Beta-amlyoid 1-42 and tau-protein in cerebrospinal fluid of patients with Parkinson's disease dementia

Salivary DJ-1 could be an indicator of Parkinson's disease progression

Objective: The goal of the current investigation was to explore whether salivary DJ-1 could be a potential biomarker for monitoring disease progression in Parkinson's disease (PD) by evaluating the association between salivary DJ-1 concentrations and nigrostriatal dopaminergic function.

Methods: First, in 74 patients with PD and 12 age-matched normal controls, single photon emission computed tomography (SPECT) imaging with labeled dopamine transporters (DAT) (^99mTc-TRODAT-1), which has been used for measuring DAT density in PD was prformed. Then, the DJ-1 level in their saliva was analyzed by quantitative and sensitive Luminex assay and compared to caudate or putamen DAT density. Finally, based on the above, our cross-section study was carried out in 376 research volunteers (285 patients with PD and 91 healthy controls) to measure salivary DJ-1 level.

Results: From our analysis, we found a correlation between salivary concentration of DJ-1 and putamen nucleus uptake of ^99mTc-TRODAT-1 in the PD group. Although salivary DJ-1 levels were not affected by UPDRS scores, gender, age, and pharmacotherapy, DJ-1 levels in H&Y 4 stage of PD were higher than those in H&Y 1-3 stage as well as those in healthy controls. Salivary DJ-1 also decreased significantly in mixed type PD patients compared to the tremor-dominant type (TDT) and akinetic-rigid dominant type (ARDT) PD patients.

Conclusions: According to the investigation in a large cohort, we reported for the first time the prognostic potential of the salivary DJ-1 as a biomarker for evaluating nigrostriatal dopaminergic function in PD.

Levels of cerebrospinal fluid α-synuclein oligomers are increased in Parkinson's disease with dementia and dementia with Lewy bodies compared to Alzheimer's disease

Introduction

The objective was to study whether α-synuclein oligomers are altered in the cerebrospinal fluid (CSF) of patients with dementia, including Parkinson disease with dementia (PDD), dementia with Lewy bodies (DLB), and Alzheimer disease (AD), compared with age-matched controls.

Methods

In total, 247 CSF samples were assessed in this study, including 71 patients with DLB, 30 patients with PDD, 48 patients with AD, and 98 healthy age-matched controls. Both total and oligomeric α-synuclein levels were evaluated by using well-established immunoassays.

Results

The levels of α-synuclein oligomers in the CSF were increased in patients with PDD compared with the controls (P < 0.05), but not in patients with DLB compared with controls. Interestingly, the levels of α-synuclein oligomers in the CSF were also significantly higher in patients with PDD (P < 0.01) and DLB (P < 0.05) compared with patients with AD. The levels of CSF α-synuclein oligomers and the ratio of oligomeric/total-α-synuclein could distinguish DLB or PDD patients from AD patients, with areas under the curves (AUCs) of 0.64 and 0.75, respectively. In addition, total-α-synuclein alone could distinguish DLB or PDD patients from AD patients, with an AUC of 0.80.

Conclusions

The levels of α-synuclein oligomers were increased in the CSF from α-synucleinopathy patients with dementia compared with AD cases.

Association of cerebrospinal fluid β-amyloid 1-42, T-tau, P-tau181, and α-synuclein levels with clinical features of drug-naive patients with early Parkinson disease

IMPORTANCE

We observed a significant correlation between cerebrospinal fluid (CSF) levels of tau proteins and α-synuclein, but not β-amyloid 1-42 (Aβ1-42), and lower concentration of CSF biomarkers, as compared with healthy controls, in a cohort of entirely untreated patients with Parkinson disease (PD) at the earliest stage of the disease studied so far.

OBJECTIVE

To evaluate the baseline characteristics and relationship to clinical features of CSF biomarkers (Aβ1-42, total tau [T-tau], tau phosphorylated at threonine 181 [P-tau181], and α-synuclein) in drug-naive patients with early PD and demographically matched healthy controls enrolled in the Parkinson's Progression Markers Initiative (PPMI) study.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study of the initial 102 research volunteers (63 patients with PD and 39 healthy controls) of the PPMI cohort.

MAIN OUTCOMES AND MEASURES

The CSF biomarkers were measured by INNO-BIA AlzBio3 immunoassay (Aβ1-42, T-tau, and P-tau181; Innogenetics Inc) or by enzyme-linked immunosorbent assay (α-synuclein). Clinical features including diagnosis, demographic characteristics, motor, neuropsychiatric, and cognitive assessments, and DaTscan were systematically assessed according to the PPMI study protocol.

RESULTS

Slightly, but significantly, lower levels of Aβ1-42, T-tau, P-tau181, α-synuclein, and T-tau/Aβ1-42 were seen in subjects with PD compared with healthy controls but with a marked overlap between groups. Using multivariate regression analysis, we found that lower Aβ1-42 and P-tau181 levels were associated with PD diagnosis and that decreased CSF T-tau and α-synuclein were associated with increased motor severity. Notably, when we classified patients with PD by their motor phenotypes, lower CSF Aβ1-42 and P-tau181 concentrations were associated with the postural instability-gait disturbance-dominant phenotype but not with the tremor-dominant or intermediate phenotype. Finally, we found a significant correlation of the levels of α-synuclein with the levels of T-tau and P-tau181.

CONCLUSIONS AND RELEVANCE

In this first report of CSF biomarkers in PPMI study subjects,we found that measures of CSF Aβ1-42, T-tau, P-tau181, and α-synuclein have prognostic and diagnostic potential in early-stage PD. Further investigations using the entire PPMI cohort will test the predictive performance of CSF biomarkers for PD progression

Characterizing mild cognitive impairment in incident Parkinson disease: the ICICLE-PD study

OBJECTIVE

To describe the frequency of mild cognitive impairment (MCI) in Parkinson disease (PD) in a cohort of newly diagnosed incident PD cases and the associations with a panel of biomarkers.

METHODS

Between June 2009 and December 2011, 219 subjects with PD and 99 age-matched controls participated in clinical and neuropsychological assessments as part of a longitudinal observational study. Consenting individuals underwent structural MRI, lumbar puncture, and genotyping for common variants of COMT, MAPT, SNCA, BuChE, EGF, and APOE. PD-MCI was defined with reference to the new Movement Disorder Society criteria.

RESULTS

The frequency of PD-MCI was 42.5% using level 2 criteria at 1.5 SDs below normative values. Memory impairment was the most common domain affected, with 15.1% impaired at 1.5 SDs. Depression scores were significantly higher in those with PD-MCI than the cognitively normal PD group. A significant correlation was found between visual Pattern Recognition Memory and cerebrospinal β-amyloid 1-42 levels (β standardized coefficient = 0.350; p = 0.008) after controlling for age and education in a linear regression model, with lower β-amyloid 1-42 and 1-40 levels observed in those with PD-MCI. Voxel-based morphometry did not reveal any areas of significant gray matter loss in participants with PD-MCI compared with controls, and no specific genotype was associated with PD-MCI at the 1.5-SD threshold.

CONCLUSIONS

In a large cohort of newly diagnosed PD participants, PD-MCI is common and significantly correlates with lower cerebrospinal β-amyloid 1-42 and 1-40 levels. Future longitudinal studies should enable us to determine those measures predictive of cognitive decline.

Quantitative appraisal of ventricular cerebrospinal fluid biomarkers in neuropathologically diagnosed Parkinson's disease cases lacking Alzheimer's disease pathology

Identifying biomarkers that distinguish Parkinson’s disease (PD) from normal control (NC) individuals has the potential to increase diagnostic sensitivity for the detection of early-stage PD. A previous proteomic study identified potential biomarkers in postmortem ventricular cerebrospinal fluid (V-CSF) from neuropathologically diagnosed PD subjects lacking Alzheimer’s disease (AD) neuropathology. In the present study, we assessed these biomarkers as well as p-tau¹⁸¹, Aβ42, and S100B by ELISA in PD (n = 43) and NC (n = 49) cases. The p-tau¹⁸¹/Aβ42 ratio and ApoA-1 showed statistically significant differences between groups. Multiple regression analysis demonstrated that p-tau¹⁸¹/Aβ42 had a significant odds ratio: OR = 1.42 (95% confidence interval [CI], 1.12–1.84), P = 0.006. Among the molecules investigated, intriguing correlations were observed that require further investigation. Our results suggest coexistent AD CSF biomarkers within the PD group notwithstanding that it was selected to minimize AD neuropathological lesions.

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.

Cerebrospinal fluid biomarker candidates for parkinsonian disorders

The Parkinsonian disorders are a large group of neurodegenerative diseases including idiopathic Parkinson’s disease (PD) and atypical Parkinsonian disorders (APD), such as multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, and dementia with Lewy bodies. The etiology of these disorders is not known although it is considered to be a combination of genetic and environmental factors. One of the greatest obstacles for developing efficacious disease-modifying treatment strategies is the lack of biomarkers. Reliable biomarkers are needed for early and accurate diagnosis, to measure disease progression, and response to therapy. In this review several of the most promising cerebrospinal biomarker candidates are discussed. Alpha-synuclein seems to be intimately involved in the pathogenesis of synucleinopathies and its levels can be measured in the cerebrospinal fluid and in plasma. In a similar way, tau protein accumulation seems to be involved in the pathogenesis of tauopathies. Urate, a potent antioxidant, seems to be associated to the risk of developing PD and with its progression. Neurofilament light chain levels are increased in APD compared with PD and healthy controls. The new “omics” techniques are potent tools offering new insights in the patho-etiology of these disorders. Some of the difficulties encountered in developing biomarkers are discussed together with future perspectives.

CSF and clinical hallmarks of subcortical dementias: focus on DLB and PDD

Dementia has become a relevant problem associated with the elderly in our countries. Increased interest in the field has yielded a copious literature, so far mostly centered on Alzheimer's dementia. Cerebrospinal fluid (CSF) analysis combined with neuropsychology, even in absence of neuroimaging, represents the gold standard to reach a diagnosis when cortical cognitive impairment prevails. In view of this, low levels of CSF amyloid peptides β (Aβ) and high tau/Aβ protein ratio, despite prominent impairment of executive functions or concomitant vascular burden, facilitate the diagnosis of Alzheimer's disease. Conversely, an early cognitive impairment occurring in patients suffering from Parkinson's disease (PD) or Lewy body disorders (LBDs), both diagnoses posed on pure clinical grounds, remains quite elusive in term of biomarkers or neuropsychological assessment. Whether PD with dementia (PDD) and dementia with Lewy bodies (DLB) represent further steps along with a continuum of the same progressive degeneration due to Lewy bodies deposition, rather then the association of Lewy bodies and Aβ pathology, remains a challenging issue. Aim of this work is to set a state-of-the-art on the neuropsychological profiles of both or DLB. Then, we will focus on the ongoing controversies about the specificity of the standard CSF biomarkers if applied to extrapyramidal disorders. Our conclusions are that the CSF pattern, in PDD and DLB, can certainly be distinct from that in AD, though mechanisms leading to dementia could be shared among them. It is possible that, by combining imaging tracers, neuropsychologically careful assessment and renewed CSF biomarkers, DLB can be better distinguished in subgroups, depending on the presence or absence of a relevant amyloid burden. However, more complete data, possibly collected in fieri during the progressive derangement of cognitive abilities, are needed to improve our ability to decipher and treat these entities.

Diagnostic criteria for mild cognitive impairment in Parkinson's disease: Movement Disorder Society Task Force guidelines

Mild cognitive impairment is common in nondemented Parkinson's disease (PD) patients and may be a harbinger of dementia. In view of its importance, the Movement Disorder Society commissioned a task force to delineate diagnostic criteria for mild cognitive impairment in PD. The proposed diagnostic criteria are based on a literature review and expert consensus. This article provides guidelines to characterize the clinical syndrome and methods for its diagnosis. The criteria will require validation, and possibly refinement, as additional research improves our understanding of the epidemiology, presentation, neurobiology, assessment, and long-term course of this clinical syndrome. These diagnostic criteria will support future research efforts to identify at the earliest stage those PD patients at increased risk of progressive cognitive decline and dementia who may benefit from clinical interventions at a predementia stage.

Mild cognitive impairment in Parkinson's disease

Prospective studies conducted during the last decade have shown that the majority of patients with Parkinson's disease (PD) develop dementia. In addition, using a variety of definitions and methods, more recent research suggests that approximately a quarter of PD patients without dementia have mild cognitive impairment (PD-MCI). Furthermore, several studies have shown that approximately 20% have MCI even at time of diagnosis of PD. The typical cognitive deficits include visuospatial, attentional, and executive deficits, but memory deficits have also been shown. The etiology of PD-MCI is not known, but it is likely that mechanisms known to contribute to dementia in PD (ie, limbic and cortical Lewy bodies, amyloid plaques, and cholinergic deficits) play a role, in addition to dysfunction of dopaminergic frontostriatal circuits. PD-MCI predicts a shorter time to dementia, and preliminary evidence suggests that this is particularly true for posterior cognitive deficits. There are currently no systematic clinical trials in PD-MCI.

Tau protein and beta-amyloid(1-42) CSF levels in different phenotypes of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder with highly heterogeneous clinical manifestations. This fact has prompted many attempts to divide PD patients into clinical subgroups. This could lead to a better recognition of pathogenesis, improving targeted treatment and the prognosis of PD patients. The aim of the present study was to obtain cerebrospinal fluid (CSF) samples in PD patients and to search for a relationship between neurodegenerative CSF markers (tau protein, beta-amyloid(1-42) and index tau protein/beta-amyloid(1-42)) and the clinical subtypes. PD patients were divided into three subgroups: early disease onset (EDO), tremor-dominant PD (TD-PD), and non-tremor dominant PD (NT-PD) according to the previously published classification. Neurodegenerative markers in the CSF were assessed in these three groups of patients suffering from PD (EDO-17, TD-15, NT-16 patients) and in a control group (CG) of 19 patients suffering from non-degenerative neurological diseases and 18 patients with Alzheimer's disease (AD). The NT-PD patients were found to have significantly higher levels of CSF tau protein and index tau/beta than the control subjects and other Parkinsonian subgroups, but no significant differences in these markers were found between AD and NT-PD patients. In the context of more rapid clinical progression and more pronounced neuropathological changes in the NT-PD patient group, our results corroborate the opinion that CSF level of tau protein may be regarded as a potential laboratory marker of the presence and severity of neurodegeneration.

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.

Biomarker candidates of neurodegeneration in Parkinson's disease for the evaluation of disease-modifying therapeutics

Reliable biomarkers that can be used for early diagnosis and tracking disease progression are the cornerstone of the development of disease-modifying treatments for Parkinson’s disease (PD). The German Society of Experimental and Clinical Neurotherapeutics (GESENT) has convened a Working Group to review the current status of proposed biomarkers of neurodegeneration according to the following criteria and to develop a consensus statement on biomarker candidates for evaluation of disease-modifying therapeutics in PD. The criteria proposed are that the biomarker should be linked to fundamental features of PD neuropathology and mechanisms underlying neurodegeneration in PD, should be correlated to disease progression assessed by clinical rating scales, should monitor the actual disease status, should be pre-clinically validated, and confirmed by at least two independent studies conducted by qualified investigators with the results published in peer-reviewed journals. To date, available data have not yet revealed one reliable biomarker to detect early neurodegeneration in PD and to detect and monitor effects of drug candidates on the disease process, but some promising biomarker candidates, such as antibodies against neuromelanin, pathological forms of α-synuclein, DJ-1, and patterns of gene expression, metabolomic and protein profiling exist. Almost all of the biomarker candidates were not investigated in relation to effects of treatment, validated in experimental models of PD and confirmed in independent studies.

α-Synuclein and tau concentrations in cerebrospinal fluid of patients presenting with parkinsonism: a cohort study

BACKGROUND

Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy are brain disorders characterised by intracellular α-synuclein deposits. We aimed to assess whether reduction of α-synuclein concentrations in CSF was a marker for α-synuclein deposition in the brain, and therefore diagnostic of synucleinopathies.

METHODS

We assessed potential extracellular-fluid markers of α-synuclein deposition in the brain (total α-synuclein and total tau in CSF, and total α-synuclein in serum) in three cohorts: a cross-sectional training cohort of people with Parkinson's disease, multiple system atrophy, dementia with Lewy bodies, Alzheimer's disease, or other neurological disorders; a group of patients with autopsy-confirmed dementia with Lewy bodies, Alzheimer's disease, or other neurological disorders (CSF specimens were drawn ante mortem during clinical investigations); and a validation cohort of patients who between January, 2003, and December, 2006, were referred to a specialised movement disorder hospital for routine inpatient admission under the working diagnosis of parkinsonism. CSF and serum samples were assessed by ELISA, and clinical diagnoses were made according to internationally established criteria. Mean differences in biomarkers between diagnostic groups were assessed with conventional parametric and non-parametric statistics.

FINDINGS

In our training set, people with Parkinson's disease, multiple system atrophy, and dementia with Lewy bodies had lower CSF α-synuclein concentrations than patients with Alzheimer's disease and other neurological disorders. CSF α-synuclein and tau values separated participants with synucleinopathies well from those with other disorders (p<0·0001; area under the receiver operating characteristic curve [AUC]=0·908). In the autopsy-confirmed cases, CSF α-synuclein discriminated between dementia with Lewy bodies and Alzheimer's disease (p=0·0190; AUC=0·687); in the validation cohort, CSF α-synuclein discriminated Parkinson's disease and dementia with Lewy bodies versus progressive supranuclear palsy, normal-pressure hydrocephalus, and other neurological disorders (p<0·0001; AUC=0·711). Other predictor variables tested in this cohort included CSF tau (p=0·0798), serum α-synuclein (p=0·0502), and age (p=0·0335). CSF α-synuclein concentrations of 1·6 pg/μL or lower showed 70·72% sensitivity (95% CI 65·3-76·1%) and 52·83% specificity (39·4-66·3%) for the diagnosis of Parkinson's disease. At this cutoff, the positive predictive value for any synucleinopathy was 90·7% (95% CI 87·3-94·2%) and the negative predictive value was 20·4% (13·7-27·2%).

INTERPRETATION

Mean CSF α-synuclein concentrations as measured by ELISA are significantly lower in Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy than in other neurological diseases. Although specificity was low, the high positive predictive value of CSF α-synuclein concentrations in patients presenting with synucleinopathy-type parkinsonism might be useful in stratification of patients in future clinical trials.

FUNDING

American Parkinson Disease Association, Stifterverband für die Deutsche Wissenschaft, Michael J Fox Foundation for Parkinson's Research, National Institutes of Health, Parkinson Research Consortium Ottawa, and the Government of Canada.

Plasma epidermal growth factor levels predict cognitive decline in Parkinson disease

OBJECTIVE

Most people with Parkinson disease (PD) eventually develop cognitive impairment (CI). However, neither the timing of onset nor the severity of cognitive symptoms can be accurately predicted. We sought plasma-based biomarkers for CI in PD.

METHODS

A discovery cohort of 70 PD patients was recruited. Cognitive status was evaluated with the Mattis Dementia Rating Scale-2 (DRS) at baseline and on annual follow-up visits, and baseline plasma levels of 102 proteins were determined with a bead-based immunoassay. Using linear regression, we identified biomarkers of CI in PD, that is, proteins whose levels correlated with cognitive performance at baseline and/or cognitive decline at follow-up. We then replicated the association between cognitive performance and levels of the top biomarker, using a different technical platform, with a separate cohort of 113 PD patients.

RESULTS

Eleven proteins exhibited plasma levels correlating with baseline cognitive performance in the discovery cohort. The best candidate was epidermal growth factor (EGF, p < 0.001); many of the other 10 analytes covaried with EGF across samples. Low levels of EGF not only correlated with poor cognitive test scores at baseline, but also predicted an 8-fold greater risk of cognitive decline to dementia-range DRS scores at follow-up for those with intact baseline cognition. A weaker, but still significant, relationship between plasma EGF levels and cognitive performance was found in an independent replication cohort of 113 PD patients.

INTERPRETATION

Our data suggest that plasma EGF may be a biomarker for progression to CI 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.

High cerebrospinal tau levels are associated with the rs242557 tau gene variant and low cerebrospinal β-amyloid in Parkinson disease

Cerebrospinal fluid (CSF) tau and phospho-tau levels have been associated with certain tau gene variants and low CSF amyloid-β (Aβ) levels in Alzheimer disease (AD), constituting potential biomarkers of molecular mechanisms underlying neurodegeneration. We aimed to assess whether such CSF-genetic endophenotypes are also present in Parkinson disease (PD). CSF tau, phospho-tau and Aβ levels were obtained from 38 PD patients (19 with dementia) using specific ELISA techniques. All cases were genotyped for a series of tau gene polymorphisms (rs1880753, rs1880756, rs1800547, rs1467967, rs242557, rs2471738 and rs7521). The A-allele rs242557 polymorphism was the only tau gene variant significantly associated with higher CSF tau and phospho-tau levels, under both dominant and dose-response model. This association depended on the presence of dementia, and was only observed in individuals with low (<500pg/mL) CSF Aβ levels. Such genetic-CSF endophenotypes are probably a reflection of the presence of AD-like molecular changes in part of PD patients in the setting of dementia.

Combined Analysis of CSF Tau, Aβ42, Aβ1-42% and Aβ1-40% in Alzheimer's Disease, Dementia with Lewy Bodies and Parkinson's Disease Dementia

We studied the diagnostic value of CSF Aβ42/tau versus low Aβ1-42% and high Aβ1-40(ox)% levels for differential diagnosis of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), respectively. CSF of 45 patients with AD, 15 with DLB, 21 with Parkinson's disease dementia (PDD), and 40 nondemented disease controls (NDC) was analyzed by Aβ-SDS-PAGE/immunoblot and ELISAs (Aβ42 and tau). Aβ42/tau lacked specificity in discriminating AD from DLB and PDD. Best discriminating biomarkers were Aβ1-42% and Aβ1-40(ox)% for AD and DLB, respectively. AD and DLB could be differentiated by both Aβ1-42% and Aβ1-40(ox)% with an accuracy of 80% at minimum. Thus, we consider Aβ1-42% and Aβ1-40(ox)% to be useful biomarkers for AD and DLB, respectively. We propose further studies on the integration of Aβ1-42% and Aβ1-40(ox)% into conventional assay formats. Moreover, future studies should investigate the combination of Aβ1-40(ox)% and CSF alpha-synuclein for the diagnosis of DLB.

CSF markers of neurodegeneration in Parkinson's disease

Parkinson's disease (PD) is a chronic, progressive, neurodegenerative disease with a multifactorial etiology. Protein accumulation is speculated by some to play a prominent role in the pathogenesis of PD. The severity of neurodegeneration should correlate with cerebrospinal fluid (CSF) levels of these neurodegenerative markers (NDMs). The aims of the study were to assess the CSF levels of tau protein, beta-amyloid (1-42), cystatin C, and clusterin in patients suffering from PD and in a control group, to compare the CSF levels between the two groups and to correlate them to PD duration. NDMs in the CSF were assessed in 32 patients suffering from PD and in a control group (CG) of 30 patients. The following statistically significant differences in the CSF were found: higher tau protein (p = 0.045) and clusterin levels (p = 0.004) in PD patients versus CG; higher tau protein levels (p = 0.033), tau protein/beta-amyloid (1-42) ratio (p = 0.011), and clusterin (p = 0.044) in patients suffering from PD for <2 years versus patients suffering PD for more than 2 years. No differences between beta-amyloid (1-42) and cystatin C CSF levels were found in the CG and PD patients groups. Significantly higher tau protein and clusterin CSF levels in the group of PD patients with disease duration of <2 years probably reflect the fact that most neurodegenerative changes in PD patients occur in the initial stage of disease.

Tau as a biomarker of neurodegenerative diseases

The microtubule-associated protein Tau is mainly expressed in neurons of the CNS and is crucial in axonal maintenance and axonal transport. The rationale for Tau as a biomarker of neurodegenerative diseases is that it is a major component of abnormal intraneuronal aggregates observed in numerous tauopathies, including Alzheimer's disease. The molecular diversity of Tau is very useful when analyzing it in the brain or in the peripheral fluids. Immunohistochemical and biochemical characterization of Tau aggregates in the brain allows the postmortem classification and differential diagnosis of tauopathies. As peripheral biomarkers of Alzheimer's disease in the cerebrospinal fluid, Tau proteins are now validated for diagnosis and predictive purposes. For the future, the detailed characterization of Tau in the brain and in peripheral fluids will lead to novel promising biomarkers for differential diagnosis of dementia and monitoring of therapeutics.

Diagnostic cerebrospinal fluid biomarkers for Parkinson's disease: a pathogenetically based approach

The inaccuracy of the early diagnosis of Parkinson's disease (PD) has been a major incentive for studies aimed at the identification of biomarkers. Brain-derived cerebrospinal fluid (CSF) proteins are potential biomarkers considering the major role that proteins play in PD pathogenesis. In this review, we discuss the current hypotheses about the pathogenesis of PD and identify the most promising candidate biomarkers among the CSF proteins studied so far. The list of potential markers includes proteins involved in various pathogenetic processes, such as oxidative stress and protein aggregation. This list will undoubtedly grow in the near future by application of CSF proteomics and subsequent validation of identified proteins. Probably a single biomarker will not suffice to reach high sensitivity and specificity, because PD is pathogenetically heterogeneous and shares etiological factors with other neurodegenerative diseases. Furthermore, identified candidate biomarkers will have to be thoroughly validated before they can be implemented as diagnostic aids.

Biomarkers: Parkinson disease with dementia and dementia with Lewy bodies

Dementia is a common feature in Parkinson disease (PD), the time of onset determining how patients are classified. Those patients where dementia develops prior to parkinsonism or during the first year of disease are designated as having dementia with Lewy bodies (DLB). In those where dementia develops over a year after the onset of motor signs, the condition is known as Parkinson's disease with dementia (PDD). While this seems at first sight to be a definitive way to distinguish these conditions, reality is rather different. The overlap between them is considerable, and there is much uncertainty associated with patients who have both motor symptoms and early cognitive impairment. The diagnosis is still based on medical history and clinical evaluation. It is not even certain that they can be accurately distinguished at autopsy. For this reason, the data concerning these entities have been reviewed, to examine various markers employed or measured in clinical, neuropathological, neuroimaging, and biochemical investigations. The concept of PDD and DLB being separate conditions is comparatively new, and the most promising tools with which to separate them at present are cerebrospinal fluid (CSF) markers and positron emission tomography (PET) scanning that indicate increased amyloid-beta burden in DLB compared to PDD. However as yet there are no markers that unequivocally distinguish between PDD and DLB.

Cerebrospinal tau, phospho-tau, and beta-amyloid and neuropsychological functions in Parkinson's disease

Alzheimer's disease (AD)-pathology may play a role in Parkinson's disease (PD)-related dementia (PDD). The aim of this study was to assess cerebrospinal fluid (CSF) levels of tau, phospho-tau, and beta-amyloid, proposed AD biomarkers, and their relationship with cognitive function in PD. Forty PD patients [20 nondemented (PDND); 20 PDD] and 30 controls underwent CSF tau, phospho-tau, and beta-amyloid analysis using specific ELISA techniques. All PD patients and 15 controls underwent neuropsychological testing of fronto-subcortical (attention, fluency) and neocortical (memory, naming, visuoperceptive) functions. CSF markers levels were compared between groups, and compared and correlated with neuropsychological measures in PDND and PDD separately and as a continuum (PD). CSF tau and phospho-tau were higher in PDD than in PDND and controls (P < 0.05). CSF beta-amyloid ranged from high (controls) to intermediate (PDND) and low (PDD) levels (P < 0.001). In all PD and PDD patients, high CSF tau and phospho-tau were associated with impaired memory and naming. In PDND, CSF beta-amyloid was related with phonetic fluency. These findings suggest underlying AD-pathology in PDD in association with cortical cognitive dysfunction, and that low CSF beta-amyloid in PDND patients with impaired phonetic fluency can constitute an early marker of cognitive dysfunction.

DJ-1 and alpha-synuclein in human cerebrospinal fluid as biomarkers of Parkinson's disease

Biomarkers are urgently needed for the diagnosis and monitoring of disease progression in Parkinson's disease. Both DJ-1 and alpha-synuclein, two proteins critically involved in Parkinson's disease pathogenesis, have been tested as disease biomarkers in several recent studies with inconsistent results. These have been largely due to variation in the protein species detected by different antibodies, limited numbers of patients in some studies, or inadequate control of several important variables. In this study, the nature of DJ-1 and alpha-synuclein in human cerebrospinal fluid was studied by a combination of western blotting, gel filtration and mass spectrometry. Sensitive and quantitative Luminex assays detecting most, if not all, species of DJ-1 and alpha-synuclein in human cerebrospinal fluid were established. Cerebrospinal fluid concentrations of DJ-1 and alpha-synuclein from 117 patients with Parkinson's disease, 132 healthy individuals and 50 patients with Alzheimer's disease were analysed using newly developed, highly sensitive Luminex technology while controlling for several major confounders. A total of 299 individuals and 389 samples were analysed. The results showed that cerebrospinal fluid DJ-1 and alpha-synuclein levels were dependent on age and influenced by the extent of blood contamination in cerebrospinal fluid. Both DJ-1 and alpha-synuclein levels were decreased in Parkinson's patients versus controls or Alzheimer's patients when blood contamination was controlled for. In the population aged > or = 65 years, when cut-off values of 40 and 0.5 ng/ml were chosen for DJ-1 and alpha-synuclein, respectively, the sensitivity and specificity for patients with Parkinson's disease versus controls were 90 and 70% for DJ-1, and 92 and 58% for alpha-synuclein. A combination of the two markers did not enhance the test performance. There was no association between DJ-1 or alpha-synuclein and the severity of Parkinson's disease. Taken together, this represents the largest scale study for DJ-1 or alpha-synuclein in human cerebrospinal fluid so far, while using newly established sensitive Luminex assays, with controls for multiple variables. We have demonstrated that total DJ-1 and alpha-synuclein in human cerebrospinal fluid are helpful diagnostic markers for Parkinson's disease, if variables such as blood contamination and age are taken into consideration.

Peripheral expression of key regulatory kinases in Alzheimer's disease and Parkinson's disease

Alteration of key regulatory kinases may cause aberrant protein phosphorylation and aggregation in Alzheimer's disease (AD) and Parkinson's disease (PD). In this study, we investigated expression and phosphorylation status of glycogen synthase kinase 3 (GSK-3), protein kinase B (Akt) and tau protein in peripheral blood lymphocytes of 20 AD, 25 PD patients and 20 healthy controls. GSK-3 was increased in AD and PD patients. In these latter, GSK-3 levels were positively correlated with daily L-Dopa intake. Phosphorylated Akt expression was augmented in both groups; total Akt levels were increased only in AD patients and were positively correlated with disease duration and severity. Total and phosphorylated tau were increased only in AD, with phospho-tau levels being positively correlated with levels of total tau, Akt, and disease duration. No correlations between protein levels and clinical variables were found in PD patients. Investigation of peripheral changes in the expression of specific kinases may, therefore, lead to the development of innovative biomarkers of neurodegeneration, particularly for AD.

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).

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 alpha-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.

Cerebrospinal fluid biomarkers in Parkinson's disease with dementia and dementia with Lewy bodies

BACKGROUND

Clinical criteria for differentiating Parkinson's disease (PD) with dementia (PDD) from dementia with Lewy bodies (DLB) are unsatisfactory. Their existence as distinct clinicopathologic entities is still debated, although the burden of Alzheimer's disease (AD) pathology seems higher in DLB. Thus, analysis of cerebrospinal fluid (CSF) biomarkers (beta-amyloid(1-42) [Abeta42], total tau, and hyperphosphorylated tau [p-tau]) in living subjects might provide significant pathophysiological information on these diseases.

METHODS

Cerebrospinal fluid biomarkers were measured in DLB (n = 19), PDD (n = 18), and AD (n = 23) subjects matched for age, sex, and dementia severity, as well as in PD (n = 20) and normal control subjects (n = 20).

RESULTS

DLB showed the lowest mean CSF Abeta42 levels, with a negative association to dementia duration (rho = -.42, p = .07). In DLB patients, mean CSF total tau levels were significantly lower than in AD patients (508 +/- 387 vs. 960 +/- 619, respectively) but twofold to threefold higher than in PDD (286 +/- 184), PD (160 +/- 64), or normal control subjects (177 +/- 76), with a positive association to dementia severity (Mini-Mental State Examination: rho = -.54, p = .02; Milan Overall Dementia Assessment: rho = -.66, p = .002). PDD patients had mean CSF Abeta42 and total tau levels similar to those seen in PD patients. Hyperphosphorylated tau was significantly increased in the AD group only.

CONCLUSIONS

Cerebrospinal fluid Abeta42 and total tau have a different behavior in DLB and PDD, being related to duration and severity of dementia in DLB alone. Hyperphosphorylated tau is not significantly altered in these conditions.

Cerebrospinal fluid biomarkers of neurodegeneration in chronic neurological diseases

Chronic neurological diseases (CND) like amyotrophic lateral sclerosis (ALS), dementia or multiple sclerosis (MS) share a chronic progressive course of disease that frequently leads to the common pathological pathway of neurodegeneration, including neuroaxonal damage, apoptosis and gliosis. There is an ongoing search for biomarkers that could support early diagnosis of CND and help to identify responders to interventions in therapeutic treatment trials. Cerebrospinal fluid (CSF) is a promising source of biomarkers in CND, since the CSF compartment is in close anatomical contact with the brain interstitial fluid, where biochemical changes related to CND are reflected. We review recent advances in CSF biomarkers research in CND and thereby focus on markers associated with neurodegeneration.

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.

Multiplex analysis of cytokines in the serum and cerebrospinal fluid of patients with Alzheimer's disease by color-coded bead technology

Background and purpose

The availability and promise of effective treatments for neurodegenerative disorders are increasing the importance of early diagnosis. Having molecular and biochemical markers of Alzheimer's disease (AD) would complement clinical approaches, and further the goals of early and accurate diagnosis. Combining multiple biomarkers in evaluations significantly increases the sensitivity and specificity of the biochemical tests.

Methods

In this study, we used color-coded bead-based Luminex technology to test the potential of using chemokines and cytokines as biochemical markers of AD. We measured the levels of 22 chemokines and cytokines in the serum and cerebrospinal fluid (CSF) of 32 de novo patients (13 controls, 11 AD, and 8 Parkinson's disease [PD]).

Results

MCP-1 was the only cytokine detectable in CSF, and its levels did not differ between control and disease groups. However, the serum concentration of eotaxin was significantly higher in AD patients than in the control group.

Conclusions

The analysis of multiple inflammatory mediators revealed marginal differences in their CSF and serum concentrations for the differential diagnosis of AD and PD. These results provide evidence that immunological responses are not major contributors to the pathogenesis of AD and PD.

Direct quantification of CSF alpha-synuclein by ELISA and first cross-sectional study in patients with neurodegeneration

Because accumulation of alpha-synuclein (alphaS) in the brain is a hallmark of Parkinson disease (PD) and related disorders, we examined its occurrence in human cerebrospinal fluid (CSF). Following affinity enrichment and trypsin digestion of CSF collected from a neurologically healthy donor, we identified several alphaS-derived peptides by mass spectrometry. The concentration of alphaS amounted to <0.001% of the CSF proteome. We then built, validated and optimized a sandwich-type, enzyme-linked immunoadsorbent assay (ELISA) to measure total alphaS levels in unconcentrated CSF. In a cross-sectional study of 100 living donors, we examined cell-free CSF samples from subjects clinically diagnosed with advanced PD, dementia with Lewy bodies (DLB), Alzheimer disease (AD), and a group of non-neurodegenerative disease controls (NCO). In these four groups the CSF alphaS concentrations ranged from 0.8 to 16.2 pg/microl. Mean CSF alphaS values were lower in donors with a primary synucleinopathy (PD, DLB: n=57) than in the other two groups (AD, NCO: n=35; p=0.025). By contrast, living Creutzfeldt-Jakob disease patients showed markedly elevated CSF alphaS levels (n=8; mean, 300 pg/microl; p<0.001). Our results unequivocally confirm the presence of alphaS in adult human CSF. In a first feasibility study employing a novel ELISA, we found relatively low CSF alphaS concentrations in subjects with parkinsonism linked to synucleinopathy, PD and DLB. In definite prion disease cases, we recorded a marked rise in total CSF alphaS resulting from rapid cell death. Our results will likely aid future biomarker explorations in neurodegenerative conditions and facilitate target validation studies.

Apolipoprotein E gene polymorphism and previous alcohol withdrawal seizures

Aim of this study was to investigate the possible association of apolipoprotein E (ApoE) gene polymorphism with a history of alcohol withdrawal seizures. We included 194 patients with alcohol dependence who were divided into patients with (SZ+) and without (SZ-) previous alcohol withdrawal seizures. ApoE genotypes were determined using PCR. For statistical analysis we examined the number of ApoE alleles (ApoE2: n=36; ApoE3: n=311; ApoE4: n=41). A significant positive association with a positive history of withdrawal seizures (SZ+) was found in the ApoE3 allele group (Fisher's exact test: p=0.006) while a significant negative association was observed in the ApoE2 allele group (Fisher's exact test: p=0.029). For the ApoE4 allele group no significant differences were found regarding a history of withdrawal seizures. Our findings suggest an association between the apolipoprotein E3 gene variant and an elevated risk of alcohol withdrawal seizures. These preliminary results must be validated in further studies.

ApoE distribution and family history in genetic prion diseases in Germany

We analyzed the ApoE genotype in patients with genetic prion diseases (gPD) with respect to family history (FH) of dementia/prion disease (PD) compared to non-demented controls. Fifty-nine gPD patients and 51 sex-/age-matched controls were included. A positive FH of dementia and PD (PFH) were evaluated. The prion protein gene (PRNP) codon 129 and ApoE genotype were determined by polymerase chain reaction (PCR). The frequency of FH of neurodegenerative disorder/prion disease/dementia varied in different PRNP mutations. PFH was found in 87% of D178N patients, but was rarer in others. Although the ApoE genotype distribution was not significantly different between gPD patients and controls, the protective E2 alleles were more frequent in controls than in patients without a PFH and even less frequent in those with a PFH (18, 16, and 11%). E4 alleles as a risk factor of Alzheimer's disease were more common in controls and patients with a PFH than in those without PFH (25, 21, and 13%). No effect of the codon 129 genotype was detected. Only about two-thirds of gPD patients had PFH of PD, while in one-third, PFH of slowly progressive dementia was reported. Underreporting of PFH of gPD may play a role; however, the varying PFH frequency across various mutations is not explained by this factor only.

Blood-based neurochemical diagnosis of vascular dementia: a pilot study

Blood-based tests for the differential diagnosis of Alzheimer's disease (AD) are under intensive investigation and have shown promising results with regard to Abeta40 and Abeta42 peptide species in incipient AD. Moreover, plasma Abeta40 was suggested as an independent cerebrovascular risk factor candidate. These considerations prompted us to analyse a total of 72 plasma samples in vascular dementias (VAD, n = 15), AD with cerebrovascular disease (AD with CVD, n = 7), AD (n = 15), Parkinson's disease and Parkinson's disease dementia (PD/PDD, n = 20) and 15 patients with depression that served as controls (DC) for distinct plasma amyloid-beta (Abeta) peptide patterns. For the analysis of plasma we used immunoprecipitation followed by the quantitative Abeta-SDS-PAGE/immunoblot. For comparison, CSF tau and Abeta1-42 analyses were performed. The major outcome was an increase in Abeta1-40 in plasma of VAD paralleled by a decrease in the ratio of Abeta1-38/Abeta1-40. The ratio Abeta1-38/Abeta1-40 in plasma enabled contrasts of beyond 85% and 80% for discriminating VAD from DC and all other patients, respectively. In CSF, we confirmed the typical CSF biomarker constellation of increased tau and diminished Abeta1-42 levels for AD. The diagnostic accuracy of plasma Abeta1-38/Abeta1-40 for VAD resembled the accuracy of CSF biomarkers for AD. From the presented results, we consider the ratio of plasma Abeta1-38/Abeta1-40 peptides to be a blood-based biomarker candidate for VAD.

Type 2 diabetes and Alzheimer's disease: from common pathologies to potential new therapeutics

Type 2 diabetes constitutes a major health risk in the United States, with over 20% of individuals over the age of 60 currently suffering from this disease and an additional 1.5 million new cases diagnosed in patients over 20 years of age in 2005. Similarly, Alzheimer's disease represents a major risk to the aging population, with recent statistics estimating up to 16 million people diagnosed by 2050 in the United States alone. As type 2 diabetes and Alzheimer's disease are now recognized as members of the broader class of amyloid diseases and because the pathologies of disease progression between these indications is similar, common strategies focused on the design of next-generation therapeutics can be envisioned and are discussed herein.