CSF neurosecretory proteins VGF and neuroserpin in patients with Alzheimer's and Lewy body diseases.

BACKGROUND: VGF and neuroserpin are neurosecretory proteins involved in the pathophysiology of neurodegenerative diseases. We aimed to evaluate their cerebrospinal fluid (CSF) concentrations in patients with Alzheimer's disease (AD) and Lewy body disease (LBD). METHODS: We measured CSF VGF [AQEE] peptide and neuroserpin levels in 108 LBD patients, 76 AD patients and 37 controls, and tested their associations with clinical scores and CSF AD markers. RESULTS: We found decreased CSF levels of VGF [AQEE] in patients with LBD and dementia compared to controls (p = 0.016) and patients with AD-dementia (p = 0.011), but with significant influence of age and sex distribution. Moreover, we observed, on the one hand, a significant associations between lower VGF [AQEE] and neuroserpin levels and poorer cognitive performance (i.e., lower Mini-Mental State Examination scores). On the other hand, higher levels of CSF tau proteins, especially pTau181, were significantly associated with higher concentrations of VGF [AQEE] and neuroserpin. Indeed, LBD patients with AD-like CSF profiles, especially T+ profiles, had higher levels of VGF [AQEE] and neuroserpin compared to controls and LBD/T- cases. DISCUSSION: CSF VGF [AQEE] and neuroserpin may show a complex relationship with cognitive decline when the levels are reduced, and with AD pathology when levels are increased. They may represent novel markers of neurosecretory impairment in neurodegenerative disorders.

Predictive value for cerebrospinal fluid Alzheimer's disease profile of different measures of verbal episodic memory in patients with MCI.

Neuropsychological evidence of memory impairment represents the main feature of the clinical onset of typical Alzheimer's disease (AD). Rey's Auditory Verbal Learning Test (RAVLT) and Logical Memory (LM) are two tests both assessing verbal episodic memory, widely used in clinical practice. Our aim was to investigate the added value of their combined use in predicting cerebrospinal fluid (CSF) AD biomarkers positivity in a retrospective consecutive series of patients with mild cognitive impairment (MCI). 169 MCI patients were included. For all of them neuropsychological assessment and CSF analysis were available. According to CSF A/T/(N) profile, 109 were defined as MCI due to AD (A+T+), and 60 were non-AD MCI (A-T-). Logistic regression model and receiver-operating characteristic (ROC) curves were analyzed to evaluate the discriminatory power of single and combined sub-measures between AD and non-AD patients. The combination of RAVLT-del with LM could acceptably discriminate the two groups (AUC: 0.69, CI 95% 0.617-0.761, sens: 0.75, spec. 0.58, p < 0.001), while the single tests did not show sufficient discriminative performance. Our study shows that the combination of RAVLT delayed recall with LM better predicts the biological AD diagnosis (A+T+), showing a good discriminative power between MCI-AD from non-AD MCI. Since RAVLT and LM assess different components of verbal episodic memory, they should be considered as complementary, rather than interchangeable, tests.

A Combination of Neurofilament Light, Glial Fibrillary Acidic Protein, and Neuronal Pentraxin-2 Discriminates Between Frontotemporal Dementia and Other Dementias.

BACKGROUND: The differential diagnosis of frontotemporal dementia (FTD) is still a challenging task due to its symptomatic overlap with other neurological diseases and the lack of biofluid-based biomarkers. OBJECTIVE: To investigate the diagnostic potential of a combination of novel biomarkers in cerebrospinal fluid (CSF) and blood. METHODS: We included 135 patients from the Center for Memory Disturbances, University of Perugia, with the diagnoses FTD (n = 37), mild cognitive impairment due to Alzheimer's disease (MCI-AD, n = 47), Lewy body dementia (PDD/DLB, n = 22), and cognitively unimpaired patients as controls (OND, n = 29). Biomarker levels of neuronal pentraxin-2 (NPTX2), neuronal pentraxin receptor, neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) were measured in CSF, as well as NfL and GFAP in serum. We assessed biomarker differences by analysis of covariance and generalized linear models (GLM). We performed receiver operating characteristics analyses and Spearman correlation to determine biomarker associations. RESULTS: CSF NPTX2 and serum GFAP levels varied most between diagnostic groups. The combination of CSF NPTX2, serum NfL and serum GFAP differentiated FTD from the other groups with good accuracy (FTD versus MCI-AD: area under the curve (AUC) [95% CI] = 0.89 [0.81-0.96]; FTD versus PDD/DLB: AUC = 0.82 [0.71-0.93]; FTD versus OND: AUC = 0.80 [0.70-0.91]). CSF NPTX2 and serum GFAP correlated positively only in PDD/DLB (ρ= 0.56, p < 0.05). NPTX2 and serum NfL did not correlate in any of the diagnostic groups. Serum GFAP and serum NfL correlated positively in all groups (ρ= 0.47-0.74, p < 0.05). CONCLUSION: We show the combined potential of CSF NPTX2, serum NfL, and serum GFAP to differentiate FTD from other neurodegenerative disorders.

α-Synuclein Seed Amplification Assays for Diagnosing Synucleinopathies: The Way Forward.

Parkinson disease (PD) is the second most common neurodegenerative disease, and the most common synucleinopathy, as alpha-synuclein (α-syn), a prion-like protein, plays an important pathophysiologic role in its onset and progression. Although neuropathologic changes begin many years before the onset of motor manifestations, diagnosis still relies on the identification of the motor symptoms, which hinders to formulate an early diagnosis. Because α-syn misfolding and aggregation precede clinical manifestations, the possibility to identify these phenomena in patients with PD would allow us to recognize the disease at the earliest, premotor phases, as a consequence of the transition from a clinical to a molecular diagnosis. Seed amplification assays (SAAs) are a group of techniques that currently support the diagnosis of prion subacute encephalopathies, namely Creutzfeldt-Jakob disease. These techniques enable the detection of minimal amounts of prions in CSF and other matrices of affected patients. Recently, SAAs have been successfully applied to detect misfolded alpha-synuclein (α-syn) in CSF, olfactory mucosa, submandibular gland biopsies, skin, and saliva of patients with Parkinson disease (PD) and other synucleinopathies. In these categories, they can differentiate PD and dementia with Lewy bodies (DLBs) from control subjects, even in the prodromal stages of the disease. In differential diagnosis, SAAs satisfactorily differentiated PD, DLB, and multiple system atrophy (MSA) from nonsynucleinopathy parkinsonisms. The kinetic analysis of the SAA fluorescence profiles allowed the identification of synucleinopathy-dependent α-syn fibrils conformations, commonly referred to as strains, which have demonstrated diagnostic potential in differentiating among synucleinopathies, especially between Lewy body diseases (LBDs) (PD and DLB) and MSA. In front of these highly promising data, which make the α-syn seeding activity detected by SAAs as the most promising diagnostic biomarker for synucleinopathies, there are still preanalytical and analytical issues, mostly related to the assay standardization, which need to be solved. In this review, we discuss the key findings supporting the clinical application of α-syn SAAs to identify PD and other synucleinopathies, the unmet needs, and future perspectives.

Phosphatidylethanolamine Binding Protein 1 (PEBP1) in Alzheimer's Disease: ELISA Development and Clinical Validation.

BACKGROUND: Phosphatidylethanolamine binding protein 1 (PEBP1) is a multifunctional protein, mainly known for its specific binding of phosphatidylethanolamine and the ability to suppress the Raf1-MAPK pathway. Its potential role as an Alzheimer's disease (AD) biomarker has been proposed in several studies. However, evaluation of its discriminative value in clinical cohorts is missing. OBJECTIVE: We aimed to develop a new immunoassay for the measurement of PEBP1 in cerebrospinal fluid (CSF) and assess the possible role of this protein as AD biomarker. METHODS: We developed a sandwich enzyme-linked immunosorbent assay (ELISA) for detection of PEBP1 in CSF and performed a technical and a clinical validation on two well-characterized cohorts. The first cohort included 14 mild cognitive impairment due to AD (MCI-AD) and 11 other neurological diseases (OND) patients. The second, larger cohort, included 25 MCI-AD, 29 AD dementia (AD-dem), and 21 OND patients. RESULTS: PEBP1 is highly sensitive to pre-analytical conditions, especially to prolonged storage at room temperature or 4°C. Analysis of the first cohort showed a trend of an increase of PEBP1 level in MCI-AD patients versus OND subjects. Analysis of the second cohort did not show significant differences among diagnostic groups. Weak, positive correlation was found between CSF PEBP1 and t-tau, p-tau, and Aß40 in the AD-dem group. CONCLUSION: A novel ELISA for the detection of PEBP1 in CSF was developed. Further research is needed to assess the potential of PEBP1 in AD diagnostics. The observed dependence of the PEBP1 signal on operating procedures encourages its potential application as CSF quality control.

Clinical reporting following the quantification of cerebrospinal fluid biomarkers in Alzheimer's disease: An international overview.

INTRODUCTION: The current practice of quantifying cerebrospinal fluid (CSF) biomarkers as an aid in the diagnosis of Alzheimer's disease (AD) varies from center to center. For a same biochemical profile, interpretation and reporting of results may differ, which can lead to misunderstandings and raises questions about the commutability of tests. METHODS: We obtained a description of (pre-)analytical protocols and sample reports from 40 centers worldwide. A consensus approach allowed us to propose harmonized comments corresponding to the different CSF biomarker profiles observed in patients. RESULTS: The (pre-)analytical procedures were similar between centers. There was considerable heterogeneity in cutoff definitions and report comments. We therefore identified and selected by consensus the most accurate and informative comments regarding the interpretation of CSF biomarkers in the context of AD diagnosis. DISCUSSION: This is the first time that harmonized reports are proposed across worldwide specialized laboratories involved in the biochemical diagnosis of AD.

Seed amplification assays for diagnosing synucleinopathies: the issue of influencing factors.

Background: The prion-like misfolding and aggregation of α-synuclein (α-syn) is involved in the pathophysiology of Parkinson's disease and other synucleinopathies. Seed amplification assays (SAAs) are biophysical tools that take advantage on the peculiar properties of prion proteins by amplifying small amounts of aggregates in biological fluids at the expense of recombinant monomeric protein added in solution. SAAs have emerged as the most promising tools for the diagnosis of synucleinopathies in vivo. However, the diagnostic outcome of SAAs depends on the aggregation kinetics of α-syn, which in turn is influenced by several experimental variables. Methods: In our work, we analysed the impact on SAAs of some of the most critical experimental factors by considering models that describe the aggregation kinetics of α-syn. Results: We started our analysis by making simulations to understand which kinetic models could explain the aggregation kinetics of α-syn during incubation/shaking cycles. Subsequently, under shaking/incubation cycles similar to the ones commonly used in SAAs, we tested the influence of some analytical variables such as monomer concentration, presence/absence of glass beads, pH, addition of human cerebrospinal fluid, and use of detergents on α-syn aggregation. Conclusions: Our investigation highlighted how optimization and standardization of experimental procedures for α-syn SAAs is of utmost relevance for the ultimate goal of applying these assays in clinical routine. Although these aspects have been evaluated with specific SAA protocols, most of the experimental variables considered influenced very general aggregation mechanisms of α-syn, thus making most of the results obtained from our analyses extendable to other protocols.

High performance liquid chromatography determination of L-glutamate, L-glutamine and glycine content in brain, cerebrospinal fluid and blood serum of patients affected by Alzheimer's disease.

Altered glutamatergic neurotransmission is thought to play a crucial role in the progression of Alzheimer's disease (AD). Accordingly, the identification of peculiar biochemical patterns reflecting AD-related synaptopathy in blood and cerebrospinal fluid (CSF) could have relevant diagnostic and prognostic implications. In this study, we measured by High-Performance Liquid Chromatography the amount of glutamate, glutamine and glycine in post-mortem brain samples of AD patients, as well as in CSF and blood serum of drug-free subjects encompassing the whole AD clinical spectrum (pre-clinical AD, n = 18, mild cognitive impairment-AD, n = 29, dementia AD, n = 30). Interestingly, we found that glutamate and glycine levels, as well as total tau protein content, were significantly reduced in the superior frontal gyrus of patients with AD, compared with non-demented controls. No significant change was also found in glutamate, glutamine and glycine CSF concentrations between AD patients and neurological controls. Remarkably, serum glutamate levels were significantly higher in patients affected by early AD phases compared to controls, and were negatively correlated with CSF total tau levels. Conversely, serum glutamine concentration was significantly increased in AD patients, with a negative correlation with MMSE performances. Finally, we reported a significant correlation between serum L-glutamate concentrations and CDR score in female but not in male cohort of AD subjects. Overall, our results suggest that serum glutamate and glutamine levels in AD patients could vary across disease stages, potentially reflecting the progressive alteration of glutamatergic signaling during neurodegenerative processes.

Impulse Control Disorders and Levodopa-Induced Dyskinesias in Parkinson's Disease: Pulsatile versus Continuous Dopaminergic Stimulation.

BACKGROUND: Dopaminergic medications in Parkinson's disease (PD) are usually associated with the development of both levodopa-induced dyskinesias (LID) and impulse control and repetitive behavior disorders (ICRB). OBJECTIVE: To assess the prevalence and the severity of ICRB in a cohort of moderate and advanced PD patients and to investigate the potential interplay between ICRB, LID and dopaminergic therapies. METHODS: 117 PD patients were consecutively recruited. LID were assessed by using the Rush Dyskinesia Rating Scale (RDRS). ICRB were tested by means of Questionnaire for Impulsive Compulsive Disorders in Parkinson's Disease Rating Scale (QUIP-RS). RESULTS: 55 patients were affected by LID. Among them, 37 were treated only by oral therapy, OT (LID/OT), while 18 were on treatment with jejunal levodopa infusion, JLI (LID/JLI). 62 patients were not affected by LID (NLID) and all of them were on therapy only with oral drugs. The overall prevalence of clinically significant ICRB was 34% (95% CI = 26% to 43%) and the mean value (±SD) of QUIP-RS total score was 5.4±8.5. Prevalence of clinically significant ICRB, as well as severity of ICRB, was higher in patients with LID compared to NLID patients (p = 0.016 and p < 0.001, respectively). When considering LID/JLI, LID/OT and NLID groups, QUIP-RS total score was significantly higher in LID/OT patients compared to LID/JLI (10.4±11.8 vs. 4.9±6.0, p = 0.019) and NLID (10.4±11.8 vs. 2.5±4.8, p < 0.001) groups. CONCLUSION: PD patients with LID show ICRB more frequently and more severely than patients without LID. Among LID patients, those treated by JLI showed a lower severity of ICRB than those on OT, suggesting a potential protective effect of JLI on ICRB.

Validation of the Hemifacial Spasm Grading Scale: a clinical tool for hemifacial spasm.

BACKGROUND: To create an objective rating tool for hemifacial spasm (HFS) and validate it on a cohort of patients. METHODS: A panel of movement disorders specialists elaborated, through the Delphi method, the Hemifacial Spasm Grading Scale (HSGS). The validity of the scale was tested in a longitudinal, prospective observational study, with standardized video recording protocol before and after botulinum neurotoxin (BoNT) treatment. The video recordings obtained from each patient were then independently assessed with HSGS by three blinded raters. The scale was compared to patient-reported HFS-7 scale and to the clinical grading of spasm intensity scale. RESULTS: Intra-rater reproducibility ranged between ICC 0.73 (95% CI = 0.54-0.86) and 0.83 (0.68-0.92) and inter-rater reproducibility between 0.62 (95% CI = 0.44-0.77) and 0.82 (0.69-0.90). HSGS scores correlated with clinical grading of spasm intensity scale scores, but not with HFS-7. HSGS confirmed BoNT efficacy, with scores lowering at 1 month from treatment. CONCLUSIONS: HSGS represents an objective, quick and reliable scale for the assessment of HFS, and might be useful to monitor BoNT treatment efficacy over time.

CSF Biomarkers for Early Diagnosis of Synucleinopathies: Focus on Idiopathic RBD.

PURPOSE OF REVIEW: Idiopathic REM sleep behavior disorder (iRBD) is one of the most significant prodromal manifestations of synucleinopathies. Different predictive biomarkers for iRBD conversion have been investigated, but scarce data are present in literature about the predictive role of cerebrospinal fluid (CSF) biomarkers. In this review, we focus on CSF biomarkers in patients with both iRBD and RBD associated with synucleinopathies to explore their potential predictive power. RECENT FINDINGS: Recent studies revealed that CSF α-synuclein levels are higher in Parkinson's disease (PD) patients with RBD compared to those without RBD, even if α-synuclein does not seem to predict conversion of iRBD into PD. In the Parkinson Progression Marker Initiative (PPMI) cohort, early PD patients with RBD show lower CSF Aß42 levels, which predict faster cognitive decline. CSF prion protein and inflammatory biomarkers have been also investigated in RBD and synucleinopathies with controversial results. A variety of CSF biomarkers are promising candidate for predicting iRBD conversion into synucleinopathies. Further studies are needed in iRBD patients followed for several years in order to observe the phenoconversion in synucleinopathies and to elucidate the possible role of CSF biomarkers as predictive biomarkers of conversion.

Risk factors of levodopa-induced dyskinesia in Parkinson's disease: results from the PPMI cohort.

Levodopa-induced dyskinesias (LID) negatively impact on the quality of life of patients with Parkinson's disease (PD). We assessed the risk factors for LID in a cohort of de-novo PD patients enrolled in the Parkinson's Progression Markers Initiative (PPMI). This retrospective cohort study included all PD patients enrolled in the PPMI cohort. Main outcome was the incidence rate of dyskinesia, defined as the first time the patient reported a non-zero score in the item "Time spent with dyskinesia" of the MDS-UPDRS part IV. Predictive value for LID development was assessed for clinical and demographical features, dopamine transporter imaging (DaTscan) pattern, cerebrospinal fluid (CSF) biomarkers (Aß42, total tau, phosphorylated tau, total α synuclein) and genetic risk score for PD. Overall, data from 423 PD patients were analyzed. The cumulative incidence rate of LID was 27.4% (95% CI = 23.2-32.0%), with a mean onset time of 5.81 years from PD diagnosis. Multivariate Cox regression analysis showed several factors predicting LID development, including female gender (HR = 1.61, 95% CI = 1.05-2.47), being not completely functional independent as measured by the modified Schwab & England ADL scale (HR = 1.81, 95% CI = 0.98-3.38), higher MDS-UPDRS part III score (HR = 1.03, 95% CI = 1.00-1.05), postural instability gait disturbances or intermediate phenotypes (HR = 1.95, 95% CI = 1.28-2.96), higher DaTscan caudate asymmetry index (HR = 1.02, 95% CI = 1.00-1.03), higher polygenic genetic risk score (HR = 1.39, 95% CI = 1.08-1.78), and an anxiety trait (HR = 1.02, 95% CI = 1.00-1.04). In PD patients, cumulative levodopa exposure, female gender, severity of motor and functional impairment, non-tremor dominant clinical phenotype, genetic risk score, anxiety, and marked caudate asymmetric pattern at DaTscan at baseline represent independent risk factors for developing LID.

Long-term follow-up in pediatric patients with paroxysmal hypothermia (Shapiro's syndrome).

INTRODUCTION: Shapiro syndrome (SS) is characterized by spontaneous recurrent episodes of hypothermia, hyperhidrosis and corpus callosum (CC) agenesis. Less than 60 cases have been reported to date and the pathogenic mechanism as well as the prognosis of this syndrome are still debated. We describe the clinical features and long-term follow-up of a pediatric cohort of SS patients. METHODS: We collected 13 (10 novel) pediatric cases of SS and report their long-term follow-up and neurological outcome. RESULTS: All patients experienced recurring hypothermia, with body temperature below 35 °C during the episodes, often accompanied by hyperidrosis. CC agenesis was an inconstant structural feature in the present series (2/13 patients). Seven patients received antiepileptic drugs (AEDs) or other drug therapy for a mean period of 12 months. At long-term follow-up (mean = 61 months, range: 60-96), all individuals were free from episodes of paroxysmal hypothermia independently from previous AED use or other drug therapy. CONCLUSION: Paroxysmal hypothermia, the core symptom of SS, behaved as a age-dependent feature in our cohort, supporting a good long-term prognosis for SS. A prompt diagnosis of SS is crucial to avoid unnecessary diagnostic investigations.

Levodopa-responsive breathing discomfort in Parkinson's disease patients.

In Parkinson's disease (PD), respiratory disturbances have been reported and the effect of levodopa on respiratory function remains controversial. The objective of this study was to evaluate pulmonary function utilizing spirometric and subjective evaluations in mild to moderated PD. Thirty-four consecutive sporadic PD patients (Hoehn and Yahr scale: 1-3) were prospectively evaluated using clinimetric scales, spirometry and modified Borg scale, all in off- and on-conditions. To check the respiratory function, a follow-up was performed at 4 years in a subgroup of these patients. Spirometric results were normal for all patients in both the on- and off-conditions at baseline. After levodopa administration, in addition to a significant improvement in subjective state of breathing discomfort, the mean forced expiratory volume in 1 s (FEV1), vital capacity (VC), forced vital capacity (FVC) values and their mean percentages predicted values (FEV1%, VC%, FVC%) were significantly increased (p < 0.05). Moreover, residual volume, total lung capacity, and the FEV1/FVC ratio were not significantly different for the ON and OFF conditions. At 4-year follow-up no resulting variations in the baseline values for FEV1%, FVC% or VC% were revealed. The results from this prospective study suggest that PD patients report frequently pulmonary discomfort. Levodopa improves respiratory symptoms. Pulmonary restrictive and obstructive dysfunctions, when not present at baseline, might not be present at 4-year follow-up.