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Objective: Cerebrospinal fluid (CSF) biomarkers add accuracy to the diagnostic workup of cognitive impairment by illustrating Alzheimer's disease (AD) pathology. However, there are no universally accepted cutoff values for the interpretation of AD biomarkers. The aim of this study is to determine the viability of a decision-tree method to analyse CSF biomarkers of AD as a support for clinical diagnosis., Methods: A decision-tree method (automated classification analysis) was applied to concentrations of AD biomarkers in CSF as a support for clinical diagnosis in older adults with or without cognitive impairment in a Brazilian cohort. In brief, 272 older adults (68 with AD, 122 with mild cognitive impairment [MCI], and 82 healthy controls) were assessed for CSF concentrations of Aß1-42, total-tau, and phosphorylated-tau using multiplexed Luminex assays; biomarker values were used to generate decision-tree algorithms (classification and regression tree) in the R statistical software environment., Results: The best decision tree model had an accuracy of 74.65% to differentiate the three groups. Cluster analysis supported the combination of CSF biomarkers to differentiate AD and MCI vs. controls, suggesting the best cutoff values for each clinical condition., Conclusion: Automated analyses of AD biomarkers provide valuable information to support the clinical diagnosis of MCI and AD in research settings., Competing Interests: The authors report no conflicts of interest.

Background: Decreased cerebrospinal fluid (CSF) concentrations of the amyloid-β (Aβ), along with increased total (T-tau) and phosphorylated tau protein (P-tau), are widely accepted as core biomarkers of Alzheimer's disease (AD) pathology. Nonetheless, there are a few remaining caveats that still preclude the full incorporation of AD biomarkers into clinical practice., Objective: To determine the frequency of clinical-biological mismatches in a clinical sample of older adults with varying degrees of cognitive impairment., Methods: 204 participants were enrolled for a cross-sectional assessment and allocated into diagnostic groups: probable AD (n = 60, 29.4%); MCI (n = 84, 41.2%); or normal cognition (NC, n = 60, 29.4%). CSF concentrations of Aβ42, T-tau, and 181Thr-P-tau were determined, and Aβ42/P-tau ratio below 9.53 was used as a proxy of AD pathology. The AT(N) classification was further used as a framework to ascertain the biological evidence of AD., Results: The majority (73.7%) of patients in the AD group had the Aβ42/P-tau ratio below the cut-off score for AD, as opposed to a smaller proportion in the MCI (42.9%) and NC (23.3%) groups. In the latter, 21 subjects (35%) were classified as A+, 28 (46.7%) as T+, and 23 (38.3%) as N + . In the AD group, 66.7%of the cases were classified as A+, 78.3%as T+, and 80%as N+., Conclusion: Analysis of CSF biomarkers was able to discriminate between AD, MCI, and NC. However, clinical-biological mismatches were observed in a non-negligible proportion of cases.

Objectives: Expression of phospholipids and related molecules could provide panels of multiple biomarkers searching for the signature of Alzheimer's disease (AD). The aim of the present study was to quantify ten phospholipids and simultaneously determine phospholipase A 2 (PLA 2 ) activity in blood of mild cognitive impairment (MCI) and AD patients., Methods: Thirty-four AD, 20 MCI and 25 controls were enrolled. The phospholipids where analysed using the AbsoluteIDQ ® p180 Kit. PLA 2 activities were accessed in platelets by a radio-enzymatic assay., Results: The study failed to fix the ten phospholipids as a panel to predict AD; the levels of PCaaC36:6, PCaaC40:6 and C16:1-OH were lower in MCI than in controls (P = 0.041, P = 0.012, P = 0.044 respectively). PCaaC40:2 levels were lower in MCI than in AD (P = 0.041). The converters MCI-AD showed at baseline lower levels of PCaaC40:2 (P = 0.050) and PCaaC40:6 (P = 0.037) than controls. iPLA 2 activity was reduced in AD and MCI than in controls (P < 0.001). We found positive correlation in the control group between PCaaC38:6 and tPLA 2 (r = 0.680; P = 0.001) and sPLA 2 (r = 0.601; P = 0.004); PCaaC40:1 and iPLA 2 (r = 0.503; P = 0.020); PCaaC40:6 and tPLA 2 (r = 0.532; P = 0.013) and sPLA 2 (r = 0.523; P = 0.015)., Conclusions: Lipids metabolites in plasma might indirectly indicate changes in neuronal membrane and this deregulation can outline the transition between healthy and diseased brains.

There is increasing evidence suggesting that one of the most relevant pathophysiological features of Alzheimer's disease (AD) is neuroinflammation, which plays an important role in the production and regulation of AD-related proteins (amyloid beta (Aβ) and Tau) and exacerbates AD pathology. Neuroinflammation can also be induced by systemic influences (factors from outside the central nervous system). However, the role of systemic inflammation in AD pathophysiology is much less understood. Thus, our main objective in this study was to verify whether the presence of serum cytokines (IL-1β, IL-6, IL-10, IL-12, and TNF-α) affects different AD biomarkers: Aβ 1-42 and Tau protein levels, hippocampal volumes (HV), and default mode network functional connectivity (DMN FC) in healthy elderly controls, amnestic mild cognitive impairment (aMCI) patients due to AD, and mild AD patients. To accomplish this, we acquired 3-T MRI, blood, and cerebrospinal fluid (CSF) samples from 42 healthy controls, 55 aMCI patients due to AD, and 33 mild AD patients. Comparing the groups, we found that the mild AD patients presented smaller HV, disrupted DMN FC, and proportionally less IL-1β than the controls. The aMCI patients only differed from the controls in DMN FC. In intra-group comparison, aMCI and mild AD with detectable levels of cytokines (TNF-α, IL-1β, IL-10, and IL-12) had decreased DMN FC. On the other hand, patients with detectable levels of IL-10 and IL-12 presented a more favorable AD biomarkers profile (larger HV, more CSF Aβ 1-42 , and less p-Tau), indicating a possible protective role of these ILs. Our findings indicate a possible relationship between systemic inflammation with DMN FC disruption, hippocampal atrophy, and CSF protein levels in the subjects with mild AD and aMCI.

Introduction The search for a reliable neuroimaging biomarker in Alzheimer's disease is a matter of intense research. The presence of cerebral microbleeds seems to be a potential biomarker. However, it is not clear if the presence of microbleeds has clinical usefulness to differentiate mild Alzheimer's disease and amnestic mild cognitive impairment from normal aging. We aimed to verify if microbleed prevalence differs among three groups: mild Alzheimer's disease, amnestic mild cognitive impairment due to Alzheimer's disease, and normal controls. Moreover, we studied whether microbleeds were associated with apolipoprotein E allele ɛ4 status, cerebrospinal fluid amyloid-beta, total and phosphorylated tau protein levels, vascular factors, and cognition. Methods Twenty-eight mild Alzheimer's disease patients, 34 with amnestic mild cognitive impairment and 36 cognitively normal elderly subjects underwent: magnetic resonance imaging with a susceptibility-weighted imaging sequence on a 3T scanner, apolipoprotein E genotyping and a full neuropsychological evaluation. Only amnestic mild cognitive impairment and mild Alzheimer's disease underwent cerebrospinal fluid analysis. We compared the groups and verified if microbleeds were predicted by all other variables. Results Mild Alzheimer's disease presented a higher prevalence of apolipoprotein E allele ɛ4 in relation to amnestic mild cognitive impairment and control group. No significant differences were found between groups when considering microbleed presence. Logistic regression tests failed to find any relationship between microbleeds and the variables. We performed three different regression models using different independent variables: Model 1 - amyloid-beta, phosphorylated tau protein, total tau, apolipoprotein E allele ɛ4 status, age, and sex; Model 2 - vascular risk factors, age, and sex; Model 3 - cognitive scores sex, age, and education. Conclusion Although microbleeds might be related to the Alzheimer's disease process, their presence is not a good candidate for a neuroimaging biomarker of the disease, especially in its early phases.

Synaptic dysfunction is linked to both major depressive disorder (MDD) and Alzheimer's disease (AD). Synapse protein concentrations in cerebrospinal fluid (CSF) may be useful biomarkers to monitor synaptic dysfunction and degeneration that lead to depressive symptoms and AD, respectively. CSF neurogranin (Ng), a post-synaptic protein, has emerged as a promising tool to measure synaptic dysfunction and/or loss in AD. The aim of this study was to test the specific hypothesis that CSF neurogranin (Ng) is able to differentiate AD from MDD and cognitively normal controls. CSF samples from 44 healthy control individuals (CTRL), 86 patients with mild cognitive impairment (MCI), 36 of whom had prodromal AD as defined by a positive CSF AD biomarker signature, 25 AD dementia and 6 patients with MDD were analysed using an in house enzyme-linked immunosorbent assay for Ng. CSF Ng levels were significantly higher in AD patients and in prodromal AD (MCI patients with an "AD-like" CSF tau and Aβ42 profile) compared with CTRL individuals (p < 0.0001 for both groups) and MDD patients (p < 0.001 and p < 0.01, respectively). Significantly higher CSF Ng concentration was also seen in prodromal AD patients as compared to MCI patients without biomarker evidence of underlying AD pathology (p < 0.0001). CSF Ng correlated positively with the classical axonal injury markers CSF T-tau and P-tau (p < 0.0001), whereas correlation to plaque pathology as reflected by CSF Aβ42 was less clear. Negative correlations of CSF Ng with cognitive evaluation scores (MMSE and CAMCOG) were observed. This study strengthens the clinical utility of CSF Ng as a CSF biomarker for AD. AD patients in both MCI and dementia stages of the disease had increased CSF Ng concentrations compared with cognitively normal control individuals, patients with non-AD MCI and patients with MDD. The lowest CSF Ng concentrations were seen in patients with MDD, a finding that warrants validation in further studies.

Reduced phospholipase A2 (PLA2) activity and increased phosphorylation of glycogen synthase kinase 3B (GSK3B) participate in the production of beta-amyloid plaques and of neurofibrillary tangles, which are two neuropathological hallmarks of Alzheimer's disease (AD). Experimental evidences suggest a neuroprotective effect of the cholinesterase inhibitor donepezil in the treatment the disease. The aims of the present study were to evaluate in AD patients the effects of treatment with donepezil on PLA2 activity and GSK3B level. Thirty patients with AD were treated during 6 months with 10 mg daily of donepezil. Radio-enzymatic assays were used to measure PLA2 activity and Elisa assays for GSK3B level, both in platelets. Before treatment and after 3 and 6 months on donepezil, AD patients underwent a cognitive assessment and platelet samples were collected. Values were compared to a healthy control group of 42 sex- and age-matched elderly individuals. Before treatment, iPLA2 activity was lower in patients with AD as compared to controls (p < 0.001). At baseline, no differences were found in GSK3B level between both groups. After 3 and 6 months of treatment, we found a significant increase in iPLA2 activity (p = 0.015 and p < 0.001, respectively). iPLA2 increment was related to the cognitive improvement during treatment (p = 0.037). After 6 months, we found an increase in phosphorylated GSK3B (p = 0.02). The present findings suggest two possible mechanisms by which donepezil delays the progression of AD. The increment of iPLA2 activity may reduce the production of beta-amyloid plaques, whereas the phosphorylation of GSK3B inactivates the enzyme, reducing thus the phosphorylation of tau protein.

Lithium is a well-established therapeutic option for the acute and long-term management of bipolar disorder and major depression. More recently, based on findings from translational research, lithium has also been regarded as a neuroprotective agent and a candidate drug for disease-modification in certain neurodegenerative disorders, namely, Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and, more recently, Parkinson's disease (PD). The putative neuroprotective effects of lithium rely on the fact that it modulates several homeostatic mechanisms involved in neurotrophic response, autophagy, oxidative stress, inflammation, and mitochondrial function. Such a wide range of intracellular responses may be secondary to two key effects, that is, the inhibition of glycogen synthase kinase-3 beta (GSK-3β) and inositol monophosphatase (IMP) by lithium. In the present review, we revisit the neurobiological properties of lithium in light of the available evidence of its neurotrophic and neuroprotective properties, and discuss the rationale for its use in the treatment and prevention of neurodegenerative diseases.

Background: The cerebrospinal fluid (CSF) biomarkers amyloid β (Aβ)-42, total-tau (T-tau), and phosphorylated-tau (P-tau) demonstrate good diagnostic accuracy for Alzheimer's disease (AD). However, there are large variations in biomarker measurements between studies, and between and within laboratories. The Alzheimer's Association has initiated a global quality control program to estimate and monitor variability of measurements, quantify batch-to-batch assay variations, and identify sources of variability. In this article, we present the results from the first two rounds of the program., Methods: The program is open for laboratories using commercially available kits for Aβ, T-tau, or P-tau. CSF samples (aliquots of pooled CSF) are sent for analysis several times a year from the Clinical Neurochemistry Laboratory at the Mölndal campus of the University of Gothenburg, Sweden. Each round consists of three quality control samples., Results: Forty laboratories participated. Twenty-six used INNOTEST enzyme-linked immunosorbent assay kits, 14 used Luminex xMAP with the INNO-BIA AlzBio3 kit (both measure Aβ-(1-42), P-tau(181P), and T-tau), and 5 used Meso Scale Discovery with the Aβ triplex (AβN-42, AβN-40, and AβN-38) or T-tau kits. The total coefficients of variation between the laboratories were 13% to 36%. Five laboratories analyzed the samples six times on different occasions. Within-laboratory precisions differed considerably between biomarkers within individual laboratories., Conclusions: Measurements of CSF AD biomarkers show large between-laboratory variability, likely caused by factors related to analytical procedures and the analytical kits. Standardization of laboratory procedures and efforts by kit vendors to increase kit performance might lower variability, and will likely increase the usefulness of CSF AD biomarkers., (Copyright © 2011 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.)

Phospholipase A(2) (PLA(2)) is a key enzyme in cerebral phospholipid metabolism. Preliminary post-mortem studies have shown that PLA(2) activity is decreased in frontal and parietal areas of the AD brain, which is in accordance with recent (31)P-Magnetic Resonance Spectroscopy evidence of reduced phospholipid turnover in the pre-frontal cortex of moderately demented AD patients. Such abnormality may also be observed in peripheral cells, and reduced PLA(2) activity in platelet membranes of AD patients, and correlates with the severity of dementia. In rat hippocampal slices, PLA(2) has been implicated in mechanisms of synaptic plasticity. In adult rats, the stereotaxic injection of PLA(2) inhibitors in the CA1 area of hippocampus impaired, in a dose-dependent manner, the formation of short- and long-term memory. Additionally, such inhibition resulted in a reduction of the fluidity of hippocampal membranes. In primary cultures of cortical and hippocampal neurons, the inhibition of PLA(2) precluded neurite outgrowth, and the sustained inhibition of the enzyme in mature cultures lead to loss of viability. Taken together, these findings reinforce the involvement of PLA(2) enzymes in neurodevelopment and neurodegeneration processes, and further suggest that reduced PLA(2) activity, probably reducing membrane phospholipids breakdown, may contribute to the memory impairment in AD.

Phospholipase A(2) (PLA(2)) controls the metabolism of phospholipids in cell membranes. In the brain, PLA(2) influences the processing of the amyloid precursor protein (APP) and thus the production of the amyloid-beta peptides (Abeta), which are the major components of the senile plaques in Alzheimer's disease (AD). Reduced PLA(2) activity has been reported in brain and in platelets of AD patients. In the present study we investigated PLA(2) activity in platelets from 21 AD patients as compared to 17 healthy elderly controls and 11 individuals with mild cognitive impairment (MCI). Subjects were cognitively assessed by the Mini-Mental State Examination (MMSE) and the CAMDEX schedule. Platelet PLA(2) activity was determined by radio-enzymatic assay, which mainly detected a calcium-independent form of the enzyme present also in the brain (iPLA(2)). PLA(2) activity was significantly lower in AD than in controls (p < 0.001). Mean PLA(2) activity in MCI individuals was between the values of AD patients and controls, with a subgroup showing PLA as low as the lowest AD patients, but the differences from MCI were not significant from AD and control groups. Lower PLA(2) activity was significantly correlated with a worse cognitive performance both at the MMSE (p = 0.001) and the cognitive sub-scale of the CAMDEX inventory (p = 0.002). Our data replicate previous findings of reduced platelet PLA(2) activity in AD. Both reduced PLA(2) activity and the correlation with impaired cognition were also reported in brain tissue of AD patients, suggesting thus that the present determinations in platelets may be related to a reduction in the brain. In the brain the inhibition of PLA(2) inhibits the physiological secretion of the APP, a mechanism that increases Abeta formation. Further longitudinal studies should investigate whether those MCI individuals with the lowest PLA(2) values in platelets would be at a higher risk to develop AD during a longitudinal follow up.

Muscarinic agonists alter the metabolism of amyloid precursor protein, leading to an increase in alpha-secretase cleavage and a decreased production of amyloidogenic peptides; suggesting that these compounds might modify the Alzheimer's disease process. A second therapeutic target in AD is the accumulation of stably phosphorylated tau into neurofibrillary tangles; an early event correlating with cognitive impairment. Glycogen synthase kinase-3 (GSK-3beta) phosphorylates tau and is inhibited via protein kinase C (PKC). As certain muscarinic receptors are linked to PKC, we examined the effect of a range of agonists on GSK-3beta phosphorylation of tau. In neurons a nonspecific muscarinic agonist, carbachol, reduced tau phosphorylation. In nonneuronal cells expressing the ml receptor a range of ml agonists reduced transiently-expressed tau phosphorylation and altered its microtubulebinding properties. These findings link the two pathological process of AD-APP metabolism and tau phosphorylation - and suggest that muscarinic and other cholinergic compounds might have disease-modifying properties.