Phosphorylated tau as a candidate biomarker for amyotrophic lateral sclerosis

CSF and blood levels of Neurofilaments, T-Tau, P-Tau, and Abeta-42 in amyotrophic lateral sclerosis: a systematic review and meta-analysis

Recent literature suggests that markers of neuroaxonal damage, such as neurofilaments and tau protein, might serve as potential biomarkers for ALS. We conducted this systematic review and meta-analysis study to compare cerebrospinal fluid (CSF) and blood levels of total tau (t-tau), phosphorylated tau (p-tau), amyloid beta peptide 42 (Abeta-42), and neurofilaments in ALS patients and controls. A systematic search of Cochrane Library, PubMed, Embase, and ISI Web of Science was conducted on March 18, 2022, and updated on January 26, 2023. Observational studies that compared the concentrations of neurofilament light chain (NfL), neurofilament heavy chain (NFH), t-tau, p-tau, or Abeta-42 in CSF or peripheral blood of ALS patients and controls were included. Data from relevant studies were independently extracted and screened for quality using a standard tool, by at least two authors. Meta-analysis was conducted when a minimum of 3 studies reported the same biomarker within the same biofluid. A total of 100 studies were eligible for at least one meta-analysis. CSF and blood levels of NfL (standardized mean difference (SMD) [95% CI]; CSF: 1.46 [1.25-1.68]; blood: 1.35 [1.09-1.60]) and NFH (CSF: 1.32 [1.13-1.50], blood: 0.90 [0.58-1.22]) were significantly higher in ALS patients compared with controls. The pooled differences between ALS patients and controls were not significant for CSF t-tau, blood t-tau, and CSF Abeta-42, but CSF p-tau was lower in ALS patients (-0.27 [-0.47- -0.07]). Significantly decreased p-tau/t-tau ratios were found in ALS patients compared with controls (-0.84 [-1.16- -0.53]). Heterogeneity was considerable in most of our meta-analyses. CSF and blood neurofilament levels, as well as the CSF p-tau/t-tau ratio, might be potential candidates for improving ALS diagnosis. Further research is warranted to better understand the underlying mechanisms and the clinical implications of these biomarker alterations.

A Review of Biomarkers of Amyotrophic Lateral Sclerosis: A Pathophysiologic Approach

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive degeneration of upper and lower motor neurons. The heterogeneous nature of ALS at the clinical, genetic, and pathological levels makes it challenging to develop diagnostic and prognostic tools that fit all disease phenotypes. Limitations associated with the functional scales and the qualitative nature of mainstay electrophysiological testing prompt the investigation of more objective quantitative assessment. Biofluid biomarkers have the potential to fill that gap by providing evidence of a disease process potentially early in the disease, its progression, and its response to therapy. In contrast to other neurodegenerative diseases, no biomarker has yet been validated in clinical use for ALS. Several fluid biomarkers have been investigated in clinical studies in ALS. Biofluid biomarkers reflect the different pathophysiological processes, from protein aggregation to muscle denervation. This review takes a pathophysiologic approach to summarizing the findings of clinical studies utilizing quantitative biofluid biomarkers in ALS, discusses the utility and shortcomings of each biomarker, and highlights the superiority of neurofilaments as biomarkers of neurodegeneration over other candidate biomarkers.

Alzheimer Disease Cerebrospinal Fluid Biomarkers in a Tertiary Neurology Practice

OBJECTIVE

To evaluate the performance of Alzheimer disease (AD) cerebrospinal fluid (CSF) biomarkers in a tertiary neurology clinic setting with high frequency of non-AD cases, including normal pressure hydrocephalus (NPH).

METHODS

There were 534 patients who underwent AD CSF biomarkers (Roche Elecsys Aβ42, p-Tau181, total-Tau) from April 1, 2020, through April 23, 2021. A behavioral neurologist blinded to CSF results assigned a clinical diagnosis retrospectively on the basis of consensus criteria, and a neuroradiologist blinded to the diagnosis and CSF studies graded brain magnetic resonance images for indicators of CSF dynamics disorders. Associations between biomarkers, diagnoses, and imaging were assessed by χ2, analysis of covariance, and linear regression methods.

RESULTS

Median age at time of testing was 67 years (range, 19 to 96 years), median symptom duration was 2 years (range, 0.4 to 28 years), and median Short Test of Mental Status score was 30 (range, 0 to 38). Clinical diagnoses significantly correlated with different CSF biomarker values (χ2=208.3; P=10e-4). p-Tau181/Aβ42 ratios above 0.023 positively correlated with Alzheimer dementia (more than individual measures). This ratio also had the best performance for differentiating Alzheimer dementia from NPH (area under the curve, 0.869). Imaging markers supportive of CSF dynamics disorders correlated with low Aβ42, p-Tau181, and total-Tau.

CONCLUSION

In a heterogeneous clinical population, abnormal p-Tau181/Aβ42 ratios (>0.023) have the strongest association with Alzheimer dementia and probably represent a comorbid AD pathologic component in persons clearly matching non-AD neurodegenerative syndromes. Altered CSF dynamics were associated with lower concentrations of AD CSF biomarkers regardless of clinical diagnosis, but the ratio compensates for these changes. In the appropriate clinical setting, an isolated abnormal Aβ42 should prompt consideration of NPH.

Urinary biomarkers for amyotrophic lateral sclerosis: candidates, opportunities and considerations

Amyotrophic lateral sclerosis is a relentless neurodegenerative disease that is mostly fatal within 3-5 years and is diagnosed on evidence of progressive upper and lower motor neuron degeneration. Around 15% of those with amyotrophic lateral sclerosis also have frontotemporal degeneration, and gene mutations account for ∼10%. Amyotrophic lateral sclerosis is a variable heterogeneous disease, and it is becoming increasingly clear that numerous different disease processes culminate in the final degeneration of motor neurons. There is a profound need to clearly articulate and measure pathological process that occurs. Such information is needed to tailor treatments to individuals with amyotrophic lateral sclerosis according to an individual's pathological fingerprint. For new candidate therapies, there is also a need for methods to select patients according to expected treatment outcomes and measure the success, or not, of treatments. Biomarkers are essential tools to fulfil these needs, and urine is a rich source for candidate biofluid biomarkers. This review will describe promising candidate urinary biomarkers of amyotrophic lateral sclerosis and other possible urinary candidates in future areas of investigation as well as the limitations of urinary biomarkers.

Elevated plasma p-tau181 levels unrelated to Alzheimer's disease pathology in amyotrophic lateral sclerosis

BACKGROUND

Phosphorylated-tau181 (p-tau181), a specific marker of Alzheimer's disease (AD) pathology, was found elevated in plasma but not in cerebrospinal fluid (CSF) of patients with amyotrophic lateral sclerosis (ALS). We expanded these findings in a larger patient cohort, exploring clinical/electrophysiological associations, prognostic value and longitudinal trajectories of the biomarker.

METHODS

We obtained baseline plasma samples from 148 ALS, 12 spinal muscular atrophy (SMA), and 88 AD patients, and 60 healthy controls. Baseline CSF and longitudinal plasma samples were from 130 and 39 patients with ALS. CSF AD markers were measured with the Lumipulse platform, and plasma p-tau181 with SiMoA.

RESULTS

Patients with ALS showed higher plasma p-tau181 levels than controls (p<0.001) and lower than AD participants (p=0.02). SMA patients had higher levels than controls (p=0.03). In patients with ALS, CSF p-tau and plasma p-tau181 did not correlate (p=0.37). Plasma p-tau181 significantly increased with the number of regions showing clinical/neurophysiological lower motor neurons (LMN) signs (p=0.007) and correlated with the degree of denervation in the lumbosacral area (r=0.51, p<0.0001). Plasma p-tau181 levels were higher in classic and LMN-predominant than in bulbar phenotype (p=0.004 and p=0.006). Multivariate Cox regression confirmed plasma p-tau181 as an independent prognostic factor in ALS (HR 1.90, 95% CI 1.25 to 2.90, p=0.003). Longitudinal analysis showed a significant rise in plasma p-tau181 values over time, especially in fast progressors.

CONCLUSIONS

Plasma p-tau181 is elevated in patients with ALS, independently from CSF levels, and is firmly associated with LMN dysfunction. The finding indicates that p-tau181 of putative peripheral origin might represent a confounding factor in using plasma p-tau181 for AD pathology screening, which deserves further investigation.

The Underestimated Relevance of Alzheimer's Disease Copathology in Amyotrophic Lateral Sclerosis

Concomitant Alzheimer's disease (AD) pathology can be observed in approximately 10-15% of cases with amyotrophic lateral sclerosis (ALS). ALS-AD patients have a higher prevalence of amnestic cognitive disturbances, which may often precede motor symptoms. Cerebrospinal fluid (CSF) AD core biomarkers usually show no or slightly significant changes in ALS, whereas blood phosphorylated tau protein might be increased independently from AD copathology. Neurofilament proteins are consistently elevated in CSF and blood of ALS, but have been poorly investigated in ALS-AD. All these issues should be taken into account when using fluid biomarkers as inclusion criteria or secondary endpoints in clinical trials.

Molecular Investigations of Protein Aggregation in the Pathogenesis of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disorder characterized by selective loss of lower and upper motor neurons (MNs) in the brain and spinal cord, resulting in paralysis and eventually death due to respiratory insufficiency. Although the fundamental physiological mechanisms underlying ALS are not completely understood, the key neuropathological hallmarks of ALS pathology are the aggregation and accumulation of ubiquitinated protein inclusions within the cytoplasm of degenerating MNs. Herein, we discuss recent insights into the molecular mechanisms that lead to the accumulation of protein aggregates in ALS. This will contribute to a better understanding of the pathophysiology of the disease and may open novel avenues for the development of therapeutic strategies.

Relationship between CSF tau biomarkers and structural brain MRI measures in frontotemporal lobar degeneration

BACKGROUND

Recently in the field neurodegenerative diseases increasing attention has been pointed to CSF biomarkers and their integration with neuroimaging (1). Frontotemporal lobar degeneration (FTLD) refers to a heterogeneous group of clinical syndromes with different underlying proteinopathies including tau pathology. CSF biomarkers have been proposed as diagnostic and prognostic factors. Aim of our study was to evaluate the relationship between CSF tau biomarkers and structural MRI brain measures in FTLD.

METHODS

We included early FTLD patient. All included patients underwent lumbar puncture to evaluate amyloid, total-tau (t-tau), phospho-tau 181 (p-tau); p-tau/t-tau ratio was also calculated; brain MRI was performed to estimate whole brain volume, volume of principal deep grey matter structures and regional cortical thickness.

RESULTS

Demographic characteristics of the 28 included patients were as follows: female/male: 9/19; mean ± SD age: 68.1 ± 7.8 years. The p-tau/t-tau ratio was significantly correlated with whole brain volume (r = 0.69; p: 0.001), left putamen volume (r = 0.55 p: 0.009), left pallidum volume (r = 0.41; p: 0.01), right accumbens area (r = 0.47; p: 0.02). P-tau/t tau ratio showed also a significant correlation with cortical thickness of left temporal lobe (r = 0.74; p: 0.001) and right lateral orbital frontal cortex (r = 0.45; p: 0.03). Linear regression showed a significant relationship between p-tau/t-tau ratio and left temporal pole (p = 0.01; r²: 0.60) and brain volume (p:0.002; r²: 0.56) after controlling for age and gender.

CONCLUSIONS

Our data suggest that CSF biomarkers, especially p-tau/t-tau ratio, could play a role as prognostic factor in FTLD. Further longitudinal investigations are needed to confirm these findings.

CSF p-tau as a potential cognition impairment biomarker in ALS

Background

Cerebrospinal fluid (CSF) and serum tau (t-tau, p-tau) are potential biomarkers for neurodegeneration in Alzheimer disease (AD), but their role in amyotrophic lateral sclerosis (ALS) is unclear.

Objectives

The aim of our study was to evaluate CSF and serum p-tau and t-tau in patients with ALS and to analyze the correlation and clinical parameters between them.

Methods

CSF and serum samples were obtained from 90 patients with ALS, 48 other neurological disease (OND), and 20 with AM (ALS mimic, AM) diseases. The levels of p-tau and t-tau in the CSF and serum were assessed with an enzyme-linked immunosorbent assay, and disease progression parameters, including the duration, the ALSFRS-R score, disease progression rate (DPR), the upper motor neuron (UMN) score, the Mini-mental State Examination (MMSE) score, the Montreal Cognitive Assessment (MoCA) score, and the Edinburgh Cognitive and Behavioral ALS Screen (ECAS) results, were analyzed by registered neurologists. Statistical analyses were performed using Prism software.

Results

Compared with controls, patients with ALS displayed significantly lower levels of CSF p-tau and p-tau:t-tau ratio. The CSF p-tau level in patients with ALS and cognition impairment was higher than that in patients with ALS who did not have cognition impairment. CSF p-tau level was negatively correlated with MMSE, MoCA, and ECAS total score and the specific score of ECAS in patients with ALS and cognition impairment.

Conclusions

The CSF p-tau level and p-tau:t-tau ratio were lower in patients with ALS than patients with OND and AM. Results suggest that CSF p-tau may be used as an index of cognition impairment in patients with ALS.

Elevated Plasma Phosphorylated Tau 181 in Amyotrophic Lateral Sclerosis

OBJECTIVE

Plasma phosphorylated tau (p-tau181 ) is reliably elevated in Alzheimer's disease (AD), but less explored is its specificity relative to other neurodegenerative conditions. Here, we find novel evidence that plasma p-tau181 is elevated in amyotrophic lateral sclerosis (ALS), a neurodegenerative condition typically lacking tau pathology. We performed a detailed evaluation to identify the clinical correlates of elevated p-tau181 in ALS.

METHODS

Patients were clinically or pathologically diagnosed with ALS (n = 130) or AD (n = 79), or were healthy non-impaired controls (n = 26). Receiver operating characteristic (ROC) curves were analyzed and area under the curve (AUC) was used to discriminate AD from ALS. Within ALS, Mann-Whitney-Wilcoxon tests compared analytes by presence/absence of upper motor neuron and lower motor neuron (LMN) signs. Spearman correlations tested associations between plasma p-tau181 and postmortem neuron loss.

RESULTS

A Wilcoxon test showed plasma p-tau181 was higher in ALS than controls (W = 2,600, p = 0.000015), and ROC analyses showed plasma p-tau181 poorly discriminated AD and ALS (AUC = 0.60). In ALS, elevated plasma p-tau181 was associated with LMN signs in cervical (W = 827, p = 0.0072), thoracic (W = 469, p = 0.00025), and lumbosacral regions (W = 851, p = 0.0000029). In support of LMN findings, plasma p-tau181 was associated with neuron loss in the spinal cord (rho = 0.46, p = 0.017), but not in the motor cortex (p = 0.41). Cerebrospinal spinal fluid p-tau181 and plasma neurofilament light chain were included as reference analytes, and demonstrate specificity of findings.

INTERPRETATION

We found strong evidence that plasma p-tau181 is elevated in ALS and may be a novel marker specific to LMN dysfunction. ANN NEUROL 2022;92:807-818.

Distinguishing Frontotemporal Lobar Degeneration Tau From TDP-43 Using Plasma Biomarkers

Importance

Biomarkers are lacking that can discriminate frontotemporal lobar degeneration (FTLD) associated with tau (FTLD-tau) or TDP-43 (FTLD-TDP).

Objective

To test whether plasma biomarkers glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), or their ratio (GFAP/NfL) differ between FTLD-tau and FTLD-TDP.

Design, Setting, and Participants

This retrospective cross-sectional study included data from 2009 to 2020 from the University of Pennsylvania Integrated Neurodegenerative Disease Database, with a median (IQR) follow-up duration of 2 (0.3-4.2) years. The training sample was composed of patients with autopsy-confirmed and familial FTLD; nonimpaired controls were included as a reference group. The independent validation sample included patients with FTD with a clinical diagnosis of progressive supranuclear palsy syndrome (PSPS) associated with tau (PSPS-tau) or amytrophic lateral sclerosis (ALS) associated with TDP-43 (ALS-TDP). In patients with FTLD with autopsy-confirmed or variant-confirmed pathology, receiver operating characteristic (ROC) curves tested the GFAP/NfL ratio and established a pathology-confirmed cut point. The cut point was validated in an independent sample of patients with clinical frontotemporal dementia (FTD). Data were analyzed from February to July 2022.

Exposures

Clinical, postmortem histopathological assessments, and plasma collection.

Main Outcomes and Measures

ROC and area under the ROC curve (AUC) with 90% CIs evaluated discrimination of pure FTLD-tau from pure FTLD-TDP using plasma GFAP/NfL ratio; the Youden index established optimal cut points. Sensitivity and specificity of cut points were assessed in an independent validation sample.

Results

Of 349 participants with available plasma data, 234 met inclusion criteria (31 controls, 141 in the training sample, and 62 in the validation sample). In the training sample, patients with FTLD-tau were older than patients with FTLD-TDP (FTLD-tau: n = 46; mean [SD] age, 65.8 [8.29] years; FTLD-TDP: n = 95; mean [SD] age, 62.3 [7.82] years; t84.6 = 2.45; mean difference, 3.57; 95% CI, 0.67-6.48; P = .02) but with similar sex distribution (FTLD-tau: 27 of 46 [59%] were male; FTLD-TDP: 51 of 95 [54%] were male; χ21 = 0.14; P = .70). In the validation sample, patients with PSPS-tau were older than those with ALS-TDP (PSPS-tau: n = 31; mean [SD] age, 69.3 [7.35] years; ALS-TDP: n = 31; mean [SD] age, 54.6 [10.17] years; t54.6 = 6.53; mean difference, 14.71; 95% CI, 10.19-19.23; P < .001) and had fewer patients who were male (PSPS-tau: 9 of 31 [29%] were male; ALS-TDP: 22 of 31 [71%] were male; χ21 = 9.3; P = .002). ROC revealed excellent discrimination of FTLD-tau from FTLD-TDP by plasma GFAP/NfL ratio (AUC = 0.89; 90% CI, 0.82-0.95; sensitivity = 0.73; 90% CI, 0.65-0.89; specificity = 0.89; 90% CI, 0.78-0.98), which was higher than either GFAP level alone (AUC = 0.65; 90% CI, 0.54-0.76) or NfL levels alone (AUC = 0.75; 90% CI, 0.64-0.85). In the validation sample, there was sensitivity of 0.84 (90% CI, 0.66-0.94) and specificity of 0.81 (90% CI, 0.62-0.91) when applying the autopsy-derived plasma GFAP/NfL threshold.

Conclusions and Relevance

The plasma ratio of GFAP/NfL may discriminate FTLD-tau from FTLD-TDP.

Herbal medicine for amyotrophic lateral sclerosis: A systematic review and meta-analysis

Background: The effect of herbal medicine (HM) on amyotrophic lateral sclerosis (ALS) is controversial. Clinical trials investigating HMs continue; however, the use of HM is still questioned. We aimed to systematically review the literature pertaining to the effects and safety of HM in ALS.

Methods: Randomised controlled trials (RCTs) that investigated the efficacy of HMs in ALS patients compared to any types of controls were identified. Nine databases and six registers were searched from their inception dates to 25 March 2022. Per the PRISMA guidelines, trials were identified and extracted. The risk of bias was evaluated using the Cochrane’s tool. Certainty of evidence was assessed as per the GRADE criteria. Forest plots were constructed to assess the effect size and corresponding 95% CIs using fixed-effect models, and random-effect models were employed when required. The primary outcome was the activity limitation measured by validated tools, such as the revised ALS Functional Rating Scale.

Results: Twenty studies (N = 1,218) were eligible. Of these, only five studies were double-blinded, and two were placebo-controlled. Fourteen HMs (fifty-one single botanicals) were involved; Astragalus mongholicus Bunge, Atractylodes macrocephala Koidz., and Glycyrrhiza glabra L. were commonly used in nine, eight, and six trials, respectively. For delaying activity limitation, Jiweiling injection (MD, 2.84; 95% CI, 1.21 to 4.46; p = 0.0006) and Shenmai injection (SMD, 1.07; 0.69 to 1.45; p < 0.00001) were significantly more efficacious than Riluzole, but the evidence was low quality. For ameliorating motor neuron loss, Jiweiling injection [right abductor pollicis brevis (APB): MD, 32.42; 7.91 to 56.93; p = 0.01 and left APB: MD, 34.44; 12.85 to 56.03; p = 0.002] was favoured, but the evidence was very low quality. Nine studies reported one hundred and twenty-three adverse events, twenty-six of which occurred in the treatment groups and ninety-seven in the control groups.

Conclusion: Very low to low quality of evidence suggests that HMs seem to produce superior treatment responses for ALS without increased risk of adverse events. Additional studies with homogeneous participants, reduced methodological issues, and more efficient outcome measures are required to provide confirmatory evidence.

Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42021277443.

Integrated evaluation of a panel of neurochemical biomarkers to optimize diagnosis and prognosis in amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

This study was undertaken to determine the diagnostic and prognostic value of a panel of serum biomarkers and to correlate their concentrations with several clinical parameters in a large cohort of patients with amyotrophic lateral sclerosis (ALS).

METHODS

One hundred forty-three consecutive patients with ALS and a control cohort consisting of 70 patients with other neurodegenerative disorders (DEG), 70 patients with ALS mimic disorders (ALSmd), and 45 healthy controls (HC) were included. Serum neurofilament light chain (NfL), ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1), glial fibrillary acidic protein (GFAP), and total tau protein levels were measured using ultrasensitive single molecule array.

RESULTS

NfL correlated with disease progression rate (p < 0.001) and with the measures of upper motor neuron burden (p < 0.001). NfL was higher in the ALS patients with classic and pyramidal phenotype. GFAP was raised in ALS with cognitive-behavioral impairment compared with ALS with normal cognition. NfL displayed the best diagnostic performance in discriminating ALS from HC (area under the curve [AUC] = 0.990), DEG (AUC = 0.946), and ALSmd (AUC = 0.850). UCHL1 performed well in distinguishing ALS from HC (AUC = 0.761), whereas it was not helpful in differentiating ALS from DEG and ALSmd. In multivariate analysis, NfL (p < 0.001) and UCHL1 (p = 0.038) were independent prognostic factors. Survival analysis combining NfL and UCHL1 effectively stratified patients with lower NfL levels (p < 0.001).

CONCLUSIONS

NfL is a useful biomarker for the diagnosis of ALS and the strongest predictor of survival. UCHL1 is an independent prognostic factor helpful in stratifying survival in patients with low NfL levels, likely to have slowly progressive disease. GFAP reflects extramotor involvement, namely cognitive impairment or frontotemporal dementia.

Cerebrospinal fluid biomarkers of disease activity and progression in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a relentlessly progressive neurodegenerative disease, and only modest disease-modifying strategies have been established to date. Numerous clinical trials have been conducted in the past years, but have been severely hampered by the wide-ranging heterogeneity of both the biological origins and clinical characteristics of the disease. Thus, reliable biomarkers of disease activity are urgently needed to stratify patients into homogenous groups with aligned disease trajectories to allow a more effective design of clinical trial. In this review, the most promising candidate biomarkers in the cerebrospinal fluid (CSF) of patients with ALS will be summarised. Correlations between biomarker levels and clinical outcome parameters are discussed, while highlighting potential pitfalls and intercorrelations of these clinical parameters. Several CSF molecules have shown potential as biomarkers of progression and prognosis, but large, international, multicentric and longitudinal studies are crucial for validation. A more standardised choice of clinical endpoints in these studies, as well as the application of individualised models of clinical progression, would allow the quantification of disease trajectories, thereby allowing a more accurate analysis of the clinical implications of candidate biomarkers. Additionally, a comparative analysis of several biomarkers and ideally the application of a multivariate analysis including comprehensive genotypic, phenotypic and clinical characteristics collectively contributing to biomarker levels in the CSF, could promote their verification. Thus, reliable prognostic markers and markers of disease activity may improve clinical trial design and patient management in the direction of precision medicine.

The Role of Tau beyond Alzheimer’s Disease: A Narrative Review

Nowadays, there is a need for reliable fluid biomarkers to improve differential diagnosis, prognosis, and the prediction of treatment response, particularly in the management of neurogenerative diseases that display an extreme variability in clinical phenotypes. In recent years, Tau protein has been progressively recognized as a valuable neuronal biomarker in several neurological conditions, not only Alzheimer’s disease (AD). Cerebrospinal fluid and serum Tau have been extensively investigated in several neurodegenerative disorders, from classically defined proteinopathy, e.g., amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Parkinson’s disease (PD), but also in inflammatory conditions such as multiple sclerosis (MS), as a marker of axonal damage. In MS, total Tau (t-Tau) may represent, along with other proteins, a marker with diagnostic and prognostic value. In ALS, t-Tau and, mainly, the phosphorylated-Tau/t-Tau ratio alone or integrated with transactive DNA binding protein of ~43 kDa (TDP-43), may represent a tool for both diagnosis and differential diagnosis of other motoneuron diseases or tauopathies. Evidence indicated the crucial role of the Tau protein in the pathogenesis of PD and other parkinsonian disorders. This narrative review summarizes current knowledge regarding non-AD neurodegenerative diseases and the Tau protein.

Biomarker discovery and development for frontotemporal dementia and amyotrophic lateral sclerosis

Frontotemporal dementia refers to a group of neurodegenerative disorders characterized by behaviour and language alterations and focal brain atrophy. Amyotrophic lateral sclerosis is a rapidly progressing neurodegenerative disease characterized by loss of motor neurons resulting in muscle wasting and paralysis. Frontotemporal dementia and amyotrophic lateral sclerosis are considered to exist on a disease spectrum given substantial overlap of genetic and molecular signatures. The predominant genetic abnormality in both frontotemporal dementia and amyotrophic lateral sclerosis is an expanded hexanucleotide repeat sequence in the C9orf72 gene. In terms of brain pathology, abnormal aggregates of TAR-DNA-binding protein-43 are predominantly present in frontotemporal dementia and amyotrophic lateral sclerosis patients. Currently, sensitive and specific diagnostic and disease surveillance biomarkers are lacking for both diseases. This has impeded the capacity to monitor disease progression during life and the development of targeted drug therapies for the two diseases. The purpose of this review is to examine the status of current biofluid biomarker discovery and development in frontotemporal dementia and amyotrophic lateral sclerosis. The major pathogenic proteins implicated in different frontotemporal dementia and amyotrophic lateral sclerosis molecular subtypes and proteins associated with neurodegeneration and the immune system will be discussed. Furthermore, the use of mass spectrometry-based proteomics as an emerging tool to identify new biomarkers in frontotemporal dementia and amyotrophic lateral sclerosis will be summarized.

Pathophysiological Underpinnings of Extra-Motor Neurodegeneration in Amyotrophic Lateral Sclerosis: New Insights From Biomarker Studies

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) lie at opposing ends of a clinical, genetic, and neuropathological continuum. In the last decade, it has become clear that cognitive and behavioral changes in patients with ALS are more frequent than previously recognized. Significantly, these non-motor features can impact the diagnosis, prognosis, and management of ALS. Partially overlapping neuropathological staging systems have been proposed to describe the distribution of TAR DNA-binding protein 43 (TDP-43) aggregates outside the corticospinal tract. However, the relationship between TDP-43 inclusions and neurodegeneration is not absolute and other pathophysiological processes, such as neuroinflammation (with a prominent role of microglia), cortical hyperexcitability, and synaptic dysfunction also play a central role in ALS pathophysiology. In the last decade, imaging and biofluid biomarker studies have revealed important insights into the pathophysiological underpinnings of extra-motor neurodegeneration in the ALS-FTLD continuum. In this review, we first summarize the clinical and pathophysiological correlates of extra-motor neurodegeneration in ALS. Next, we discuss the diagnostic and prognostic value of biomarkers in ALS and their potential to characterize extra-motor neurodegeneration. Finally, we debate about how biomarkers could improve the diagnosis and classification of ALS. Emerging imaging biomarkers of extra-motor neurodegeneration that enable the monitoring of disease progression are particularly promising. In addition, a growing arsenal of biofluid biomarkers linked to neurodegeneration and neuroinflammation are improving the diagnostic accuracy and identification of patients with a faster progression rate. The development and validation of biomarkers that detect the pathological aggregates of TDP-43 in vivo are notably expected to further elucidate the pathophysiological underpinnings of extra-motor neurodegeneration in ALS. Novel biomarkers tracking the different aspects of ALS pathophysiology are paving the way to precision medicine approaches in the ALS-FTLD continuum. These are essential steps to improve the diagnosis and staging of ALS and the design of clinical trials testing novel disease-modifying treatments.

Amyotrophic lateral sclerosis: Correlations between fluid biomarkers of NfL, TDP-43, and tau, and clinical characteristics

OBJECTIVES

We previously reported the diagnostic and prognostic performance of neurofilament light chain (NfL), TAR DNA-binding protein 43 (TDP-43), and total tau (t-tau) in cerebrospinal fluid (CSF) and plasma as amyotrophic lateral sclerosis (ALS) biomarkers. The present study aimed to elucidate associations between clinical characteristics and the markers as well as mutual associations of the markers in ALS patients using the same dataset.

METHODS

NfL, TDP-43, and t-tau levels in CSF and plasma in 75 ALS patients were analyzed. The associations between those markers and clinical details were investigated by uni- and multivariate analyses. Correlations between the markers were analyzed univariately.

RESULTS

In multivariate analysis of CSF proteins, the disease progression rate (DPR) was positively correlated with NfL (β: 0.51, p = 0.007) and t-tau (β: 0.37, p = 0.03). Plasma NfL was correlated with age (β: 0.53, p = 0.005) and diagnostic grade (β: -0.42, p = 0.02) in multivariate analysis. Plasma TDP-43 was correlated negatively with split hand index (β: -0.48, p = 0.04) and positively with % vital capacity (β: 0.64, p = 0.03) in multivariate analysis. Regarding mutual biomarker analysis, a negative correlation between CSF-NfL and TDP-43 was identified (r: -0.36, p = 0.002).

CONCLUSIONS

Elevated NfL and t-tau levels in CSF may be biomarkers to predict rapid DPR from onset to sample collection. The negative relationship between CSF NfL and TDP-43 suggests that elevation of CSF TDP-43 in ALS is not a simple consequence of its release into CSF during neurodegeneration. The negative correlation between plasma TDP-43 and split hand index may support the pathophysiological association between plasma TDP-43 and ALS.

Novel genetic variants in MAPT and alterations in tau phosphorylation in amyotrophic lateral sclerosis post-mortem motor cortex and cerebrospinal fluid

Although the molecular mechanisms underlying amyotrophic lateral sclerosis (ALS) are not yet fully understood, several studies report alterations in tau phosphorylation in both sporadic and familial ALS. Recently, we have demonstrated that phosphorylated tau at S396 (pTau‐S396) is mislocalized to synapses in ALS motor cortex (mCTX) and contributes to mitochondrial dysfunction. Here, we demonstrate that while there was no overall increase in total tau, pTau‐S396, and pTau‐S404 in ALS post‐mortem mCTX, total tau and pTau‐S396 were increased in C9ORF72‐ALS. Additionally, there was a significant decrease in pTau‐T181 in ALS mCTX compared controls. Furthermore, we leveraged the ALS Knowledge Portal and Project MinE data sets and identified ALS‐specific genetic variants across MAPT, the gene encoding tau. Lastly, assessment of cerebrospinal fluid (CSF) samples revealed a significant increase in total tau levels in bulbar‐onset ALS together with a decrease in CSF pTau‐T181:tau ratio in all ALS samples, as reported previously. While increases in CSF tau levels correlated with a faster disease progression as measured by the revised ALS functional rating scale (ALSFRS‐R), decreases in CSF pTau‐T181:tau ratio correlated with a slower disease progression, suggesting that CSF total tau and pTau‐T181 ratio may serve as biomarkers of disease in ALS. Our findings highlight the potential role of pTau‐T181 in ALS, as decreases in CSF pTau‐T181:tau ratio may reflect the significant decrease in pTau‐T181 in post‐mortem mCTX. Taken together, these results indicate that tau phosphorylation is altered in ALS post‐mortem mCTX as well as in CSF and, importantly, the newly described pathogenic or likely pathogenic variants identified in MAPT in this study are adjacent to T181 and S396 phosphorylation sites further highlighting the potential role of these tau functional domains in ALS.

Although the molecular mechanisms underlying amyotrophic lateral sclerosis (ALS) are not yet fully understood, recent studies report alterations in tau phosphorylation in ALS. Our study builds on these findings and demonstrates that tau phosphorylation is altered in post‐mortem ALS motor cortex and highlights new and ALS‐specific variants in MAPT, the gene encoding tau. Lastly, we report alterations in phosphorylated tau in ALS cerebrospinal fluid that may function as a predictive biomarker for ALS.

Tau protein as a diagnostic and prognostic biomarker in amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

To test the hypothesis that total tau (tTau), tau phosphorylated at threonine 181 (pTau) and pTau/tTau ratio in the cerebrospinal fluid (CSF) are diagnostic and prognostic biomarkers of amyotrophic lateral sclerosis (ALS), we performed a retrospective observational study in a large cohort of ALS patients and controls.

METHODS

We enrolled 196 ALS patients and 91 controls, who included patients with ALS-mimicking diseases and those with non-neurodegenerative diseases. All patients underwent lumbar puncture for CSF analysis at the time of the diagnostic evaluation or to first referral. We measured tTau and pTau levels in the CSF by chemiluminescence enzyme immunoassay.

RESULTS

Patients with ALS showed significantly higher levels of CSF tTau and a lower pTau/tTau ratio than controls (tTau: 245 vs. 146 pg/ml; p < 0.001; pTau/tTau ratio: 0.12 vs. 0.18; p < 0.001, respectively). No differences in pTau levels were detected. Receiver-operating characteristic curve analysis showed a good diagnostic accuracy of tTau and pTau/tTau ratio (tTau: area under the curve [AUC] 0.685, 95% confidence interval [CI] 0.616-0.754, p = 0.039; pTau/tTau ratio: AUC 0.777, 95% CI 0.707-0.848, p < 0.001). Among ALS patients, increased tTau levels were associated with advanced age of onset, increased revised amyotrophic lateral sclerosis functional rating scale (ALSFRS-R) score (ΔFS) rate of progression, and spinal onset. Multivariate analysis showed that in ALS patients, this biomarker was an independent negative predictor of overall survival.

CONCLUSIONS

Our findings suggest that tTau and pTau/tTau ratio can be diagnostic biomarkers of ALS. In addition, CSF tTau level at diagnosis might play a relevant prognostic role in the disease.

Prognostic Role of CSF β-amyloid 1-42/1-40 Ratio in Patients Affected by Amyotrophic Lateral Sclerosis

The involvement of β-amyloid (Aβ) in the pathogenesis of amyotrophic lateral sclerosis (ALS) has been widely discussed and its role in the disease is still a matter of debate. Aβ accumulates in the cortex and the anterior horn neurons of ALS patients and seems to affect their survival. To clarify the role of cerebrospinal fluid (CSF) Aβ 1–42 and Aβ 42/40 ratios as a potential prognostic biomarker for ALS, we performed a retrospective observational study on a cohort of ALS patients who underwent a lumbar puncture at the time of the diagnosis. CSF Aβ 1–40 and Aβ 1–42 ratios were detected by chemiluminescence immunoassay and their values were correlated with clinical features. We found a significant correlation of the Aβ 42/40 ratio with age at onset and Mini Mental State Examination (MMSE) scores. No significant correlation of Aβ 1–42 or Aβ 42/40 ratios to the rate of progression of the disease were found. Furthermore, when we stratified patients according to Aβ 1–42 concentration and the Aβ 42/40 ratio, we found that patients with a lower Aβ 42/40 ratio showed a shorter survival. Our results support the hypothesis that Aβ 1–42 could be involved in some pathogenic mechanism of ALS and we suggest the Aβ 42/40 ratio as a potential prognostic biomarker.

Plasma Tau and Neurofilament Light in Frontotemporal Lobar Degeneration and Alzheimer Disease

OBJECTIVE

To test the hypothesis that plasma total tau (t-tau) and neurofilament light chain (NfL) concentrations may have a differential role in the study of frontotemporal lobar degeneration syndromes (FTLD-S) and clinically diagnosed Alzheimer disease syndromes (AD-S), we determined their diagnostic and prognostic value in FTLD-S and AD-S and their sensitivity to pathologic diagnoses.

METHODS

We measured plasma t-tau and NfL with the Simoa platform in 265 participants: 167 FTLD-S, 43 AD-S, and 55 healthy controls (HC), including 82 pathology-proven cases (50 FTLD-tau, 18 FTLD-TDP, 2 FTLD-FUS, and 12 AD) and 98 participants with amyloid PET. We compared cross-sectional and longitudinal biomarker concentrations between groups, their correlation with clinical measures of disease severity, progression, and survival, and cortical thickness.

RESULTS

Plasma NfL, but not plasma t-tau, discriminated FTLD-S from HC and AD-S from HC. Both plasma NfL and t-tau were poor discriminators between FLTD-S and AD-S. In pathology-confirmed cases, plasma NfL was higher in FTLD than AD and in FTLD-TDP compared to FTLD-tau, after accounting for age and disease severity. Plasma NfL, but not plasma t-tau, predicted clinical decline and survival and correlated with regional cortical thickness in both FTLD-S and AD-S. The combination of plasma NfL with plasma t-tau did not outperform plasma NfL alone.

CONCLUSION

Plasma NfL is superior to plasma t-tau for the diagnosis and prediction of clinical progression of FTLD-S and AD-S.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that plasma NfL has superior diagnostic and prognostic performance vs plasma t-tau in FTLD and AD.

Aβ1-42 and Tau as Potential Biomarkers for Diagnosis and Prognosis of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease, but its definitive diagnosis delays around 12 months. Although the research is highly active in the biomarker field, the absence of specific biomarkers for diagnosis contributes to this long delay. Another strategy of biomarker identification based on less specific but sensitive molecules may be of interest in clinical practice. For example, markers related to other neurodegenerative diseases such as Alzheimer's disease (AD) could be fully explored. Here, we compared baseline levels of amyloidβ1-42 (Aβ1-42), total Tau, and phosphorylated-Tau (phospho-Tau) protein in the cerebrospinal fluid (CSF) of ALS patients to controls and correlated it with clinical parameters of ALS progression collected over 12 months. We observed increased levels of Aβ1-42 (controls: 992.9 ± 358.3 ng/L; ALS: 1277.0 ± 296.6 ng/L; p < 0.0001) and increased Aβ1-42/phospho-Tau ratio and Innotest Amyloid Tau Index (IATI) (both p < 0.0001). IATI and the phospho-Tau/total Tau ratio correlated positively with ALSFRS-R and weight at baseline. Multivariate analysis revealed that baseline ALSFRS-R was associated with Aβ1-42 and phospho-Tau/total Tau ratio (p = 0.0109 and p = 0.0013, respectively). Total Tau and phospho-Tau levels correlated negatively with ALSFRS-R variation at months 6 and 9, respectively (p = 0.02 and p = 0.04, respectively). Phospho-Tau/total Tau ratio correlated positively with ALSFRS-R variation at month 9 (p = 0.04). CSF levels of Aβ1-42 could be used as a complementary tool to ALS diagnosis, and total Tau and phospho-Tau levels may help establishing the prognosis of ALS. Further studies merit exploring the pathophysiological mechanisms associated with these markers. Despite their lack of specificity, phospho-Tau/total Tau and Aβ1-42 should be combined to other biological and clinical markers in order to improve ALS management.

Brain Ventricular System and Cerebrospinal Fluid Development and Function: Light at the End of the Tube: A Primer with Latest Insights

The brain ventricular system is a series of connected cavities, filled with cerebrospinal fluid (CSF), that forms within the vertebrate central nervous system (CNS). The hollow neural tube is a hallmark of the chordate CNS, and a closed neural tube is essential for normal development. Development and function of the ventricular system is examined, emphasizing three interdigitating components that form a functional system: ventricle walls, CSF fluid properties, and activity of CSF constituent factors. The cellular lining of the ventricle both can produce and is responsive to CSF. Fluid properties and conserved CSF components contribute to normal CNS development. Anomalies of the CSF/ventricular system serve as diagnostics and may cause CNS disorders, further highlighting their importance. This review focuses on the evolution and development of the brain ventricular system, associated function, and connected pathologies. It is geared as an introduction for scholars with little background in the field.

Neurofilament Light Chain as a Biomarker, and Correlation with Magnetic Resonance Imaging in Diagnosis of CNS-Related Disorders

The search for diagnostic and prognostic biomarkers for neurodegenerative conditions is of high importance, since these disorders may present difficulties in differential diagnosis. Biomarkers with high sensitivity and specificity are required. Neurofilament light chain (NfL) is a unique biomarker related to axonal damage and neural cell death, which is elevated in a number of neurological disorders, and can be detected in cerebrospinal fluid (CSF), as well as blood, serum, or plasma samples. Although the NfL concentration in CSF is higher than that in blood, blood measurement may be easier in practice due to its lesser invasiveness, reproducibility, and convenience. Many studies have investigated NfL in both CSF and serum/plasma as a potential biomarker of neurodegenerative disorders. Neuroimaging biomarkers can also potentially improve detection of CNS-related disorders at an early stage. Magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) are sensitive techniques to visualize neuroaxonal loss. Therefore, investigating the combination of NfL levels with indices extracted from MRI and DTI scans could potentially improve diagnosis of CNS-related disorders. This review summarizes the evidence for NfL being a reliable biomarker in the early detection and disease management in several CNS-related disorders. Moreover, we highlight the correlation between MRI and NfL and ask whether they can be combined.

Proteomics in cerebrospinal fluid and spinal cord suggests UCHL1, MAP2 and GPNMB as biomarkers and underpins importance of transcriptional pathways in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease and the proteins and pathways involved in the pathophysiology are not fully understood. Even less is known about the preclinical disease phase. To uncover new ALS-related proteins and pathways, we performed a comparative proteomic analysis in cerebrospinal fluid (CSF) of asymptomatic (n = 14) and symptomatic (n = 14) ALS mutation carriers and sporadic ALS patients (n = 12) as well as post-mortem human spinal cord tissue (controls: n = 7, ALS, n = 8). Using a CSF-optimized proteomic workflow, we identified novel (e.g., UCHL1, MAP2, CAPG, GPNMB, HIST1H4A, HIST1H2B) and well-described (e.g., NEFL, NEFH, NEFM, CHIT1, CHI3L1) protein level changes in CSF of sporadic and genetic ALS patients with enrichment of proteins related to transcription, cell cycle and lipoprotein remodeling (total protein IDs: 2303). No significant alteration was observed in asymptomatic ALS mutation carriers representing the prodromal disease phase. We confirmed UCHL1, MAP2, CAPG and GPNMB as novel biomarker candidates for ALS in an independent validation cohort of patients (n = 117) using multiple reaction monitoring. In spinal cord tissue, 292 out of 6810 identified proteins were significantly changed in ALS with enrichment of proteins involved in mRNA splicing and of the neurofilament compartment. In conclusion, our proteomic data in asymptomatic ALS mutation carriers support the hypothesis of a sudden disease onset instead of a long preclinical phase. Both CSF and tissue proteomic data indicate transcriptional pathways to be amongst the most affected. UCHL1, MAP2 and GPNMB are promising ALS biomarker candidates which might provide additional value to the established neurofilaments in patient follow-up and clinical trials.

Interactive Effects of Racial Identity and Repetitive Head Impacts on Cognitive Function, Structural MRI-Derived Volumetric Measures, and Cerebrospinal Fluid Tau and Aβ

BACKGROUND

Factors of increased prevalence among individuals with Black racial identity (e.g., cardiovascular disease, CVD) may influence the association between exposure to repetitive head impacts (RHI) from American football and later-life neurological outcomes. Here, we tested the interaction between racial identity and RHI on neurobehavioral outcomes, brain volumetric measures, and cerebrospinal fluid (CSF) total tau (t-tau), phosphorylated tau (p-tau181), and Aβ1 - 42 in symptomatic former National Football League (NFL) players.

METHODS

68 symptomatic male former NFL players (ages 40-69; n = 27 Black, n = 41 White) underwent neuropsychological testing, structural MRI, and lumbar puncture. FreeSurfer derived estimated intracranial volume (eICV), gray matter volume (GMV), white matter volume (WMV), subcortical GMV, hippocampal volume, and white matter (WM) hypointensities. Multivariate generalized linear models examined the main effects of racial identity and its interaction with a cumulative head impact index (CHII) on all outcomes. Age, years of education, Wide Range Achievement Test, Fourth Edition (WRAT-4) scores, CVD risk factors, and APOEε4 were included as covariates; eICV was included for MRI models. P-values were false discovery rate adjusted.

RESULTS

Compared to White former NFL players, Black participants were 4 years younger (p = 0.04), had lower WRAT-4 scores (mean difference = 8.03, p = 0.002), and a higher BMI (mean difference = 3.09, p = 0.01) and systolic blood pressure (mean difference = 8.15, p = 0.03). With regards to group differences on the basis of racial identity, compared to White former NFL players, Black participants had lower GMV (mean adjusted difference = 45649.00, p = 0.001), lower right hippocampal volume (mean adjusted difference = 271.96, p = 0.02), and higher p-tau181/t-tau ratio (mean adjusted difference = -0.25, p = 0.01). There was not a statistically significant association between the CHII with GMV, right hippocampal volume, or p-tau181/t-tau ratio. However, there was a statistically significant Race x CHII interaction for GMV (b = 2206.29, p = 0.001), right hippocampal volume (b = 12.07, p = 0.04), and p-tau181/t-tau ratio concentrations (b = -0.01, p = 0.004).

CONCLUSION

Continued research on racial neurological disparities could provide insight into risk factors for long-term neurological disorders associated with American football play.

Recent advances in understanding frontotemporal degeneration

Frontotemporal degeneration (FTD) is a heterogeneous spectrum of neurodegenerative disorders characterized by diverse clinical presentations, neuropathological characteristics, and underlying genetic causes. In the last few years, several advances in the knowledge of clinical and biological aspects have been accomplished and three major scenarios have emerged that will represent the core issues in the FTD scene over the next few years. Foremost, the development of cerebrospinal fluid and blood biomarkers as well as neuroimaging techniques will aid the pursuit of new diagnostic and prognostic markers able to identify the ongoing proteinopathy and predict disease progression, which is key in identifying and stratifying patients for enrolment in clinical trials as well as evaluating response to treatment. On the other hand, current research has focused on the first attempts to slow down or revert disease progression, with the identification of disease modulators associated with disease onset and the ongoing development of the first pharmacological treatments for both sporadic and genetic FTD. Future research will certainly improve our knowledge of FTD and possibly open up a new era of disease-modifying therapies for this still-orphan disorder.

Combined use of CSF NfL and CSF TDP-43 improves diagnostic performance in ALS

OBJECTIVE

To determine the diagnostic and prognostic significance of neurofilament light chain (NfL), TAR DNA-binding protein 43 (TDP-43), and total tau (t-tau) in cerebrospinal fluid (CSF) and plasma of patients with amyotrophic lateral sclerosis (ALS) and to investigate whether the combined use of those biomarker candidates can improve their diagnostic performance.

METHODS

This was a single-center, prospective, longitudinal study. CSF and plasma samples were collected at the time of enrollment from a discovery cohort of 29 patients with ALS and 29 age-matched controls without neurodegenerative disease. In a validation cohort, there were 46 patients with ALS, and 46 control (not age-matched) patients with motor weakness resulting from neuromuscular diseases. NfL, TDP-43, and t-tau levels in CSF and plasma were measured using ultrasensitive single molecule assay (Simoa) technology.

RESULTS

The following findings were reproducibly observed among the discovery and validation cohorts: increased levels of CSF NfL, plasma NfL, and CSF TDP-43 in ALS compared with control groups; shorter survival associated with higher levels of CSF and plasma NfL. When the CSF NfL and CSF TDP-43 levels were combined, the areas under the ROC curves (AUC) were slightly improved relative to AUCs for each biomarker alone.

INTERPRETATION

CSF and plasma NfL may not only serve as diagnostic biomarkers but also provide a measure of disease progression. CSF TDP-43 is also useful as a diagnostic biomarker of ALS, but has no prognostic value. The combined use of CSF NfL and CSF TDP-43 may be a useful biomarker for the diagnosis of ALS.

Abnormal trunk control determines postural abnormalities in Amyotrophic Lateral Sclerosis

BACKGROUND:

Postural instability in Amyotrophic Lateral Sclerosis (ALS) occurs at an early stage of the disease and often results in falls. As ALS is considered a multisystem neurodegenerative disorder, postural instability may result from motor, sensory and central processing deficits.

OBJECTIVE AND METHODS:

We analysed postural control of 12 ALS patients and 12 healthy age-matched control subjects. Postural control was characterised by spontaneous sway measures and measures of postural reactions to pseudorandom anterior-posterior platform tilts, which were then correlated with clinical test scores.

RESULTS:

Spontaneous sway amplitudes and velocities were significantly larger and sway frequencies higher in ALS patients than in control subjects. ALS patients’ body excursions following platform tilts were smaller, with relatively higher upper body excursions. We found high correlations between abnormal postural reactions and clinical tests representing motor or balance deficits.

CONCLUSIONS:

We conclude that ALS patients’ postural abnormalities are mainly determined by an abnormal axial control and abnormally small body excursions as a function of support surface tilts, seemingly indicating better postural stabilization than control subjects. The latter contradicts the hypothesis that muscle weakness is the main source for this deficit. Instead, we suggest an altered central control strategy.

A 2-Step Cerebrospinal Algorithm for the Selection of Frontotemporal Lobar Degeneration Subtypes

Importance

Cerebrospinal fluid (CSF) core Alzheimer disease (AD) biomarkers have shown an excellent capacity for the in vivo detection of AD. Previous studies have shown that CSF levels of phosphorylated tau (p-tau) also correlate with tau pathology in frontotemporal lobar degeneration (FTLD) after accounting for AD copathology.

Objective

To develop an algorithm based on core AD CSF measures to exclude cases with AD pathology and then differentiate between FTLD-tau and FTLD transactive response DNA-binding protein of approximately 43kDa (FTLD-TDP).

Design, Setting, and Participants

A case-control study at the University of Pennsylvania. Participants were selected from a database of 1796 patients included between 1992 and 2016 with different neurodegenerative diseases with available CSF. Three patient cohorts were included: a cohort of patients with sporadic, autopsy-confirmed FTLD and AD (n = 143); a cohort of patients with frontotemporal degeneration (FTD) with TDP-associated or tau-associated mutations (n = 60); and a living cohort of patients with syndromes highly predictive of FTLD (progressive supranuclear palsy and FTD-amyotrophic lateral sclerosis; n = 62).

Main Outcomes and Measures

Cerebrospinal fluid values of amyloid β1-42 (Aβ1-42), total tau (t-tau), and p-tau obtained using the INNO-BIA AlzBio3 (xMAP; Luminex) assay or INNOTEST enzyme-linked immunosorbent assay transformed using a previously validated algorithm. Sensitivities and specificities for differentiating AD from FTLD groups were calculated.

Results

This autopsy cohort included FTLD-tau (n = 27; mean [SD] age at onset, 60.8 [9.7] years), FTLD-TDP (n = 13; mean [SD] age at onset, 62.4 [8.5] years), AD (n = 89, mean [SD] age at onset, 66.5 [9.7] years); and mixed FTLD-AD (n = 14, mean [SD] age at onset, 70.6 [8.5] years).The p-tau/Aβ1-42 ratio showed an excellent diagnostic accuracy to exclude AD cases in the autopsy cohort with single neurodegenerative pathologies (area under the curve [AUC], 0.98; 95% CI, 0.96-1.00). Cerebrospinal fluid p-tau levels showed a good AUC (0.87; 95% CI, 0.73-1.00) for discriminating pure FTLD-TDP from pure FTLD-tau. The application of an algorithm using cutpoints of CSF p-tau to Aβ1-42 ratio and p-tau allowed a good discrimination of pure FTLD-TDP cases from the remaining FTLD-tau and mixed FTLD cases. The diagnostic value of this algorithm was confirmed in an independent cohort of living patients with progressive supranuclear palsy and FTD-amyotrophic lateral sclerosis (AUC, 0.9; 95% CI, 0.81-0.99). However, the algorithm was less useful in FTD cases carrying a pathogenic mutation (AUC, 0.58; 95% CI, 0.38-0.77) owing to elevated p-tau levels in TDP-associated mutation carriers.

Conclusions and Relevance

Alzheimer disease CSF core biomarkers can be used with high specificity for the in vivo identification of patients with pure FTLD-TDP and FTLD-tau when accounting for comorbid AD and genetic status.

Linked CSF reduction of phosphorylated tau and IL-8 in HIV associated neurocognitive disorder

HIV-associated neurocognitive disorder (HAND) is a common condition in both developed and developing nations, but its cause is largely unknown. Previous research has inconsistently linked Alzheimer's disease (AD), viral burden, and inflammation to the onset of HAND in HIV-infected individuals. Here we simultaneously measured cerebrospinal fluid (CSF) levels of established amyloid and tau biomarkers for AD, viral copy numbers, and six key cytokines in 41 HIV-infected individuals off combination anti-retroviral therapy (14 with HAND) who underwent detailed clinical and neuropsychological characterization, and compared their CSF patterns with those from young healthy subjects, older healthy subjects with normal cognition, and older people with AD. HAND was associated with the lowest CSF levels of phosphorylated tau (p-Tau181) after accounting for age and race. We also found very high CSF levels of the pro-inflammatory interferon gamma-induced protein 10 (IP-10/CXCL10) in HIV regardless of cognition, but elevated CSF interleukin 8 (IL-8/CXCL8) only in HIV-NC but not HAND. Eleven HIV-infected subjects underwent repeat CSF collection six months later and showed strongly correlated longitudinal changes in p-Tau181 and IL-8 levels (R = 0.841). These data suggest reduced IL-8 relative to IP-10 and reduced p-Tau181 to characterize HAND.

Biomarkers for diseases with TDP-43 pathology

The discovery that aggregated transactive response DNA-binding protein 43 kDa (TDP-43) is the major component of pathological ubiquitinated inclusions in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) caused seminal progress in the unveiling of the genetic bases and molecular characteristics of these now so-called TDP-43 proteinopathies. Substantial increase in the knowledge of clinic-pathological coherencies, especially for FTLD variants, could be made in the last decade, but also revealed a considerable complexity of TDP-43 pathology and often a poor correlation of clinical and molecular disease characteristics. To date, an underlying TDP-43 pathology can be predicted only for patients with mutations in the genes C9orf72 and GRN, but is dependent on neuropathological verification in patients without family history, which represent the majority of cases. As etiology-specific therapies for neurodegenerative proteinopathies are emerging, methods to forecast TDP-43 pathology at patients' lifetime are highly required. Here, we review the current status of research pursued to identify specific indicators to predict or exclude TDP-43 pathology in the ALS-FTLD spectrum disorders and findings on candidates for prognosis and monitoring of disease progression in TDP-43 proteinopathies with a focus on TDP-43 with its pathological forms, neurochemical and imaging biomarkers.

Cerebrospinal fluid tau, Aβ, and sTREM2 in Former National Football League Players: Modeling the relationship between repetitive head impacts, microglial activation, and neurodegeneration

INTRODUCTION

Cerebrospinal fluid (CSF) protein analysis may facilitate detection and elucidate mechanisms of neurological consequences from repetitive head impacts (RHI), such as chronic traumatic encephalopathy. We examined CSF concentrations of total tau (t-tau), phosphorylated tau, and amyloid β1-42 and their association with RHI in former National Football League (NFL) players. The role of microglial activation (using sTREM2) was examined as a pathogenic mechanism of chronic traumatic encephalopathy.

METHODS

Sixty-eight former NFL players and 21 controls underwent lumbar puncture to quantify t-tau, p-tau181, amyloid β1-42, and sTREM2 in the CSF using immunoassays. The cumulative head impact index estimated RHI.

RESULTS

No between-group differences for CSF analytes emerged. In the former NFL players, the cumulative head impact index predicted higher t-tau concentrations (P = .041), and higher sTREM2 levels were associated with higher t-tau concentrations (P = .009).

DISCUSSION

In this sample of former NFL players, greater RHI and increased microglial activation were associated with higher CSF t-tau concentrations.

Diagnostic Performance of Neurofilaments in Chinese Patients With Amyotrophic Lateral Sclerosis: A Prospective Study

Several studies have attempted to reduce diagnostic delay and identify biomarkers for drug development in amyotrophic lateral sclerosis (ALS). In this study, we aimed to evaluate the diagnostic accuracy for ALS of cerebrospinal fluid (CSF) neurofilament (Nf), Tau protein, and inflammatory factors such as interleukin (IL)-2, IL-6, IL-10, IL-15, and granulocyte-macrophage colony-stimulating factor (GMCSF) in Chinese patients. Our prospective study measured the concentration of phosphorylated Nf heavy chain (pNfH), Nf light chain (NfL), Tau, pTau, and inflammatory factors in the CSF of 85 patients. Detailed clinical data and laboratory, neuroimaging, and neurophysiological findings were recorded. The concentrations of pNfH and NfL were higher in the ALS group than in the control group. At the 1104 pg/mL pNfH cutoff, the specificity was 68.8%, the sensitivity 100%, and the area under the curve (AUC) 0.907. At the 1,139 pg/mL NfL cutoff, the specificity was 56.3%, the sensitivity 96.2%, and the AUC 0.775. There was no significant difference in the concentrations of Tau, pTau, IL-2, IL-6, IL-10, IL-15, and GMCSF between the ALS and control groups (p > 0.05). In the ALS group, the concentration of pNfH in the CSF was correlated with disease duration (r = −0.475, p < 0.001). This is the first prospective study to confirm the diagnostic value of Nf for ALS in Chinese patients.

Diagnostic and prognostic power of CSF Tau in amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that still lacks reliable diagnostic biomarkers. This study aims to evaluate the diagnostic and prognostic potential of CSF total Tau (t-Tau), phospho-Tau (p-Tau) and p-Tau/t-Tau ratio in ALS patients using CSF neurofilament light (NFL) as the reference biomarker.

METHODS

Eighty-five incident ALS, 30 ALS-mimicking (AM) diseases and 51 other non-neurodegenerative diseases (ONND) were included in the study.

RESULTS

ALS patients had higher levels of CSF t-Tau and lower p-Tau/t-Tau ratio than AM (p = 0.005 and p = 0.006) and ONND (p < 0.001). CSF t-Tau levels discriminated ALS from AM with a sensitivity of 69% and specificity of 60%, and from ONND with a sensitivity of 88% and specificity of 51%. These values were lower than the accuracy of CSF NFL in ALS (sensitivity 86% and specificity 87% in distinguishing ALS from AM and sensitivity 83% and specificity 75% from ONND); CSF t-Tau correlated with progression rate and SNIP. CSF p-Tau did not show relation with any ALS clinical features. CSF NFL significantly correlated with all considered clinical parameters. High levels of CSF t-Tau and NFL were related to poor survival.

CONCLUSION

CSF t-Tau showed no reliable diagnostic significance but the relation between the high levels of CSF t-Tau and short survival suggests the potential prognostic role of this biomarker in ALS. However, CSF NFL was confirmed to be the most reliable and efficient tool for diagnosis and prediction of clinical progression and survival in ALS patients.

Pazopanib Reduces Phosphorylated Tau Levels and Alters Astrocytes in a Mouse Model of Tauopathy

Hyperphosphorylation and aggregation of tau protein is a critical factor in many neurodegenerative diseases. These diseases are increasing in prevalence, and there are currently no cures. Previous work from our group and others has shown that tyrosine kinase inhibitors (TKIs) can stimulate autophagy, decrease pathological proteins, and improve symptoms in models of neurodegeneration. Here we examined the role of pazopanib in mouse models that express either human mutant P301L tau (TauP301L) or triple mutant amyloid precursor protein (3x-AβPP). The TauP301L mouse expresses P301L tau under the control of a prion promoter in both neurons and astrocytes, reminiscent of some human tauopathies. Pazopanib crosses the blood-brain barrier with no detectable peripheral off-side effects, and decreases p-tau in TauP301L mice. Pazopanib reaches a brain concentration sufficient for inhibition of several tyrosine kinases, including vascular endothelial growth factor receptors (VEGFRs). Further, pazopanib does not affect microglia but reduces astrocyte levels toward nontransgenic controls in TauP301L mice. Pazopanib does not alter amyloid beta levels or astrocytes in 3x-AβPP mice but modulates a number of inflammatory markers (IP-10, MIP-1α, MIP-1β, and RANTES). These data suggest that pazopanib may be involved in p-tau clearance and modulation of astrocytic activity in models of tauopathies.

Emerging Diagnostic and Therapeutic Strategies for Tauopathies

PURPOSE OF REVIEW

Tauopathies represent a spectrum of incurable and progressive age-associated neurodegenerative diseases that currently are diagnosed definitively only at autopsy. Few clinical diagnoses, such as classic Richardson's syndrome of progressive supranuclear palsy, are specific for underlying tauopathy and no clinical syndrome is fully sensitive to reliably identify all forms of clinically manifest tauopathy. Thus, a major unmet need for the development and implementation of tau-targeted therapies is precise antemortem diagnosis. This article reviews new and emerging diagnostic therapies for tauopathies including novel imaging techniques and biomarkers and also reviews recent tau therapeutics.

RECENT FINDINGS

Building evidence from animal and cell models suggests that prion-like misfolding and propagation of pathogenic tau proteins between brain cells are central to the neurodegenerative process. These rapidly growing developments build rationale and motivation for the development of therapeutics targeting this mechanism through altering phosphorylation and other post-translational modifications of the tau protein, blocking aggregation and spread using small molecular compounds or immunotherapy and reducing or silencing expression of the MAPT tau gene. New clinical criteria, CSF, MRI, and PET biomarkers will aid in identifying tauopathies earlier and more accurately which will aid in selection for new clinical trials which focus on a variety of agents including immunotherapy and gene silencing.

Clinical value of neurofilament and phospho-tau/tau ratio in the frontotemporal dementia spectrum

Objective

To examine the clinical value of neurofilament light chain (NfL) and the phospho-tau/total tau ratio (p/t-tau) across the entire frontotemporal dementia (FTD) spectrum in a large, well-defined cohort.

Methods

CSF NfL and p/t-tau levels were studied in 361 patients with FTD: 179 behavioral variant FTD, 17 FTD with motor neuron disease (FTD-MND), 36 semantic variant primary progressive aphasia (PPA), 19 nonfluent variant PPA, 4 logopenic variant PPA (lvPPA), 42 corticobasal syndrome, and 64 progressive supranuclear palsy. Forty-five cognitively healthy controls were also included. Definite pathology was known in 68 patients (49 frontotemporal lobar degeneration [FTLD]-TDP, 18 FTLD-tau, 1 FTLD-FUS).

Results

NfL was higher in all diagnoses, except lvPPA (n = 4), than in controls, equally elevated in behavioral variant FTD, semantic variant PPA, nonfluent variant PPA, and corticobasal syndrome, and highest in FTD-MND. The p/t-tau was lower in all clinical groups, except lvPPA, than in controls and lowest in FTD-MND. NfL did not discriminate between TDP and tau pathology, while the p/t-tau ratio had a good specificity (76%) and moderate sensitivity (67%). Both high NfL and low p/t-tau were associated with poor survival (hazard ratio on tertiles 1.7 for NfL, 0.7 for p/t-tau).

Conclusion

NfL and p/t-tau similarly discriminated FTD from controls, but not between clinical subtypes, apart from FTD-MND. Both markers predicted survival and are promising monitoring biomarkers for clinical trials. Of note, p/t-tau, but not NfL, was specific to discriminate TDP from tau pathology in vivo.

Classification of evidence

This study provides Class III evidence that for patients with cognitive issues, CSF NfL and p/t-tau levels discriminate between those with and without FTD spectrum disorders.

Biological, Neuroimaging, and Neurophysiological Markers in Frontotemporal Dementia: Three Faces of the Same Coin

Frontotemporal dementia (FTD) is a heterogeneous clinical, genetic, and neuropathological disorder. Clinical diagnosis and prediction of neuropathological substrates are hampered by heterogeneous pictures. Diagnostic markers are key in clinical trials to differentiate FTD from other neurodegenerative dementias. In the same view, identifying the neuropathological hallmarks of the disease is key in light of future disease-modifying treatments. The aim of the present review is to unravel the progress in biomarker discovery, discussing the potential applications of available biological, imaging, and neurophysiological markers.

Ante mortem cerebrospinal fluid tau levels correlate with postmortem tau pathology in frontotemporal lobar degeneration

OBJECTIVE

To test the hypotheses that (1) antemortem cerebrospinal fluid (CSF) tau levels correlate with postmortem tau pathology in frontotemporal lobar degeneration (FTLD) and (2) tauopathy patients have higher phosphorylated-tau levels compared to transactivation response element DNA-binding protein 43 (TDP-43) proteinopathy patients while accounting for Alzheimer's disease (AD) copathology.

METHODS

Patients had autopsy-confirmed FTLD with tauopathy (n = 31), TDP-43 proteinopathy (n = 49), or AD (n = 26) with antemortem CSF. CSF tau levels were compared between groups and correlated with digital histology measurement of postmortem tau pathology averaged from three cerebral regions (angular gyrus, mid-frontal cortex, and anterior cingulate gyrus). Multivariate linear regression tested the association of ante mortem CSF tau levels with postmortem tau pathology adjusting for demographics.

RESULTS

Multivariate regression found an independent association of ante mortem CSF phosphorylated tau levels with postmortem cerebral tau pathology in FTLD (Beta = 1.3; 95% confidence interval = 0.2-2.4; p < 0.02). After excluding patients with coincident AD-associated tau pathology accompanying sporadic FTLD, we found lower CSF phosphorylated tau levels in the TDP-43 group (median = 7.4pg/ml; interquartile range [IQR] = 6.0, 12.3; n = 26) compared to the tauopathy group (median = 12.5pg/ml; IQR = 10.7, 15.0; n = 23; Z = 2.6; p < 0.01).

INTERPRETATION

CSF phosphorylated-tau levels are positively associated with cerebral tau burden in FTLD. In vivo detection of AD copathology in sporadic FTLD patients may help stratify clinical cohorts with pure neuropathology in which low CSF phosphorylated-tau levels may have diagnostic utility to distinguish TDP-43 proteinopathy from tauopathy. Autopsy-confirmed samples are critical for FTLD biomarker development and validation. Ann Neurol 2017;82:247-258.

Drugs in clinical development for the treatment of amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic Lateral Sclerosis (ALS) is a fatal motor neuron progressive disorder for which no treatment exists to date. However, there are other investigational drugs and therapies currently under clinical development may offer hope in the near future. Areas covered: We have reviewed all the ALS ongoing clinical trials (until November 2016) and collected in Clinicaltrials.gov or EudraCT. We have described them in a comprehensive way and have grouped them in the following sections: biomarkers, biological therapies, cell therapy, drug repurposing and new drugs. Expert opinion: Despite multiple obstacles that explain the absence of effective drugs for the treatment of ALS, joint efforts among patient's associations, public and private sectors have fueled innovative research in this field, resulting in several compounds that are in the late stages of clinical trials. Drug repositioning is also playing an important role, having achieved the approval of some orphan drug applications, in late phases of clinical development. Endaravone has been recently approved in Japan and is pending in USA.

The Mental Status Examination in Patients With Suspected Dementia

PURPOSE OF REVIEW

This article describes a comprehensive approach to the mental status examination and diagnostic workup of patients suspected of having an emerging neurodegenerative dementia. Key strategies for obtaining a history and bedside examination techniques are highlighted.

RECENT FINDINGS

Classic descriptions of behavioral neurology syndromes were largely based on clinicopathologic correlations of strategic lesions in stroke patients. While still very important, advances in neuroimaging have expanded our armamentarium of cognitive evaluations to include assessments of findings in nonstroke anatomic distributions of disease. These efforts support comprehensive assessments of large-scale cerebral networks in cognitive neurology.

SUMMARY

A thorough and focused mental status examination is essential for the evaluation of patients with cognitive symptoms. Selective use of laboratory testing and neuroimaging can aid in the diagnosis of dementia by excluding non-neurodegenerative etiologies. Neurodegenerative disease-specific tests are in development and will enhance diagnosis and efforts for disease-modifying therapy development.