Leonardo Biscetti

Cerebrospinal fluid biomarkers in Alzheimer's and Parkinson's diseases—From pathophysiology to clinical practice

This review provides an update on the role, development, and validation of CSF biomarkers in the diagnosis and prognosis of Alzheimers disease and PD. Some recent developments on novel biomarkers are also discussed. We also give an overview of methodological/technical factors still hampering the global validation and standardization of CSF Alzheimers disease and PD biomarkers. CSF biomarkers have the potential to improve the diagnostic accuracy at the early stages not only for Alzheimers disease but also for PD. This step is essential in view of the availability of disease‐modifying treatments. Our vision for the future is that analyzing biomarker panels on a minute amount of CSF could provide important information on the whole spectrum of the molecular pathogenic events characterizing these neurodegenerative disorders. CSF core biomarkers have already been included in the diagnostic criteria for Alzheimers disease, and they are also under consideration as tools to monitor the effects of disease‐modifying drugs. With respect to PD, their potential for improving diagnostic accuracy in early diagnosis is under intense research, resembling the same path followed for Alzheimers disease.

Performance Evaluation of an Automated ELISA System for Alzheimer’s Disease Detection in Clinical Routine

The variability of Alzheimers disease (AD) cerebrospinal fluid (CSF) biomarkers undermines their full-fledged introduction into routine diagnostics and clinical trials. Automation may help to increase precision and decrease operator errors, eventually improving the diagnostic performance. Here we evaluated three new CSF immunoassays, EUROIMMUNtrademark amyloid-β 1-40 (Aβ1-40), amyloid-β 1-42 (Aβ1-42), and total tau (t-tau), in combination with automated analysis of the samples. The CSF biomarkers were measured in a cohort consisting of AD patients (n = 28), mild cognitive impairment (MCI, n = 77), and neurological controls (OND, n = 35). MCI patients were evaluated yearly and cognitive functions were assessed by Mini-Mental State Examination. The patients clinically diagnosed with AD and MCI were classified according to the CSF biomarkers profile following NIA-AA criteria and the Erlangen score. Technical evaluation of the immunoassays was performed together with the calculation of their diagnostic performance. Furthermore, the results for EUROIMMUN Aβ1-42 and t-tau were compared to standard immunoassay methods (INNOTESTtrademark). EUROIMMUN assays for Aβ1-42 and t-tau correlated with INNOTEST (r = 0.83, p < 0.001 for both) and allowed a similar interpretation of the CSF profiles. The Aβ1-42/Aβ1-40 ratio measured with EUROIMMUN was the best parameter for AD detection and improved the diagnostic accuracy of Aβ1-42 (area under the curve = 0.93). In MCI patients, the Aβ1-42/Aβ1-40 ratio was associated with cognitive decline and clinical progression to AD.The diagnostic performance of the EUROIMMUN assays with automation is comparable to other currently used methods. The variability of the method and the value of the Aβ1-42/Aβ1-40 ratio in AD diagnosis need to be validated in large multi-center studies.

Diagnostic utility of cerebrospinal fluid α-synuclein in Parkinson's disease: A systematic review and meta-analysis

The accumulation of misfolded α‐synuclein aggregates is associated with PD. However, the diagnostic value of the α‐synuclein levels in CSF is still under investigation.

Differential role of CSF fatty acid binding protein 3, α-synuclein, and Alzheimer’s disease core biomarkers in Lewy body disorders and Alzheimer’s dementia

BackgroundNeurodegenerative disorders such as Alzheimer’s disease (AD), Parkinson’s disease with dementia (PDD), and dementia with Lewy bodies (DLB) share clinical and molecular features. Cerebrospinal fluid (CSF) biomarkers may help the characterization of these diseases, improving the differential diagnosis. We evaluated the diagnostic performance of five CSF biomarkers across a well-characterized cohort of patients diagnosed with AD, DLB, PDD, and Parkinson’s disease (PD).MethodsA total of 208 patients were enrolled in 3 European centers. The diagnostic groups (AD, n = 48; DLB, n = 40; PDD, n = 20; PD, n = 54) were compared with cognitively healthy neurological control subjects (patients with other neurological diseases [OND], n = 46). CSF levels of fatty acid binding protein 3, heart type (FABP3), α-synuclein (α-syn), amyloid-β peptide 1–42, total tau (t-tau), and phosphorylated tau 181 (p-tau) were assessed with immunoassays. Univariate and multivariate statistical analyses were applied to calculate the diagnostic value of the biomarkers as well as their association with clinical scores.ResultsFABP3 levels were significantly increased in patients with AD and DLB compared with those with PD and OND (p < 0.001). CSF t-tau, p-tau, and α-syn were significantly higher in patients with AD than in patients with PDD, DLB, PD, and OND. Combination of FABP3 with p-tau showed high accuracy for the differential diagnosis between AD and DLB (AUC 0.92), whereas patients with AD were separated from those with PDD using a combination of p-tau, FABP3, and α-syn (AUC 0.96). CSF FABP3 was inversely associated with Mini Mental State Examination score in the whole cohort (r = −0.42, p < 0.001).ConclusionsThe combination of CSF biomarkers linked to different aspects of neurodegeneration, such as FABP3, α-syn, and AD biomarkers, improves the biochemical characterization of AD and Lewy body disorders.

Diagnostic utility of CSF α-synuclein species in Parkinson's disease: protocol for a systematic review and meta-analysis

Introduction The diagnostic criteria currently used for Parkinsons disease (PD) are mainly based on clinical motor symptoms. For these reasons many biomarkers are under investigation to support the diagnosis at the early stage. The neuropathological hallmark of PD is represented by Lewy bodies (LBs), which are intracytoplasmic inclusions in substantia nigra neurons. The major component of LBs, α-synuclein (α-syn), has been implicated in the pathogenesis of PD and in other ‘synucleinopathies’ such as multisystem atrophy (MSA) and dementia with LBs (DLBs). Several studies have investigated this presynaptic protein as a potential biomarker of PD. The aim of our meta-analysis is to determine the ability of cerebrospinal fluid (CSF) concentrations of total α-syn, oligomeric α-syn and phosphorylated α-syn to discriminate patients with PD from healthy participants, non-degenerative neurological controls and patients suffering from parkinsonism and or synucleinopathies. Methods and analysis This systematic review protocol has been developed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses Protocol (PRISMA-P) 2015 statement and was registered on PROSPERO (CRD42016013217). We will search Cochrane Library, Web of Science, MEDLINE (via PubMed) and EMBASE from inception, using appropriate search strategies. Two independent reviewers will screen titles, abstracts and full-text articles, and will complete data abstraction. We will include studies that involved patients with PD, DLB, MSA, progressive supranuclear palsy, corticobasal disease and vascular PD, and in which at least one between total α-syn, oligomeric α-syn and phosphorylated α-syn was measured in CSF. To evaluate the risk of bias and applicability of primary diagnostic accuracy studies, we will use QUADAS-2. Ethics and dissemination Our study will not include confidential data, and no intervention will be involved, so ethical approval is not required. The results of the study will be reported in international peer-reviewed journals.

Case of posterior cortical atrophy (PCA) evolved to PCA-CBS

A 68-year-old lawyer developed insidious disturbances in topographic orientation and apraxia. He underwent a geriatric evaluation, only documenting slight cognitive disturbances, and a 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), showing mild right-lateralised frontoparietal hypometabolism. After 1 year, because of worsening in spatial orientation and the onset of dressing apraxia, he was referred to our memory clinic. The neuropsychological evaluation documented proeminent visuospatial, praxis deficits and dysgraphia. Cerebrospinal fluid biomarker analysis showed mild increase of total-τ, with normal Aβ1–42, ruling out Alzheimer’s disease. Progression of the right parietal hypometabolism at FDG-PET and right superior longitudinal fasciculus damage at high-field MRI revealed a probable neurodegenerative aetiology. The neurological examination disclosed then Gerstmann’s and Balint’s syndromes, and extrapyramidal signs later appeared, suggesting the diagnosis of posterior cortical atrophy associated with corticobasal syndrome. Genetic analysis for mutations inmicrotubule-associated protein tau (MAPT), C9orf72 and GRN genes was negative. A 1-year follow-up documented significant worsening of the cognitive and functional impairment, revealing a frank dementia.

Diagnostic utility of cerebrospinal fluid α-synuclein in Parkinson's disease: A systematic review and meta-analysis

The accumulation of misfolded α‐synuclein aggregates is associated with PD. However, the diagnostic value of the α‐synuclein levels in CSF is still under investigation.

Diagnostic utility of cerebrospinal fluid α-synuclein in Parkinson's disease: A systematic review and meta-analysis: CSF α-Synuclein for PD Diagnosis

The accumulation of misfolded α‐synuclein aggregates is associated with PD. However, the diagnostic value of the α‐synuclein levels in CSF is still under investigation.

DIFFERENTIAL ROLE OF CSF FATTY ACID BINDING PROTEIN 3, α-SYNUCLEIN AND ALZHEIMER’S DISEASE CORE BIOMARKERS IN LEWY BODY DISORDERS AND ALZHEIMER’S DEMENTIA

Background: Accumulation of ubiquitinated proteins and UPSassociated protein is a common feature in many neurodegenerative diseases. To address the link between proteasome impairment, AD and LBD pathology, cognition decline and noncognitive symptom, the reduction of RPT6 and the alteration of the other proteasome components and activities were investigated in to identify clinico-pathological correlations, these includes: i) Possible relationships between reduction of RPT6 and the alteration of the other proteasome components and semi-quantitative scores of AD and LBD pathology in different brain areas. ii) Possible relationships between proteasome dysfunction and the cognition function and non-cognitive symptom in LBD and AD. Methods:The analysis of the relationships between non-cognitive behaviours and mood and proteasome markers were exploratory and unbiased as there were no compelling hypotheses linking them. Furthermore, due to the different regional patterns for the protein changes and the linkage of particular behavioural symptoms to a specific brain area, each brain region was analysed separately. Results:Reductions in RPT6 and proteasome activities were found to be associated with the semi-quantitative scores for plaques and neurofibrillary tangles. Semi-quantitative plaque scores were significantly predicted by RPT6 in BA9, 40 and 24. Semi-quantitative tangle scores were significantly predicted by RPT6 in BA40 and 24. Semi-quantitative a-synuclein scores were significantly predicted by RPT6 in BA9 only. Cognitive impairment was significantly predicted by RPT6 in BA9, 40 and 24. Persecution was significantly predicted by RPT6 expression in brain regions BA9 and BA40. Depression was significantly predicted by RPT6 expression in BA9. Conclusions:Our results indicated reductions in the key proteasome component RPT6 and proteasome activity. These reductions were associated with cognitive decline, non-cognitive symptoms and protein aggregates. These data suggested that the activating of the UPS could be a therapeutic target for treating DLB, PDD and AD.

COMBINATION OF CEREBROSPINAL FLUID H-FABP AND CORE ALZHEIMER'S DISEASE BIOMARKERS IMPROVES THE DIFFERENTIAL DIAGNOSIS OF NEURODEGENERATIVE DISORDERS

Background:Cognitive deficits are common clinical signs of depression and AD. Biomarkers may help to distinguish between early stages of AD and depression not associated with AD. Recently, cerebrospinal (CSF) levels of the synaptic proteins neurogranin and BACE1 have shown potential as progression markers for AD. Here, we analyzed CSF neurogranin, as well as CSF levels of the protein BACE1, in AD and depressed patients with and without cognitive deficits. Methods: We used research prototype ELISAs for measuring neurogranin and BACE1 in CSF of mild (n1⁄421) and moderate (n1⁄419) AD patients and depressed patients with (n1⁄420) or without (n1⁄420) cognitive malfunction. We also quantified CSF levels of Ab(1-38), Ab(1-40), Ab(1-42) and total-tau. Cognitive performance was tested by the CERAD test battery. Results:As expected, we found significantly increased CSF levels of neurogranin and BACE1 in moderate AD patients compared to depressed patients without cognitive deficits. Neurogranin CSF levels were already significantly increased in mild AD. Interestingly, the ratio of neurogranin/BACE1 enhanced the discrimination between mild AD and depression. Moreover, the ratio also significantly distinguished between mild AD and depression with cognitive deficits. For none of the analytes, significant differences were noted between both groups of depressed patients, although we saw a trend of increased CSF levels of neurogranin, BACE1 and tau. Finally, BACE1 and neurogranin were highly correlated in all groups.Conclusions:Neurogranin and BACE1 can be reliably detected in CSF of depressed and AD patients and might serve as biomarkers to facilitate clinical assignment of cognitive dysfunction. It would be valuable to assess the CSF neurogranin/BACE1 ratio in remitted formerly depressed patients via longitudinally sampling, to determine whether this ratio changes over time and correlates with clinical deterioration of cognition.