Extreme phenotypic heterogeneity in non-expansion spinocerebellar ataxias.

Although the best-known spinocerebellar ataxias (SCAs) are triplet repeat diseases, many SCAs are not caused by repeat expansions. The rarity of individual non-expansion SCAs, however, has made it difficult to discern genotype-phenotype correlations. We therefore screened individuals who had been found to bear variants in a non-expansion SCA-associated gene through genetic testing, and after we eliminated genetic groups that had fewer than 30 subjects, there were 756 subjects bearing single-nucleotide variants or deletions in one of seven genes: CACNA1A (239 subjects), PRKCG (175), AFG3L2 (101), ITPR1 (91), STUB1 (77), SPTBN2 (39), or KCNC3 (34). We compared age at onset, disease features, and progression by gene and variant. There were no features that reliably distinguished one of these SCAs from another, and several genes-CACNA1A, ITPR1, SPTBN2, and KCNC3-were associated with both adult-onset and infantile-onset forms of disease, which also differed in presentation. Nevertheless, progression was overall very slow, and STUB1-associated disease was the fastest. Several variants in CACNA1A showed particularly wide ranges in age at onset: one variant produced anything from infantile developmental delay to ataxia onset at 64 years of age within the same family. For CACNA1A, ITPR1, and SPTBN2, the type of variant and charge change on the protein greatly affected the phenotype, defying pathogenicity prediction algorithms. Even with next-generation sequencing, accurate diagnosis requires dialogue between the clinician and the geneticist.

Comparing Cerebellar tDCS and Cerebellar tACS in Neurodegenerative Ataxias Using Wearable Sensors: A Randomized, Double-Blind, Sham-Controlled, Triple-Crossover Trial.

Cerebellar transcranial direct current stimulation (tDCS) represents a promising therapeutic approach for both motor and cognitive symptoms in neurodegenerative ataxias. Recently, transcranial alternating current stimulation (tACS) was also demonstrated to modulate cerebellar excitability by neuronal entrainment. To compare the effectiveness of cerebellar tDCS vs. cerebellar tACS in patients with neurodegenerative ataxia, we performed a double-blind, randomized, sham controlled, triple cross-over trial with cerebellar tDCS, cerebellar tACS or sham stimulation in twenty-six participants with neurodegenerative ataxia. Before entering the study, each participant underwent motor assessment with wearable sensors considering gait cadence (steps/minute), turn velocity (degrees/second) and turn duration (seconds), and a clinical evaluation with the scale for the Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS). After each intervention, participants underwent the same clinical assessment along with cerebellar inhibition (CBI) measurement, a marker of cerebellar activity. The gait cadence, turn velocity, SARA, and ICARS significantly improved after both tDCS and tACS, compared to sham stimulation (all p<0.010). Comparable effects were observed for CBI (p<0.001). Overall, tDCS significantly outperformed tACS on clinical scales and CBI (p<0.01). A significant correlation between changes of wearable sensors parameters from baseline and changes of clinical scales and CBI scores was detected. Cerebellar tDCS and cerebellar tACS are effective in ameliorating symptoms of neurodegenerative ataxias, with the former being more beneficial than the latter. Wearable sensors may serve as rater-unbiased outcome measures in future clinical trials. ClinicalTrial.gov Identifier: NCT05621200.

Anti-GluA3 autoantibodies define a new sub-population of frontotemporal lobar degeneration patients with distinct neuropathological features.

Autoantibodies directed against the GluA3 subunit (anti-GluA3 hIgGs) of AMPA receptors have been identified in 20%-25% of patients with frontotemporal lobar degeneration (FTLD). Data from patients and in vitro/ex vivo pre-clinical studies indicate that anti-GluA3 hIgGs negatively affect glutamatergic neurotransmission. However, whether and how the chronic presence of anti-GluA3 hIgGs triggers synaptic dysfunctions and the appearance of FTLD-related neuropathological and behavioural signature has not been clarified yet. To address this question, we developed and characterized a pre-clinical mouse model of passive immunization with anti-GluA3 hIgGs purified from patients. In parallel, we clinically compared FTLD patients who were positive for anti-GluA3 hIgGs to negative ones. Clinical data showed that the presence of anti-GluA3 hIgGs defined a subgroup of patients with distinct clinical features. In the preclinical model, anti-GluA3 hIgGs administration led to accumulation of phospho-tau in the postsynaptic fraction and dendritic spine loss in the prefrontal cortex. Remarkably, the preclinical model exhibited behavioural disturbances that mostly reflected the deficits proper of patients positive for anti-GluA3 hIgGs. Of note, anti-GluA3 hIgGs-mediated alterations were rescued in the animal model by enhancing glutamatergic neurotransmission with a positive allosteric modulator of AMPA receptors. Overall, our study clarified the contribution of anti-GluA3 autoantibodies to central nervous system symptoms and pathology and identified a specific subgroup of FTLD patients. Our findings will be instrumental in the development of a therapeutic personalised medicine strategy for patients positive for anti-GluA3 hIgGs.

Defining the Role of Frailty in the Transition from Mild Cognitive Impairment to Dementia and in Dementia Progression.

INTRODUCTION: Neurodegenerative diseases are a growing concern in an aging global population. Frailty, often conceptualized as a state of diminished physiological reserve and increased susceptibility to stressors, emerges as a pivotal factor in this context. While frailty may be modified, it is essential to recognize its frequently irreversible nature, necessitating a careful approach when considering its role and influence in the progression from mild cognitive impairment (MCI) to dementia and within dementia progression. METHODS: A retrospective study including 1,284 participants, attending a Cognitive Disturbances and Dementia unit from January 2021 to May 2023, was conducted. Frailty was assessed using the clinical frailty scale (CFS) score. Multilevel univariate and multivariate logistic regression models were developed to determine the contributions of patient characteristics, including frailty, to disease progression. RESULTS: Frailty significantly increased with higher global clinical dementia rating (CDR) subgroups, suggesting escalating frailty burden with disease progression. Age, CFS, and mini-mental state examination (MMSE) scores were significant predictors of progression from MCI to dementia and to more severe dementia stages, even when considering the independence from variables contributing to frailty. Patients transitioning to a higher CDR group exhibited higher CFS scores. Age, education, anticholinergic burden, cumulative illness rating scale - geriatric, MMSE, and neuropsychiatric inventory scores significantly contributed to frailty. CONCLUSIONS: Frailty plays a critical role in the transition from MCI to dementia and within dementia progression. Age, cognitive impairment, and frailty were identified as significant predictors of disease progression. The CFS is a clinically applicable tool for frailty assessment. Regular frailty assessments may be valuable in early detection and management of dementia.

Detection of TDP-43 seeding activity in the olfactory mucosa from patients with frontotemporal dementia.

INTRODUCTION: We assessed TAR DNA-binding protein 43 (TDP-43) seeding activity and aggregates detection in olfactory mucosa of patients with frontotemporal lobar degeneration with TDP-43-immunoreactive pathology (FTLD-TDP) by TDP-43 seeding amplification assay (TDP43-SAA) and immunocytochemical analysis. METHODS: The TDP43-SAA was optimized using frontal cortex samples from 16 post mortem cases with FTLD-TDP, FTLD with tau inclusions, and controls. Subsequently, olfactory mucosa samples were collected from 17 patients with FTLD-TDP, 15 healthy controls, and three patients carrying MAPT variants. RESULTS: TDP43-SAA discriminated with 100% accuracy post mortem cases presenting or lacking TDP-43 neuropathology. TDP-43 seeding activity was detectable in the olfactory mucosa, and 82.4% of patients with FTLD-TDP tested positive, whereas 86.7% of controls tested negative (P < 0.001). Two out of three patients with MAPT mutations tested negative. In TDP43-SAA positive samples, cytoplasmatic deposits of phosphorylated TDP-43 in the olfactory neural cells were detected. DISCUSSION: TDP-43 aggregates can be detectable in olfactory mucosa, suggesting that TDP43-SAA might be useful for identifying and monitoring FTLD-TDP in living patients.

Increasing Brain Gamma Activity Improves Episodic Memory and Restores Cholinergic Dysfunction in Alzheimer's Disease.

OBJECTIVE: This study aimed to assess whether non-invasive brain stimulation with transcranial alternating current stimulation at gamma-frequency (γ-tACS) applied over the precuneus can improve episodic memory and modulate cholinergic transmission by modulating cerebral rhythms in early Alzheimer's disease (AD). METHODS: In this randomized, double-blind, sham controlled, crossover study, 60 AD patients underwent a clinical and neurophysiological evaluation including assessment of episodic memory and cholinergic transmission pre and post 60 minutes treatment with γ-tACS targeting the precuneus or sham tACS. In a subset of 10 patients, EEG analysis and individualized modelling of electric field distribution were carried out. Predictors to γ-tACS efficacy were evaluated. RESULTS: We observed a significant improvement in the Rey Auditory Verbal Learning (RAVL) test immediate recall (p < 0.001) and delayed recall scores (p < 0.001) after γ-tACS but not after sham tACS. Face-name associations scores improved with γ-tACS (p < 0.001) but not after sham tACS. Short latency afferent inhibition, an indirect measure of cholinergic transmission, increased only after γ-tACS (p < 0.001). ApoE genotype and baseline cognitive impairment were the best predictors of response to γ-tACS. Clinical improvement correlated with the increase in gamma frequencies in posterior regions and with the amount of predicted electric field distribution in the precuneus. INTERPRETATION: Precuneus γ-tACS, able to increase γ-power activity on the posterior brain regions, showed a significant improvement of episodic memory performances, along with restoration of intracortical excitability measures of cholinergic transmission. Response to γ-tACS was dependent on genetic factors and disease stage. ANN NEUROL 2022;92:322-334.

Neurophysiological correlates of altered time awareness in Alzheimer's disease and frontotemporal dementia.

BACKGROUND: Alterations in time awareness have been reported in dementia, particularly in Alzheimer's disease (AD) and frontotemporal dementia (FTD). However, the neurophysiological correlates underlying these alterations remain largely unexplored. This study aimed to investigate the neurophysiological correlates of altered time awareness in AD and FTD patients. METHODS: A total of 150 participants (50 AD patients, 50 FTD patients, and 50 healthy controls [HC]) underwent a standardized neuropsychological assessment, an altered time awareness survey, and transcranial magnetic stimulation (TMS) to assess cholinergic (short latency afferent inhibition-SAI), GABAergic (short interval intracortical inhibition-SICI), and glutamatergic (intracortical facilitation-ICF) circuits. RESULTS: In AD patients, the most frequent symptom was difficulty in ordering past events (52.0%), while FTD patients primarily struggled with estimating temporal intervals between events (40.0%). Significant differences were observed between HC and both patient groups, as well as between AD and FTD patients in their tendency to re-live past events. Binomial logistic regression analysis revealed that impairments in glutamatergic and cholinergic circuits significantly predicted the likelihood of participants manifesting altered time awareness symptoms. CONCLUSIONS: This study provides novel insights into the neurophysiological correlates of altered time awareness in AD and FTD patients, highlighting the involvement of specific neurotransmitter circuits, particularly glutamatergic and cholinergic circuits. Further research is needed to explore the potential clinical implications and therapeutic targets arising from these findings.

Motor and cognitive outcomes of cerebello-spinal stimulation in neurodegenerative ataxia.

Cerebellar ataxias represent a heterogeneous group of disabling disorders characterized by motor and cognitive disturbances, for which no effective treatment is currently available. In this randomized, double-blind, sham-controlled trial, followed by an open-label phase, we investigated whether treatment with cerebello-spinal transcranial direct current stimulation (tDCS) could improve both motor and cognitive symptoms in patients with neurodegenerative ataxia at short and long-term. Sixty-one patients were randomized in two groups for the first controlled phase. At baseline (T0), Group 1 received placebo stimulation (sham tDCS) while Group 2 received anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks (T1), with a 12-week (T2) follow-up (randomized, double-blind, sham controlled phase). At the 12-week follow-up (T2), all patients (Group 1 and Group 2) received a second treatment of anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks, with a 14-week (T3), 24-week (T4), 36-week (T5) and 52-week follow-up (T6) (open-label phase). At each time point, a clinical, neuropsychological and neurophysiological evaluation was performed. Cerebellar-motor cortex connectivity was evaluated using transcranial magnetic stimulation. We observed a significant improvement in all motor scores (scale for the assessment and rating of ataxia, international cooperative ataxia rating scale), in cognition (evaluated with the cerebellar cognitive affective syndrome scale), in quality-of-life scores, in motor cortex excitability and in cerebellar inhibition after real tDCS compared to sham stimulation and compared to baseline (T0), both at short and long-term. We observed an addon-effect after two repeated treatments with real tDCS compared to a single treatment with real tDCS. The improvement at motor and cognitive scores correlated with the restoration of cerebellar inhibition evaluated with transcranial magnetic stimulation. Cerebello-spinal tDCS represents a promising therapeutic approach for both motor and cognitive symptoms in patients with neurodegenerative ataxia, a still orphan disorder of any pharmacological intervention.

Imaging features and ultraearly hematoma growth in intracerebral hemorrhage associated with COVID-19.

PURPOSE: Intracerebral hemorrhage (ICH) is an uncommon but deadly event in patients with COVID-19 and its imaging features remain poorly characterized. We aimed to describe the clinical and imaging features of COVID-19-associated ICH. METHODS: Multicenter, retrospective, case-control analysis comparing ICH in COVID-19 patients (COV19 +) versus controls without COVID-19 (COV19 -). Clinical presentation, laboratory markers, and severity of COVID-19 disease were recorded. Non-contrast computed tomography (NCCT) markers (intrahematoma hypodensity, heterogeneous density, blend sign, irregular shape fluid level), ICH location, and hematoma volume (ABC/2 method) were analyzed. The outcome of interest was ultraearly hematoma growth (uHG) (defined as NCCT baseline ICH volume/onset-to-imaging time), whose predictors were explored with multivariable linear regression. RESULTS: A total of 33 COV19 + patients and 321 COV19 - controls with ICH were included. Demographic characteristics and vascular risk factors were similar in the two groups. Multifocal ICH and NCCT markers were significantly more common in the COV19 + population. uHG was significantly higher among COV19 + patients (median 6.2 mL/h vs 3.1 mL/h, p = 0.027), and this finding remained significant after adjustment for confounding factors (systolic blood pressure, antiplatelet and anticoagulant therapy), in linear regression (B(SE) = 0.31 (0.11), p = 0.005). This association remained consistent also after the exclusion of patients under anticoagulant treatment (B(SE) = 0.29 (0.13), p = 0.026). CONCLUSIONS: ICH in COV19 + patients has distinct NCCT imaging features and a higher speed of bleeding. This association is not mediated by antithrombotic therapy and deserves further research to characterize the underlying biological mechanisms.

Hyperconnectivity in Dementia Is Early and Focal and Wanes with Progression.

We investigated in a longitudinal multicenter cohort study functional cortical connectivity changes along the course of frontotemporal dementia (FTD) and Alzheimer's disease (AD) from the prodromal stage of the diseases. Electroencephalography (EEG) was recorded in 18 FTD and 18 AD patients at the prodromal stage of dementia, at dementia onset, and 3 years after dementia onset. Twenty healthy controls (HC) underwent EEG recordings at the same time interval as the patients. Mutual information (MI) analysis measured the strength of functional network connectivity. FTD and AD patients showed greater MI at the prodromal stage of dementia (FTD vs. HC P = 2 × 10-8; AD vs. HC P = 4 × 10-3). Local connectivity was higher in left and right frontal areas of FTD (P = 7 × 10-5 and 0.03) and in left and right posterior areas in AD (P = 3 × 10-5 and 5 × 10-5) versus HC. We showed cortical hyperconnectivity at the prodromal stage of dementia in areas involved in the specific pathological process of FTD (frontal regions) and AD (posterior regions). Hyperconnectivity disappeared during follow-up, thus suggesting that it is an early electrophysiological feature of dementia, potentially useful to identify prodromal FTD and AD.

Sex influences clinical phenotype in frontotemporal dementia.

INTRODUCTION: Frontotemporal dementia (FTD) encompasses a wide spectrum of genetic, clinical, and histological findings. Sex is emerging as a potential biological variable influencing FTD heterogeneity; however, only a few studies explored this issue with nonconclusive results. OBJECTIVE: To estimate the role of sex in a single-center large cohort of FTD patients. METHODS: Five hundred thirty-one FTD patients were consecutively enrolled. Demographic, clinical, and neuropsychological features, survival rate, and serum neurofilament light (NfL) concentration were determined and compared between sex. RESULTS: The behavioral variant of FTD was more common in men, whereas primary progressive aphasia was overrepresented in women (p < 0.001). While global cognitive impairment was comparable, females had a more severe cognitive impairment, namely in Trail Making Test parts A and B (p = 0.003), semantic fluency (p = 0.03), Short Story Recall Test (p = 0.003), and the copy of Rey Complex Figure (p = 0.005). On the other hand, men exhibited more personality/behavioral symptoms (Frontal Behavior Inventory [FBI] AB, p = 0.003), displaying higher scores in positive FBI subscales (FBI B, p < 0.001). In particular, apathy (p = 0.02), irritability (p = 0.006), poor judgment (p = 0.033), aggressivity (p = 0.008), and hypersexuality (p = 0.006) were more common in men, after correction for disease severity. NfL concentration and survival were not statistically different between men and women (p = 0.167 and p = 0.645, respectively). DISCUSSION: The present study demonstrated that sex is a potential factor in determining FTD phenotype, while it does not influence survival. Although the pathophysiological contribution of sex in neurodegeneration is not well characterized yet, our findings highlight its role as deserving biological variable in FTD.

Serum neurofilament light in professional soccer players: goal on safety.

BACKGROUND: Sports-related concussion (SRC) is a subset of mild traumatic brain injuries occurring in contact sports. Most people recover spontaneously, but in retired professional players, the risk for neurodegenerative diseases is increased. A biomarker, such as neurofilament light chains (NfL), would help to address this issue and demonstrate sports' safety. Assessing NfL in professional soccer players may be the best way to investigate if repetitive head-impact exposure in the typical lower and asymptomatic range is harmful. OBJECTIVE: To evaluate whether the NfL in serum is a sensitive biomarker to detect mild brain injury in professional soccer players. METHODS: Thirty-six soccer players belonging to a professional Italian team underwent serum NfL assessment using ultrasensitive single-molecule array technology. Sixteen healthy nonathletic controls were also enrolled. Differences between groups and changes over time, considering pre-season vs. season, were considered. RESULTS: Serum NfL concentrations were comparable in the soccer professional players (median [interquartile range], 6.44 pg/mL [4.60-8.27] and controls (6.50 pg/mL [5.26-7.04]), with a median difference of - 0.06 pg/mL (95% CI -1.36 to 1.18), p = 0.957. No significant differences according to players' role (goalkeeper, defender, midfielder or forward) or according to timing of sampling (pre-season vs. season) were found. CONCLUSIONS: These results suggest that professional soccer, even when played at the highest level of competition, may be considered safe. Future studies assessing serum NfL levels after soccer-related concussions should be carried out, to evaluate their usefulness as a return-to-play marker avoiding second impact syndrome.

Clinical outcome of neurological patients with COVID-19: the impact of healthcare organization improvement between waves.

OBJECTIVE: The aim of this study is to evaluate the differences in clinical presentations and the impact of healthcare organization on outcomes of neurological COVID-19 patients admitted during the first and second pandemic waves. METHODS: In this single-center cohort study, we included all patients with SARS-CoV-2 infection admitted to a Neuro-COVID Unit. Demographic, clinical, and laboratory data were compared between patients admitted during the first and second waves of the COVID-19 pandemic. RESULTS: Two hundred twenty-three patients were included, of whom 112 and 111 were hospitalized during the first and second pandemic waves, respectively. Patients admitted during the second wave were younger and exhibited pulmonary COVID-19 severity, resulting in less oxygen support (n = 41, 36.9% vs n = 79, 70.5%, p < 0.001) and lower mortality rates (14.4% vs 31.3%, p = 0.004). The different healthcare strategies and early steroid treatment emerged as significant predictors of mortality independently from age, pre-morbid conditions and COVID-19 severity in Cox regression analyses. CONCLUSIONS: Differences in healthcare strategies during the second phase of the COVID-19 pandemic probably explain the differences in clinical outcomes independently of disease severity, underlying the importance of standardized early management of neurological patients with SARS-CoV-2 infection.

Conceptual framework for the definition of preclinical and prodromal frontotemporal dementia.

The presymptomatic stages of frontotemporal dementia (FTD) are still poorly defined and encompass a long accrual of progressive biological (preclinical) and then clinical (prodromal) changes, antedating the onset of dementia. The heterogeneity of clinical presentations and the different neuropathological phenotypes have prevented a prior clear description of either preclinical or prodromal FTD. Recent advances in therapeutic approaches, at least in monogenic disease, demand a proper definition of these predementia stages. It has become clear that a consensus lexicon is needed to comprehensively describe the stages that anticipate dementia. The goal of the present work is to review existing literature on the preclinical and prodromal phases of FTD, providing recommendations to address the unmet questions, therefore laying out a strategy for operationalizing and better characterizing these presymptomatic disease stages.

Clinical Presentation and Outcomes of Severe Acute Respiratory Syndrome Coronavirus 2-Related Encephalitis: The ENCOVID Multicenter Study.

BACKGROUND: Several preclinical and clinical investigations have argued for nervous system involvement in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Some sparse case reports have described various forms of encephalitis in coronavirus disease 2019 (COVID-19) disease, but very few data have focused on clinical presentations, clinical course, response to treatment, and outcomes. METHODS: The SARS-CoV-2 related encephalopaties (ENCOVID) multicenter study included patients with encephalitis with full infectious screening, cerebrospinal fluid (CSF), electroencephalography (EEG), and magnetic resonance imaging (MRI) data and confirmed SARS-CoV-2 infection recruited from 13 centers in northern Italy. Clinical presentation and laboratory markers, severity of COVID-19 disease, response to treatment, and outcomes were recorded. RESULTS: Twenty-five cases of encephalitis positive for SARS-CoV-2 infection were included. CSF showed hyperproteinorrachia and/or pleocytosis in 68% of cases whereas SARS-CoV-2 RNA by reverse-transcription polymerase chain reaction resulted negative. Based on MRI, cases were classified as acute demyelinating encephalomyelitis (ADEM; n = 3), limbic encephalitis (LE; n = 2), encephalitis with normal imaging (n = 13), and encephalitis with MRI alterations (n = 7). ADEM and LE cases showed a delayed onset compared to the other encephalitis cases (P = .001) and were associated with previous, more severe COVID-19 respiratory involvement. Patients with MRI alterations exhibited worse response to treatment and final outcomes compared to those with other encephalitis. CONCLUSIONS: SARS-CoV-2 infection is associated with a wide spectrum of encephalitis characterized by different clinical presentation, response to treatment, and outcomes.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Encephalitis Is a Cytokine Release Syndrome: Evidences From Cerebrospinal Fluid Analyses.

BACKGROUND: Recent findings indicated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related neurological manifestations involve cytokine release syndrome along with endothelial activation, blood brain barrier dysfunction, and immune-mediated mechanisms. Very few studies have fully investigated the cerebrospinal fluid (CSF) correlates of SARS-CoV-2 encephalitis. METHODS: Patients with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection and encephalitis (COV-Enc), encephalitis without SARS-CoV-2 infection (ENC), and healthy controls (HC) underwent an extended panel of CSF neuronal (neurofilament light chain [NfL], T-tau), glial (glial fibrillary acidic protein [GFAP], soluble triggering receptor expressed on myeloid cells 2 [sTREM2], chitinase-3-like protein 1 [YKL-40]) and inflammatory biomarkers (interleukin [IL]-1ß, IL-6, Il-8, tumor necrosis factor [TNF] α, CXCL-13, and ß2-microglobulin). RESULTS: Thirteen COV-Enc, 21 ENC, and 18 HC entered the study. In COV-Enc cases, CSF was negative for SARS-CoV-2 real-time PCR but exhibited increased IL-8 levels independently from presence of pleocytosis/hyperproteinorracchia. COV-Enc patients showed increased IL-6, TNF- α, and ß2-microglobulin and glial markers (GFAP, sTREM2, YKL-40) levels similar to ENC but normal CXCL13 levels. Neuronal markers NfL and T-tau were abnormal only in severe cases. CONCLUSIONS: SARS-CoV-2-related encephalitis were associated with prominent glial activation and neuroinflammatory markers, whereas neuronal markers were increased in severe cases only. The pattern of CSF alterations suggested a cytokine-release syndrome as the main inflammatory mechanism of SARS-CoV-2-related encephalitis.

Classification Accuracy of Transcranial Magnetic Stimulation for the Diagnosis of Neurodegenerative Dementias.

OBJECTIVE: Transcranial magnetic stimulation (TMS) has been suggested as a reliable, noninvasive, and inexpensive tool for the diagnosis of neurodegenerative dementias. In this study, we assessed the classification performance of TMS parameters in the differential diagnosis of common neurodegenerative disorders, including Alzheimer disease (AD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). METHODS: We performed a multicenter study enrolling patients referred to 4 dementia centers in Italy, in accordance with the Standards for Reporting of Diagnostic Accuracy. All patients underwent TMS assessment at recruitment (index test), with application of reference clinical criteria, to predict different neurodegenerative disorders. The investigators who performed the index test were masked to the results of the reference test and all other investigations. We trained and tested a random forest classifier using 5-fold cross-validation. The primary outcome measures were the classification accuracy, precision, recall, and F1 score of TMS in differentiating each neurodegenerative disorder. RESULTS: A total of 694 participants were included, namely 273 patients diagnosed as AD, 67 as DLB, and 207 as FTD, and 147 healthy controls (HC). A series of 3 binary classifiers was employed, and the prediction model exhibited high classification accuracy (ranging from 0.89 to 0.92), high precision (0.86-0.92), high recall (0.93-0.98), and high F1 scores (0.89-0.95) in differentiating each neurodegenerative disorder. INTERPRETATION: TMS is a noninvasive procedure that reliably and selectively distinguishes AD, DLB, FTD, and HC, representing a useful additional screening tool to be used in clinical practice. Ann Neurol 2020;87:394-404.

GluA3 autoantibodies induce alterations in dendritic spine and behavior in mice.

Autoantibodies targeting the GluA3 subunit of AMPA receptors (AMPARs) have been found in patients with Rasmussen's encephalitis and different types of epilepsy and were associated with the presence of learning and attention deficits. Our group recently identified the presence of anti-GluA3 immunoglobulin G (IgG) in about 25% of patients with frontotemporal dementia (FTD), thus suggesting a novel pathogenetic role also in chronic neurodegenerative diseases. However, the in vivo behavioral, molecular and morphological effects induced these antibodies are still unexplored. We injected anti-GluA3 IgG purified from the serum of FTD patients, or control IgG, in mice by intracerebroventricular infusion. Biochemical analyses showed a reduction of synaptic levels of GluA3-containing AMPARs in the prefrontal cortex (PFC), and not in the hippocampus. Accordingly, animals injected with anti-GluA3 IgG showed significant changes in recognition memory and impairments in social behavior and in social cognitive functions. As visualized by confocal imaging, functional outcomes were paralleled by profound alterations of dendritic spine morphology in the PFC. All observed behavioral, molecular and morphological alterations were transient and not detected 10-14 days from anti-GluA3 IgG injection. Overall, our in vivo preclinical data provide novel insights into autoimmune encephalitis associated with anti-GluA3 IgG and indicate an additional pathological mechanism affecting the excitatory synapses in FTD patients carrying anti-GluA3 IgG that could contribute to clinical symptoms.

Diagnostic and prognostic value of serum NfL and p-Tau181 in frontotemporal lobar degeneration.

OBJECTIVE: To assess the diagnostic and prognostic value of serum neurofilament light (NfL) and serum phospho-Tau181 (p-Tau181) in a large cohort of patients with frontotemporal lobar degeneration (FTLD). METHODS: In this retrospective study, performed on 417 participants, we analysed serum NfL and p-Tau181 concentrations with an ultrasensitive single molecule array (Simoa) approach. We assessed the diagnostic values of serum biomarkers in the differential diagnosis between FTLD, Alzheimer's disease (AD) and healthy ageing; their role as markers of disease severity assessing the correlation with clinical variables, cross-sectional brain imaging and neurophysiological data; their role as prognostic markers, considering their ability to predict survival probability in FTLD. RESULTS: We observed significantly higher levels of serum NfL in patients with FTLD syndromes, compared with healthy controls, and lower levels of p-Tau181 compared with patients with AD. Serum NfL concentrations showed a high accuracy in discriminating between FTLD and healthy controls (area under the curve (AUC): 0.86, p<0.001), while serum p-Tau181 showed high accuracy in differentiating FTLD from patients with AD (AUC: 0.93, p<0.001). In FTLD, serum NfL levels correlated with measures of cognitive function, disease severity and behavioural disturbances and were associated with frontotemporal atrophy and indirect measures of GABAergic deficit. Moreover, serum NfL concentrations were identified as the best predictors of survival probability. CONCLUSIONS: The assessment of serum NfL and p-Tau181 may provide a comprehensive view of FTLD, aiding in the differential diagnosis, in staging disease severity and in defining survival probability.

Non-Invasive Cerebellar Stimulation in Neurodegenerative Ataxia: A Literature Review.

Cerebellar ataxias are a heterogenous group of degenerative disorders for which we currently lack effective and disease-modifying interventions. The field of non-invasive brain stimulation has made much progress in the development of specific stimulation protocols to modulate cerebellar excitability and try to restore the physiological activity of the cerebellum in patients with ataxia. In light of limited evidence-based pharmacologic and non-pharmacologic treatment options for patients with ataxia, several different non-invasive brain stimulation protocols have emerged, particularly employing repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) techniques. In this review, we summarize the most relevant rTMS and tDCS therapeutic trials and discuss their implications in the care of patients with degenerative ataxias.