI after excluding patients with major depression (MDD) and to examine the immune profiles of quantitative aMCI (qMCI) and distress symptoms of old age (DSOA) scores. A case-control study was conducted on 61 Thai aMCI participants and 60 healthy old adults (both without MDD). The Bio-Plex Pro human cytokine 27-plex test kit was used to assay cytokines/chemokines/growth factors in fasting plasma samples. aMCI is characterized by a significant immunosuppression, and reductions in T helper 1 (Th)1 and T cell growth profiles, the immune-inflammatory responses system, interleukin (IL)1β, IL6, IL7, IL12p70, IL13, GM-CSF, and MCP-1. These 7 cytokines/chemokines exhibit neuroprotective effects at physiologic concentrations. In multivariate analyses, three neurotoxic chemokines, CCL11, CCL5, and CXCL8, emerged as significant predictors of aMCI. Logistic regression showed that aMCI was best predicted by combining IL7, IL1β, MCP-1, years of education (all inversely associated) and CCL5 (positively associated). We found that 38.2% of the variance in the qMCI score was explained by IL7, IL1β, MCP-1, IL13, years of education (inversely associated) and CCL5 (positively associated). The DSOA was not associated with any immune data. An imbalance between lowered levels of neuroprotective cytokines and chemokines, and relative increases in neurotoxic chemokines are key factors in aMCI. Future MCI research should always control for the confounding effects of affective symptoms.

In a circuit necessary for cognition and emotional affect, Alzheimer's-like pathology associates with neuroinflammation, cognitive and motivational deficits in the young adult TgF344-AD rat

In addition to extracellular amyloid plaques, intracellular neurofibrillary tau tangles, and inflammation, cognitive and emotional affect perturbations are characteristic of Alzheimer's disease (AD). The cognitive and emotional domains impaired by AD include several forms of decision making (such as intertemporal choice), blunted motivation (increased apathy), and impaired executive function (such as working memory and cognitive flexibility). However, the interaction between these domains of the mind and their supporting neurobiological substrates at prodromal stages of AD, or whether these interactions can be predictive of AD severity (individual variability), remain unclear. In this study, we employed a battery of cognitive and emotional tests in the young adult (5-7 mo) transgenic Fisher-344 AD (TgF344-AD; TgAD) rat model of AD. We also assessed whether markers of inflammation or AD-like pathology in the prelimbic cortex (PrL) of the medial prefrontal cortex (mPFC), basolateral amygdala (BLA), or nucleus accumbens (NAc), all structures that directly support the aforementioned behaviors, were predictive of behavioral deficits. We found TgAD rats displayed maladaptive decision making, greater apathy, and impaired working memory that was indeed predicted by AD-like pathology in the relevant brain structures, even at an early age. Moreover, we report that the BLA is an early epicenter of inflammation, and notably, AD-like pathology in the PrL, BLA, and NAc was predictive of BLA inflammation. These results suggest that operant-based battery testing may be sensitive enough to determine pathology trajectories, including neuroinflammation, from early stages of AD.

Importance of serum albumin in machine learning-based prediction of cognitive function in the elderly using a basic blood test

Introduction

In this study, we investigated the correlation between serum albumin levels and cognitive function, and examined the impact of including serum albumin values in the input layer on the prediction accuracy when forecasting cognitive function using deep learning and other machine learning models.

Methods

We analyzed the electronic health record data from Osaka Medical and Pharmaceutical University Hospital between 2014 and 2021. The study included patients who underwent cognitive function tests during this period; however, patients from whom blood test data was not obtained up to 30 days before the cognitive function tests and those with values due to measurement error in blood test results were excluded. The Mini-Mental State Examination (MMSE) was used as the cognitive function test, and albumin levels were examined as the explanatory variable. Furthermore, we estimated MMSE scores from blood test data using deep learning models (DLM), linear regression models, support vector machines (SVM), decision trees, random forests, extreme gradient boosting (XGBoost), and light gradient boosting machines (LightGBM).

Results

Out of 5,017 patients who underwent cognitive function tests, 3,663 patients from whom blood test data had not been obtained recently and two patients with values due to measurement error were excluded. The final study population included 1,352 patients, with 114 patients (8.4%) aged below 65 and 1,238 patients (91.6%) aged 65 and above. In patients aged 65 and above, the age and male sex showed significant associations with MMSE scores of less than 24, while albumin and potassium levels showed negative associations with MMSE scores of less than 24. Comparing MMSE estimation performance, in those aged below 65, the mean squared error (MSE) of DLM was improved with the inclusion of albumin. Similarly, the MSE improved when using SVM, random forest and XGBoost. In those aged 65 and above, the MSE improved in all models.

Discussion

Our study results indicated a positive correlation between serum albumin levels and cognitive function, suggesting a positive correlation between nutritional status and cognitive function in the elderly. Serum albumin levels were shown to be an important explanatory variable in the estimation of cognitive function for individuals aged 65 and above.

Analysis of the mechanism of fibrauretine alleviating Alzheimer's disease based on transcriptomics and proteomics

The dried rattan stem of the Fibraurea Recisa Pierre plant contains the active ingredient known as fibrauretine (FN). Although it greatly affects Alzheimer's disease (AD), the mechanism of their effects still remains unclear. Proteomics and transcriptomics analysis methods were used in this study to determine the mechanism of FN in the treatment of AD. AD model is used through bilateral hippocampal injection of Aβ1-40. After successful modeling, FN was given for 30 days. The results showed that FN could improve the cognitive dysfunction of AD model rats, reduce the expression of Aβ and P-Tau, increase the content of acetylcholine and reduce the activity of acetylcholinesterase. The Kyoto Encyclopedia of Genes and Genomes enriched differentially expressed genes and proteins are involved in signaling pathways including metabolic pathway, AD, pathway in cancer, PI3K-AKT signaling pathway, and cAMP signaling pathway. Transcriptomics and proteomics sequencing resulted in 19 differentially expressed genes and proteins. Finally, in contrast to the model group, after FN treatment, the protein expressions and genes associated with the PI3K-AKT pathway were significantly improved in RT-qPCR and Western blot and assays. This is consistent with the findings of transcriptomic and proteomic analyses. Our study found that, FN may improve some symptoms of AD model rats through PI3K-AKT signaling pathway.

The association between serum albumin and depressive symptoms: a cross-sectional study of NHANES data during 2005-2018

AIMS

The association between serum albumin and depressive symptoms has been unclear in previous epidemiological studies. We explored whether serum albumin is associated with depressive symptoms based on the National Health and Nutrition Examination Survey (NHANES) data.

METHODS

This cross-sectional study included 13,681 participants aged ≥ 20 years from the NHANES performed during 2005-2018, which produced nationally representative database. Depressive symptoms were assessed using the Patient Health Questionnaire-9. Serum albumin concentration was measured using the bromocresol purple dye method, and participants were divided into quartiles of serum albumin concentrations. Weighted data were calculated according to analytical guidelines. Logistics regression and linear regression models were used to assess and quantify the association between serum albumin and depressive symptoms. Univariate and stratified analyses were also performed.

RESULTS

There were 1551 (10.23%) adults (aged ≥ 20 years) with depressive symptoms among the 13,681. A negative association was found between serum albumin concentration and depressive symptoms. Compared with the lowest albumin quartile, the multivariate-adjusted effect size (95% confidence interval) for depressive symptoms of the fully adjusted model in the highest albumin quartile was 0.77 (0.60 to 0.99) and - 0.38 (- 0.66 to - 0.09) using logistics regression and linear regression models respectively. Current smoking status modified the association between serum albumin concentration and PHQ-9 scores (p for interaction = 0.033).

CONCLUSION

This cross-sectional study revealed that albumin concentration is significantly more likely to be a protective factor for depressive symptoms, with the association being more pronounced in non-smokers.

Testing the link between isoaspartate and Alzheimer's disease etiology

Isoaspartate (isoAsp) is a damaging amino acid residue formed in proteins as a result of spontaneous deamidation. IsoAsp disrupts protein structures, making them prone to aggregation. Here we strengthened the link between isoAsp and Alzheimer's disease (AD) by novel approaches to isoAsp analysis in human serum albumin (HSA), the most abundant blood protein and a major carrier of amyloid beta (Aβ) and phosphorylated tau (p-tau) in blood. We discovered a reduced amount of anti-isoAsp antibodies (P < 0.0001), an elevated isoAsp level in HSA (P < 0.001), more HSA aggregates (P < 0.0001), and increased levels of free Aβ (P < 0.01) in AD blood compared to controls. We also found that deamidation significantly reduces HSA capacity to bind with Aβ and p-tau (P < 0.05). These suggest the presence in AD of a bottleneck in clearance of Aβ and p-tau, leading to their increased concentrations in the brain and facilitating their aggregations there.

The Tryptophan Catabolite or Kynurenine Pathway in Alzheimer's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Alzheimer's disease (AD), which is characterized by progressive brain dysfunction and memory loss, is one of the most significant global health concerns for older adults. Neuroinflammation and increased oxidative stress contribute to the pathophysiology of AD, thereby presumably inducing tryptophan (TRP) degradation through the TRP catabolite (TRYCAT) pathway.

OBJECTIVE

To delineate the activity of the TRYCAT pathway along with levels of TRP and tryptophan catabolites (TRYCATs) in AD patients.

METHODS

We used PubMed, Google Scholar, Web of Science, and SciFinder during the month of January 2022 to gather the pertinent publications. We found 19 eligible articles which involved 738 patients and 665 healthy controls.

RESULTS

Our results revealed a significant difference (p = 0.008) in the kynurenine (KYN)/TRP ratio (standardized mean difference, SMD = 0.216, 95% confidence interval, CI: 0.057; 0.376), and a significant decrease in TRP in AD patients (SMD = -0.520, 95% CI: -0.738; -0.302, p < 0.0001). Moreover, we also found a significant increase in the central nervous system (CNS), brain, and cerebrospinal fluid kynurenic acid (KA)/KYN ratio but not in peripheral blood, as well as a significant decrease in plasma KA and xanthurenic acid in the CNS and blood.

CONCLUSION

AD is characterized by TRP depletion but not by an overactivity of the TRYCAT pathway. IDO-induced production of neurotoxic TRYCATs is not a key factor in the pathophysiology of AD.

Altered peripheral factors affecting the absorption, distribution, metabolism, and excretion of oral medicines in Alzheimer's disease

Alzheimer's disease (AD) has traditionally been considered solely a neurological condition. Therefore, numerous studies have been conducted to identify the existence of pathophysiological changes affecting the brain and the blood-brain barrier in individuals with AD. Such studies have provided invaluable insight into possible changes to the central nervous system exposure of drugs prescribed to individuals with AD. However, there is now increasing recognition that extra-neurological systems may also be affected in AD, such as the small intestine, liver, and kidneys. Examination of these peripheral pathophysiological changes is now a burgeoning area of scientific research, owing to the potential impact of these changes on the absorption, distribution, metabolism, and excretion (ADME) of drugs used for both AD and other concomitant conditions in this population. The purpose of this review is to identify and summarise available literature reporting alterations to key organs influencing the pharmacokinetics of drugs, with any changes to the small intestine, liver, kidney, and circulatory system on the ADME of drugs described. By assessing studies in both rodent models of AD and samples from humans with AD, this review highlights possible dosage adjustment requirements for both AD and non-AD drugs so as to ensure the achievement of optimum pharmacotherapy in individuals with AD.

Human serum albumin in neurodegeneration

Serum albumin (SA) exists in relatively high concentrations, in close contact with most cells. However, in the adult brain, except for cerebrospinal fluid (CSF), SA concentration is relatively low. It is mainly produced in the liver to serve as the main protein of the blood plasma. In the plasma, it functions as a carrier, chaperon, antioxidant, source of amino acids, osmoregulator, etc. As a carrier, it facilitates the stable presence and transport of the hydrophobic and hydrophilic molecules, including free fatty acids, steroid hormones, medicines, and metal ions. As a chaperon, SA binds to and protects other proteins. As an antioxidant, thanks to a free sulfhydryl group (-SH), albumin is responsible for most antioxidant properties of plasma. These functions qualify SA as a major player in, and a mirror of, overall health status, aging, and neurodegeneration. The low concentration of SA is associated with cognitive deterioration in the elderly and negative prognosis in multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). SA has been shown to be structurally modified in neurological conditions such as Alzheimer's disease (AD). During blood-brain barrier damage albumin enters the brain tissue and could trigger epilepsy and neurodegeneration. SA is able to bind to the precursor agent of the AD, amyloid-beta (Aβ), preventing its toxic effects in the periphery, and is being tested for treating this disease. SA therapy may also be effective in brain rejuvenation. In the current review, we will bring forward the prominent properties and roles of SA in neurodegeneration.

The clinical correlation of proinflammatory and anti-inflammatory biomarkers with Alzheimer disease: a meta-analysis

BACKGROUND

Numerous studies have indicated the role of inflammation in the pathogenesis of Alzheimer's disease (AD). However, the exact role of inflammatory markers in AD is still unclear.

OBJECTIVE

The main objective of the current study was to find out the association between the level of inflammatory markers and AD.

MATERIAL AND METHODS

The relevant articles have been extracted from PubMed as per the inclusion and exclusion criteria of the study. The mean value with standard deviation and number of participants in AD and control groups were extracted from relevant articles. The inverse variance was used as a statistical method and standard mean difference (SMD) as effect measure with 95% C.I. The random effect model was used and all analyses were done using Rev. Man 5.0.

RESULTS

A total of 38 articles have been found relevant and selected for analysis. The overall estimate results have shown that the level of IL-6, TGF-β1, and IL-1α were increased significantly in AD patients as compared to the control group among all other pro-inflammatory, inflammatory and anti-inflammatory mediators.

CONCLUSION

The findings of the current study suggest that IL-6, TGF-β1, and IL-1α may be a useful early marker in AD. However, further studies are required to confirm the exact utility of these inflammatory markers.

First Immunoassay for Measuring Isoaspartate in Human Serum Albumin

Isoaspartate (isoAsp) is a damaging amino acid residue formed in proteins mostly as a result of spontaneous deamidation of asparaginyl residues. An association has been found between isoAsp in human serum albumin (HSA) and Alzheimer’s disease (AD). Here we report on a novel monoclonal antibody (mAb) 1A3 with excellent specificity to isoAsp in the functionally important domain of HSA. Based on 1A3 mAb, an indirect enzyme-linked immunosorbent assay (ELISA) was developed, and the isoAsp occupancy in 100 healthy plasma samples was quantified for the first time, providing the average value of (0.74 ± 0.13)%. These results suggest potential of isoAsp measurements for supplementary AD diagnostics as well as for assessing the freshness of stored donor blood and its suitability for transfusion.

Inflammation and Mitochondrial Dysfunction in Autism Spectrum Disorder

Autism Spectrum Disorders (ASD) is a severe childhood psychiatric condition with an array of cognitive, language and social impairments that can significantly impact family life. ASD is classically characterized by reduced communication skills and social interactions, with limitations imposed by repetitive patterns of behavior, interests, and activities. The pathophysiology of ASD is thought to arise from complex interactions between environmental and genetic factors within the context of individual development. A growing body of research has raised the possibility of identifying the aetiological causes of the disorder. This review highlights the roles of immune-inflammatory pathways, nitro-oxidative stress and mitochondrial dysfunctions in ASD pathogenesis and symptom severity. The role of NK-cells, T helper, T regulatory and B-cells, coupled with increased inflammatory cytokines, lowered levels of immune-regulatory cytokines, and increased autoantibodies and microglial activation is elucidated. It is proposed that alterations in mitochondrial activity and nitrooxidative stress are intimately associated with activated immune-inflammatory pathways. Future research should determine as to whether the mitochondria, immune-inflammatory activity and nitrooxidative stress changes in ASD affect the development of amygdala-frontal cortex interactions. A number of treatment implications may arise, including prevention-orientated prenatal interventions, treatment of pregnant women with vitamin D, and sodium butyrate. Treatments of ASD children and adults with probiotics, sodium butyrate and butyrate-inducing diets, antipurinergic therapy with suramin, melatonin, oxytocin and taurine are also discussed.

Peripheral Blood Biomarkers Coupled with the Apolipoprotein E4 Genotype Are Strongly Associated with Semantic and Episodic Memory Impairments in Elderly Subjects with Amnestic Mild Cognitive Impairment and Alzheimer's Disease

BACKGROUND

The Apolipoprotein E4 (ApoE4) genotype is strongly associated with Alzheimer's disease (AD), although the presence of the ApoE4 allele alone is not sufficient to explain AD. The pathophysiology of amnestic mild cognitive impairment (aMCI) remains unclear.

OBJECTIVE

This study aims to examine associations between peripheral blood biomarkers coupled with ApoE4 and episodic and semantic memory.

METHODS

The CERAD battery was completed and various biomarkers were assayed in 60 subjects with aMCI, 60 with AD, and 62 healthy controls.

RESULTS

Deficits in semantic and episodic memory were significantly predicted by anion gap and bicarbonate, albumin, and glucose coupled with ApoE4. Furthermore, these peripheral biomarkers interacted with ApoE to predict greater memory impairments.

CONCLUSIONS

Peripheral blood biomarkers may interact with pathways related to ApoE4 to predict greater semantic and episodic memory impairments, thus contributing to the pathophysiology of aMCI and AD. Our data suggest that the transition from aMCI to AD could at least in some cases be associated with significant interactions between ApoE4 and those peripheral blood biomarkers.

Alterations in drug disposition in older adults: a focus on geriatric syndromes

INTRODUCTION

Age-associated physiological changes can alter the disposition of drugs, however, pathophysiological changes associated with geriatric syndromes in older adults may lead to even greater heterogeneity in pharmacokinetics. Geriatric syndromes are common health problems in older adults which have multifactorial causes and do not fit into distinct organ-based disease categories. With older adults being the greatest users of medications, understanding both age- and geriatric syndrome-related changes is important clinically to ensure safe and effective medication use.

AREAS COVERED

This review provides an overview of current evidence regarding pharmacokinetic alterations that occur with aging and in common geriatric syndromes, including frailty, sarcopenia, dementia, polypharmacy and enteral feeding. The evidence is presented according to the four primary pharmacokinetic processes (Absorption, Distribution, Metabolism and Excretion).

EXPERT OPINION

There is some evidence to inform our understanding of the impact of chronological aging and various geriatric syndromes on drug disposition. However, many areas require more research, including drug induced inhibition and induction of cytochrome P450 enzymes and the clinical utility of emerging methods for estimating renal function. There is a need to develop tools to predict alterations in drug disposition in subgroups of older adults, particularly where the currently available clinical information is sparse.

Serum albumin and beta-amyloid deposition in the human brain

Objectives

To investigate the relationships of serum albumin with in vivo Alzheimer disease (AD) pathologies, including cerebral β-amyloid (Aβ) protein deposition, neurodegeneration of AD-signature regions, and cerebral white matter hyperintensities (WMH), in the human brain.

Methods

A total of 396 older adults without dementia underwent comprehensive clinical assessments, measurement of serum albumin level, and multimodal brain imaging, including [¹¹C] Pittsburgh compound B-PET, ¹⁸F-fluorodeoxyglucose-PET, and MRI. Serum albumin was categorized as follows: <4.4 g/dL (low albumin), 4.4 to 4.5 g/dL (middle albumin), and >4.5 g/dL (high albumin; used as a reference category). Aβ positivity, AD-signature region cerebral glucose metabolism (AD-CM), AD-signature region cortical thickness (AD-CT), and WMH volume were used as outcome measures.

Results

Serum albumin level (as a continuous variable) was inversely associated with Aβ deposition and Aβ positivity. The low albumin group showed a significantly higher Aβ positivity rate compared to the high albumin group (odds ratio 3.40, 95% confidence interval 1.67–6.92, p = 0.001), while the middle albumin group showed no difference (odds ratio 1.74, 95% confidence interval 0.80–3.77, p = 0.162). Neither serum albumin level (as a continuous variable) nor albumin categories were related to AD-CM, AD-CT, or WMH volume.

Conclusions

Low serum albumin may increase the risk of AD dementia by elevating amyloid accumulation. In terms of AD prevention, more attention needs to be paid to avoid a low serum albumin level, even within the clinical normal range, by clinicians.

Machine Learning to Understand the Immune-Inflammatory Pathways in Fibromyalgia

Fibromyalgia (FM) is a chronic syndrome characterized by widespread musculoskeletal pain, and physical and emotional symptoms. Although its pathophysiology is largely unknown, immune-inflammatory pathways may be involved. We examined serum interleukin (IL)-6, high sensitivity C-reactive protein (hs-CRP), CXCL-8, and IL-10 in 67 female FM patients and 35 healthy women while adjusting for age, body mass index (BMI), and comorbid disorders. We scored the Fibromyalgia Severity Score, Widespread Pain Index (WPI), Symptom Severity Scale (SSS), Hospital Anxiety (HADS-A), and Depression Scale and the Perceived Stress Scale (PSS-10). Clinical rating scales were significantly higher in FM patients than in controls. After adjusting for covariates, IL-6, IL-10, and CXCL-8 were lower in FM than in HC, whereas hs-CRP did not show any difference. Binary regression analyses showed that the diagnosis FM was associated with lowered IL-10, quality of sleep, aerobic activities, and increased HADS-A and comorbidities. Neural networks showed that WPI was best predicted by quality of sleep, PSS-10, HADS-A, and the cytokines, while SSS was best predicted by PSS-10, HADS-A, and IL-10. Lowered levels of cytokines are associated with FM independently from confounders. Lowered IL-6 and IL-10 signaling may play a role in the pathophysiology of FM.

Serum albumin/globulin ratio is associated with cognitive function in community-dwelling older people: The Septuagenarians, Octogenarians, Nonagenarians Investigation with Centenarians study

AIM

The objective of this study was to clarify the relationship between cognitive function and the serum albumin/globulin ratio (A/G ratio) in community-dwelling Japanese older adults.

METHODS

Randomly extracted residents in both urban and rural parts of Japan were enrolled in this study. A total of 1827 participants with a mean age of 70 or 80 years were recruited. A venue survey method was carried out with comprehensive studies, including interviews, blood collection, physical examination and cognitive function tests.

RESULTS

Univariate analysis showed a significant positive correlation between the total Japanese version of the Montreal Cognitive Assessment score and the serum A/G ratio at the age of 70 and 80 years, in which better cognitive function was associated with a high serum A/G ratio. Multiple regression analysis with the total Japanese version of the Montreal Cognitive Assessment score as the dependent variable showed that the serum albumin level, serum globulin level, serum A/G ratio, C-reactive protein, years of formal education and sex were related to the Japanese version of the Montreal Cognitive Assessment total score at the age of 70 years, and that the serum albumin level, serum globulin level, serum A/G ratio, C-reactive protein, years of formal education and stroke were related at the age of 80 years. The serum A/G ratio showed a better correlation than the serum globulin levels at the age of 70 and 80 years (70 years: β = 0.131 vs -0.111, 80 years: β = 0.108 vs -0.071).

CONCLUSIONS

We found a correlation between cognitive function and the serum A/G ratio in community-dwelling older people, suggesting that nutritional status and chronic inflammation might influence cognitive function. Geriatr Gerontol Int 2019; 19: 967-971.

Association between decreased serum albumin levels and depressive symptoms in patients with schizophrenia in a Chinese Han population: A pilot study

Albumin is a metal-binding protein with free-radical scavenging properties and is recognized as a vital antioxidant. Moreover, an excess of free radicals may contribute to depressive symptoms and the psychopathology of psychiatric disorders. This study examined serum albumin levels, depressive symptoms, and their association in patients with schizophrenia. Thirty-four patients with schizophrenia (diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth edition) and 136 healthy controls were consecutively enrolled in this case-control study. The clinical psychiatric symptoms in patients with schizophrenia were assessed using the Positive and Negative Syndrome Scale (PANSS). Serum albumin levels were measured in all participants using an immunoturbidimetric method. This study was conducted between 2016 and 2017. Serum albumin levels were significantly lower in patients with schizophrenia compared to healthy controls after adjusting for gender, age and education (F = 16.04, p = 0.000). Serum albumin levels were negatively correlated with the depressive score of PANSS in patients with schizophrenia (r = -0.37, p = 0.03). Additionally, a further stepwise multivariate regression analysis showed that serum albumin levels were significantly associated with the depressive score of PANSS in patients with schizophrenia (ß = -0.37, t = -2.25, p = 0.03). Our data suggested that decreased serum albumin levels may contribute to the psychopathology of schizophrenia and that a decline in serum albumin levels was associated with the severity of depressive symptoms in patients with schizophrenia.

Genetic reduction of Nrf2 exacerbates cognitive deficits in a mouse model of Alzheimer's disease

Aging is the major risk factor for several neurodegenerative diseases, including Alzheimer's disease (AD). However, the mechanisms by which aging contributes to neurodegeneration remain elusive. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a transcription factor that regulates expression of a vast number of genes by binding to the antioxidant response element. Nrf2 levels decrease as a function of age, and reduced Nrf2 levels have been reported in postmortem human brains and animal models of AD. Nevertheless, it is still unknown whether Nrf2 plays a role in the cognitive deficits associated with AD. To address this question, we used a genetic approach to remove the Nrf2 gene from APP/PS1 mice, a widely used animal model of AD. We found that the lack of Nrf2 significantly exacerbates cognitive deficits in APP/PS1, without altering gross motor function. Specifically, we found an exacerbation of deficits in spatial learning and memory, as well as in working and associative memory. Different brain regions control these behavioral tests, indicating that the lack of Nrf2 has a global effect on brain function. The changes in cognition were linked to an increase in Aβ and interferon-gamma (IFNγ) levels, and microgliosis. The changes in IFNγ levels are noteworthy as previously published evidence indicates that IFNγ can increase microglia activation and induce Aβ production. Our data suggest a clear link between Nrf2 and AD-mediated cognitive decline and further strengthen the connection between Nrf2 and AD.

Phase angle is related with inflammatory and oxidative stress biomarkers in older women

BACKGROUND

The aim of this study was to examine the relation between phase angle (PhA) and inflammatory and oxidative stress biomarkers in older women.

METHODS

One hundred and fifty-five physically independent older women participated in this study (67.7±5.7years, 27.0±4.4kg/m2). Inflammatory markers included interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and acute phase reactive protein (CRP). Oxidative stress biomarkers comprised superoxide dismutase (SOD), catalase (CAT), advanced oxidation protein products (AOPP), and total radical-trapping antioxidant potential (TRAP). A spectral bioelectrical impedance device was used to estimate resistance (R) and reactance (Xc) at frequency 50kHz, and subsequently PhA was calculated as arc-tangent (Xc/R)×180°/π. The covariates appendicular lean soft-tissue (ALST), trunk fat mass, and total body fat were determined by whole-body dual-energy X-ray absorptiometry. Linear regression analysis was conducted to further test if PhA is related with the dependent variables, after adjusting for potential covariates.

RESULTS

After controlling for the potential covariates (age, trunk fat mass, ALST, and number of diseases) PhA exhibited a significant inverse relation with IL-6 (β=-0.97; P<0.01), TNF-α (β=-0.84; P<0.01), and CRP (β=-0.58; P<0.01). Conversely, PhA was significantly related to CAT (β=7.27; P<0.01), SOD (β=10.55; P<0.01) and TRAP (β=73.08; P<0.01). The AOPP did not demonstrate a significant correlation with PhA (P>0.05).

CONCLUSION

Our findings show that PhA is a simple and relevant explanatory variable which is related inflammatory and stress oxidative markers in physically independent older women, regardless of age, number of diseases, and body composition.

Serum albumin levels and depression in people living with Human Immunodeficiency Virus infection: a cross-sectional study

BACKGROUND

Lower serum albumin levels and depression are common among HIV-infected persons. High serum albumin levels may provide protection against depression through its defensive role in inflammation and infection. We tested the hypothesis of an independent relationship between serum albumin levels and depressive symptoms in a cohort of HIV-infected persons.

METHODS

A cross-sectional survey was conducted among 310 HIV-infected persons (176 men and 134 women) aged 20-60years residing in the Kathmandu Valley, Nepal. The bromocresol green method was used to measure serum albumin levels and the Beck Depression Inventory method was used to measure depressive symptoms, with a cut off score of 20 or higher indicating likely depression. The relationship between serum albumin levels and depressive symptoms was assessed using both multiple linear regression analysis and multiple logistic regression analysis, with adjustment for sociodemographic, cardiovascular, life-style, and HIV-related clinical and treatment confounding factors.

RESULTS

Serum albumin levels were inversely associated with depressive symptoms scores (beta for 1 unit change in serum albumin levels: β=-3.91; p=0.001) for the total participant sample. This inverse association was significant in both men (β=-3.93; p=0.009) and women (β=-4.47; p=0.03). A significantly decreased risk of depression was observed among participants with the highest serum albumin levels, with odds ratio and 95% CI for those with >5.0g/dL versus <4.0g/dL of 0.22 (0.06-0.80) (p=0.01).

CONCLUSION

Serum albumin levels were inversely associated with depressive symptoms scores in HIV-infected persons.

Serum Copper, Zinc, and Iron Levels in Patients with Alzheimer's Disease: A Meta-Analysis of Case-Control Studies

Background: Many publications have investigated the association between metal ions and the risk of Alzheimer's disease (AD), but the results were ambiguous.

Aims: The objective of this study was to assess the association between the serum levels of metals (copper/zinc/iron) and the risk of AD via meta-analysis of case-control studies.

Methods: We screened literatures published after 1978 in the Pubmed, Embase, Cochrane library, Web of Science and ClinicalTrials.gov. Electronic databases. By using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, we performed a systematic review of the 407 publications, there are 44 of these publications met all inclusion criteria. The Review Manager 5.3 software was used to calculate available data from each study.

Results: Consistent with the conclusions of other meta-analysis, our results demonstrated serum copper levels were significantly higher [MD = 9.27, 95% CI (5.02–13.52); p < 0.0001], and the serum zinc levels were significantly lower in AD patients than in healthy controls [MD = −6.12, 95% CI (−9.55, −2.69); p = 0.0005]. Serum iron levels were significantly lower in AD patients than in healthy controls after excluded two studies [MD = −13.01, 95% CI (−20.75, −5.27); p = 0.001].

Conclusion: The results of our meta-analysis provided rigorous statistical support for the association of the serum levels of metals and the risk of AD, suggesting a positive relationship between the serum copper levels and AD risk, and a negative relationship between the serum zinc/iron levels and AD risk.

Cardiovascular risk factors and inflammatory activity among centenarians with and without dementia

A better knowledge of the differences existing between individuals who maintain cognition up to 100 years of age or more and those of the same age who present dementia syndrome may be of help in understanding the dementia of the very elderly people. The aim of this study was to assess cardiovascular risk factors and inflammatory markers among centenarians with and without dementia. A population-based cross-sectional study was conducted on centenarians residing in a middle-size city. Volunteers were evaluated by comprehensive geriatric assessment at home. General laboratory examinations were performed and cardiovascular risk and inflammatory activity markers were determined. Mean subject age was 101 ± 2 years, and 82 % were women. Assessment of dementia syndrome revealed that 36.4 % of the centenarians had preserved cognition. Centenarians with dementia had lower schooling (p < 0.01), lower body mass index (p = 0.02) and higher homocysteine levels (p < 0.01) and tended to have a lower systolic blood pressure (p = 0.05). Regarding the markers of inflammatory activity, demented subjects had high levels of interleukin-6 (p < 0.01), high-sensitivity C-reactive protein (p = 0.02), and erythrocyte sedimentation rate (p = 0.01) and lower albumin levels (p = 0.02) compared to centenarians without dementia. Concluding, centenarians with preserved cognition had better nutritional status, lower homocysteinemia, tendency to higher blood pressure and lower inflammatory activity compared to demented subjects.

Serum Iron, Zinc, and Copper Levels in Patients with Alzheimer's Disease: A Replication Study and Meta-Analyses

To evaluate whether iron, zinc, and copper levels in serum are disarranged in Alzheimer's disease (AD), we performed meta-analyses of all studies on the topic published from 1984 to 2014 and contextually carried out a replication study in serum as well. Our meta-analysis results showed that serum zinc was significantly lower in AD patients. Our replication and meta-analysis results showed that serum copper was significantly higher in AD patients than in healthy controls, so our findings were consistent with the conclusions of four previously published copper meta-analyses. Even if a possible role of iron in the pathophysiology of the disease could not be ruled out, the results of our meta-analysis showed no change of serum iron levels in AD patients, but this conclusion was not robust and requires further investigation. The meta-regression analyses revealed that in some studies, differences in serum iron levels could be due to the different mean ages, while differences in zinc levels appeared to be due to the different sex ratios. However, the effect of sex ratio on serum zinc levels in our meta-analysis is subtle and needs further confirmation. Also, diverse demographic terms and methodological approaches appeared not to explain the high heterogeneity of our copper meta-analysis. Therefore, when investigating trace elements, covariants such as age and sex have to be taken into account in the analyses. In the light of these findings, we suggest that the possible alteration of serum zinc and copper levels are involved in the pathogenesis of AD.

Functional measures, inflammatory markers and endothelin-1 as predictors of 360-day survival in centenarians

Centenarians represent a rapidly growing population. To better characterize this specific age group, we have performed a cross-sectional study to observe associations between functional measures and a range of biochemical markers, including inflammatory markers and their significance as predictors of 360-day survival. Medical history and physical and functional assessment (Mini-Mental State Examination (MMSE), Katz Index (activities of daily living, ADL) and Barthel Index (Barthel Index) of Activities of Daily Living, and Lawton Instrumental Activities of Daily Living Scale (Lawton IADL)) were conducted on 86 101.9 ± 1.2-year-old (mean ± SD) subjects (70 women, 16 men). Blood tests were performed on 84 subjects of whom 43 also had extended biomarker assessment. As a reference group 30 51.8 ± 5.0-year old healthy subjects (20 women, 10 men) were recruited. The centenarians received follow-up phone calls. Fifty-two centenarians (60 %) survived ≥360 days. Longer survival was associated with higher MMSE (hazard ratio, HR = 0.934, 95 % confidence interval (CI) 0.896-0.975, P = .002), ADL (HR = 0.840, 95 % CI 0.716-0.985, P = .032), Barthel Index (HR = 0.988, 95 % CI 0.977-0.999, P = .026), and albumin level (HR .926, 95 % CI 0.870-0.986, P .016) and with lower white blood cell (WBC) (HR = 1.161, 95 % CI 1.059-1.273, P = .001), C-reactive protein (CRP) (HR = 1.032, 95 % CI 1.014-1.050, P < .001), IL-6 (HR = 1.182, 95 % CI 1.047-1.335, P = .007), and endothelin-1 (ET-1) level (HR = 3.711, 95 % CI 1.233-11.169, P = .020). Centenarians had higher 360-day survival probability with MMSE ≥13 (P < .001), ADL ≥1 (P < .001), Barthel Index ≥15 (P < .001), Lawton IADL ≥10 points (P = .009), WBC <8.3 G/L (P = .039), CRP <10 mg/L (P < .001), IL-6 <6 pg/mL (P .002), and ET-1 <1.1 pg/mL (P .007). Our results indicate that functional measures, inflammatory markers, and endothelin-1 are predictors of 360-day survival in centenarians.

Slowing the progression of Alzheimer's disease; what works?

Alzheimer's disease (AD) is an age-related progressive dementia, which is increasing in prevalence world-wide. Typically affecting short-term memory at onset, this devastating illness advances to impair all aspects of cognition, as well as non-cognitive domains. Although much effort has been made in recent years to develop disease-modifying treatments, medications which provided promising results in pre-clinical research have so far faltered in human clinical trials. Attention has recently shifted into trying to identify preventative measures that may delay the onset of the illness. Preventative factors include physical activity, proper diet, cognitive stimulation and the management of conditions such as hypertension, diabetes and obesity. However, it remains imperative to identify approaches that may help patients already diagnosed with the illness. Alongside pharmacological research, much work has been done on uncovering strategies which may slow down the progression of AD. This review aims to summarize evidence supporting or refuting methods impacting on the progression of the disease. AD remains a chronic and serious condition, therefore any intervention delaying the onset of moderate/severe symptoms will have a significant impact on patients and their families.

Neuropsychological performance is positively associated with plasma albumin in healthy adults

BACKGROUND

Albumin serves a range of physiological functions that are vital to overall brain and cognitive health. Indeed, associations between cognitive performance and albumin have been demonstrated in individuals with chronic liver or kidney disease and in patients with a high urinary excretion of albumin. However, an association of plasma albumin with cognitive performance has not been reported in otherwise healthy participants with clinically acceptable plasma albumin concentrations.

METHOD

This study utilized a wide-ranging neuropsychological test battery to investigate the relationship between cognitive performance and plasma albumin homeostasis in 222 healthy participants (143 females) between the ages of 43 and 84 years (mean 65 years).

RESULTS

Albumin both with and without the covariates of age, sex and acute-phase proteins was positively associated with enhanced performance on a range of neuropsychological domains including perceptual speed, Stroop and verbal ability. Albumin manifested generally positive but less robust associations with secondary and primary memory.

CONCLUSION

The results indicate that there is a positive association between albumin and cognitive performance in physiologically healthy participants free of chronic renal or liver disease.

There are no differences in IL-6, CRP and homocystein concentrations between women whose mothers had AD and women whose mothers did not have AD

A wide range of recent studies have detected inflammation as one of the most influent factors in the appearance and spreading of neurodegenerative brain diseases. We aimed to understand the influence of Interleukin-6 (IL-6), C-reactive protein (CRP) and homocysteine (Hcy) on patients suffering from Alzheimer׳s disease (AD) and on their descendants. Three groups of subjects were analyzed: 55 patients suffering from AD, 51 middle-aged daughters of the patients of the first group, and 53 subjects without positive family history of AD. The results of the conducted research are in accordance with the present scientific knowledge, namely a statistically significant difference for examined parameters has been determined between women suffering from AD and their daughters and control group examinees. No difference was found in serum concentrations of IL-6, highly sensitive C-reactive protein (hsCRP) and Hcy between the groups of the middle-aged descendants of patients with AD and healthy controls without family history of AD. This finding supports the hypothesis that these markers may not play causal role in the development of AD. This is supported by the obtained positive correlation between IL-6 and hsCRP and IL-6 and Hcy in AD patients while there is no such correlation between female subjects with or without a family history of AD.

Body fluid cytokine levels in mild cognitive impairment and Alzheimer's disease: a comparative overview

This article gives a comprehensive overview of cytokine and other inflammation associated protein levels in plasma, serum and cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). We reviewed 118 research articles published between 1989 and 2013 to compare the reported levels of 66 cytokines and other proteins related to regulation and signaling in inflammation in the blood or CSF obtained from MCI and AD patients. Several cytokines are evidently regulated in (neuro-) inflammatory processes associated with neurodegenerative disorders. Others do not display changes in the blood or CSF during disease progression. However, many reports on cytokine levels in MCI or AD are controversial or inconclusive, particularly those which provide data on frequently investigated cytokines like tumor necrosis factor alpha (TNF-α) or interleukin-6 (IL-6). The levels of several cytokines are possible indicators of neuroinflammation in AD. Some of them might increase steadily during disease progression or temporarily at the time of MCI to AD conversion. Furthermore, elevated body fluid cytokine levels may correlate with an increased risk of conversion from MCI to AD. Yet, research results are conflicting. To overcome interindividual variances and to obtain a more definite description of cytokine regulation and function in neurodegeneration, a high degree of methodical standardization and patients collective characterization, together with longitudinal sampling over years is essential.

Dysregulated relationship of inflammation and oxidative stress in major depression

Chronic inflammation and oxidative stress have been implicated in the pathophysiology of Major Depressive Disorder (MDD), as well as in a number of chronic medical conditions. The aim of this study was to examine the relationship between peripheral inflammatory and oxidative stress markers in un-medicated subjects with MDD compared to non-depressed healthy controls and compared to subjects with MDD after antidepressant treatment. We examined the relationships between IL-6, IL-10, and the IL-6/IL-10 inflammatory ratio vs. F2-isoprostanes (F2-IsoP), a marker of oxidative stress, in un-medicated MDD patients (n=20) before and after 8 weeks of open-label sertraline treatment (n=17), compared to healthy non-depressed controls (n=20). Among the un-medicated MDD subjects, F2-IsoP concentrations were positively correlated with IL-6 concentrations (p<0.05) and were negatively correlated with IL-10 concentrations (p<0.01). Accordingly, F2-IsoP concentrations were positively correlated with the ratio of IL-6/IL-10 (p<0.01). In contrast, in the control group, there were no significant correlations between F2-IsoPs and either cytokine or their ratio. After MDD subjects were treated with sertraline for 8 weeks, F2-IsoPs were no longer significantly correlated with IL-6, IL-10 or the IL-6/IL-10 ratio. These data suggest oxidative stress and inflammatory processes are positively associated in untreated MDD. Our findings are consistent with the hypothesis that the homeostatic buffering mechanisms regulating oxidation and inflammation in healthy individuals become dysregulated in untreated MDD, and may be improved with antidepressant treatment. These findings may help explain the increased risk of comorbid medical illnesses in MDD.

Inflammation, aging, and adiposity: implications for physical therapists

BACKGROUND

Physical therapists treat older individuals, characterized as both a needy and expanding population. Frailty, a predisability condition with links to chronic inflammatory conditions, is estimated to affect 7% of individuals older than 60 years and 40% of people older than 80 years. Chronic inflammation is one of the most important physiologic correlates of the frailty syndrome and high levels of proinflammatory cytokines, related to both aging and increasing adiposity in older individuals are related to an increased risk of mortality, sarcopenia, reduced muscle strength and decreased mobility.

PURPOSE

The purpose of this narrative review is to inform the physical therapist of the effects of aging and increasing adiposity on chronic inflammation and the association of inflammation with muscle loss, strength, and mobility impairments in older adults; and to review the current evidence to provide clinical recommendations on physical activity and exercise regimes that may mitigate chronic inflammation in older adults.

DISCUSSION

As physical therapists help manage and treat an increasingly older population, understanding how the inflammatory milieu changes with aging and increasing adiposity and how these changes can be impacted by physical therapists via exercise and physical activity is critical.

CONCLUSION

Exercise is a potent preventive intervention strategy and countermeasure for chronic inflammation and adiposity. Exercise can also benefit the frail older individual by combating the negative effects of chronic inflammation and optimally balancing the production of pro and anti-inflammatory cytokines. In addition to providing an anti-inflammatory environment within muscle to mitigate the effects of chronic inflammation, exercise has the added benefit of improving muscle mass and function and decreasing adiposity in older adults.

Essential trace element status and clinical outcomes in long-term dialysis patients: a two-year prospective observational cohort study

BACKGROUND & AIMS

Essential trace elements are involved in many biological processes for normal cell function including immunological defense against oxidation and infection. Deficiency of these elements generally leads to illness or even death in the general population. Therefore, we investigated the predictive values of trace element status on clinical outcomes in dialysis patients, who are more prone to trace element deficiency.

METHODS

We enrolled 111 prevalent patients on maintenance dialysis from a Taipei tertiary-care referral hospital and measured serum levels of selenium, copper, and zinc. Patients were followed for 2 years or until death or withdrawal.

RESULTS

Multivariate Cox regression analysis indicated that patients with diabetes mellitus (HR, 2.162 [95% CI, 1.105-4.232], p=0.024), prior stroke (HR, 3.876 [95% CI, 1.136-13.221], p=0.030), and zinc deficiency (HR, 0.979 [95% CI, 0.966-0.992], p=0.002) were more likely to be hospitalized for infectious diseases. Furthermore, beyond traditional risk factors, such as old age and hypoalbuminemia, multivariate Cox regression also indicated that lower serum level of zinc independently predicts overall mortality (HR, 0.973 [95% CI, 0.948-0.999], p=0.046).

CONCLUSIONS

In long-term dialysis patients, the serum level of zinc was an independent predictor of future hospitalization due to infectious diseases and of overall mortality.

Cerebrospinal fluid and blood biomarkers in Alzheimer’s disease

Due to an ever aging society and growing prevalence of Alzheimer’s disease (AD), the challenge to meet social and health care system needs will become increasingly difficult. Unfortunately, a definite ante mortem diagnosis is not possible. Thus, an early diagnosis and identification of AD patients is critical for promising, early pharmacological interventions as well as addressing health care needs. The most advanced and most reliable markers are β-amyloid, total tau and phosphorylated tau in cerebrospinal fluid (CSF). In blood, no single biomarker has been identified despite an intense search over the last decade. The most promising approaches consist of a combination of several blood-based markers increasing the reliability, sensitivity and specificity of the AD diagnosis. However, contradictory data make standardized testing methods in longitudinal and multi-center studies extremely difficult. In this review, we summarize a range of the most promising CSF and blood biomarkers for diagnosing AD.

Blood-based protein biomarkers for diagnosis and classification of neurodegenerative diseases: current progress and clinical potential

Biomarker research is a rapidly advancing field in medicine. Recent advances in genomic, genetic, epigenetic, neuroscientific, proteomic, and metabolomic knowledge and technologies have opened the way to thriving research. In the most general sense, a biomarker refers to any useful characteristic that can be measured and used as an indicator of a normal biologic process, a pathogenic process, or a pharmacologic response to a therapeutic agent. Despite the extensive resources concentrated on this area, there are very few biomarkers currently available that qualify and are satisfactorily validated for mental disorders, and there is still a major lack of biomarkers for typifying neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. This article provides an overview of this field of research and focuses on recent advances in biomarker research in Alzheimer's disease and Parkinson's disease.

Supplemented zinc does not alter mood in healthy older European adults – a randomised placebo-controlled trial: the Zenith study

Objective

Older people are vulnerable to zinc deficiency, which may impact upon their mood. This randomised, placebo-controlled, double-blind intervention study aimed to investigate the effect of oral zinc gluconate supplementation (15 mg/d; 30 mg/d; and placebo) on subjective mood (affect) in older Europeans.

Subjects

Healthy volunteers (n 387) aged 55–87 years were recruited.

Setting

Volunteers in Rome (Italy; n 108) and Grenoble (France; n 91) were aged 70–87 years and those in Coleraine (Northern Ireland; n 93) and Clermont-Ferrand (France; n 95) were aged 55–70 years.

Design

Mood was measured using the Positive and Negative Affect Scale on four occasions per day over 4 d at baseline, 3 and 6 months post-intervention.

Results

Mixed ANOVA indicated that neither positive nor negative affect altered in response to zinc (15 mg/d or 30 mg/d) compared to placebo in either the 55–70 years or the ≥70 years age group.

Conclusions

These results suggest that zinc does not benefit mood in healthy older people.

A meta-analysis of cytokines in Alzheimer's disease

BACKGROUND

Studies suggest that inflammation is involved in the neurodegenerative cascade leading to Alzheimer's disease (AD) pathology and symptoms. This study sought to quantitatively summarize the clinical cytokine data.

METHODS

Original English language peer-reviewed studies measuring cytokine concentrations in AD and healthy control subjects were included. Mean (± standard deviation) cytokine concentrations for AD and control subjects were extracted.

RESULTS

Forty studies measuring peripheral blood cytokine concentrations and 14 measuring cerebrospinal fluid (CSF) cytokine concentrations were included. In peripheral blood, there were significantly higher concentrations (weighted mean difference [95% confidence interval]) of interleukin (IL)-6 (2.86 [1.68, 4.04] pg/mL, p < .00001, N[AD/control subjects] = 985/680, 14 studies), tumor necrosis factor (TNF)-α (3.25 [.76, 5.74] pg/mL, p = .01, N = 680/447, 14 studies), IL-1β (.55 [.32, .78] pg/mL, p < .00001, N = 574/370, 10 studies), transforming growth factor (TGF)-β (67.23 [28.62, 105.83] pg/mL, p = .0006, N = 190/158, 5 studies), IL-12 (7.60 [5.58, 9.62] pg/mL, p < .00001, N = 148/106, 5 studies), and IL-18 (15.82 [1.98, 29.66] pg/mL, p = .03, N = 131/94, 4 studies) but not of IL-4, IL-8, IL-10, interferon-γ, or C-reactive protein in AD subjects compared with control subjects. There were significantly higher concentrations of TGF-β (7.81 [2.27, 13.35] pg/mL, p =.006, N = 113/114, 5 studies) but not IL-6, TNF-α, and IL-1β in the CSF of AD subjects compared with control subjects.

CONCLUSIONS

These results strengthen the clinical evidence that AD is accompanied by an inflammatory response, particularly higher peripheral concentrations of IL-6, TNF-α, IL-1β, TGF-β, IL-12 and IL-18 and higher CSF concentrations of TGF-β.

Serum albumin concentration and cognitive impairment

Results from clinical samples suggest low serum albumin may be associated with cognitive impairment, though evidence from population-based studies is inconclusive. Participants were 1,752 adults (699 men and 1,053 women) aged 65 years and over from the Health Survey for England 2000, a nationally representative population-based study. Cognitive impairment was assessed using the Abbreviated Mental Test Score. The cross-sectional relation of serum albumin quartiles to cognitive impairment was modelled using logistic regression. Two hundred and twelve participants were cognitively impaired (68 men and 144 women). Odds ratios (95% confidence intervals) for cognitive impairment in the first (2.2-3.8 g/dl), second (3.9-4.0 g/dl), and third (4.1-4.3 g/dl) quartiles of serum albumin compared with the fourth (4.4-5.3 g/dl) were 2.5 (1.3-5.1), 1.7 (0.9-3.5), and 1.5 (0.7-2.9), after adjustment for age, sex, education and additional risk factors for cognitive impairment (p for linear trend = 0.002). A highly similar pattern of associations was observed for men and women. Our data provide new evidence to suggest that low serum albumin is independently associated with increased odds of cognitive impairment in the elderly population.

Biological marker candidates of Alzheimer's disease in blood, plasma, and serum

At the earliest clinical stages of Alzheimer's disease (AD), when first symptoms are mild, making a reliable and accurate diagnosis is difficult. AD related brain pathology and underlying molecular mechanisms precede symptoms. Biological markers can serve as supportive early screening and diagnostic tools as well as indicators of presymptomatic biochemical change. Moreover, biomarkers cover a variety of roles and functions such as disease prediction, indicating disease acuity and progression, and may ensure biological mapping of treatment outcome. Early screening, detection, and diagnosis of AD would permit earlier disease modifying intervention at potentially reversible stages. To date, most established biological markers from both cerebrospinal fluid neurochemistry and structural and functional neuroimaging have not reached widespread clinical application. Crucial remaining problems, such as easy acceptance and application of a test, cost-effectiveness, and noninvasiveness, need to be resolved. The development and validation of precise, reliable, and robust tests and biomarkers in blood, plasma, or serum has therefore been for a long time the ultimate focus of many research groups worldwide. Blood-based testing will most likely be the prerequisite to future sensitive screening of large populations at risk of AD and the baseline in a diagnostic flow approach to AD. The status and emerging perspectives on hypothesis and exploratory-based candidate biomarkers derived from blood, plasma, and serum are reviewed and discussed.

Interferon-{gamma} differentially affects Alzheimer's disease pathologies and induces neurogenesis in triple transgenic-AD mice

Inflammatory processes, including the episodic and/ or chronic elaboration of cytokines, have been identified as playing key roles in a number of neurological disorders. Whether these activities impart a disease-resolving and/or contributory outcome depends at least in part on the disease context, stage of pathogenesis, and cellular milieu in which these factors are released. Interferon-gamma (IFNgamma) is one such cytokine that produces pleiotropic effects in the brain. It is protective by ensuring maintenance of virus latency after infection, yet deleterious by recruiting and activating microglia that secrete potentially damaging factors at sites of brain injury. Using the triple-transgenic mouse model of Alzheimer's disease (3xTg-AD), which develops amyloid and tau pathologies in a pattern reminiscent of human Alzheimer's disease, we initiated chronic intrahippocampal expression of IFNgamma through delivery of a serotype-1 recombinant adeno-associated virus vector (rAAV1-IFNgamma). Ten months of IFNgamma expression led to an increase in microglial activation, steady-state levels of proinflammatory cytokine and chemokine transcripts, and severity of amyloid-related pathology. In contrast, these rAAV1-IFNgamma-treated 3xTg-AD mice also exhibited diminished phospho-tau pathology and evidence of increased neurogenesis. Overall, IFNgamma mediates what seem to be diametrically opposed functions in the setting of AD-related neurodegeneration. Gaining an understanding as to how these apparently divergent functions are interrelated and controlled could elucidate new therapeutic strategies designed to harness the neuroprotective activity of IFNgamma.

Cytokines in Alzheimer's disease and vascular dementia

The levels of interleukin 1beta, interleukin 6, and interleukin 10 were elevated in the serum of patients with dementia. No statistically significant correlation was recorded in the interleukin levels among patients with Alzheimer's disease and vascular dementia. Also, no significant correlation was observed in the interleukin levels in the serum and the severity of dementia. However, a significant correlation was found between IL-6 and tumor necrosis factor-alpha (TNF-alpha) levels and age. The levels of IL-1beta and IL-6 were positively correlated with hypertension, and IL-2 levels were negatively correlated. No correlation was found between depressive symptoms and levels of cytokines in the serum.

Albumin, apolipoprotein E-epsilon4 and cognitive decline in community-dwelling Chinese older adults

OBJECTIVES

To examine the association between serum albumin and cognitive impairment and decline in community-living older adults.

DESIGNS

Population-based cohort study, followed up to 2 years; serum albumin, apolipoprotein E (APOE)-epsilon4, and cognitive impairment measured at baseline and cognitive decline (> or =2-point drop in Mini-Mental State Examination (MMSE) score). Odds ratios were controlled for age, sex, education, medical comorbidity, hypertension, diabetes mellitus, cardiac disease, stroke, smoking, alcohol drinking, depression, APOE-epsilon4, nutritional status, body mass index, anemia, glomerular filtration rate, and baseline MMSE.

SETTINGS

Local area whole population.

PARTICIPANTS

One thousand six hundred sixty-four Chinese older adults aged 55 and older.

RESULTS

The mean age of the cohort was 66.0+/-7.3, 65% were women, mean serum albumin was 42.3+/-3.1 g/L, and mean MMSE score was 27.2+/-3.2. Lower albumin tertile was associated with greater risk of cognitive impairment in cross-sectional analysis (low, odds ratio (OR)=2.30, 95% confidence interval (CI)=1.31-4.03); medium, OR=1.59, 95% CI=0.88-2.88) versus high (P for trend=.002); and with cognitive decline in longitudinal analyses: low, OR=1.73, 95% CI=1.18-2.55; medium, OR=1.32, 95% CI=0.89-1.95, vs high (P for trend=.004). In cognitively unimpaired respondents at baseline (MMSE> or =24), similar associations with cognitive decline were observed (P for trends <.002). APOE-epsilon4 appeared to modify the association, due mainly to low rates of cognitive decline in subjects with the APOE-epsilon4 allele and high albumin.

CONCLUSION

Low albumin was an independent risk marker for cognitive decline in community-living older adults.

Biomarkers for Alzheimer disease in cerebrospinal fluid, urine, and blood

Alzheimer disease is the most common cause of dementia, yet its clinical diagnosis remains uncertain until an eventual postmortem histopathology examination. Currently, therapy for patients with Alzheimer disease only treats the symptoms; however, it is anticipated that new disease-modifying drugs will soon become available.Diagnostic tools for detecting Alzheimer disease at an incipient stage that can reliably differentiate the disease from other forms of dementia are of key importance for optimal treatment. Biomarkers have the potential to aid in a correct diagnosis, and great progress has been made in the discovery and development of potentially useful biomarkers in recent years. This includes single protein biomarkers in the cerebrospinal fluid, as well as multi-component biomarkers, and biomarkers based on gene expression. Novel biomarkers that use blood and urine, the more easily available clinical samples, are also being discovered and developed. The plethora of potential biomarkers currently being investigated may soon provide biomarkers that fulfill different functions, not only for diagnostic purposes but also for drug development and to follow disease progression.

Biomarkers of Alzheimer's disease

Although a battery of neuropsychological tests is often used in making a clinical diagnosis of Alzheimer's disease (AD), definitive diagnosis still relies on pathological evaluation at autopsy. The identification of AD biomarkers may allow for a less invasive and more accurate diagnosis as well as serve as a predictor of future disease progression and treatment response. Importantly, biomarkers may also allow for the identification of individuals who are already developing the underlying pathology of AD such as plaques and tangles yet who are not yet demented, i.e. "preclinical" AD. Attempts to identify biomarkers have included fluid and imaging studies, with a number of candidate markers showing significant potential. More recently, better reagent availability and novel methods of assessment have further spurred the search for biomarkers of AD. This review will discuss promising fluid and imaging markers to date.

Age-related changes to tumor necrosis factor receptors affect neuron survival in the presence of beta-amyloid

Inflammation including local accumulations of tumor necrosis factor alpha (TNF-alpha) is a part of Alzheimer's disease pathology and may exacerbate age-related neurodegeneration. Most studies on TNF-alpha and TNF neuronal receptors are conducted by using embryonic neurons. Few studies consider age-related deficits that may occur in neurons. Age-related changes in susceptibility to TNF-alpha through TNF receptor 1 (TNFR1) and receptor 2 (TNFR2) expression could increase susceptibility to beta-amyloid (1-42, Abeta42). Evidence is conflicting about which receptor mediates survival and/or apoptosis. We determined how aging affects receptor expression in cultured adult rat cortical neurons. Old neurons were more susceptible to Abeta42 toxicity than middle-aged neurons, and the addition of TNF-alpha was neuroprotective in middle-aged neurons, but exacerbated the toxicity from Abeta42 in old neurons. These pathologic and protective responses in old and middle-aged neurons, respectively, correlated with higher starting TNFR1 and TNFR2 mRNA levels in old vs. middle-aged neurons. Middle-aged neurons treated with TNF-alpha plus Abeta42 did not show an increase in either TNFR1 or TNFR2 mRNA, but old neurons showed an up-regulation in TNFR2 mRNA and not TNFR1 mRNA. Despite these mRNA changes, surface immunoreactivity of both TNFR1 and TNFR2 increased with the dose of TNF-alpha in middle-aged neurons. However, middle-aged neurons treated with TNF-alpha plus Abeta42 showed an up-regulation in both TNFR1 and TNFR2 surface expression, whereas old neurons failed to up-regulate surface expression of either receptor. These findings support the hypothesis that age-related changes in TNF-alpha surface receptor expression contribute to the neuronal loss associated with inflammation in Alzheimer's disease.

Albumin, haemoglobin, BMI and cognitive performance in older adults

OBJECTIVES

to examine the relationships between serum albumin, haemoglobin and body mass index (BMI) with cognitive performance among community-living older adults.

METHOD

design--population-based cross-sectional study; setting--local community in Southeast Region of Singapore; subjects--Chinese older adults aged 55 and above (N = 2, 550); measurements--serum albumin, haemoglobin, BMI and Mini-Mental State Examination (MMSE).

RESULTS

in multivariable analyses controlling for gender, age, education and vascular risk factors, low albumin in the bottom quintile (OR 2.04; 95% CI 1.22-3.41) and low haemoglobin in the bottom quintile (OR 1.56; 95% CI 1.00-2.47) and low BMI with chronic comorbidity (OR 1.73; 95%CI 1.02-2.95) were independently associated with poor cognitive performance (MMSE < or = 23). Among cognitively intact respondents (MMSE > or = 24), albumin concentration showed a significant inverse linear relationship with MMSE scores (P for trend =0.002).

CONCLUSION

low albumin, low haemoglobin and low BMI (in the presence of chronic comorbidity) are independently associated with poor cognitive performance in community-living older adults.

Oxidative protein damage is associated with elevated serum interleukin-6 levels among older moderately to severely disabled women living in the community

BACKGROUND

Elevated interleukin (IL)-6 is associated with adverse outcomes. Our objective was to determine whether serum protein carbonyls, an indicator of oxidative protein damage and oxidative stress, were associated with IL-6.

METHODS

Serum protein carbonyls and IL-6 were measured in 739 women, age > or =65 years, in the Women's Health and Aging Study I.

RESULTS

Geometric mean of protein carbonyls was 0.082 nmol/mg. After adjusting for age and smoking status, log(e) serum protein carbonyls were associated with log(e) IL-6 (beta = 0.143, standard error [SE] = 0.048, p =.003) in linear regression analyses and with elevated IL-6 (> or =2.5 pg/mL) (odds ratio = 1.38, 95% confidence interval, 1.02-1.86, p =.037) in logistic regression analyses. CONCLUSION. Oxidative damage to proteins is independently associated with serum IL-6 among older women living in the community. Increased oxidative stress may be a factor involved in the pathogenesis of the proinflammatory state that occurs in older adults.