Tauopathies and synucleinopathies: Do cerebrospinal fluid β-amyloid peptides reflect disease-specific pathogenesis?

Head-to-head comparison of 6 plasma biomarkers in early multiple system atrophy

There is a dire need for reliable biomarkers to solidify an early and accurate diagnosis of multiple system atrophy (MSA). We sought to compare the ability of emerging plasma markers in distinguishing MSA from its mimics and healthy controls in early disease stages, and to evaluate their performance in detecting disease severity and brain atrophy. Plasma neurofilament light (NfL), glial fibrillary acidic protein (GFAP), phosphorylated tau181, amyloid-β (Aβ)42, and Aβ40 were measured using ultrasensitive Simoa in early-stage patients with MSA (n = 73), spinocerebellar ataxia (SCA, n = 29), Parkinson's disease (PD, n = 28), and healthy controls (n = 100). We observed that elevated NfL outperformed other biomarkers in distinguishing MSA and its subtypes (AUC = 0.9) versus controls. Intriguingly, when separating MSA from its mimics, increased GFAP (AUC = 0.717) in MSA-C and decreased Aβ40 (AUC = 0.807) in MSA-P best discriminated from SCA and PD respectively. Plasma levels were comparable between MSA-C and MSA-P and the differentiation by plasma index alone was poor. Combining plasma markers noticeably improved the discriminatory efficacy. Of note, among MSA patients, higher GFAP and NfL were correlated with the atrophy of brain regions vulnerable to MSA (e.g., cerebellum, pons, or putamen). They could also aggravate the severity of MSA, and this association was partially mediated by cerebral volumes. In contrast, no obvious associations of phosphorylated tau and Aβ with disease severity were observed. Collectively, plasma biomarkers, especially in combination, are useful to facilitate the discriminatory work-up of MSA at early stages. Moreover, NfL and GFAP may be promising biomarkers to monitor the disease severity of MSA.

Cerebrospinal Fluid Biomarkers in Multiple System Atrophy Relative to Parkinson's Disease: A Meta-Analysis

Objective

To investigate the differences of candidate cerebrospinal fluid (CSF) biomarkers associated with multiple system atrophy (MSA) and Parkinson's disease (PD).

Method

Here, a systematic review and meta-analysis were conducted on studies related to CSF biomarkers associated with MSA and PD obtained from PubMed, Web of Science, Embase, and Cochrane databases. Data were pooled where appropriate and used to calculate standardized mean differences (SMDs) with 95% confidence intervals (CI). Heterogeneity was assessed using the I² statistic while Egger's test was used to test for existing publication bias.

Results

MSA patients had higher CSF t-tau (SMD = 0.41, 95% CI: 0.10 to 0.72) and YKL-40 (SMD = 0.63, 95% CI 0.12 to1.15) as well as DJ-1 (SMD = 1.05, 95% CI 0.67 to 1.42) levels than PD patients, while CSF p-tau (SMD = −0.17, 95% CI, -0.31 to -0.02) and Aβ-42 (SMD = −0.33, 95% CI, -0.55 to -0.12) levels in MSA patients were lower than those in PD patients. There were no differences in CSF's GFAP and Flt3 ligand levels in both MSA and PD patients.

Conclusion

The study revealed the differences in CSF biomarker levels between MSA and PD cohorts that can be further explored to clinically distinguish MSA from PD.

Laboratory-Supported Multiple System Atrophy beyond Autonomic Function Testing and Imaging: A Systematic Review by the MoDiMSA Study Group

Background

Neuroimaging has been used to support a diagnosis of possible multiple system atrophy (MSA). Only blood pressure changes upon standing are included in the second consensus criteria but other autonomic function tests (AFT) are also useful to diagnose widespread and progressive autonomic failure typical of MSA. Additional diagnostic tools are of interest to improve accuracy of MSA diagnosis.

Objectives

To assess the utility of diagnostic tools beyond brain imaging and AFT in enhancing a laboratory-supported diagnosis of MSA to support the upcoming revision of the consensus criteria.

Methods

The International Parkinson and Movement Disorders Society MSA Study Group (MoDiMSA) performed a systematic review of original papers on biomarkers, sleep studies, genetic, neuroendocrine, neurophysiological, neuropsychological and other tests including olfactory testing and acute levodopa challenge test published before August 2019.

Results

Evaluation of history of levodopa responsiveness and olfaction is useful in patients in whom MSA-parkinsonian subtype is suspected. Neuropsychological testing is useful to exclude dementia at time of diagnosis. Applicability of sphincter EMG is limited. When MSA-cerebellar subtype is suspected, a screening for the common causes of adult-onset progressive ataxia is useful, including spinocerebellar ataxias in selected patients. Diagnosing stridor and REM sleep behavior disorder is useful in both MSA subtypes. However, none of these tools are validated in large longitudinal cohorts of postmortem confirmed MSA cases.

Conclusions

Despite limited evidence, additional laboratory work-up of patients with possible MSA beyond imaging and AFT should be considered to optimize the clinical diagnostic accuracy.

The discriminative capacity of CSF β-amyloid 42 and Tau in neurodegenerative diseases in the Chinese population

INTRODUCTION

In the past few years, the β-amyloid 42 peptide and tau protein in cerebrospinal fluid (CSF) have become primary diagnostic biomarkers in differentiating Alzheimer's disease (AD) and cognitive normal controls. As we know, several neurodegenerative diseases have been reported to overlap with AD in neuropathology and clinical symptoms. To examine the discriminative utility of these biomarkers in AD and other neurodegenerative diseases, we measured them in a cohort of Chinese population.

METHODS

We measured CSF Aβ₄₂, t-tau and p-tau₁₈₁ by ELISA tests and calculated the ratios of t-tau/Aβ₄₂ and p-tau₁₈₁/Aβ₄₂ in 240 Chinese Han patients with AD (n = 82), frontotemporal dementia (FTD, n = 20), Huntington's disease (HD, n = 27), multiple system atrophy (MSA, n = 24), spinocerebellar ataxia type-3 (SCA3, n = 27), amyotrophic lateral sclerosis (ALS, n = 36) and controls (n = 24).

RESULTS

As expected, all biomarkers showed high discriminative capacity between AD and non-AD groups (p < .05) except for the elevated CSF t-tau in FTD (p > .05). Comparing with the controls, tau related biomarkers significantly elevated in the FTD (p < .001) and MSA (p < .05) groups. Surprisingly, comparing with controls, we found that CSF Aβ₄₂ increased remarkably in the SCA3 (p < .05), HD and ALS groups (p < .001), achieving a high specificity, respectively.

CONCLUSION

To our best knowledge, this is the first comprehensive study in the Han Chinese population that confirmed the discriminative utility of CSF Aβ₄₂ and tau biomarkers between AD and other neurodegenerative diseases.

Corticobasal degeneration and corticobasal syndrome: A review

Corticobasal degeneration (CBD) is a rare neurodegenerative disorder. The most common presentation of CBD is the corticobasal syndrome (CBS), which is a constellation of cortical and extrapyramidal symptoms and signs. Clinical-pathological studies have illustrated that CBD can present with diverse clinical phenotypes, including a non-fluent, agrammatic primary progressive aphasia syndrome, a behavioral, dysexecutive and visuospatial syndrome, as well as a progressive supranuclear palsy-like syndrome. Conversely, multiple pathologies, such as CBD, Alzheimer's disease and progressive supranuclear palsy may underlie a patient with CBS. This clinical-pathological overlap emphasizes the need for biomarkers that will assist in the accurate diagnosis of patients with CBS. This review presents an overview of the pathological, genetic, clinical and therapeutic characteristics of CBD, with an emphasis on the imaging (structural and functional) and biochemical (cerebrospinal fluid) biomarkers of CBD.

CSF Biomarkers and Its Associations with 18F-AV133 Cerebral VMAT2 Binding in Parkinson's Disease-A Preliminary Report

OBJECTIVE

Cerebrospinal fluid (CSF) biomarkers, such as α-synuclein (α-syn), amyloid beta peptide 1-42 (Aβ1-42), phosphorylated tau (181P) (p-tau), and total tau (t-tau), have long been associated with the development of Parkinson disease (PD) and other neurodegenerative diseases. In this investigation, we reported the assessment of CSF biomarkers and their correlations with vesicular monoamine transporter 2 (VMAT2) bindings measured with 18F-9-fluoropropyl-(+)-dihydrotetrabenazine (18F-AV133) that is being developed as a biomarker for PD. We test the hypothesis that monoaminergic degeneration was correlated with CSF biomarker levels in untreated PD patients.

METHODS

The available online data from the Parkinson's Progression Markers Initiative study (PPMI) project were collected and analyzed, which include demographic information, clinical evaluations, CSF biomarkers (α-syn, Aβ1-42, p-tau, and t-tau), 18F-AV133 brain PET, and T1 weighted MRIs. Region of interest (ROI) and voxel-wise Pearson correlation between standardized uptake value ratio (SUVR) and CSF biomarkers were calculated.

RESULTS

Our major findings are: 1) Compared with controls, CSF α-syn and tau levels decreased significantly in PD; 2) α-syn was closely correlated with Aβ1-42 and tau in PD, especially in early-onset patients; and 3) hypothesis-driven ROI analysis found a significant negative correlation between CSF Aβ1-42 levels and VMAT2 densities in post cingulate, left caudate, left anterior putamen, and left ventral striatum in PDs. CSF t-tau and p-tau levels were significantly negatively related to VMAT2 SUVRs in substantia nigra and left ventral striatum, respectively. Voxel-wise analysis showed that left caudate, parahippocampal gyrus, insula and temporal lobe were negatively correlated with Aβ1-42. In addition, superior frontal gyrus and transverse temporal gyrus were negatively correlated with CSF p-tau levels.

CONCLUSION

These results suggest that monoaminergic degeneration in PD is correlated with CSF biomarkers associated with cognitive impairment in neurodegenerative diseases including Alzheimer's disease. The association between loss of dopamine synaptic function and pathologic protein accumulations in PD indicates an important role of CSF biomarkers in PD development.

Fluid biomarkers in multiple system atrophy: A review of the MSA Biomarker Initiative

Despite growing research efforts, no reliable biomarker currently exists for the diagnosis and prognosis of multiple system atrophy (MSA). Such biomarkers are urgently needed to improve diagnostic accuracy, prognostic guidance and also to serve as efficacy measures or surrogates of target engagement for future clinical trials. We here review candidate fluid biomarkers for MSA and provide considerations for further developments and harmonization of standard operating procedures. A PubMed search was performed until April 24, 2015 to review the literature with regard to candidate blood and cerebrospinal fluid (CSF) biomarkers for MSA. Abstracts of 1760 studies were retrieved and screened for eligibility. The final list included 60 studies assessing fluid biomarkers in patients with MSA. Most studies have focused on alpha-synuclein, markers of axonal degeneration or catecholamines. Their results suggest that combining several CSF fluid biomarkers may be more successful than using single markers, at least for the diagnosis. Currently, the clinically most useful markers may comprise a combination of the light chain of neurofilament (which is consistently elevated in MSA compared to controls and Parkinson's disease), metabolites of the catecholamine pathway and proteins such as α-synuclein, DJ-1 and total-tau. Beyond future efforts in biomarker discovery, the harmonization of standard operating procedures will be crucial for future success.

Cerebrospinal fluid proteomics and protein biomarkers in frontotemporal lobar degeneration: Current status and future perspectives

Frontotemporal lobar degeneration (FTLD) comprises a spectrum of rare neurodegenerative diseases with an estimated prevalence of 15-22 cases per 100,000 persons including the behavioral variant of frontotemporal dementia (bvFTD), progressive non-fluent aphasia (PNFA), semantic dementia (SD), FTD with motor neuron disease (FTD-MND), progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS). The pathogenesis of the diseases is still unclear and clinical diagnosis of FTLD is hampered by overlapping symptoms within the FTLD subtypes and with other neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Intracellular protein aggregates in the brain are a major hallmark of FTLD and implicate alterations in protein metabolism or function in the disease's pathogenesis. Cerebrospinal fluid (CSF) which surrounds the brain can be used to study changes in neurodegenerative diseases and to identify disease-related mechanisms or neurochemical biomarkers for diagnosis. In the present review, we will give an overview of the current literature on proteomic studies in CSF of FTLD patients. Reports of targeted and unbiased proteomic approaches are included and the results are discussed in regard of their informative value about disease pathology and the suitability to be used as diagnostic biomarkers. Finally, we will give some future perspectives on CSF proteomics and a list of candidate biomarkers which might be interesting for validation in further studies. This article is part of a Special Issue entitled: Neuroproteomics: Applications in neuroscience and neurology.

Longitudinal assessment of tau and amyloid beta in cerebrospinal fluid of Parkinson disease

Tau gene has been consistently associated with the risk of Parkinson disease in recent genome wide association studies. In addition, alterations of the levels of total tau, phosphorylated tau [181P], and amyloid beta 1-42 in cerebrospinal fluid have been reported in patients with sporadic Parkinson disease and asymptomatic carriers of leucine-rich repeat kinase 2 mutations, in patterns that clearly differ from those typically described for patients with Alzheimer disease. To further determine the potential roles of these molecules in Parkinson disease pathogenesis and/or in tracking the disease progression, especially at early stages, the current study assessed all three proteins in 403 Parkinson disease patients enrolled in the DATATOP (Deprenyl and tocopherol antioxidative therapy of parkinsonism) placebo-controlled clinical trial, the largest cohort to date with cerebrospinal fluid samples collected longitudinally. These initially drug-naive patients at early disease stages were clinically evaluated, and cerebrospinal fluid was collected at baseline and then at endpoint, defined as the time at which symptomatic anti-Parkinson disease medications were determined to be required. General linear models were used to test for associations between baseline cerebrospinal fluid biomarker levels or their rates of change and changes in the Unified Parkinson Disease Rating Scale (total or part III motor score) over time. Robust associations among candidate markers are readily noted. Baseline levels of amyloid beta were weakly but negatively correlated with baseline Unified Parkinson Disease Rating Scale total scores. Baseline phosphorylated tau/total tau and phosphorylated tau/amyloid beta were significantly and negatively correlated with the rates of the Unified Parkinson Disease Rating Scale change. While medications (deprenyl and/or tocopherol) did not appear to alter biomarkers appreciably, a weak but significant positive correlation between the rate of change in total tau or total tau/amyloid beta levels and the change of the Unified Parkinson Disease Rating Scale was observed. Notably, these correlations did not appear to be influenced by APOE genotype. These results are one of the very first pieces of evidence suggesting that tau and amyloid beta are critically involved in early Parkinson disease progression, potentially by a different mechanism than that in Alzheimer disease, although their applications as Parkinson disease progression markers will likely require the addition of other proteins.

Cerebrospinal fluid biomarkers in Parkinson disease

Clinical diagnosis of Parkinson disease (PD) is difficult in early stages of disease, with high risk of misdiagnosis. The long preclinical phase of PD provides the possibility for early therapeutic intervention once disease-modifying therapies have been developed, but lack of biomarkers for early diagnosis and monitoring of disease progression represents a major obstacle to achievement of this goal. Accordingly, research efforts aimed at identification of novel biomarkers have been increasing in the past 5 years. Cerebrospinal fluid (CSF) is an accessible source of brain-derived proteins, which mirror molecular changes that take place in the CNS. In this Review, we discuss evidence from numerous studies that have focused on identification of candidate CSF biomarkers for PD. Notably, molecular pathways related to α-synuclein, tau and β-amyloid peptides have received considerable attention. CSF levels of the protein DJ-1 are also of interest, although further investigation of this candidate marker is required. These studies support the usefulness of a combination of various CSF biomarkers of PD to increase diagnostic accuracy during early phases of the disease, and to differentiate PD from other neurodegenerative disorders.

Interaction between pathogenic proteins in neurodegenerative disorders

The misfolding and progressive aggregation of specific proteins in selective regions of the nervous system is a seminal occurrence in many neurodegenerative disorders, and the interaction between pathological/toxic proteins to cause neurodegeneration is a hot topic of current neuroscience research. Despite clinical, genetic and experimental differences, increasing evidence indicates considerable overlap between synucleinopathies, tauopathies and other protein-misfolding diseases. Inclusions, often characteristic hallmarks of these disorders, suggest interactions of pathological proteins enganging common downstream pathways. Novel findings that have shifted our understanding in the role of pathologic proteins in the pathogenesis of Alzheimer, Parkinson, Huntington and prion diseases, have confirmed correlations/overlaps between these and other neurodegenerative disorders. Emerging evidence, in addition to synergistic effects of tau protein, amyloid-β, α-synuclein and other pathologic proteins, suggests that prion-like induction and spreading, involving secreted proteins, are major pathogenic mechanisms in various neurodegenerative diseases, depending on genetic backgrounds and environmental factors. The elucidation of the basic molecular mechanisms underlying the interaction and spreading of pathogenic proteins, suggesting a dualism or triad of neurodegeneration in protein-misfolding disorders, is a major challenge for modern neuroscience, to provide a deeper insight into their pathogenesis as a basis of effective diagnosis and treatment.

Bacterial contamination and the transport vial material affect cerebrospinal fluid concentrations of β-Amyloid and Tau protein as determined by enzyme immunoassay

BACKGROUND/AIMS

Determination of marker proteins of neuronal degeneration in cerebrospinal fluid (CSF) is of increasing importance. However, preanalytical problems may compromise the results.

METHODS

We studied the influence of the transport tube material and shaking at room temperature on the CSF concentrations of β-amyloid and tau protein determined by enzyme immunoassays.

RESULTS

The materials of the transport tube moderately influenced the CSF concentrations of β-amyloid and tau protein. Polyethylene and polypropylene tubes were well suited, but glass, polycarbonate and polystyrene tubes caused a decrease in the CSF β-amyloid and tau protein concentrations. The strongest impact, however, was caused by bacterial contamination of samples. Contamination with high concentrations of Pseudomonas aeruginosa and related species rendered β-amyloid undetectable and strongly diminished tau protein concentrations. The effects of several Gram-positive bacteria were less pronounced. Addition of 0.1% sodium azide prior to bacterial contamination increased the interval at which CSF could be kept at room temperature without a substantial reduction of the β-amyloid or tau protein concentration.

CONCLUSION

Polyethylene or polypropylene tubes are suitable transport vessels for CSF samples. Bacterial contamination during sampling and portioning must be avoided. Addition of sodium azide may be an option when transport of the sample is delayed.

Interaction between α-synuclein and other proteins in neurodegenerative disorders

Protein aggregation is a common characteristic of many neurodegenerative disorders, and the interaction between pathological/toxic proteins to cause neurodegeneration is a hot topic of current neuroscience research. Despite clinical, genetic, and experimental differences, evidence increasingly indicates considerable overlap between synucleinopathies and tauopathies or other protein-misfolding diseases. Inclusions, characteristics of these disorders, also occurring in other neurodegenerative diseases, suggest interactions of pathological proteins engaging common downstream pathways. Novel findings that have shifted our understanding in the role of pathologic proteins in the pathogenesis of Parkinson and Alzheimer diseases have confirmed correlations/overlaps between these and other neurodegenerative disorders. The synergistic effects of α-synuclein, hyperphosphorylated tau, amyloid-β, and other pathologic proteins, and the underlying molecular pathogenic mechanisms, including induction and spread of protein aggregates, are critically reviewed, suggesting a dualism or triad of neurodegeneration in protein-misfolding disorders, although the etiology of most of these processes is still mysterious.

Amyloid-β and τ biomarkers in Parkinson's disease-dementia

Dementia is a frequent and devastating non-motor complication of advanced Parkinson's disease (PD). There is growing evidence of a synergistic role of Alzheimer's-type brain lesions containing τ and amyloid-β (Aβ) proteins and cortical Lewy aggregates in PD-related dementia (PDD). Therefore, biomarkers of both τ and Aβ may be seen as diagnostic and predictive markers of PDD. Here, we review the available studies in PD and PDD using cerebrospinal fluid (CSF) total τ, phospho-τ, and/or Aβ levels, and PET probes targeting Alzheimer's-type lesions. Overall, high CSF τ and phospho-τ levels and/or low CSF Aβ levels have been found in part of PDD patients, and a longitudinal study has found greater worsening in cognitive performance over time in non-demented PD patients with low baseline CSF Aβ levels. Few studies are available on the use of PET imaging in PD, all of them using the Pittsburgh B compound (PIB), and with figures of about 30% of scans with PIB uptake in the AD-range in PDD. We conclude that these CSF and PET markers deserve further evaluation as candidate biomarkers of dementia in PD. According to this, we are currently undertaking a longitudinal project on the predictive value of dementia of the combined use of CSF τ and Aβ and (18)F-FDDNP PET in PD.

Cerebrospinal fluid biomarkers for Parkinson disease diagnosis and progression

OBJECTIVE

There is a clear need to develop biomarkers for Parkinson disease (PD) diagnosis, differential diagnosis of Parkinsonian disorders, and monitoring disease progression. We and others have demonstrated that a decrease in DJ-1 and/or α-synuclein in the cerebrospinal fluid (CSF) is a potential index for Parkinson disease diagnosis, but not for PD severity.

METHODS

Using highly sensitive and quantitative Luminex assays, we measured total tau, phosphorylated tau, amyloid beta peptide 1-42 (Aβ(1-42)), Flt3 ligand, and fractalkine levels in CSF in a large cohort of PD patients at different stages as well as healthy and diseased controls. The utility of these 5 markers was evaluated for disease diagnosis and severity/progression correlation alone, as well as in combination with DJ-1 and α-synuclein. The major results were further validated in an independent cohort of cross-sectional PD patients as well as in PD cases with CSF samples collected longitudinally.

RESULTS

The results demonstrated that combinations of these biomarkers could differentiate PD patients not only from normal controls but also from patients with Alzheimer disease (AD) and multiple system atrophy. Particularly, with CSF Flt3 ligand, PD could be clearly differentiated from multiple system atrophy, a disease that overlaps with PD clinically, with excellent sensitivity (99%) and specificity (95%). In addition, we identified CSF fractalkine/Aβ(1-42) that positively correlated with PD severity in cross-sectional samples as well as with PD progression in longitudinal samples.

INTERPRETATION

We have demonstrated that this panel of 7 CSF proteins could aid in Parkinson disease diagnosis, differential diagnosis, and correlation with disease severity and progression.

Problems associated with fluid biomarkers for Parkinson's disease

This article focuses on biochemical markers that may be used in the diagnostics of Parkinson's disease and associated disorders, and to identify early cases and stratify patients into subgroups. We present an updated account of some currently available candidate fluid biomarkers, and discuss their diagnostic performance and limitations. We also discuss some of the general problems with Parkinson's disease biomarkers and possible ways of moving forward. It may be concluded that a diagnostically useful fluid biomarker for Parkinson's disease is yet to be identified. However, some interesting candidates exist and may prove useful in the future, alone or when analyzed together in patterns.

Biomarkers for cognitive impairment in Parkinson disease

Cognitive impairment, including dementia, is commonly seen in those afflicted with Parkinson disease (PD), particularly at advanced disease stages. Pathologically, PD with dementia (PD-D) is most often associated with the presence of cortical Lewy bodies, as is the closely related dementia with Lewy bodies (DLB). Both PD-D and DLB are also frequently complicated by the presence of neurofibrillary tangles and amyloid plaques, features most often attributed to Alzheimer disease. Biomarkers are urgently needed to differentiate among these disease processes and predict dementia in PD as well as monitor responses of patients to new therapies. A few clinical assessments, along with structural and functional neuroimaging, have been utilized in the last few years with some success in this area. Additionally, a number of other strategies have been employed to identify biochemical/molecular biomarkers associated with cognitive impairment and dementia in PD, e.g. targeted analysis of candidate proteins known to be important to PD pathogenesis and progression in cerebrospinal fluid or blood. Finally, interesting results are emerging from preliminary studies with unbiased and high throughput genomic, proteomic and metabolomic techniques. The current findings and perspectives of applying these strategies and techniques are reviewed in this article, together with potential areas of advancement.

Neurochemical biomarkers in the differential diagnosis of movement disorders

In recent years, the neurochemical analysis of neuronal proteins in cerebrospinal fluid (CSF) has become increasingly accepted for the diagnosis of neurodegenerative dementia diseases such as Alzheimer's disease and Creutzfeldt-Jakob disease. CSF surrounds the central nervous system, and in the composition of CSF proteins one finds brain-specific proteins that are prioritized from blood-derived proteins. Levels of specific CSF proteins could be very promising biomarkers for central nervous system diseases. We need the development of more easily accessible biomarkers, in the blood. In neurodegenerative diseases with and without dementia, studies on CSF and blood proteins have investigated the usefulness of biomarkers in differential diagnosis. The clinical diagnoses of Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration still rely mainly on clinical symptoms as defined by international classification criteria. In this article, we review CSF biomarkers in these movement disorders and discuss recent published reports on the neurochemical intra vitam diagnosis of neurodegenerative disorders (including recent CSF alpha-synuclein findings).

Tauopathies with parkinsonism: clinical spectrum, neuropathologic basis, biological markers, and treatment options

Tauopathies with parkinsonism represent a spectrum of disease entities unified by the pathologic accumulation of hyperphosphorylated tau protein fragments within the central nervous system. These pathologic characteristics suggest shared pathogenetic pathways and possible molecular targets for disease-modifying therapeutic interventions. Natural history studies, for instance, in progressive supranuclear palsy, frontotemporal dementia with parkinsonism linked to chromosome 17, corticobasal degeneration, and Niemann-Pick disease type C as well as in amyotrophic lateral sclerosis/Parkinson-dementia complex permit clinical characterization of the disease phenotypes and are crucial to the development and validation of biological markers for differential diagnostics and disease monitoring, for example, by use of neuroimaging or proteomic approaches. The wide pathologic and clinical spectrum of the tauopathies with parkinsonism is reviewed in this article, and perspectives on future advances in the understanding of the pathogenesis are given, together with potential therapeutic strategies.

Neurochemical approaches in the laboratory diagnosis of Parkinson and Parkinson dementia syndromes: a review

The diagnosis of Parkinson disease (PD) is rendered on the basis of clinical parameters, whereby laboratory chemical tests or morphological imaging is only called upon to exclude other neurodegenerative diseases. The differentiation between PD and other diseases of the basal ganglia, especially the postsynaptic Parkinson syndromes multisystem atrophy (MSA) and progressive supranuclear palsy (PSP), is of decisive importance, on the one hand, for the response to an appropriate therapy, and on the other hand, for the respective prognosis of the disease. However, particularly at the onset of symptoms, it is difficult to precisely distinguish these diseases from each other, presenting with an akinetic‐rigid syndrome. It is not yet possible to conduct a neurochemical differentiation of Parkinson syndromes. Therefore, a reliable biomarker is still to be found that might predict the development of Parkinson dementia. Since this situation is currently the subject of various different studies, the following synopsis is intended to provide a brief summary of the investigations addressing the field of the early neurochemical differential diagnosis of Parkinson syndromes and the early diagnosis of Parkinson dementia, from direct α‐synuclein detection to proteomic approaches. In addition, an overview of the tested biomarkers will be given with regard to their possible introduction as a screening method.

Biomarkers for early diagnosis of Alzheimer disease: 'ALZheimer ASsociated gene'--a new blood biomarker?

Simple, non-invasive tests for an early detection of degenerative dementia by use of biomarkers are urgently required. However, up to the present, no validated extracerebral diagnostic markers (plasma/serum, platelets, urine, connective tissue) for the early diagnosis of Alzheimer disease (AD) are available. In disease stages with evident cognitive disturbances, the clinical diagnosis of probable AD is made with around 90% accuracy using modern clinical, neuropsychological and imaging methods. Diagnostic sensitivity and specificity even in early disease stages are improved by CSF markers, in particular combined tau and amyloid beta peptides (Abeta) and plasma markers (eg, Abeta-42/Abeta-40 ratio). Recently, a novel gene/protein--ALZAS (Alzheimer Associated Protein)--with a 79 amino acid sequence, containing the amyloid beta-42 fragment (Abeta-42), the amyloid precursor protein (APP) transmembrane signal and a 12 amino acid C-terminal, not present in any other known APP alleles, has been discovered on chromosome 21 within the APP region. Reverse transcriptase-PCR revealed the expression of the transcript of this protein in the cortex and hippocampal regions as well as in lymphocytes of human AD patients. The expression of ALZAS is mirrored by a specific autoimmune response in AD patients, directed against the ct-12 end of the ALZAS-peptide but not against the Abeta-sequence. ELISA studies of plasma detected highest titers of ALZAS in patients with mild cognitive impairment (presymptomatic AD), but only moderately increased titers in autopsy-confirmed AD, whereas low or undetectable ct-12 titers were found in cognitively intact age-matched subjects and young controls. The antigen, ALZAS protein, was detected in plasma in later clinical stages of AD. It is suggested that ALZAS represents an indicator in a dynamic equilibrium between both peripheral and brain degenerative changes in AD and may become a useful "non-invasive" diagnostic marker via a simple blood test.