Serum urate levels and neurodegenerative outcomes: a prospective cohort study and mendelian randomization analysis of the UK Biobank

BACKGROUND

Previous studies on the associations between serum urate levels and neurodegenerative outcomes have yielded inconclusive results, and the causality remains unclear. This study aimed to investigate whether urate levels are associated with the risks of Alzheimer's disease and related dementias (ADRD), Parkinson's disease (PD), and neurodegenerative deaths.

METHODS

This prospective study included 382,182 participants (45.7% men) from the UK Biobank cohort. Cox proportional hazards models were used to assess the associations between urate levels and risk of neurodegenerative outcomes. In the Mendelian randomization (MR) analysis, urate-related single-nucleotide polymorphisms were identified through a genome-wide association study. Both linear and non-linear MR approaches were utilized to investigate the potential causal associations.

RESULTS

During a median follow-up period of 12 years, we documented 5,400 ADRD cases, 2,553 PD cases, and 1,531 neurodegenerative deaths. Observational data revealed that a higher urate level was associated with a decreased risk of ADRD (hazard ratio [HR]: 0.93, 95% confidence interval [CI]: 0.90, 0.96), PD (HR: 0.87, 95% CI: 0.82, 0.91), and neurodegenerative death (HR: 0.88, 95% CI: 0.83, 0.94). Negative linear associations between urate levels and neurodegenerative events were observed (all P-values for overall < 0.001 and all P-values for non-linearity > 0.05). However, MR analyses yielded no evidence of either linear or non-linear associations between genetically predicted urate levels and the risk of the aforementioned neurodegenerative events.

CONCLUSION

Although the prospective cohort study demonstrated that elevated urate levels were associated with a reduced risk of neurodegenerative outcomes, MR analyses found no evidence of causality.

Lipoprotein Particles in Cerebrospinal Fluid

The brain is the most lipid-rich organ in the body, and the intricate interplay between lipid metabolism and pathologies associated with neurodegenerative disorders is being increasingly recognized. The brain is bathed in cerebrospinal fluid (CSF), which, like plasma, contains lipid-protein complexes called lipoproteins that are responsible for extracellular lipid transport. Multiple CSF lipoprotein populations exist, some of which are produced de novo in the central nervous system and others that appear to be generated from protein constituents that are produced in the periphery. These CSF lipoproteins are thought to play key roles in maintaining lipid homeostasis in the central nervous system, while little else is known due to their limited accessibility and their low abundance in CSF. Recent work has provided new insights into the compositional complexity of CSF lipoprotein families and their metabolism in cerebral circulation. The purpose of this review is to summarize our current state of knowledge on the composition, origin, and metabolism of CSF lipoproteins.

Alzheimer's and neurodegenerative disease biomarkers in blood predict brain atrophy and cognitive decline

BACKGROUND

Although blood-based biomarkers have been identified as cost-effective and scalable alternatives to PET and CSF markers of neurodegenerative disease, little is known about how these biomarkers predict future brain atrophy and cognitive decline in cognitively unimpaired individuals. Using data from the Baltimore Longitudinal Study of Aging (BLSA), we examined whether plasma biomarkers of Alzheimer's disease (AD) pathology (amyloid-β [Aβ42/40], phosphorylated tau [pTau-181]), astrogliosis (glial fibrillary acidic protein [GFAP]), and neuronal injury (neurofilament light chain [NfL]) were associated with longitudinal brain volume loss and cognitive decline. Additionally, we determined whether sex, APOEε4 status, and plasma amyloid-β status modified these associations.

METHODS

Plasma biomarkers were measured using Quanterix SIMOA assays. Regional brain volumes were measured by 3T MRI, and a battery of neuropsychological tests assessed five cognitive domains. Linear mixed effects models adjusted for demographic factors, kidney function, and intracranial volume (MRI analyses) were completed to relate baseline plasma biomarkers to baseline and longitudinal brain volume and cognitive performance.

RESULTS

Brain volume analyses included 622 participants (mean age ± SD: 70.9 ± 10.2) with an average of 3.3 MRI scans over 4.7 years. Cognitive performance analyses included 674 participants (mean age ± SD: 71.2 ± 10.0) with an average of 3.9 cognitive assessments over 5.7 years. Higher baseline pTau-181 was associated with steeper declines in total gray matter volume and steeper regional declines in several medial temporal regions, whereas higher baseline GFAP was associated with greater longitudinal increases in ventricular volume. Baseline Aβ42/40 and NfL levels were not associated with changes in brain volume. Lower baseline Aβ42/40 (higher Aβ burden) was associated with a faster decline in verbal memory and visuospatial performance, whereas higher baseline GFAP was associated with a faster decline in verbal fluency. Results were generally consistent across sex and APOEε4 status. However, the associations of higher pTau-181 with increasing ventricular volume and memory declines were significantly stronger among individuals with higher Aβ burden, as was the association of higher GFAP with memory decline.

CONCLUSIONS

Among cognitively unimpaired older adults, plasma biomarkers of AD pathology (pTau-181) and astrogliosis (GFAP), but not neuronal injury (NfL), serve as markers of future brain atrophy and cognitive decline.

Red Blood Cells' Thermodynamic Behavior in Neurodegenerative Pathologies and Aging

The main trend of current research in neurodegenerative diseases (NDDs) is directed towards the discovery of novel biomarkers for disease diagnostics and progression. The pathological features of NDDs suggest that diagnostic markers can be found in peripheral fluids and cells. Herein, we investigated the thermodynamic behavior of the peripheral red blood cells (RBCs) derived from patients diagnosed with three common NDDs—Parkinson’s disease (PD), Alzheimer’s disease (AD), and amyotrophic lateral sclerosis (ALS) and compared it with that of healthy individuals, evaluating both fresh and aged RBCs. We established that NDDs can be differentiated from the normal healthy state on the basis of the variation in the thermodynamic parameters of the unfolding of major RBCs proteins—the cytoplasmic hemoglobin (Hb) and the membrane Band 3 (B3) protein. A common feature of NDDs is the higher thermal stability of both Hb and B3 proteins along the RBCs aging, while the calorimetric enthalpy can distinguish PD from ALS and AD. Our data provide insights into the RBCs thermodynamic behavior in two complex and tightly related phenomena—neurodegenerative pathologies and aging, and it suggests that the determined thermodynamic parameters are fingerprints of the altered conformation of Hb and B3 protein and modified RBCs’ aging in the studied NDDs.

Crossed cerebellar diaschisis on 18F-FDG PET: Frequency across neurodegenerative syndromes and association with 11C-PIB and 18F-Flortaucipir

We used 18F-FDG-PET to investigate the frequency of crossed cerebellar diaschisis (CCD) in 197 patients with various syndromes associated with neurodegenerative diseases. In a subset of 117 patients, we studied relationships between CCD and cortical asymmetry of Alzheimer's pathology (β-amyloid (11C-PIB) and tau (18F-Flortaucipir)). PET images were processed using MRIs to derive parametric SUVR images and define regions of interest. Indices of asymmetry were calculated in the cerebral cortex, basal ganglia and cerebellar cortex. Across all patients, cerebellar 18F-FDG asymmetry was associated with reverse asymmetry of 18F-FDG in the cerebral cortex (especially frontal and parietal areas) and basal ganglia. Based on our operational definition (cerebellar asymmetry >3% with contralateral supratentorial hypometabolism), significant CCD was present in 47/197 (24%) patients and was most frequent in corticobasal syndrome and semantic and logopenic variants of primary progressive aphasia. In β-amyloid-positive patients, mediation analyses showed that 18F-Flortaucipir cortical asymmetry was associated with cerebellar 18F-FDG asymmetry, but that cortical 18F-FDG asymmetry mediated this relationship. Analysis of 18F-FDG-SUVR values suggested that CCD might also occur in the absence of frank cerebellar 18F-FDG asymmetry due to symmetrical supratentorial degeneration resulting in a bilateral diaschisis process.

Overview of Beneficial Effects of (Poly)phenol Metabolites in the Context of Neurodegenerative Diseases on Model Organisms

The rise of neurodegenerative diseases in an aging population is an increasing problem of health, social and economic consequences. Epidemiological and intervention studies have demonstrated that diets rich in (poly)phenols can have potent health benefits on cognitive decline and neurodegenerative diseases. Meanwhile, the role of gut microbiota is ever more evident in modulating the catabolism of (poly)phenols to dozens of low molecular weight (poly)phenol metabolites that have been identified in plasma and urine. These metabolites can reach circulation in higher concentrations than parent (poly)phenols and persist for longer periods of time. However, studies addressing their potential brain effects are still lacking. In this review, we will discuss different model organisms that have been used to study how low molecular weight (poly)phenol metabolites affect neuronal related mechanisms gathering critical insight on their potential to tackle the major hallmarks of neurodegeneration.

Different miRNA Profiles in Plasma Derived Small and Large Extracellular Vesicles from Patients with Neurodegenerative Diseases

Identifying biomarkers is essential for early diagnosis of neurodegenerative diseases (NDs). Large (LEVs) and small extracellular vesicles (SEVs) are extracellular vesicles (EVs) of different sizes and biological functions transported in blood and they may be valid biomarkers for NDs. The aim of our study was to investigate common and different miRNA signatures in plasma derived LEVs and SEVs of Alzheimer’s disease (AD), Parkinson’s disease (PD), Amyotrophic Lateral Sclerosis (ALS) and Fronto-Temporal Dementia (FTD) patients. LEVs and SEVs were isolated from plasma of patients and healthy volunteers (CTR) by filtration and differential centrifugation and RNA was extracted. Small RNAs libraries were carried out by Next Generation Sequencing (NGS). MiRNAs discriminate all NDs diseases from CTRs and they can provide a signature for each NDs. Common enriched pathways for SEVs were instead linked to ubiquitin mediated proteolysis and Toll-like receptor signaling pathways and for LEVs to neurotrophin signaling and Glycosphingolipid biosynthesis pathway. LEVs and SEVs are involved in different pathways and this might give a specificity to their role in the spreading of the disease. The study of common and different miRNAs transported by LEVs and SEVs can be of great interest for biomarker discovery and for pathogenesis studies in neurodegeneration.

Serum Metabolomics Profiling of Commercially Mixed Functional Foods—Effects in Beta-Amyloid Induced Rats Measured Using 1H NMR Spectroscopy

Functional foods such as pomegranate, dates and honey were shown by various previous studies to individually have a neuroprotective effect, especially in neurodegenerative disease such as Alzheimer’s disease (AD). In this novel and original study, an ¹H NMR spectroscopy tool was used to identify the metabolic neuroprotective mechanism of commercially mixed functional foods (MFF) consisting of pomegranate, dates and honey, in rats injected with amyloid-beta 1-42 (Aβ-42). Forty-five male albino Wistar rats were randomly divided into five groups: NC (0.9% normal saline treatment + phosphate buffer solution (PBS) solution injection), Abeta (0.9% normal saline treatment + 0.2 µg/µL Aβ-42 injection), MFF (4 mL/kg MFF treatment + PBS solution injection), Abeta–MFF (4 mL/kg MFF treatment + 0.2 µg/µL Aβ-42 injection) and Abeta–NAC (150 mg/kg N-acetylcysteine + 0.2 µg/µL Aβ-42 injection). Based on the results, the MFF and NAC treatment improved the spatial memory and learning using Y-maze. In the metabolic analysis, a total of 12 metabolites were identified, for which levels changed significantly among the treatment groups. Systematic metabolic pathway analysis found that the MFF and NAC treatments provided a neuroprotective effect in Aβ-42 injected rats by improving the acid amino and energy metabolisms. Overall, this finding showed that MFF might serve as a potential neuroprotective functional food for the prevention of AD.

Circulating exosomal MicroRNAs: New non-invasive biomarkers of non-communicable disease

Exosomes are vesicles, ranging of 30-150 nm in diameter, which are released by different cell types into the extracellular space. Exosomes are capable of transporting several biomolecules such as proteins, lipids, DNA, mRNA, and non-coding RNA, including microRNAs (miRs). miRs signatures have been linked to the development of non-communicable diseases and their classification into various subtypes and/or stages. Interestingly, the miRs contained in exosomes (exomiRs) are suitable candidates as non-invasive biomarkers due to their stability in body fluids and harsh conditions, as well as they are considered critical players involved in intercellular communication; so that they can be a promising diagnostic tool for several diseases. Besides, exomiRs allow discrimination between different stages of the disease and could be a valuable strategy for the early detection of several pathologies in a non-invasive approach. This review aims to describe exomiRs present in biologic fluids that can be used as a tool for the diagnosis and prognosis of non-communicable diseases such as cancer, cardiovascular, kidney, and neurodegenerative disease.

Classifications of Neurodegenerative Disorders Using a Multiplex Blood Biomarkers-Based Machine Learning Model

Easily accessible biomarkers for Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia (FTD), and related neurodegenerative disorders are urgently needed in an aging society to assist early-stage diagnoses. In this study, we aimed to develop machine learning algorithms using the multiplex blood-based biomarkers to identify patients with different neurodegenerative diseases. Plasma samples (n = 377) were obtained from healthy controls, patients with AD spectrum (including mild cognitive impairment (MCI)), PD spectrum with variable cognitive severity (including PD with dementia (PDD)), and FTD. We measured plasma levels of amyloid-beta 42 (Aβ42), Aβ40, total Tau, p-Tau181, and α-synuclein using an immunomagnetic reduction-based immunoassay. We observed increased levels of all biomarkers except Aβ40 in the AD group when compared to the MCI and controls. The plasma α-synuclein levels increased in PDD when compared to PD with normal cognition. We applied machine learning-based frameworks, including a linear discriminant analysis (LDA), for feature extraction and several classifiers, using features from these blood-based biomarkers to classify these neurodegenerative disorders. We found that the random forest (RF) was the best classifier to separate different dementia syndromes. Using RF, the established LDA model had an average accuracy of 76% when classifying AD, PD spectrum, and FTD. Moreover, we found 83% and 63% accuracies when differentiating the individual disease severity of subgroups in the AD and PD spectrum, respectively. The developed LDA model with the RF classifier can assist clinicians in distinguishing variable neurodegenerative disorders.

Homocysteine aggravates DNA damage by impairing the FA/Brca1 Pathway in NE4C murine neural stem cells

There is existing evidence that elevated homocysteine (Hcy) levels are risk factors for some neurodegenerative disorders. The pathogenesis of neurological diseases could be contributed to excessive cell dysfunction and death caused by defective DNA damage response (DDR) and accumulated DNA damage. Hcy is a neurotoxic amino acid and acts as a DNA damage inducer. However, it is not clear whether Hcy participates in the DDR. To investigate the effects of Hcy on DNA damage and the DDR, we employed mitomycin C (MMC) to cause DNA damage in NE4C murine neural stem cells (NSCs). Compared to treatment with MMC alone, we found that co-treatment with MMC and Hcy worsened DNA damage and increased death in NE4C cells. Intriguingly, in this DNA damage model mimicked by MMC, immunoblotting results showed that the monoubiquitination levels of Fanconi anemia complementation group I (Fanci) and Fanconi anemia complementation group D2 (Fancd2) were decreased to about 60.3% and 55.7% by supplementing cell culture medium with Hcy, indicating Hcy inactivates the function of Fanci and Fancd2 in DNA damage conditions. Given Breast Cancer 1 (BRCA1) is an important downstream of FANCD2, we next detected the interaction between Fancd2 and Brca1 in NE4C cells. Compared to treatment with MMC alone, the Fancd2-Brca1 interaction and the amount of Brca1 on chromatin were decreased when cells were co-exposed to MMC and Hcy, suggesting Hcy could impair the Fanconi anemia (FA)/Brca1 pathway. Taken together, our study demonstrates that Hcy may enhance cell death, which contributes to the accumulation of DNA damage and promotion of hypersensitivity to cytotoxicity by impairing the FA/Brca1 pathway in murine NSCs in the presence of DNA damage.

Discriminative Accuracy of Plasma Phospho-tau217 for Alzheimer Disease vs Other Neurodegenerative Disorders

Importance

There are limitations in current diagnostic testing approaches for Alzheimer disease (AD).

Objective

To examine plasma tau phosphorylated at threonine 217 (P-tau217) as a diagnostic biomarker for AD.

Design, Setting, and Participants

Three cross-sectional cohorts: an Arizona-based neuropathology cohort (cohort 1), including 34 participants with AD and 47 without AD (dates of enrollment, May 2007-January 2019); the Swedish BioFINDER-2 cohort (cohort 2), including cognitively unimpaired participants (n = 301) and clinically diagnosed patients with mild cognitive impairment (MCI) (n = 178), AD dementia (n = 121), and other neurodegenerative diseases (n = 99) (April 2017-September 2019); and a Colombian autosomal-dominant AD kindred (cohort 3), including 365 PSEN1 E280A mutation carriers and 257 mutation noncarriers (December 2013-February 2017).

Exposures

Plasma P-tau217.

Main Outcomes and Measures

Primary outcome was the discriminative accuracy of plasma P-tau217 for AD (clinical or neuropathological diagnosis). Secondary outcome was the association with tau pathology (determined using neuropathology or positron emission tomography [PET]).

Results

Mean age was 83.5 (SD, 8.5) years in cohort 1, 69.1 (SD, 10.3) years in cohort 2, and 35.8 (SD, 10.7) years in cohort 3; 38% were women in cohort 1, 51% in cohort 2, and 57% in cohort 3. In cohort 1, antemortem plasma P-tau217 differentiated neuropathologically defined AD from non-AD (area under the curve [AUC], 0.89 [95% CI, 0.81-0.97]) with significantly higher accuracy than plasma P-tau181 and neurofilament light chain (NfL) (AUC range, 0.50-0.72; P < .05). The discriminative accuracy of plasma P-tau217 in cohort 2 for clinical AD dementia vs other neurodegenerative diseases (AUC, 0.96 [95% CI, 0.93-0.98]) was significantly higher than plasma P-tau181, plasma NfL, and MRI measures (AUC range, 0.50-0.81; P < .001) but not significantly different compared with cerebrospinal fluid (CSF) P-tau217, CSF P-tau181, and tau-PET (AUC range, 0.90-0.99; P > .15). In cohort 3, plasma P-tau217 levels were significantly greater among PSEN1 mutation carriers, compared with noncarriers, from approximately 25 years and older, which is 20 years prior to estimated onset of MCI among mutation carriers. Plasma P-tau217 levels correlated with tau tangles in participants with (Spearman ρ = 0.64; P < .001), but not without (Spearman ρ = 0.15; P = .33), β-amyloid plaques in cohort 1. In cohort 2, plasma P-tau217 discriminated abnormal vs normal tau-PET scans (AUC, 0.93 [95% CI, 0.91-0.96]) with significantly higher accuracy than plasma P-tau181, plasma NfL, CSF P-tau181, CSF Aβ42:Aβ40 ratio, and MRI measures (AUC range, 0.67-0.90; P < .05), but its performance was not significantly different compared with CSF P-tau217 (AUC, 0.96; P = .22).

Conclusions and Relevance

Among 1402 participants from 3 selected cohorts, plasma P-tau217 discriminated AD from other neurodegenerative diseases, with significantly higher accuracy than established plasma- and MRI-based biomarkers, and its performance was not significantly different from key CSF- or PET-based measures. Further research is needed to optimize the assay, validate the findings in unselected and diverse populations, and determine its potential role in clinical care.

Cerebrospinal fluid and plasma biomarkers in individuals at risk for genetic prion disease

BACKGROUND

Prion disease is neurodegenerative disease that is typically fatal within months of first symptoms. Clinical trials in this rapidly declining symptomatic patient population have proven challenging. Individuals at high lifetime risk for genetic prion disease can be identified decades before symptom onset and provide an opportunity for early therapeutic intervention. However, randomizing pre-symptomatic carriers to a clinical endpoint is not numerically feasible. We therefore launched a cohort study in pre-symptomatic genetic prion disease mutation carriers and controls with the goal of evaluating biomarker endpoints that may enable informative trials in this population.

METHODS

We collected cerebrospinal fluid (CSF) and blood from pre-symptomatic individuals with prion protein gene (PRNP) mutations (N = 27) and matched controls (N = 16), in a cohort study at Massachusetts General Hospital. We quantified total prion protein (PrP) and real-time quaking-induced conversion (RT-QuIC) prion seeding activity in CSF and neuronal damage markers total tau (T-tau) and neurofilament light chain (NfL) in CSF and plasma. We compared these markers cross-sectionally, evaluated short-term test-retest reliability over 2-4 months, and conducted a pilot longitudinal study over 10-20 months.

RESULTS

CSF PrP levels were stable on test-retest with a mean coefficient of variation of 7% for both over 2-4 months in N = 29 participants and over 10-20 months in N = 10 participants. RT-QuIC was negative in 22/23 mutation carriers. The sole individual with positive RT-QuIC seeding activity at two study visits had steady CSF PrP levels and slightly increased tau and NfL concentrations compared with the others, though still within the normal range, and remained asymptomatic 1 year later. T-tau and NfL showed no significant differences between mutation carriers and controls in either CSF or plasma.

CONCLUSIONS

CSF PrP will be interpretable as a pharmacodynamic readout for PrP-lowering therapeutics in pre-symptomatic individuals and may serve as an informative surrogate biomarker in this population. In contrast, markers of prion seeding activity and neuronal damage do not reliably cross-sectionally distinguish mutation carriers from controls. Thus, as PrP-lowering therapeutics for prion disease advance, "secondary prevention" based on prodromal pathology may prove challenging; instead, "primary prevention" trials appear to offer a tractable paradigm for trials in pre-symptomatic individuals.

Irritable Bowel Syndrome and Neurological Deficiencies: Is There A Relationship? The Possible Relevance of the Oxidative Stress Status

Background: Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders, exhibiting complex and controversial pathological features. Both oxidative stress and inflammation-related reactive oxygen species production may be involved in IBS pathological development. Thus, we focused on several aspects regarding the causes of oxidative stress occurrence in IBS. Additionally, in the molecular context of oxidative changes, we tried to discuss these possible neurological implications in IBS. Methods: The literature search included the main available databases (e.g., ScienceDirect, Pubmed/Medline, Embase, and Google Scholar). Articles in the English language were taken into consideration. Our screening was conducted based on several words such as “irritable bowel syndrome”, “gut brain axis”, “oxidative stress”, “neuroendocrine”, and combinations. Results: While no consistent evidence suggests clear pathway mechanisms, it seems that the inflammatory response may also be relevant in IBS. The mild implication of oxidative stress in IBS has been described through clinical studies and some animal models, revealing changes in the main markers such as antioxidant status and peroxidation markers. Moreover, it seems that the neurological structures involved in the brain-gut axis may be affected in IBS rather than the local gut tissue and functionality. Due to a gut-brain axis bidirectional communication error, a correlation between neurological impairment, emotional over-responsiveness, mild inflammatory patterns, and oxidative stress can be suggested. Conclusions: Therefore, there is a possible correlation between neurological impairment, emotional over-responsiveness, mild inflammatory patterns, and oxidative stress that are not followed by tissue destruction in IBS patients. Moreover, it is not yet clear whether oxidative stress, inflammation, or neurological impairments are key determinants or in which way these three interact in IBS pathology. However, the conditions in which oxidative imbalances occur may be an interesting research lead in order to find possible explanations for IBS development.

Extrachromosomal Circular DNA: Current Knowledge and Implications for CNS Aging and Neurodegeneration

Still unresolved is the question of how a lifetime accumulation of somatic gene copy number alterations impact organ functionality and aging and age-related pathologies. Such an issue appears particularly relevant in the broadly post-mitotic central nervous system (CNS), where non-replicative neurons are restricted in DNA-repair choices and are prone to accumulate DNA damage, as they remain unreplaced over a lifetime. Both DNA injuries and consecutive DNA-repair strategies are processes that can evoke extrachromosomal circular DNA species, apparently from either part of the genome. Due to their capacity to amplify gene copies and related transcripts, the individual cellular load of extrachromosomal circular DNAs will contribute to a dynamic pool of additional coding and regulatory chromatin elements. Analogous to tumor tissues, where the mosaicism of circular DNAs plays a well-characterized role in oncogene plasticity and drug resistance, we suggest involvement of the "circulome" also in the CNS. Accordingly, we summarize current knowledge on the molecular biogenesis, homeostasis and gene regulatory impacts of circular extrachromosomal DNA and propose, in light of recent discoveries, a critical role in CNS aging and neurodegeneration. Future studies will elucidate the influence of individual extrachromosomal DNA species according to their sequence complexity and regional distribution or cell-type-specific abundance.

Homocysteine: Its Possible Emerging Role in At-Risk Population Groups

Increased plasma homocysteine is a risk factor for several pathological disorders. The present review focused on the role of homocysteine (Hcy) in different population groups, especially in risk conditions (pregnancy, infancy, old age), and on its relevance as a marker or etiological factor of the diseases in these age groups, focusing on the nutritional treatment of elevated Hcy levels. In pregnancy, Hcy levels were investigated in relation to the increased risk of adverse pregnancy outcomes such as small size for gestational age at birth, preeclampsia, recurrent abortions, low birth weight, or intrauterine growth restriction. In pediatric populations, Hcy levels are important not only for cardiovascular disease, obesity, and renal disease, but the most interesting evidence concerns study of elevated levels of Hcy in autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Finally, a focus on the principal pathologies of the elderly (cardiovascular and neurodegenerative disease, osteoporosis and physical function) is presented. The metabolism of Hcy is influenced by B vitamins, and Hcy-lowering vitamin treatments have been proposed. However, clinical trials have not reached a consensus about the effectiveness of vitamin supplementation on the reduction of Hcy levels and improvement of pathological condition, especially in elderly patients with overt pathologies, suggesting that other dietary and non-dietary factors are involved in high Hcy levels. The importance of novel experimental designs focusing on intra-individual variability as a complement to the typical case-control experimental designs and the study of interactions between different factors it should be emphasized.

Nutritional Mushroom Treatment in Meniere's Disease with Coriolus versicolor: A Rationale for Therapeutic Intervention in Neuroinflammation and Antineurodegeneration

Meniere's disease (MD) represents a clinical syndrome characterized by episodes of spontaneous vertigo, associated with fluctuating, low to medium frequencies sensorineural hearing loss (SNHL), tinnitus, and aural fullness affecting one or both ears. To date, the cause of MD remains substantially unknown, despite increasing evidence suggesting that oxidative stress and neuroinflammation may be central to the development of endolymphatic hydrops and consequent otholitic degeneration and displacement in the reuniting duct, thus originating the otolithic crisis from vestibular otolithic organs utricle or saccule. As a starting point to withstand pathological consequences, cellular pathways conferring protection against oxidative stress, such as vitagenes, are also induced, but at a level not sufficient to prevent full neuroprotection, which can be reinforced by exogenous nutritional approaches. One emerging strategy is supplementation with mushrooms. Mushroom preparations, used in traditional medicine for thousands of years, are endowed with various biological actions, including antioxidant, immunostimulatory, hepatoprotective, anticancer, as well as antiviral effects. For example, therapeutic polysaccharopeptides obtained from Coriolus versicolor are commercially well established. In this study, we examined the hypothesis that neurotoxic insult represents a critical primary mediator operating in MD pathogenesis, reflected by quantitative increases of markers of oxidative stress and cellular stress response in the peripheral blood of MD patients. We evaluated systemic oxidative stress and cellular stress response in MD patients in the absence and in the presence of treatment with a biomass preparation from Coriolus. Systemic oxidative stress was estimated by measuring, in plasma, protein carbonyls, hydroxynonenals (HNE), and ultraweak luminescence, as well as by lipidomics analysis of active biolipids, such as lipoxin A4 and F2-isoprostanes, whereas in lymphocytes we determined heat shock proteins 70 (Hsp72), heme oxygenase-1 (HO-1), thioredoxin (Trx), and γ-GC liase to evaluate the systemic cellular stress response. Increased levels of carbonyls, HNE, luminescence, and F2-isoprostanes were found in MD patients with respect to the MD plus Coriolus-treated group. This was paralleled by a significant (p < 0.01) induction, after Coriolus treatment, of vitagenes such as HO-1, Hsp70, Trx, sirtuin-1, and γ-GC liase in lymphocyte and by a significant (p < 0.05) increase in the plasma ratio-reduced glutathione (GSH) vs. oxidized glutathione (GSSG). In conclusion, patients affected by MD are under conditions of systemic oxidative stress, and the induction of vitagenes after mushroom supplementation indicates a maintained response to counteract intracellular pro-oxidant status. The present study also highlights the importance of investigating MD as a convenient model of cochlear neurodegenerative disease. Thus, searching innovative and more potent inducers of the vitagene system can allow the development of pharmacological strategies capable of enhancing the intrinsic reserve of vulnerable neurons, such as ganglion cells to maximize antidegenerative stress responses and thus providing neuroprotection.

Peripheral immune biomarkers and neurodegenerative diseases: A prospective cohort study with 20 years of follow-up

OBJECTIVE

To assess the associations of several blood immune biomarkers with the future risks of amyotrophic lateral sclerosis and Parkinson disease in a prospective cohort study with 20 years of follow-up.

METHODS

The Swedish Apolipoprotein-Related Mortality Risk study is a longitudinal cohort study including 812,073 participants with repeated blood biomarker measurements between 1985 and 1996 and a follow-up until 2011. Using a Cox model, we first estimated hazard ratios of amyotrophic lateral sclerosis and Parkinson disease in relation to leukocytes, immunoglobulin G, haptoglobin, and uric acid. We further described the temporal changes of these biomarkers during the 20 years prior to the diagnosis of these diseases.

RESULTS

A total of 585 incident cases of amyotrophic lateral sclerosis and 3,769 incident cases of Parkinson disease were identified during the follow-up. Increasing concentrations of leukocytes, haptoglobin, and uric acid were associated with a lower risk of Parkinson disease. No statistically significant association was, however, noted between the studied biomarkers and amyotrophic lateral sclerosis. Parkinson disease patients appeared to have lower levels of leukocytes and haptoglobin between 20 and 10 years before diagnosis and lower levels of uric acid during the 20 years before diagnosis, compared to controls, although statistically significant differences were only noted during parts of the respective time intervals after multivariable adjustment. No clear differences were noted between patients with amyotrophic lateral sclerosis and controls.

INTERPRETATION

If verified in studies of independent populations, our findings may suggest a different role of systemic inflammation on the risk of Parkinson disease compared to amyotrophic lateral sclerosis. ANN NEUROL 2019;86:913-926.

A caspase-6-cleaved fragment of Glial Fibrillary Acidic Protein as a potential serological biomarker of CNS injury after cardiac arrest

Blood levels of Glial Fibrillary Acidic protein (GFAP) reflect processes associated with different types of CNS injury. Evidence suggests that GFAP is cleaved by caspases during CNS injury, hence positioning GFAP fragments as potential biomarkers of injury-associated processes. We set out to develop an assay detecting the neo-epitope generated by caspase-6 cleavage of GFAP (GFAP-C6), and to assess the ability of GFAP-C6 to reflect pathological processes in patients suffering a cardiac arrest and subsequent global cerebral ischemia. Anti-GFAP-C6 antibodies recognized their specific target sequence, and dilution and spike recoveries in serum were within limits of ±20% reflecting high precision and accuracy of measurements. Intra- and inter-assay CVs were below limits of 10% and 15%, respectively. Serological levels of GFAP-C6 were significantly elevated 72 hours after CA (Mean±SD) (20.39±10.59 ng/mL) compared to time of admission (17.79±10.77 ng/mL, p<0.0001), 24 hours (17.40±7.99 ng/mL, p<0.0001) and 48 hours (17.87±8.56 ng/mL, p<0.0001) after CA, but were not related to neurological outcome at day 180. GFAP-C6 levels at admission, 24, 48, and 72 hours after cardiac arrest correlated with two proteolytic fragments of tau, tau-A (r = 0.30, r = 0.40, r = 0.50, r = 0.53, p < 0.0001) and tau-C (r = 54, r = 0.48, r = 0.55, r = 0.54, p < 0.0001), respectively. GFAP-C6 levels did not correlate with other markers of CNS damage; total tau, NSE and S100B. In conclusion, we developed the first assay detecting a caspase-6 cleaved fragment of GFAP in blood. Increased levels at 72 hours after cardiac arrest as well as moderate correlations between GFAP-C6 and two other blood biomarkers of neurodegeneration suggest the ability of GFAP-C6 to reflect pathological processes of the injured brain. Investigations into the potential of GFAP-C6 in other types of CNS injury are warranted.

Specific Signatures of Serum miRNAs as Potential Biomarkers to Discriminate Clinically Similar Neurodegenerative and Vascular-Related Diseases

Neurodegenerative diseases (NDs) are age-dependent; among them, Alzheimer's disease (AD) and Parkinson's disease (PD) are the most frequent. Similarly, cerebrovascular damage can induce the development of vascular-related disorders that share common features with AD and PD, respectively, named vascular dementia (VD) and vascular parkinsonism (VP). To date, ND diagnosis is mainly clinical; therefore, since these disorders show similar symptoms, their correct discrimination may be difficult. We detected 23 ND-associated microRNAs (miRNAs) by literature mining and investigated their serum expression in a cohort of 139 patients including AD, PD, VD, and VP patients and healthy controls. TaqMan RT-PCR data showed that miR-23a upregulation was associated with an ongoing neurodegenerative process, similar to miR-22* and miR-29a, while let-7d, miR-15b, miR-24, miR-142-3p, miR-181c, and miR-222 showed an altered expression in Parkinson-like phenotypes, as well as miR-34b, miR-125b, and miR-130b in Alzheimer-like disorders. By computing logistic regression models and ROC curves, we identified signatures of neuro-miRNAs specific for each disease, showing good diagnostic performance. Interestingly, we found that miR-23a, miR-29a, miR-34b, and miR-125b exhibited a different distribution between exosomes and vesicle-free serum, suggesting a heterogeneity of secretion for these miRNAs. Our results suggest that miRNA signatures could discriminate in a non-invasive manner neurodegenerative disorders, thus improving clinical diagnoses.

Panoramic Visualization of Circulating MicroRNAs Across Neurodegenerative Diseases in Humans

Neurodegenerative diseases (NDs) such as Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and dementia pose one of the greatest health challenges this century. Although these NDs have been looked at as single entities, the underlying molecular mechanisms have never been collectively visualized to date. With the advent of high-throughput genomic and proteomic technologies, we now have the opportunity to visualize these diseases in a whole new perspective, which will provide a clear understanding of the primary and secondary events vital in achieving the final resolution of these diseases guiding us to new treatment strategies to possibly treat these diseases together. We created a knowledge base of all microRNAs known to be differentially expressed in various body fluids of ND patients. We then used several bioinformatic methods to understand the functional intersections and differences between AD, PD, ALS, and MS. These results provide a unique panoramic view of possible functional intersections between AD, PD, MS, and ALS at the level of microRNA and their cognate genes and pathways, along with the entities that unify and separate them. While the microRNA signatures were apparent for each ND, the unique observation in our study was that hsa-miR-30b-5p overlapped between all four NDS, and has significant functional roles described across NDs. Furthermore, our results also show the evidence of functional convergence of miRNAs which was associated with the regulation of their cognate genes represented in pathways that included fatty acid synthesis and metabolism, ECM receptor interactions, prion diseases, and several signaling pathways critical to neuron differentiation and survival, underpinning their relevance in NDs. Envisioning this group of NDs together has allowed us to propose new ways of utilizing circulating miRNAs as biomarkers  and in visualizing diverse NDs more holistically . The critical molecular insights gained through the discovery of ND-associated miRNAs, overlapping miRNAs, and the functional convergence of microRNAs on vital pathways strongly implicated in neurodegenerative processes can prove immensely valuable in the identifying new generation of biomarkers, along with the development of miRNAs into therapeutics.

Plasma Metabolites Associated with Brain MRI Measures of Neurodegeneration in Older Adults in the Atherosclerosis Risk in Communities⁻Neurocognitive Study (ARIC-NCS)

Background: Plasma metabolites are associated with cognitive and physical function in the elderly. Because cerebral small vessel disease (SVD) and neurodegeneration are common causes of cognitive and physical function decline, the primary objective of this study was to investigate the associations of six plasma metabolites (two plasma phosphatidylcholines [PCs]: PC aa C36:5 and PC aa 36:6 and four sphingomyelins [SMs]: SM C26:0, SM [OH] C22:1, SM [OH] C22:2, SM [OH] C24:1) with magnetic resonance imaging (MRI) features of cerebral SVD and neurodegeneration in older adults. Methods: This study included 238 older adults in the Atherosclerosis Risk in Communities study at the fifth exam. Multiple linear regression was used to assess the association of each metabolite (log-transformed) in separate models with MRI measures except lacunar infarcts, for which binary logistic regression was used. Results: Higher concentrations of plasma PC aa C36:5 had adverse associations with MRI features of cerebral SVD (odds ratio of 1.69 [95% confidence interval: 1.01, 2.83] with lacunar infarct, and beta of 0.16 log [cm3] [0.02, 0.30] with log [White Matter Hyperintensities (WMH) volume]) while higher concentrations of 3 plasma SM (OH)s were associated with higher total brain volume (beta of 12.0 cm3 [5.5, 18.6], 11.8 cm3 [5.0, 18.6], and 7.3 cm3 [1.2, 13.5] for SM [OH] C22:1, SM [OH] C22:2, and SM [OH] C24:1, respectively). Conclusions: This study identified associations between certain plasma metabolites and brain MRI measures of SVD and neurodegeneration in older adults, particularly higher SM (OH) concentrations with higher total brain volume.

On the fluxes of side-chain oxidized oxysterols across blood-brain and blood-CSF barriers and origin of these steroids in CSF (Review)

In contrast to cholesterol itself the side-chain oxidized metabolites 24S-hydroxycholesterol (24OH) and 27-hydroxycholesterol (27OH) are able to pass the blood-brain barrier and the blood-CSF barrier. Most 27OH in circulation is formed extracerebrally and according to catheterization experiments about 5 mg of it is taken up by the brain per 24 h. 24OH is almost exclusively produced in the brain and about 6 mg fluxes from the brain into the circulation per 24 h. In addition to these major fluxes a very minor fraction of these two oxysterols flux from the circulation into CSF. Isotope experiments have shown that almost all 27OH in CSF originates from the circulation and evidence has been presented that this is the case also with a substantial part of 24OH. The levels of both 24OH and 27OH in CSF are thus affected by the integrity of the blood-CSF barrier with higher levels when the barrier is defect. Both levels of 24OH and 27OH in CSF are increased in connection with neurodegeneration and in general the increase in 24OH levels is higher than the increase in 27OH levels. A number of observations in different type of patients including measurements of other biochemical markers support that the increase in levels of 24OH due to neurodegeneration is due to a release of this oxysterol or its precursor cholesterol from dying neuronal cells. In contrast the increase in levels of 27OH is likely to be a consequence of reduced metabolism due to loss of the neuronal enzyme CYP7B1. We discuss the driving forces behind the fluxes of oxysterols in the brain, the limitations in the flux across the barriers and the diagnostic potential for side-chain oxidized oxysterols in CSF.

Ultraclean paired sampling for metal analysis in neurodegenerative disorders

The causes of neurodegenerative disorders are largely unknown. Environmental factors seem to contribute to neurodegeneration in genetically susceptible individuals. Increasing evidence point towards a key role for environmental exposure in the causation of neurodegenerative disorders and specifically for metal exposure. Alterations of metalloproteins seem to be a common motif in neurodegeneration and enough evidence has now accumulated to designate these disorders as metallopathies. Paired sampling refers to the simultaneous sampling of CSF and blood and by comparing metal concentrations between CSF and blood conclusions about exposure and barrier properties can be drawn. However previous reports on metal concentrations in body fluids in neurodegenerative disorders show a wide variation in results hampering firm conclusions on the role of metals in degeneration of nerve cells. Here we suggest some steps and measures to minimise this variation, most important sampling performed in a cleanroom with filtered air and the use of acid washed perfluoroalkoxy vials. By strict adherence to ultraclean paired sampling technique conclusive results concerning the role of metals in neurodegenerative disorders can be generated.

Mass spectrometry-based metabolomics: Targeting the crosstalk between gut microbiota and brain in neurodegenerative disorders

Metabolomics seeks to take a "snapshot" in a time of the levels, activities, regulation and interactions of all small molecule metabolites in response to a biological system with genetic or environmental changes. The emerging development in mass spectrometry technologies has shown promise in the discovery and quantitation of neuroactive small molecule metabolites associated with gut microbiota and brain. Significant progress has been made recently in the characterization of intermediate role of small molecule metabolites linked to neural development and neurodegenerative disorder, showing its potential in understanding the crosstalk between gut microbiota and the host brain. More evidence reveals that small molecule metabolites may play a critical role in mediating microbial effects on neurotransmission and disease development. Mass spectrometry-based metabolomics is uniquely suitable for obtaining the metabolic signals in bidirectional communication between gut microbiota and brain. In this review, we summarized major mass spectrometry technologies including liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry, and imaging mass spectrometry for metabolomics studies of neurodegenerative disorders. We also reviewed the recent advances in the identification of new metabolites by mass spectrometry and metabolic pathways involved in the connection of intestinal microbiota and brain. These metabolic pathways allowed the microbiota to impact the regular function of the brain, which can in turn affect the composition of microbiota via the neurotransmitter substances. The dysfunctional interaction of this crosstalk connects neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease and Huntington's disease. The mass spectrometry-based metabolomics analysis provides information for targeting dysfunctional pathways of small molecule metabolites in the development of the neurodegenerative diseases, which may be valuable for the investigation of underlying mechanism of therapeutic strategies.

Cerebrospinal fluid and blood biomarkers for neurodegenerative dementias: An update of the Consensus of the Task Force on Biological Markers in Psychiatry of the World Federation of Societies of Biological Psychiatry

In the 12 years since the publication of the first Consensus Paper of the WFSBP on biomarkers of neurodegenerative dementias, enormous advancement has taken place in the field, and the Task Force takes now the opportunity to extend and update the original paper. New concepts of Alzheimer's disease (AD) and the conceptual interactions between AD and dementia due to AD were developed, resulting in two sets for diagnostic/research criteria. Procedures for pre-analytical sample handling, biobanking, analyses and post-analytical interpretation of the results were intensively studied and optimised. A global quality control project was introduced to evaluate and monitor the inter-centre variability in measurements with the goal of harmonisation of results. Contexts of use and how to approach candidate biomarkers in biological specimens other than cerebrospinal fluid (CSF), e.g. blood, were precisely defined. Important development was achieved in neuroimaging techniques, including studies comparing amyloid-β positron emission tomography results to fluid-based modalities. Similarly, development in research laboratory technologies, such as ultra-sensitive methods, raises our hopes to further improve analytical and diagnostic accuracy of classic and novel candidate biomarkers. Synergistically, advancement in clinical trials of anti-dementia therapies energises and motivates the efforts to find and optimise the most reliable early diagnostic modalities. Finally, the first studies were published addressing the potential of cost-effectiveness of the biomarkers-based diagnosis of neurodegenerative disorders.

The Omega-6:Omega-3 ratio: A critical appraisal and possible successor

The well-known health effects of the long-chain, marine omega-3 (n-3) fatty acids (FAs) has led to a growing interest in the prognostic value that blood levels of these FAs might have vis-à-vis cardiovascular and neurocognitive diseases. The measurement and expression of n-3 FA levels is not straight-forward, however, and a wide variety of means of expression of n-3 FA status have been used in research and clinical medicine. This has led to considerable confusion as to what "optimal" n-3 FA status is. The n-6:n-3 ratio has enjoyed relatively widespread use, but this apparently simple metric has both theoretical and practical difficulties that have contributed to misunderstandings in this field. Just as the once-popular polyunsaturated:saturated FA ratio has largely disappeared from the nutritional and medical literature, it may be time to replace the n-6:n-3 ratio with a newer metric that focuses on the primary deficiency in Western diets - the lack of eicosapentaenoic and docosahexaenoic acids (EPA and DHA). The Omega-3 Index (red blood cell EPA+DHA) has much to recommend it in this regard.

Relationships between Rapid Eye Movement Sleep Behavior Disorder and Neurodegenerative Diseases: Clinical Assessments, Biomarkers, and Treatment

OBJECTIVE

Rapid eye movement sleep behavior disorder (RBD) is characterized by dream enactment and loss of muscle atonia during rapid eye movement sleep. RBD is closely related to α-synucleinopathies including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Many studies have investigated the markers of imaging and neurophysiological, genetic, cognitive, autonomic function of RBD and their predictive value for neurodegenerative diseases. This report reviewed the progress of these studies and discussed their limitations and future research directions.

DATA SOURCES

Using the combined keywords: "RBD", "neurodegenerative disease", "Parkinson disease", and "magnetic resonance imaging", the PubMed/MEDLINE literature search was conducted up to January 1, 2018.

STUDY SELECTION

A total of 150 published articles were initially identified citations. Of the 150 articles, 92 articles were selected after further detailed review. This study referred to all the important English literature in full.

RESULTS

Single-nucleotide polymorphisms in SCARB2 (rs6812193) and MAPT (rs12185268) were significantly associated with RBD. The olfactory loss, autonomic dysfunction, marked electroencephalogram slowing during both wakefulness and rapid eye movement sleep, and cognitive impairments were potential predictive markers for RBD conversion to neurodegenerative diseases. Traditional structural imaging studies reported relatively inconsistent results, whereas reduced functional connectivity between the left putamen and substantia nigra and dopamine transporter uptake demonstrated by functional imaging techniques were relatively consistent findings.

CONCLUSIONS

More longitudinal studies should be conducted to evaluate the predictive value of biomarkers of RBD. Moreover, because the glucose and dopamine metabolisms are not specific for assessing cognitive cognition, the molecular metabolism directly related to cognition should be investigated. There is a need for more treatment trials to determine the effectiveness of interventions of RBD on preventing the conversion to neurodegenerative diseases.

Augmented frontal cortex diacylglycerol levels in Parkinson's disease and Lewy Body Disease

Background

Research from our laboratory, and that of other investigators, has demonstrated augmented levels of diacylglycerols (DAG) in the frontal cortex and plasma of subjects with Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI). We have extended these observations to investigate the frontal cortex of subjects with Parkinson’s disease (PD) and Lewy Body Disease (LBD), with and without coexisting pathologic features of AD.

Methods/Principal findings

Utilizing a high-resolution mass spectrometry analytical platform, we clearly demonstrate that DAG levels are significantly increased in the frontal cortex of subjects with PD, LBD with intermediate neocortical AD neuropathology, and in LBD with established neocortical AD neuropathology. In the case of the PD cohort, increases in cortical DAG levels were detected in cases with no neocortical pathology but were greater in subjects with neocortical pathology. These data suggest that DAG changes occur early in the disease processes and are amplified as cortical dysfunction becomes more established.

Conclusions

These findings suggest that altered DAG synthesis/metabolism is a common feature of neurodegenerative diseases, characterized by proteinopathy, that ultimately result in cognitive deficits. With regard to the mechanism responsible for these biochemical alterations, selective decrements in cortical levels of phosphatidylcholines in LBD and PD suggest that augmented degradation and/or decreased synthesis of these structural glycerophospholipids may contribute to increases in the pool size of free DAGs. The observed augmentation of DAG levels may be phospholipase-driven since neuroinflammation is a consistent feature of all disease cohorts. If this conclusion can be validated it would support utilizing DAG levels as a biomarker of the early disease process and the investigation of early intervention with anti-inflammatory agents.

Non-musculoskeletal benefits of vitamin D

The aim of this study is to determine and critically evaluate the plausible relationships of vitamin D with extra-skeletal tissues in humans. Severe vitamin D deficiency results in rickets in children and osteomalacia in adults; these beneficial effects in the musculoskeletal system and certain physiological functions are well understood. Nevertheless, mounting reports support additional beneficial effects of vitamin D, outside the musculoskeletal system. This review explores the recent advances in knowledge about the non-skeletal effects of vitamin D. Peer-reviewed papers were extracted from research databases using key words, to assess correlations between vitamin D and extra-skeletal diseases and conditions. As per the guidelines of the Preferred Reporting Items for Systematic Reviews (PRISMA); general interpretations of results are included; taking into consideration the broader evidence and implications. This review summarizes current knowledge of the effects of vitamin D status on extra-skeletal tissues with special attention given to relationships between vitamin D status and various diseases commonly affecting adults; the effects of intervention with vitamin D and exposure to sunlight. Evidence suggests that vitamin D facilitates the regulation of blood pressure; and cardiac; endothelial; and smooth muscle cell functions; playing an important role in cardiovascular protection. In addition; 1,25(OH)₂D improves immunity; subdues inflammation; and reduces the incidence and severity of common cancers; autoimmune diseases and infectious diseases. Almost all adequately powered; epidemiological and biological studies that use; adequate doses of vitamin D supplementation in D-deficient populations have reported favorable outcomes. These studies have concluded that optimizing 25(OH)D status improves the functionality of bodily systems; reduces comorbidities; improves the quality of life; and increases survival. Although accumulating evidence supports biological associations of vitamin D sufficiency with improved physical and mental functions; no definitive evidence exists from well-designed; statistically powered; randomized controlled clinical trials. Nevertheless, most studies point to significant protective effects of vitamin D in humans when the minimum 25(OH)D serum level exceeds 30ng/mL and is maintained throughout the year.

Midlife systemic inflammatory markers are associated with late-life brain volume: The ARIC study

OBJECTIVE

To clarify the temporal relationship between systemic inflammation and neurodegeneration, we examined whether a higher level of circulating inflammatory markers during midlife was associated with smaller brain volumes in late life using a large biracial prospective cohort study.

METHODS

Plasma levels of systemic inflammatory markers (fibrinogen, albumin, white blood cell count, von Willebrand factor, and Factor VIII) were assessed at baseline in 1,633 participants (mean age 53 [5] years, 60% female, 27% African American) enrolled in the Atherosclerosis Risk in Communities Study. Using all 5 inflammatory markers, an inflammation composite score was created for each participant. We assessed episodic memory and regional brain volumes, using 3T MRI, 24 years later.

RESULTS

Each SD increase in midlife inflammation composite score was associated with 1,788 mm3 greater ventricular (p = 0.013), 110 mm3 smaller hippocampal (p = 0.013), 519 mm3 smaller occipital (p = 0.009), and 532 mm3 smaller Alzheimer disease signature region (p = 0.008) volumes, and reduced episodic memory (p = 0.046) 24 years later. Compared to participants with no elevated (4th quartile) midlife inflammatory markers, participants with elevations in 3 or more markers had, on average, 5% smaller hippocampal and Alzheimer disease signature region volumes. The association between midlife inflammation and late-life brain volume was modified by age and race, whereby younger participants and white participants with higher levels of systemic inflammation during midlife were more likely to show reduced brain volumes subsequently.

CONCLUSIONS

Our prospective findings provide evidence for what may be an early contributory role of systemic inflammation in neurodegeneration and cognitive aging.

SIGNALING PATHWAYS REGULATED BY BRASSICACEAE EXTRACT INHIBIT THE FORMATION OF ADVANCED GLYCATED END PRODUCTS IN RAT BRAIN

BACKGROUND

The goal of this study was identification signaling molecules mediated the formation of AGEs in brain of rats injected with CdCl2 and the role of camel whey proteins and Brassicaceae extract on formation of AGEs in brain.

METHODS

Ninety male rats were randomly grouped into five groups; Normal control (GpI) and the other rats (groups II-V) were received a single dose of cadmium chloride i.p (5 μg/kg/b.w) for induction of neurodegeneration. Rats in groups III-V were treated daily with whey protein (1g/kg b.w) or Brassicaceae extract (1mg/kg b.w) or combined respectively for 12 weeks.

RESULTS

It was found that whey protein combined with Brassicaceae extract prevented the formation of AGEs and enhance the antioxidant activity compared with untreated group (p <0.001). Serum tumor necrosis factor (TNF-α) and interleukine (IL-6) levels were significantly decreased (p<0.01) in rats treated with whey protein and Brassicaceae extract formation compared with untreated. The combined treatment showed a better impact than individual ones (p<0.001). The level of cAMP but not cGMP were lowered in combined treatment than individual (p<0.01).

CONCLUSION

It can be postulated that Whey protein + Brassicaceae extract formation could have potential benefits in the prevention of the onset and progression of neuropathy in patients.

Determination of the coenzyme Q10 status in a large Caucasian study population

Coenzyme Q10 (CoQ10 ) exists in a reduced (ubiquinol) and an oxidized (ubiquinone) form in all human tissues and functions, amongst others, in the respiratory chain, redox-cycles, and gene expression. As the status of CoQ10 is an important risk factor for several diseases, here we determined the CoQ10 status (ubiquinol, ubiquinone) in a large Caucasian study population (n = 1,911). The study population covers a wide age range (age: 18-83 years, 43.4% men), has information available on more than 10 measured clinical phenotypes, more than 30 diseases (presence vs. absence), about 30 biomarkers, and comprehensive genetic information including whole-genome SNP typing (>891,000 SNPs). The major aim of this long-term resource in CoQ10 research is the comprehensive analysis of the CoQ10 status with respect to integrated health parameters (i.e., fat metabolism, inflammation), disease-related biomarkers (i.e., liver enzymes, marker for heart failure), common diseases (i.e., neuropathy, myocardial infarction), and genetic risk in humans. Based on disease status, biomarkers, and genetic variants, our cohort is also useful to perform Mendelian randomisation approaches. In conclusion, the present study population is a promising resource to gain deeper insight into CoQ10 status in human health and disease.

2D gel blood serum biomarkers reveal differential clinical proteomics of the neurodegenerative diseases

This review addresses the challenges of neuroproteomics and recent progress in biomarkers and tests for neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. The review will discuss how the application of quantitative 2D gel electrophoresis, combined with appropriate single-variable and multivariate biostatistics, allows for selection of disease-specific serum biomarkers. It will also address how the use of large cohorts of specifically targeted patient blood serum samples and complimentary age-matched controls, in parallel with the use of selected panels of these biomarkers, are being applied to the development of blood tests to specifically address unmet pressing needs in the differential diagnosis of these diseases, and to provide potential avenues for mechanism-based drug targeting and treatment monitoring. While exploring recent findings in this area, the review discusses differences in critical pathways of immune/inflammation and amyloid formation between Parkinson's disease and amyotrophic lateral sclerosis, as well as discernable synergistic relationships between these pathways that are revealed by this approach. The potential for pathway measurement in blood tests for differential diagnosis, disease burden and therapeutic monitoring is also outlined.

Hepatic and hippocampus iron status is not altered in response to increased serum ceruloplasmin and serum "free" copper in Wistar rat model for non-Wilsonian brain copper toxicosis

Copper and iron dyshomeostasis has been implicated directly or indirectly in the pathogenesis of neurodegenerative diseases. Previously, we have shown the first in vivo evidence of significant increase in the hippocampus copper and zinc content with spatial memory impairments, astrocytes swelling (Alzheimer type-II cells) coupled with increase in the number of astrocytes, copper deposition in the choroid plexus, and degenerated neurons in copper-intoxicated Wistar rats. In continuation with our previous study, the aim of this study was to further investigate the effects of intraperitoneally injected copper lactate (0.15 mg Cu/100 g body weight) daily for 90 days on serum "free" copper levels, iron levels in the liver, and hippocampus by atomic absorption spectrophotometry and histopathological study of the liver and brain tissues of Wistar rats using Perls' Prussian blue (PPB) stain. A massive significant increase in serum "free" copper (79.48% increase) along with strong correlation (r = 0.978) was found between serum copper and serum "free" copper in copper-intoxicated rats. No significant difference was detected in hepatic and hippocampus iron levels between control and copper-intoxicated rats. PPB stain demonstrated very few scattered grade 1 haemosiderin deposits within sinusoidal cells predominantly Kupffer cells; however, brain sections were negatively stained with PPB stain. In conclusion, the current study demonstrates that chronic copper toxicity causes increase in serum "free" copper, which may serve as predisposing factor for the development of neurodegeneration and memory deficits, and grade 1 haemosiderin deposition in Kupffer cells without altering hepatic and hippocampus iron levels in male Wistar rats.

Secondary bilateral striopallidodentate calcinosis associated with generalized pustular psoriasis (Von Zumbusch)

Bilateral striopallidodentate calcinosis (BSPDC) mentioned in the literature as Fahr's disease (a misnomer), is characterized by symmetrical and bilateral intracerebral calcifications located in the basal ganglia with or without deposits in the dentate nucleus, thalamus, and white matter. This entity is usually asymptomatic but may be manifested by neurological symptoms. Idiopathic BSPDC can occur either as sporadic or autosomal dominant familial forms. Secondary presentations of BSPDC are associated with infections, neoplastic diseases, toxicological or traumatic factors, and metabolic disorders. We describe a case of generalized pustular psoriasis associated with secondary BSPDC owing to pseudohypoparathyroidism. Laboratory tests revealed hypocalcemia, hyperphosphatemia, and a normal serum level of parathormone. The correction of the phosphorus-calcium metabolism disorder produced clinical improvement.

Liver X receptors, nervous system, and lipid metabolism

Lipids in the nervous system are represented by cholesterol and phospholipids as constituents of cell membranes and, in particular, of myelin. Therefore, lipids are finely regulated to guarantee physiological functions. In the central nervous system, cholesterol is locally synthesized due to the presence of the blood brain barrier. In the peripheral nervous system cholesterol is either up-taken by lipoproteins and/or produced by de novo biosynthesis. Defects in lipid homeostasis in these tissues lead to structural and functional changes that often result in different pathological conditions depending on the affected pathways (i.e. cholesterol biosynthesis, cholesterol efflux, fatty acid biosynthesis etc.). Alterations in cholesterol metabolism in the central nervous system are linked to several disorders such as Alzheimer's disease, Huntington disease, Parkinson disease, Multiple sclerosis, Smith-Lemli-Opitz syndrome, Niemann-Pick type C disease, and glioblastoma. In the peripheral nervous system changes in lipid metabolism are associated with the development of peripheral neuropathy that may be caused by metabolic disorders, injuries, therapeutics, and autoimmune diseases. Transcription factors, such as the Liver X receptors (LXR), regulate both cholesterol and fatty acid metabolism in several tissues including the nervous system. In the last few years several studies elucidated the biology of LXR in the nervous system due to the availability of knock-out mice and the development of synthetic ligands. Here, we review a survey of the literature focused on the central and peripheral nervous system and in physiological and pathological settings with particular attention to the roles played by LXR in both districts.

[Monoclonal antibodies from neurological and neuropsychological perspective]

The role of monoclonal antibodies and other proinflammatory cytokines in the regulatory processes of the central and peripheral nervous system is not yet fully understood. Clinical studies show that they are involved in the pathogenesis of Alzheimer's disease, Parkinson's disease or other neurodegenerative disabilities with cognitive impairments. Genetic basis of these disorders is still in research. In the past few years it has been shown that increased levels of TNF-alpha and IL-6 in plasma play role in patients with ischemic stroke in the acute phase as well as transient ischemic episodes. Also the negative impact of TNF-alpha has been demonstrated on neck and coronary vessels, including the composition of plaques in the carotid arteries. A few reports indicate the involvement of tumor necrosis factor in such complex processes such as emotions, behavior or personality. Recent studies point to the important role of proinflammatory cytokines in the pathogenesis of sleep disorders such as narcolepsy, cataplexy and sleep paralysis. TNF-alpha can also activate nociceptive pathways, causing the intensity of neuropathic pain. However discloses asymmetric subtypes share TNF-1, TNF-2 in the induction and the maintenance of pain. The phenomenon of complex neurohormonal control mechanism support the proinflammatory cytokines is not fully understood and needs further empirical verification.

[Homocysteine and its role in pathogenesis of Parkinson's disease and other neurodegenerative disorders]

Homocysteine (Hcy) has recently become the focus of interest in the research on Parkinson's disease (PD) and other neurodegenarative disorders. Chronic treatment with levodopa (LD), considered the standard treatment for PD, leads to an increase in homocysteine concentration in serum and cerebro-spinal fluid. Independently from this effect, homocysteine is also regarded as a marker of neurodegenerative disorders. Main interest was focused on hyperhomocysteinemia (hHcy) as the potential risk factor for atheromatosis. Subsequently, its role in neuropsychiatric diseases, e.g. depression, mild cognitive impairment and dementia was investigated. The potential pathogenic role of Hcy in peripheral neuropathy in patients with PD that are treated with LD is an interesting hypothesis but the literature is scarce. Confirmation of this association may lead to introduction of preventive therapies, e.g. administration of vitamin B and inhibitors of catechol-O-methyl transferase (COMT) that may decrease the Hcy blood concentrations.

Decreased plasma levels of soluble low density lipoprotein receptor-related protein-1 (sLRP) and the soluble form of the receptor for advanced glycation end products (sRAGE) in the clinical diagnosis of Alzheimer's disease

Soluble low density lipoprotein receptor-related protein-1 (sLRP) and the soluble form of the receptor for advanced glycation end products (sRAGE) may reflect some peripheral plasma features of the pathophysiological process of Alzheimer's disease (AD). Decreased plasma levels of sLRP and sRAGE in patients with AD have been documented. However, whether different levels of these proteins can differentiate AD from other types of dementia has not been described. In the present study we assessed the concentrations of these two proteins in 126 patients with AD, 96 with vascular dementia (VaD), 30 with non-AD neurodegenerative dementias (NND) and 98 cognitively normal controls (NC). Plasma sLRP was significantly lower in the group with AD compared with any of the other three groups (p<0.001). Sensitivity of sLRP was 77.8% for AD, whereas specificity was 93.3% for NND, 85.7% for the NC and 58.3% for those with VaD. Plasma sRAGE showed a significantly lower concentration in the group with AD compared with those in the VaD or NC group, but there were no significant differences between the AD compared to the NND group or the VaD compared to the NND group. Sensitivity of sRAGE was 82.5% for patients with AD, whereas specificity was 53.5% for NND, 73.5% for the NC group and 43.8% for those with VaD. The receiving operator characteristic analysis of combined sLRP and sRAGE showed a higher diagnostic accuracy (area under the curve, 0.88; 95% confidence interval, 0.84-0.93) than that of either sLRP or sRAGE considered singly. The results support the possibility that these two biomarkers may help with the diagnosis of AD.

Brain, blood, and iron: perspectives on the roles of erythrocytes and iron in neurodegeneration

The terms "neuroacanthocytosis" (NA) and "neurodegeneration with brain iron accumulation" (NBIA) both refer to groups of genetically heterogeneous disorders, classified together due to similarities of their phenotypic or pathological findings. Even collectively, the disorders that comprise these sets are exceedingly rare and challenging to study. The NBIA disorders are defined by their appearance on brain magnetic resonance imaging, with iron deposition in the basal ganglia. Clinical features vary, but most include a movement disorder. New causative genes are being rapidly identified; however, the mechanisms by which mutations cause iron accumulation and neurodegeneration are not well understood. NA syndromes are also characterized by a progressive movement disorder, accompanied by cognitive and psychiatric features, resulting from mutations in a number of genes whose roles are also basically unknown. An overlapping feature of the two groups, NBIA and NA, is the occurrence of acanthocytes, spiky red cells with a poorly-understood membrane dysfunction. In this review we summarise recent developments in this field, specifically insights into cellular mechanisms and from animal models. Cell membrane research may shed light upon the significance of the erythrocyte abnormality, and upon possible connections between the two sets of disorders. Shared pathophysiologic mechanisms may lead to progress in the understanding of other types of neurodegeneration.

Evaluation of a prototype point-of-care instrument based on monochromatic x-ray fluorescence spectrometry: potential for monitoring trace element status of subjects with neurodegenerative disease

Assessment of trace elements such as Cu, Zn, and Se in patients with neurodegenerative disease, such as Alzheimer's (AD) and Parkinson's disease (PD), may be useful in etiologic studies and in assessing the risk of developing these conditions. A prototype point-of-care (POC) instrument based on monochromatic x-ray fluorescence (M-XRF) was assembled and evaluated for the determination of Cu, Zn, and Se in whole blood, plasma, and urine. The prototype instrument was validated using certified reference materials for Cu and Zn in serum/plasma, and the reported bias and relative imprecision were <10%. The M-XRF prototype performance was further assessed using human specimens collected from AD and PD subjects, and was found to be satisfactory (<20% bias) for monitoring Cu and Zn levels in plasma and whole blood. However, the prototype M-XRF sensitivity was not sufficient for quantifying Cu, Zn, or Se in urine. Nonetheless, while validating the prototype instrument, body fluids (whole blood, plasma, and urine) were collected from 19 AD patients, 23 PD patients, and 24 controls specifically for trace element analysis using well-validated methods based on inductively coupled plasma mass spectrometry (ICP-MS). This limited biomonitoring study provided robust data for up to 16 elements including Sb, As, Ba, Cd, Cs, Co, Cr, Cu, Hg, Pb, Mo, Se, Tl, Sn, Zn, and U in plasma, whole blood, and urine. The results did not indicate any significant differences in most trace elements studied between AD or PD patients compared to controls, although the sample size is limited. A statistically significant increase in plasma Se was identified for PD patients relative to AD patients, but this could be due to age differences.

Role of cerebrospinal fluid and plasma biomarkers in the diagnosis of neurodegenerative disorders and mild cognitive impairment

Biomarkers are one type of laboratory testing being developed in response to the therapeutic imperative for diseases that cause cognitive impairment and dementia. The role of biomarkers is already transforming the organization and conduct of clinical trials, and if successful will likely contribute in the future to the medical management of patients with these diseases. Despite the obvious utility of practicality of blood- or urine-based biomarkers, so far results from these fluid compartments have not been reproducible. In contrast, substantial progress has been made in cerebrospinal fluid biomarkers. Here we review the stages of cerebrospinal fluid biomarker development for several common and unusual diseases that cause cognitive impairment and dementia, stressing the distinction between diagnostic and mechanistic biomarkers. Future applications will likely focus on diagnosis of latent or early-stage disease, assessment of disease progression, mechanism of injury, and response to experimental therapeutics.

Increased plasma peroxides and serum oxidized low density lipoprotein antibodies in major depression: markers that further explain the higher incidence of neurodegeneration and coronary artery disease

BACKGROUND

Major depression is characterized by a decreased antioxidant status, an induction of the inflammatory and oxidative and nitrosative (IO&NS) pathways and inflammatory-neurodegenerative (I&ND) pathways. This study examines two markers of oxidative stress in depression, i.e. plasma peroxides and serum oxidized LDL (oxLDL) antibodies.

METHODS

Blood was sampled in 54 patients with major depression (mean+/-SD age=43.5+/-11.6 years) and 37 normal volunteers (43.6+/-11.1 years). The severity of illness was measured by means of the Hamilton Depression Rating Scale. The Fibromyalgia and Chronic Fatigue Syndrome Rating Scale was used to measure severity of "psychosomatic" symptoms in depression.

RESULTS

We found significantly higher plasma peroxides (p=0.002) and serum oxLDL antibodies (p=0.0002) in depressed patients as compared to normal controls. There was no significant correlation between both markers and both independently from each other predicted major depression. There were significant correlations between the oxLDL antibodies and the scores on two items of the FF scale, i.e. gastro-intestinal symptoms and headache.

DISCUSSION

The results show that major depression is accompanied by increased oxidative stress and lipid peroxidation. These results further extend the IO&NS pathophysiology of major depression. Since increased peroxides and oxLDL antibodies are predictors of coronary artery disease (CAD) and neurodegeneration, our findings suggest that IO&NS pathways are involved in the increased incidence of both CAD and neurodegeneration in depression.

Synergy of serum and cerebrospinal fluid antibodies against axonal cytoskeletal proteins in patients with different neurological diseases

Autoantibodies against different axonal cytoskeletal proteins [the light (NFL) and medium (NFM) subunit of neurofilament and tubulin (TUB)] in serum and cerebrospinal fluid may be generated in response to the release of cytoskeleton from damaged neurons. We studied the relationships among these autoantibodies. Paired cerebrospinal fluid (CSF) and serum samples were obtained from 47 multiple sclerosis (MS) patients, 14 patients with neurodegenerative diseases, 21 patients with various neurological diseases and 16 normal control subjects. Levels of antibodies against NFL, NFM and TUB were related to each other in CSF in all groups, whereas close association of anti-cytoskeletal antibodies in serum was found in the MS group only. A concordant spectrum of anti-cytoskeletal antibodies is present in serum of MS patients, unlike in other neurological patients. The synergy between the spectrum of anti-cytoskeletal antibodies in serum and CSF might be one of the immunological features typical for the MS patients.

Hypopituitarism (GHD) and neurodegenerative diseases

Neurodegenerative diseases are a major focus of scientific and clinical interest because of their increasing medical and social importance. Due to the intimate connections between central nervous and endocrine systems, it is reasonable to suspect that important, and in some cases clinically relevant, endocrine modifications may accompany the progression of neurodegenerative diseases. Data on endocrine modifications in different neurodegenerative diseases have been reported, but results have often been non-conclusive, or conflicting. Accumulating evidence suggests that the GH/IGF-I axis is involved in the regulation of brain growth, development, and metabolism and in the regulation of muscle function. Dysfunctions in GH/IGF-I axis in most of neurodegenerative diseases are therefore reviewed. Alterations of this system could be actors in the complex network leading to (at least some) neurodegenerative diseases. A thorough effort in investigating every possible involvement is warranted, in the light of future therapeutic strategies.

Determination of alpha-synuclein concentration in human plasma using ELISA

The nerve cell protein alpha-synuclein is important in Parkinson's disease and dementia with Lewy bodies, and its expression levels are directly linked to development of the diseases. Quantification of the plasma level of alpha-synuclein may therefore be important as a biomarker for disease susceptibility. We present a quantitative measurement of alpha-synuclein in the plasma of healthy control subjects in relation to their age using a novel enzyme-linked immunosorbent assay (ELISA). The plasma concentration among the 44 blood donors displayed a median of 5.6 microg/L (range 2.1-19.4 microg/L) with a narrow distribution (25 % and 75 % percentiles, 4.0 and 7.2 microg/L) and there was no correlation with age and gender. This narrow concentration range and the ease of measuring the quantitative ELISA support future investigations of plasma alpha-synuclein in relation to neurodegenerative diseases.

Regional CBF changes in Parkinson’s disease: a correlation with motor dysfunction

PURPOSE

The purpose of this study was to further localize cerebral perfusion abnormalities, and to better correlate these abnormalities with the clinical severity of Parkinson's disease (PD).

METHODS

A single-photon emission computed tomography (SPECT) study was performed on 27 patients with PD and 24 age-matched controls. SPECT images were spatially normalized, concatenated, and then decomposed using Infomax independent component analysis (ICA). The resulting image components were separated by logistic regression into two subspaces: "disease-related" components whose subject weights differed between groups, and "disease-unrelated" components. The resultant regional cerebral blood flow (rCBF) subspace images were normalized to global CBF for each subject, and then processed using statistical parametric mapping to compare rCBF values between PD and control subjects.

RESULTS

In the disease-related image subspace, patients with PD exhibited significantly higher adjusted rCBF in the putamen, globus pallidum, thalamus, brainstem, and the anterior lobe of the cerebellum, and significant hypoperfusion in the parieto-temporo-occipital cortex, the dorsolateral prefrontal cortex, the insula, and the cingulate gyrus. The motor Unified Parkinson's Disease Rating Scale scores correlated negatively with rCBF in the insula and cingulate gyrus. In the disease-unrelated image subspace, no brain voxels exhibited a significant group difference.

CONCLUSION

ICA-based separation of normalized images into disease-related and disease-unrelated subspaces revealed many disease-related group blood flow differences. The regions revealed by ICA are consistent with the current model of PD. These rCBF changes in PD have not been fully demonstrated in any single functional imaging study previously.