Comparison of CSF and plasma NfL and pNfH for Alzheimer's disease diagnosis: a memory clinic study

Plasma neurofilament light chain (NfL) is a promising biomarker of axonal damage for the diagnosis of neurodegenerative diseases. Phosphorylated neurofilament heavy chain (pNfH) has demonstrated its value in motor neuron diseases diagnosis, but has less been explored for dementia diagnosis. In a cross-sectional study, we compared cerebrospinal fluid (CSF) and plasma NfL and pNfH levels in n = 188 patients from Lariboisière Hospital, Paris, France, including AD patients at mild cognitive impairment stage (AD-MCI, n = 36) and dementia stage (n = 64), non-AD MCI (n = 38), non-AD dementia (n = 28) patients and control subjects (n = 22). Plasma NfL, plasma and CSF pNfH levels were measured using Simoa and CSF NfL using ELISA. The correlation between CSF and plasma levels was stronger for NfL than pNfH (rho = 0.77 and rho = 0.52, respectively). All neurofilament markers were increased in AD-MCI, AD dementia and non-AD dementia groups compared with controls. CSF NfL, CSF pNfH and plasma NfL showed high performance to discriminate AD at both MCI and dementia stages from control subjects [AUC (area under the curve) = 0.82-0.91]. Plasma pNfH displayed overall lower AUCs for discrimination between groups compared with CSF pNfH. Neurofilament markers showed similar moderate association with cognition. NfL levels displayed significant association with mediotemporal lobe atrophy and white matter lesions in the AD group. Our results suggest that CSF NfL and pNfH as well as plasma NfL levels display equivalent performance in both positive and differential AD diagnosis in memory clinic settings. In contrast to motoneuron disorders, plasma pNfH did not demonstrate added value as compared with plasma NfL.

The role of adiponectin in Alzheimer's disease: A translational review

Adiponectin is an adipokine playing a central role in the regulation of energy homeostasis, carbohydrate and lipid metabolism, as well as immunomodulation. The relationship between Alzheimer's disease (AD) and body composition has highlighted the bidirectional crosstalk between AD's pathophysiology and metabolic disorders. This review aimed to report the current state of knowledge about cellular and molecular mechanisms linking adiponectin and AD, in preclinical studies. Then, we reviewed human studies to assess the relationship between adiponectin levels and AD diagnosis. We also examined the risk of incident AD regarding the participants' baseline adiponectin level, as well as the relationship of adiponectin and cognitive decline in patients with AD. We conducted a systematic review, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline, of studies published over the last decade on MEDLINE and Cochrane databases. Overall, we reviewed 34 original works about adiponectin in AD, including 11 preclinical studies, two both preclinical and human studies and 21 human studies. Preclinical studies brought convincing evidence for the neuroprotective role of adiponectin on several key mechanisms of AD. Human studies showed conflicting results regarding the relationship between AD and adiponectin levels, as well as regarding the cross-sectional association between cognitive function and adiponectin levels. Adiponectin did not appear as a predictor of incident AD, nor as a predictor of cognitive decline in patients with AD. Despite solid preclinical evidence suggesting the protective role of adiponectin in AD, inconsistent results in humans supports the need for further research.

CSF p-tau205: a biomarker of tau pathology in Alzheimer's disease

Post-mortem staging of Alzheimer's disease (AD) neurofibrillary pathology is commonly performed by immunohistochemistry using AT8 antibody for phosphorylated tau (p-tau) at positions 202/205. Thus, quantification of p-tau205 and p-tau202 in cerebrospinal fluid (CSF) should be more reflective of neurofibrillary tangles in AD than other p-tau epitopes. We developed two novel Simoa immunoassays for CSF p-tau205 and p-tau202 and measured these phosphorylations in three independent cohorts encompassing the AD continuum, non-AD cases and cognitively unimpaired participants: a discovery cohort (n = 47), an unselected clinical cohort (n = 212) and a research cohort well-characterized by fluid and imaging biomarkers (n = 262). CSF p-tau205 increased progressively across the AD continuum, while CSF p-tau202 was increased only in AD and amyloid (Aβ) and tau pathology positive (A+T+) cases (P < 0.01). In A+ cases, CSF p-tau205 and p-tau202 showed stronger associations with tau-PET (rSp205 = 0.67, rSp202 = 0.45) than Aβ-PET (rSp205 = 0.40, rSp202 = 0.09). CSF p-tau205 increased gradually across tau-PET Braak stages (P < 0.01), whereas p-tau202 only increased in Braak V-VI (P < 0.0001). Both showed stronger regional associations with tau-PET than with Aβ-PET, and CSF p-tau205 was significantly associated with Braak V-VI tau-PET regions. When assessing the contribution of Aβ and tau pathologies (indexed by PET) to CSF p-tau205 and p-tau202 variance, tau pathology was found to be the most prominent contributor in both cases (CSF p-tau205: R2 = 69.7%; CSF p-tau202: R2 = 85.6%) Both biomarkers associated with brain atrophy measurements globally (rSp205 = - 0.36, rSp202 = - 0.33) and regionally, and correlated with cognition (rSp205 = - 0.38/- 0.40, rSp202 = - 0.20/- 0.29). In conclusion, we report the first high-throughput CSF p-tau205 immunoassay for the in vivo quantification of tau pathology in AD, and a potentially cost-effective alternative to tau-PET in clinical settings and clinical trials.

Psychosis in Neurodegenerative Dementias: A Systematic Comparative Review

Background

Psychosis, characterized by delusions and/or hallucinations, is frequently observed during the progression of Alzheimer's disease (AD) and other neurodegenerative dementias (ND) (i.e., dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD)) and cause diagnostic and management difficulties.

Objective

This review aims at presenting a concise and up-to-date overview of psychotic symptoms that occur in patients with ND with a comparative approach.

Methods

A systematic review was conducted following the PRISMA guidelines. 98 original studies investigating psychosis phenotypes in neurodegenerative dementias were identified (40 cohort studies, 57 case reports).

Results

Psychosis is a frequently observed phenomenon during the course of ND, with reported prevalence ranging from 22.5% to 54.1% in AD, 55.9% to 73.9% in DLB, and 18% to 42% in FTD. Throughout all stages of these diseases, noticeable patterns emerge depending on their underlying causes. Misidentification delusions (16.6-78.3%) and visual hallucinations (50-69.6%) are frequently observed in DLB, while paranoid ideas and somatic preoccupations seem to be particularly common in AD and FTD, (respectively 9.1-60.3% and 3.10-41.5%). Limited data were found regarding psychosis in the early stages of these disorders.

Conclusions

Literature data suggest that different ND are associated with noticeable variations in psychotic phenotypes, reflecting disease-specific tendencies. Further studies focusing on the early stages of these disorders are necessary to enhance our understanding of early psychotic manifestations associated with ND and help in differential diagnosis issues.

Mass spectrometric simultaneous quantification of tau species in plasma shows differential associations with amyloid and tau pathologies

Blood phosphorylated tau (p-tau) biomarkers, at differing sites, demonstrate high accuracy to detect Alzheimer's disease (AD). However, knowledge on the optimal marker for disease identification across the AD continuum and the link to pathology is limited. This is partly due to heterogeneity in analytical methods. In this study, we employed an immunoprecipitation mass spectrometry method to simultaneously quantify six phosphorylated (p-tau181, p-tau199, p-tau202, p-tau205, p-tau217 and p-tau231) and two non-phosphorylated plasma tau peptides in a total of 214 participants from the Paris Lariboisière and Translational Biomarkers of Aging and Dementia cohorts. Our results indicate that p-tau217, p-tau231 and p-tau205 are the plasma tau forms that best reflect AD-related brain changes, although with distinct emergences along the disease course and correlations with AD features-amyloid and tau. These findings support the differential association of blood p-tau variants with AD pathology, and our method offers a potential tool for disease staging in clinical trials.

Lumbar puncture training with healthcare simulation improves self-confidence and practical skills of French medical residents in geriatrics

PURPOSE

To assess the skill level and self-confidence of medical residents in geriatrics with regard to conducting the lumbar puncture (LP) procedure and to study the potential benefits of training with simulation and virtual reality.

METHODS

First, a questionnaire survey was conducted among all French residents in geriatrics in the Paris area to assess their knowledge and self-confidence regarding the practice of LP in older adults. Second, we set up a simulation LP training session combined with virtual reality (3D video) training for selected respondents of the first survey. Third, we performed post-simulation survey for the attendees of the simulation training. Finally, a follow-up survey was conducted to examine the change in self-confidence and the success rate in clinical practice.

RESULTS

Fifty-five residents responded to the survey (response rate = 36.4%). The importance of mastering LP was fully recognized by the residents in geriatrics (95.3%), so most of them (94.5%) advocated for the need for additional practical training. Fourteen residents took part in the training (average rating = 4.7 on a 5-point scale). Simulation was regarded by 83% of the respondents as the most useful tool for their practice. We observed a significant pre/post-training mean improvement in self-estimated success of 20.6% (Wilcoxon matched-pairs signed-rank W = - 36, p = 0.008). The post-training success rate of the residents in real-life clinical practice was good (85.8%).

CONCLUSION

Residents were aware of the importance of mastering LP and requested additional training. Simulation may represent a major driver to improve their self-confidence and practical skills.

Clinical performance and head-to-head comparison of CSF p-tau235 with p-tau181, p-tau217 and p-tau231 in two memory clinic cohorts

BACKGROUND

Cerebrospinal fluid (CSF) p-tau235 is a novel biomarker highly specific of Alzheimer's disease (AD). However, CSF p-tau235 has only been studied in well-characterized research cohorts, which do not fully reflect the patient landscape found in clinical settings. Therefore, in this multicentre study, we investigated the performance of CSF p-tau235 to detect symptomatic AD in clinical settings and compared it with CSF p-tau181, p-tau217 and p-tau231.

METHODS

CSF p-tau235 was measured using an in-house single molecule array (Simoa) assay in two independent memory clinic cohorts: Paris cohort (Lariboisière Fernand-Widal University Hospital Paris, France; n=212) and BIODEGMAR cohort (Hospital del Mar, Barcelona, Spain; n=175). Patients were classified by the syndromic diagnosis (cognitively unimpaired [CU], mild cognitive impairment [MCI] or dementia) and their biological diagnosis (amyloid-beta [Aβ]+ or Aβ -). Both cohorts included detailed cognitive assessments and CSF biomarker measurements (clinically validated core AD biomarkers [Lumipulse CSF Aβ1-42/40 ratio, p-tau181 and t-tau] and in-house developed Simoa CSF p-tau181, p-tau217 and p-tau231).

RESULTS

High CSF p-tau235 levels were strongly associated with CSF amyloidosis regardless of the clinical diagnosis, being significantly increased in MCI Aβ+ and dementia Aβ+ when compared with all other Aβ- groups (Paris cohort: P ˂0.0001 for all; BIODEGMAR cohort: P ˂0.05 for all). CSF p-tau235 was pronouncedly increased in the A+T+ profile group compared with A-T- and A+T- groups (P ˂0.0001 for all). Moreover, CSF p-tau235 demonstrated high diagnostic accuracies identifying CSF amyloidosis in symptomatic cases (AUCs=0.86 to 0.96) and discriminating AT groups (AUCs=0.79 to 0.98). Overall, CSF p-tau235 showed similar performances to CSF p-tau181 and CSF p-tau231 when discriminating CSF amyloidosis in various scenarios, but lower than CSF p-tau217. Finally, CSF p-tau235 associated with global cognition and memory domain in both cohorts.

CONCLUSIONS

CSF p-tau235 was increased with the presence of CSF amyloidosis in two independent memory clinic cohorts. CSF p-tau235 accurately identified AD in both MCI and dementia patients. Overall, the diagnostic performance of CSF p-tau235 was comparable to that of other CSF p-tau measurements, indicating its suitability to support a biomarker-based AD diagnosis in clinical settings.

Plasma neurofilament light chain in memory clinic practice: Evidence from a real-life study

OBJECTIVE

To explore the accuracy of plasma neurofilament light chain (NfL) as a biomarker for diagnosis and staging of cognitive impairment, in a large cohort with of previously diagnosed patients in clinical practice.

METHODS

Retrospective, cross-sectional, monocentric study, from a tertiary memory clinic. Patients underwent cerebrospinal fluid core Alzheimer's disease (AD) biomarker evaluation using ELISA or Elecsys methods, and plasma NfL analysis using the single molecule array technology. The patients' biomarker data were examined for associations with: i/cognitive status ii/presence of neurodegenerative disease and iii/diagnostic groups. Associations between core CSF biomarkers and plasma NfL were determined.

RESULTS

Participants (N = 558, mean age = 69.2 ± 8.8, 56.5% women) were diagnosed with AD (n = 274, considering dementia and MCI stages), frontotemporal dementia (FTD, n = 55), Lewy body disease (LBD, n = 40, considering MCI and dementia stages), other neurodegenerative diseases, n = 57 (e.g Supranuclear Palsy, Corticobasal syndrome), non-neurodegenerative cognitive impairment (NND, n = 79, e.g. vascular lesions, epilepsy or psychiatric disorders) or subjective cognitive impairment (SCI, n = 53). Mean plasma NfL (log, pg/mL) levels were higher in neurodegenerative than non-neurodegenerative disorders (1.35 ± 0.2 vs 1.16 ± 0.23, p < 0.001), higher in all diagnostic groups than in SCI (1.06 ± 0.23) p < 0.001), and associated with the stage of cognitive impairment (p < 0.001). The addition of plasma NfL to a clinical model (age, MMSE and APOE ε4 carriership) marginally improved the discrimination of degenerative from non-degenerative disorders in ROC analysis (AUC clinical model: 0.81, 95% CI = [0.77;0.85] AUC clinical model + plasma NfL: AUC = 0.83 95% CI = [0.78;0.87], delta Akaike information criterion = -11.7).

DISCUSSION

Plasma NfL could help discrimination between degenerative and non-degenerative cognitive disorders, albeit not better than comprehensive clinical evaluation.

Plasma tau, NfL, GFAP and UCHL1 as candidate biomarkers of alcohol withdrawal-associated brain damage: A pilot study

In this translational study, we investigated the plasma tau protein, neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCHL1), which are established biomarkers of neurological injury, as predictive biomarkers of alcohol withdrawal-associated brain toxicity. In the clinical study, patients with severe alcohol use disorder (AUD) on D1 of hospitalization for alcohol cessation (AC) (N = 36) were compared to severe AUD patients with at least 3 months of abstinence (N = 16). Overall, patients were 40 men (76.9%), aged 49.8 years [SD ±9.9]. Tau, NfL, GFAP and UCHL1 levels were measured using SIMOA and analysed with a quasipoisson regression model adjusted for age and sex. The NfL level was higher in the AC group (p = 0.013). In the AC group, the tau (p = 0.021) and UCHL1 (p = 0.021) levels were positively associated with the dose of diazepam per weight, and the tau (p = 0.045), NfL (p = 4.9 × 10^-3 ) and UCHL1 (p = 0.036) levels were higher in the presence of signs of Wernicke's encephalopathy (n = 9). In the preclinical study, NfL and GFAP levels were assessed in the alcohol deprivation effect (ADE) procedure (N = 17) and control Wistar rats (N = 15). Furthermore, ADE rats were prospectively assessed: after 24 h (T1) and 3 weeks of AC (T2) (paired-samples Wilcoxon and Mann-Whitney tests). The NfL level was higher in the ADE model than in the control rats at both T1 and T2 (p = 0.033 and p = 1.3 × 10^-3 ) and higher at T2 than at T1 (p = 0.040). Plasma tau, NfL and UCHL1 are potential biomarkers of brain suffering during alcohol withdrawal.

Plasma neuregulin 1 as a synaptic biomarker in Alzheimer's disease: a discovery cohort study

BACKGROUND

Synaptic dysfunction is an early core feature of Alzheimer's disease (AD), closely associated with cognitive symptoms. Neuregulin 1 (NRG1) is a growth and differentiation factor with a key role in the development and maintenance of synaptic transmission. Previous reports have shown that changes in cerebrospinal fluid (CSF) NRG1 concentration are associated with cognitive status and biomarker evidence of AD pathology. Plasma biomarkers reflecting synaptic impairment would be of great clinical interest.

OBJECTIVE

To measure plasma NRG1 concentration in AD patients in comparison with other neurodegenerative disorders and neurological controls (NC) and to study its association with cerebrospinal fluid (CSF) core AD and synaptic biomarkers.

METHODS

This retrospective study enrolled 127 participants including patients with AD at mild cognitive impairment stage (AD-MCI, n = 27) and at dementia stage (n = 35), non-AD dementia (n = 26, Aβ-negative), non-AD MCI (n = 19), and neurological controls (n=20). Plasma and CSF NRG1, as well as CSF core AD biomarkers (Aβ 42/Aβ 40 ratio, phospho-tau, and total tau), were measured using ELISA. CSF synaptic markers were measured using ELISA for GAP-43 and neurogranin and through immunoprecipitation mass spectrometry for SNAP-25.

RESULTS

Plasma NRG1 concentration was higher in AD-MCI and AD dementia patients compared with neurological controls (respectively P = 0.005 and P < 0.001). Plasma NRG1 differentiated AD MCI patients from neurological controls with an area under the curve of 88.3%, and AD dementia patients from NC with an area under the curve of 87.3%. Plasma NRG1 correlated with CSF NRG1 (β = 0.372, P = 0.0056, adjusted on age and sex). Plasma NRG1 was associated with AD CSF core biomarkers in the whole cohort and in Aβ-positive patients (β = -0.197-0.423). Plasma NRG1 correlated with CSF GAP-43, neurogranin, and SNAP-25 (β = 0.278-0.355). Plasma NRG1 concentration correlated inversely with MMSE in the whole cohort and in Aβ-positive patients (all, β = -0.188, P = 0.038; Aβ+: β = -0.255, P = 0.038).

CONCLUSION

Plasma NRG1 concentration is increased in AD patients and correlates with CSF core AD and synaptic biomarkers and cognitive status. Thus, plasma NRG1 is a promising non-invasive biomarker to monitor synaptic impairment in AD.

Using virtual reality in lumbar puncture training improves students learning experience

BACKGROUND

Lumbar puncture (LP) is a commonly performed medical procedure in a wide range of indications. Virtual reality (VR) provides a stimulating, safe and efficient learning environment. We report the design and the evaluation of a three dimensions (3D) video for LP training.

METHODS

We recorded a stereoscopic 180-degrees 3D video from two LPs performed in clinical settings in Fernand Widal Lariboisière University Hospital, Paris, France. The video was administered to third-year medical students as well as to a residents and attendings group during LP simulation-based training sessions.

RESULTS

On 168 participants (108 novice third-year medical students, and 60 residents and attendings with prior LP experience), satisfaction after video exposure was high (rated 4.7 ± 0.6 on a 5-point scale). No significant discomfort was reported (comfort score graded 4.5 ± 0.8 on 5). LP-naive students displayed higher satisfaction and perceived benefit than users with prior LP experience (overall, P < 0.05). Trainees evaluated favorably the 3D feature and supported the development of similar tutorials for other medical procedures (respectively, 3.9 ± 1.1 and 4.4 ± 0.9 on 5).

CONCLUSION

We report our experience with a 3D video for LP training. VR support could increase knowledge retention and skill acquisition in association to LP simulation training.

N-terminal and mid-region tau fragments as fluid biomarkers in neurological diseases

Brain-derived tau secreted into CSF and blood consists of different N-terminal and mid-domain fragments, which may have a differential temporal course and thus, biomarker potential across the Alzheimer’s disease continuum or in other neurological diseases. While current clinically validated total tau assays target mid-domain epitopes, comparison of these assays with new biomarkers targeting N-terminal epitopes using the same analytical platform may be important to increase the understanding of tau pathophysiology.

We developed three total tau immunoassays targeting specific N-terminal (NTA and NTB total tau) or mid-region (MR total tau) epitopes, using single molecule array technology. After analytical validation, the diagnostic performance of these biomarkers was evaluated in CSF and compared with the Innotest total tau (and as proof of concept, with N-p-tau181 and N-p-tau217) in three clinical cohorts (n = 342 total). The cohorts included participants across the Alzheimer’s disease continuum (n = 276), other dementias (n = 22), Creutzfeldt–Jakob disease (n = 24), acute neurological disorders (n = 18) and progressive supranuclear palsy (n = 22). Furthermore, we evaluated all three new total tau biomarkers in plasma (n = 44) and replicated promising findings with NTA total tau in another clinical cohort (n = 50).

In CSF, all total tau biomarkers were increased in Alzheimer’s disease compared with controls (P < 0.0001) and correlated with each other (r_s = 0.53−0.95). NTA and NTB total tau, but not other total tau assays, distinguished amyloid-positive and amyloid-negative mild cognitive impairment with high accuracies (AUCs 84% and 82%, P < 0.001) matching N-p-tau217 (AUC 83%; DeLong test P = 0.93 and 0.88). All total tau assays were excellent in differentiating Alzheimer’s disease from other dementias (P < 0.001, AUCs 89–100%). In Creutzfeldt–Jakob disease and acute neurological disorders, N-terminal total tau biomarkers had significantly higher fold changes versus controls in CSF (45–133-fold increase) than Innotest or MR total tau (11–42-fold increase, P < 0.0001 for all). In progressive supranuclear palsy, CSF concentrations of all total tau biomarkers were similar to those in controls. Plasma NTA total tau concentrations were increased in Alzheimer’s disease compared with controls in two independent cohorts (P = 0.0056 and 0.0033), while Quanterix total tau performed poorly (P = 0.55 and 0.44).

Taken together, N-terminal-directed CSF total tau biomarkers increase ahead of standard total tau alternatives in the Alzheimer’s disease continuum, increase to higher degrees in Creutzfeldt–Jakob disease and acute neurological diseases and show better potential than Quanterix total tau as Alzheimer’s disease blood biomarkers. For progressive supranuclear palsy, other tau biomarkers should continue to be investigated.

Quantification of the trans-synaptic partners neurexin-neuroligin in CSF of neurodegenerative diseases by parallel reaction monitoring mass spectrometry

BACKGROUND

Synaptic proteins are increasingly studied as biomarkers for synaptic dysfunction and loss, which are early and central events in Alzheimer's disease (AD) and strongly correlate with the degree of cognitive decline. In this study, we specifically investigated the synaptic binding partners neurexin (NRXN) and neuroligin (Nlgn) proteins, to assess their biomarker's potential.

METHODS

we developed a parallel reaction monitoring mass spectrometric method for the simultaneous quantification of NRXNs and Nlgns in cerebrospinal fluid (CSF) of neurodegenerative diseases, focusing on AD. Specifically, NRXN-1α, NRXN-1β, NRXN-2α, NRXN-3α and Nlgn1, Nlgn2, Nlgn3 and Nlgn4 proteins were targeted.

FINDINGS

The proteins were investigated in a clinical cohort including CSF from controls (n=22), mild cognitive impairment (MCI) due to AD (n=44), MCI due to other conditions (n=46), AD (n=77) and a group of non-AD dementia (n=28). No difference in levels of NRXNs and Nlgns was found between AD (both at dementia and MCI stages) or controls or the non-AD dementia group for any of the targeted proteins. NRXN and Nlgn proteins correlated strongly with each other, but only a weak correlation with the AD core biomarkers and the synaptic biomarkers neurogranin and growth-associated protein 43, was found, possibly reflecting different pathogenic processing at the synapse.

INTERPRETATION

we conclude that NRXN and Nlgn proteins do not represent suitable biomarkers for synaptic pathology in AD. The panel developed here could aid in future investigations of the potential involvement of NRXNs and Nlgns in synaptic dysfunction in other disorders of the central nervous system.

FUNDING

a full list of funding can be found under the acknowledgments section.

P-tau235: a novel biomarker for staging preclinical Alzheimer's disease

Alzheimer's disease (AD) is characterised by a long preclinical phase. Although phosphorylated tau (p-tau) species such as p-tau217 and p-tau231 provide accurate detection of early pathological changes, other biomarkers capable of staging disease progression during preclinical AD are still needed. Combining exploratory and targeted mass spectrometry methods in neuropathologically confirmed brain tissue, we observed that p-tau235 is a prominent feature of AD pathology. In addition, p-tau235 seemed to be preceded by p-tau231, in what appeared to be a sequential phosphorylation event. To exploit its biomarker potential in cerebrospinal fluid (CSF), we developed and validated a new p-tau235 Simoa assay. Using three clinical cohorts, we demonstrated that (i) CSF p-235 increases early in AD continuum, and (ii) changes in CSF p-tau235 and p-tau231 levels during preclinical AD are consistent with the sequential phosphorylation evidence in AD brain. In conclusion, CSF p-tau235 appears to be not only a highly specific biomarker of AD but also a promising staging biomarker for the preclinical phase. Thus, it could prove useful tracking disease progression and help enriching clinical trial recruitment.

Association of Amyotrophic Lateral Sclerosis and Alzheimer's Disease: New Entity or Coincidence? A Case Series

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia have a strong clinical, genetic, and pathological connection but association of ALS with Alzheimer's disease (AD) is seldom reported. We report a series of 5 cases of AD associated with ALS. Our patients presented with cognitive deterioration with episodic memory impairment meeting criteria for AD. ALS occurred subsequently in all cases and its phenotype was not homogenous. Amyloid process was confirmed in four cases with cerebrospinal fluid biomarkers. One case underwent postmortem exam, demonstrating hallmarks lesions of both diseases. This series highlights that ALS-AD phenotype could be a specific underexplored entity.

Differences Between Plasma and Cerebrospinal Fluid Glial Fibrillary Acidic Protein Levels Across the Alzheimer Disease Continuum

Question

What are the levels of plasma glial fibrillary acidic protein (GFAP) throughout the Alzheimer disease (AD) continuum, and how do they compare with the levels of cerebrospinal fluid (CSF) GFAP?

Findings

In this cross-sectional study, plasma GFAP levels were elevated in the preclinical and symptomatic stages of AD, with levels higher than those of CSF GFAP. Plasma GFAP had a higher accuracy than CSF GFAP to discriminate between amyloid-β (Aβ)–positive and Aβ-negative individuals, also at the preclinical stage.

Meaning

This study suggests that plasma GFAP is a sensitive biomarker that significantly outperforms CSF GFAP in indicating Aβ pathology in the early stages of AD.

Importance

Glial fibrillary acidic protein (GFAP) is a marker of reactive astrogliosis that increases in the cerebrospinal fluid (CSF) and blood of individuals with Alzheimer disease (AD). However, it is not known whether there are differences in blood GFAP levels across the entire AD continuum and whether its performance is similar to that of CSF GFAP.

Objective

To evaluate plasma GFAP levels throughout the entire AD continuum, from preclinical AD to AD dementia, compared with CSF GFAP.

Design, Setting, and Participants

This observational, cross-sectional study collected data from July 29, 2014, to January 31, 2020, from 3 centers. The Translational Biomarkers in Aging and Dementia (TRIAD) cohort (Montreal, Canada) included individuals in the entire AD continuum. Results were confirmed in the Alzheimer’s and Families (ALFA+) study (Barcelona, Spain), which included individuals with preclinical AD, and the BioCogBank Paris Lariboisière cohort (Paris, France), which included individuals with symptomatic AD.

Main Outcomes and Measures

Plasma and CSF GFAP levels measured with a Simoa assay were the main outcome. Other measurements included levels of CSF amyloid-β 42/40 (Aβ42/40), phosphorylated tau181 (p-tau181), neurofilament light (NfL), Chitinase-3-like protein 1 (YKL40), and soluble triggering receptor expressed on myeloid cells 2 (sTREM2) and levels of plasma p-tau181 and NfL. Results of amyloid positron emission tomography (PET) were available in TRIAD and ALFA+, and results of tau PET were available in TRIAD.

Results

A total of 300 TRIAD participants (177 women [59.0%]; mean [SD] age, 64.6 [17.6] years), 384 ALFA+ participants (234 women [60.9%]; mean [SD] age, 61.1 [4.7] years), and 187 BioCogBank Paris Lariboisière participants (116 women [62.0%]; mean [SD] age, 69.9 [9.2] years) were included. Plasma GFAP levels were significantly higher in individuals with preclinical AD in comparison with cognitively unimpaired (CU) Aβ-negative individuals (TRIAD: Aβ-negative mean [SD], 185.1 [93.5] pg/mL, Aβ-positive mean [SD], 285.0 [142.6] pg/mL; ALFA+: Aβ-negative mean [SD], 121.9 [42.4] pg/mL, Aβ-positive mean [SD], 169.9 [78.5] pg/mL). Plasma GFAP levels were also higher among individuals in symptomatic stages of the AD continuum (TRIAD: CU Aβ-positive mean [SD], 285.0 [142.6] pg/mL, mild cognitive impairment [MCI] Aβ-positive mean [SD], 332.5 [153.6] pg/mL; AD mean [SD], 388.1 [152.8] pg/mL vs CU Aβ-negative mean [SD], 185.1 [93.5] pg/mL; Paris: MCI Aβ-positive, mean [SD], 368.6 [158.5] pg/mL; AD dementia, mean [SD], 376.4 [179.6] pg/mL vs CU Aβ-negative mean [SD], 161.2 [67.1] pg/mL). Plasma GFAP magnitude changes were consistently higher than those of CSF GFAP. Plasma GFAP more accurately discriminated Aβ-positive from Aβ-negative individuals than CSF GFAP (area under the curve for plasma GFAP, 0.69-0.86; area under the curve for CSF GFAP, 0.59-0.76). Moreover, plasma GFAP levels were positively associated with tau pathology only among individuals with concomitant Aβ pathology.

Conclusions and Relevance

This study suggests that plasma GFAP is a sensitive biomarker for detecting and tracking reactive astrogliosis and Aβ pathology even among individuals in the early stages of AD.

Amyloid pathology and synaptic loss in pathological aging

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive memory dysfunction and cognitive decline. Pathological aging (PA) describes patients who are amyloid-positive but cognitively unimpaired at time of death. Both AD and PA contain amyloid plaques dominated by amyloid β (Aβ) peptides. In this study, we investigated and compared synaptic protein levels, amyloid plaque load, and Aβ peptide patterns between AD and PA. Two cohorts of post-mortem brain tissue were investigated. In the first, consisting of controls, PA, AD, and familial AD (FAD) individuals, synaptic proteins extracted with tris(hydroxymethyl)aminomethane-buffered saline (TBS) were analyzed. In the second, consisting of tissue from AD and PA patients from three different regions (occipital lobe, frontal lobe, and cerebellum), a two-step extraction was performed. Five synaptic proteins were extracted using TBS, and from the remaining portion Aβ peptides were extracted using formic acid. Subsequently, immunoprecipitation with several antibodies targeting different proteins/peptides was performed for both fractions, which were subsequently analyzed by mass spectrometry. The levels of synaptic proteins were lower in AD (and FAD) compared with PA (and controls), confirming synaptic loss in AD patients. The amyloid plaque load was increased in AD compared with PA, and the relative amount of Aβ40 was higher in AD while for Aβ42 it was higher in PA. In AD loss of synaptic function was associated with increased plaque load and increased amounts of Aβ40 compared with PA cases, suggesting that synaptic function is preserved in PA cases even in the presence of Aβ.

COVID-19 in adults with dementia: clinical features and risk factors of mortality-a clinical cohort study on 125 patients

BACKGROUND

There is limited evidence on the characteristics and outcome of patients with dementia hospitalised for novel coronavirus infection (COVID-19).

METHOD

We conducted a prospective study in 2 gerontologic COVID units in Paris, France, from March 14, 2020, to May 7, 2020. Patients with dementia hospitalised for confirmed COVID-19 infection were systematically enrolled. A binary logistic regression analysis was performed to identify factors associated with mortality at 21 days.

RESULTS

We included 125 patients. Median age was 86 (IQI 82-90); 59.4% were female. Most common causes of dementia were Alzheimer's disease, mixed dementia and vascular dementia. 67.2% had ≥ 2 comorbidities; 40.2% lived in a long-term care facility. The most common symptoms at COVID-19 onset were confusion and delirium (82.4%), asthenia (76.8%) and fever (72.8%) before polypnea (51.2%) and desaturation (50.4%). Falls were frequent at the initial phase of the disease (35.2%). The fatality rate at 21 days was 22.4%. Chronic kidney disease and CRP at admission were independent factors of death. Persisting confusion, mood and behavioural disorders were observed in survivors (19.2%).

CONCLUSION

COVID-19 in demented individuals is associated with severe outcome in SARS-CoV-2 infection and is characterised by specific clinical features and complications, with confusion and delirium at the forefront. COVID-19 testing should be considered in front of any significant change from baseline.

Épidémie de COVID19 dans une unité de neuropsychogériatrie aiguë : aspects particuliers de la prise en charge chez des patients doublement vulnérables

Introduction

Les sujets âgés constituent le groupe le plus vulnérable au SARS-Cov2, avec une mortalité élevée. Les troubles neurocognitifs sont une comorbidité fréquente chez les patients âgés. Néanmoins, les spécificités de la COVID-19 chez ces patients restent mal connues.

Objectifs

Notre étude a visé à décrire les caractéristiques cliniques et le pronostic de l’infection à SARS-Cov2 ainsi qu’à élucider les défis de prise en charge chez des patients souffrant de troubles neurocognitifs admis dans un service de neuropsychogériatrie.

Patients et méthodes

Nous avons réalisé une étude prospective observationnelle entre mars et mai 2020 dans le service de neuropsychogériatrie de l’hôpital Leopold-Bellan. Les patients présentant des troubles cognitifs, pour lesquels une infection à SARS-Cov2 (PCR ou TDM thoracique) a été confirmée, ont été systématiquement inclus. Les données démographiques, cliniques et paracliniques ont été collectées sur toute la durée de l’hospitalisation.

Résultats

Trente-six patients (âge médian : 86 ans, 62–98) ont été inclus. L’infection à SARS-Cov2 n’était pas toujours le motif d’hospitalisation. Les symptômes les plus fréquents étaient l’asthénie et la fièvre, la confusion et les chutes. Les complications notées : un état dépressif dans 42 % des cas, un comportement de déambulation (42 %), la survenue d’un syndrome de détresse respiratoire aiguë (28 %), la survenue d’AVC (4 patients) et de crises convulsives (3 patients). La mortalité intra-hospitalière à la phase aiguë était de 27,8 %, secondaire aux complications respiratoires.

Discussion

La fréquence des évènements neuropsychiatriques à la phase aiguë du COVID-19 dans notre cohorte est significative. Les troubles cognitifs et la déambulation dans le cadre de l’isolement ont été un défi à relever dans la prise en charge. La prise en charge thérapeutique et le consentement aux protocoles ont soulevé des questionnements éthiques importants.

Conclusion

Les personnes âgées souffrant de troubles cognitifs et contractant le SARS-COV2 présentent un double défi de prise en charge, sur le plan de la COVID-19 et des troubles psychocomportementaux en lien avec leur pathologie et les mesures sanitaires imposées.

Full-length and C-terminal neurogranin in Alzheimer's disease cerebrospinal fluid analyzed by novel ultrasensitive immunoassays

Background

Neurogranin (Ng) is a neuron-specific and postsynaptic protein that is abundantly expressed in the brain, particularly in the dendritic spine of the hippocampus and cerebral cortex. The enzymatic cleavage of Ng produces fragments that are released into cerebrospinal (CSF), which have been shown to be elevated in Alzheimer’s disease (AD) patients and predict cognitive decline. Thus, quantification of distinctive cleavage products of Ng could elucidate different features of the disease.

Methods

In this study, we developed novel ultrasensitive single molecule array (Simoa) assays for measurement of full-length neurogranin (FL-Ng) and C-terminal neurogranin (CT-Ng) fragments in CSF. The Ng Simoa assays were evaluated in CSF samples from AD patients (N = 23), mild cognitive impairment due to AD (MCI-AD) (N = 18), and from neurological controls (N = 26).

Results

The intra-assay repeatability and inter-assay precision of the novel methods had coefficients of variation below 7% and 14%, respectively. CSF FL-Ng and CSF CT-Ng median concentrations were increased in AD patients (6.02 ng/L, P < 0.00001 and 452 ng/L, P = 0.00001, respectively) and in patients with MCI-AD (5.69 ng/L, P < 0.00001 and 566 ng/L, P < 0.00001) compared to neurological controls (0.644 ng/L and 145 ng/L). The median CSF ratio of CT-Ng/FL-Ng were decreased in AD patients (ratio = 101, P = 0.008) and in patients with MCI-AD (ratio = 115, P = 0.016) compared to neurological controls (ratio = 180). CSF of FL-Ng, CT-Ng, and ratio of CT-Ng/FL-Ng could each significantly differentiate AD patients from controls (FL-Ng, AUC = 0.907; CT-Ng, AUC = 0.913; CT-Ng/FL-Ng, AUC = 0.775) and patients with MCI-AD from controls (FL-Ng, AUC = 0.937; CT-Ng, AUC = 0.963; CT-Ng/FL-Ng, AUC = 0.785).

Conclusions

Assessments of the FL-Ng and CT-Ng levels in CSF with the novel sensitive immunoassays provide a high separation of AD from controls, even in early phase of the disease. The novel Ng assays are robust and highly sensitive and may be valuable tools to study synaptic alteration in AD, as well as to monitor the effect on synaptic integrity of novel drug candidates in clinical trials.

Head-to-head comparison of clinical performance of CSF phospho-tau T181 and T217 biomarkers for Alzheimer's disease diagnosis

Introduction

Phosphorylated tau (p‐tau) in cerebrospinal fluid (CSF) is an established Alzheimer's disease (AD) biomarker. Novel immunoassays targeting N‐terminal and mid‐region p‐tau181 and p‐tau217 fragments are available, but head‐to‐head comparison in clinical settings is lacking.

Methods

N‐terminal‐directed p‐tau217 (N‐p‐tau217), N‐terminal‐directed p‐tau181 (N‐p‐tau181), and standard mid‐region p‐tau181 (Mid‐p‐tau181) biomarkers in CSF were evaluated in three cohorts (n = 503) to assess diagnostic performance, concordance, and associations with amyloid beta (Aβ).

Results

CSF N‐p‐tau217 and N‐p‐tau181 had better concordance (88.2%) than either with Mid‐p‐tau181 (79.7%–82.7%). N‐p‐tau217 and N‐p‐tau181 were significantly increased in early mild cognitive impairment (MCI)‐AD (A+T–N–) without changes in Mid‐p‐tau181 until AD‐dementia. N‐p‐tau217 and N‐p‐tau181 identified Aβ pathophysiology (area under the curve [AUC] = 94.8%–97.1%) and distinguished MCI‐AD from non‐AD MCI (AUC = 82.6%–90.5%) signficantly better than Mid‐p‐tau181 (AUC = 91.2% and 70.6%, respectively). P‐tau biomarkers equally differentiated AD from non‐AD dementia (AUC = 99.1%–99.8%).

Discussion

N‐p‐tau217 and N‐p‐tau181 could improve diagnostic accuracy in prodromal‐AD and clinical trial recruitment as both identify Aβ pathophysiology and differentiate early MCI‐AD better than Mid‐p‐tau181.

COVID-19 in Older Adults: A Series of 76 Patients Aged 85 Years and Older with COVID-19

BACKGROUND

Clinical presentation and risk factors of death in COVID‐19 in oldest adults have not been well characterized.

OBJECTIVES

To describe clinical features and outcome of COVID‐19 in patients older than 85 years and study risk factors for mortality.

DESIGN

Prospective cohort.

PARTICIPANTS AND SETTING

Patients aged 85 years and older, admitted in noncritical care units at the University Hospital Lariboisière Fernand‐Widal (Paris, France) for confirmed severe acute respiratory syndrome coronavirus 2 infection were included and followed up for 21 days.

MEASUREMENTS

Clinical and laboratory findings were collected. Cox survival analysis was performed to explore factors associated with death.

RESULTS

From March 14 to April 11, 2020, 76 patients (median age = 90 (86–92) years; women = 55.3%) were admitted for confirmed COVID‐19. Of the patients, 64.5% presented with three or more comorbidities. Most common symptoms were asthenia (76.3%), fever (75.0%) and confusion and delirium (71.1%). An initial fall was reported in 25.0% of cases, and digestive symptoms were reported in 22.4% of cases. COVID‐19 was severe in 51.3% of cases, moderate in 32.9%, and mild in 15.8%. Complications included acute respiratory syndrome (28.9%), cardiac decompensation (14.5%), and hypotensive shock (9.0%). Fatality at 21 days was 28.9%, after a median course of disease of 13 (8–17) days. Males were overrepresented in nonsurvivors (68.2%). In survivors, median length of stay was 12 (9–19.5) days. Independent predictive factors of death were C‐reactive protein level at admission and lymphocyte count at nadir.

CONCLUSION

Specific clinical features, multiorgan injury, and high case fatality rate are observed in older adults with COVID‐19. However, rapid diagnosis, appropriate care, and monitoring seem to improve prognosis.