Essential tremor with tau pathology features seeds indistinguishable in conformation from Alzheimer's disease and primary age-related tauopathy.

Neurodegenerative tauopathies are characterized by the deposition of distinct fibrillar tau assemblies whose rigid core structures correlate with defined neuropathological phenotypes. Essential tremor (ET) is a progressive neurological disease disease that, in some cases, is associated with cognitive impairment and tau accumulation.. Consequently, we explored the tau assembly conformation in ET patients with tau pathology using cytometry-based tau biosensor assays. These assays quantify tau prion seeding activity present in brain homogenates based on conversion of intracellular tau-fluorescent protein fusions from a soluble to an aggregated state. Prions exhibit seeding barriers, whereby a specific assembly structure cannot serve as a template for a native monomer if the amino acids are not compatible. We recently exploited the tau prion species barrier to define tauopathies by systematically substituting alanine (Ala) in the tau monomer and measuring its incorporation into seeded aggregates within biosensor cells. The Ala scan precisely classified the conformation of tau seeds from diverse tauopathies. We next studied 18 ET patient brains with tau pathology. Only one case had concurrent high amyloid-ß plaque pathology consistent with Alzheimer's disease (AD). We detected robust tau seeding activity in 9 (50%) of the patients. This predominantly localized to the temporal pole and temporal cortex. We examined 8 ET cases with the Ala scan and determined that the amino acid requirements for tau monomer incorporation into aggregates seeded from these ET brain homogenates were identical to those of AD and primary age-related tauopathy (PART), and completely distinct from other tauopathies such as corticobasal degeneration, chronic traumatic encephalopathy, and progressive supranuclear palsy. Based on these studies, tau assembly cores in a pathologically confined subset of ET cases with high tau pathology are identical to AD and PART. This could facilitate more precise diagnosis and therapy for ET patients with cognitive impairment.

Exploring the association of disease-modifying therapies for multiple sclerosis and BTK inhibitors with epilepsy.

Background: Multiple lines of evidence suggest a role of inflammation in epilepsy. Seizure incidence in patients with multiple sclerosis (MS) is twofold to threefold higher than the age-matched general population. Objectives: To explore the association of MS disease-modifying therapies (DMTs) and FDA-approved Bruton tyrosine kinase inhibitors (for lymphocytic malignancies) with the occurrence of epilepsy using the US Food and Drug Administration Adverse Event Reporting System (FAERS) database. Design: Secondary analysis of the FAERS database. Methods: We conducted a disproportionality analysis of FAERS between 2003-Q4 and 2023-Q3. MS DMTs and the Bruton tyrosine kinase inhibitor, ibrutinib, were included in the analysis. An inverse association was defined by a 95% confidence interval (CI) upper limit of reporting odds ratio (ROR) <1. Results: We found an inverse association of ibrutinib, ocrelizumab, ofatumumab, rituximab, and teriflunomide with epilepsy. The strongest inverse association was seen with ibrutinib (ROR: 0.338; 95% CI: 0.218-0.524). Conclusion: Our findings suggest the possibility of considering these medications for repurposing opportunities in epilepsy and support a potential pathogenic role of leukocyte subsets in seizure perpetuation.

How multiple sclerosis treatments and Bruton tyrosine kinase inhibitors may be linked to epilepsy The research presented in this manuscript attempts to elucidate the potential relationship between inflammation and epilepsy. Multiple sclerosis (MS) is the most common inflammatory disorder of the brain and spinal cord in humans. There are over 20 FDA-approved disease-modifying therapies (DMTs) for MS. Other anti-inflammatory agents called Bruton tyrosine kinase (BTK) inhibitors are in clinical development. We show that the use of some DMTs and a BTK inhibitor appear to be associated with a lower chance of epilepsy.

Neuromyelitis Optica Spectrum Disorder Resembling Wernicke's Encephalopathy: A Case Report and Review of the Literature.

We describe a case of Neuromyelitis Optica Spectrum Disorder (NMOSD) mimicking Wernicke's Encephalopathy (WE) to highlight an atypical presentation of NMOSD. A 39-year-old female presented with subacute encephalopathy and progressive ophthalmoplegia. Her MRI revealed T2 hyperintensities involving the mammillary bodies, periaqueductal grey matter, medial thalami, third ventricle, and area postrema. Whole blood thiamine levels were elevated and she did not improve with IV thiamine. CSF was notable for lymphocytic pleocytosis and elevated protein. She tested positive for serum Aquaporin-4 (AQP4) antibody. Subsequent imaging revealed multilevel lesions in the cervical and thoracic spinal cord. Her CSF GFAP antibody also came back positive. She steadily and significantly improved after high-dose IV steroids and plasmapheresis. She later started on chronic rituximab therapy. This represents a unique case of NMOSD presenting with the classical clinical and imaging features of WE, as opposed to the typical presenting symptoms of NMOSD. As such, demyelinating disorders should be considered when there is concern for diencephalic and midline pathologies, particularly without classic WE risk factors. Conversely, clinicians should be aware of secondary nutritional complications arising from severe area postrema syndrome.

Blood Markers in Relation to a History of Traumatic Brain Injury Across Stages of Cognitive Impairment in a Diverse Cohort.

BACKGROUND: Traumatic brain injury (TBI) has been linked to multiple pathophysiological processes that could increase risk for Alzheimer's disease and related dementias (ADRD). However, the impact of prior TBI on blood biomarkers for ADRD remains unknown. OBJECTIVE: Using cross-sectional data, we assessed whether a history of TBI influences serum biomarkers in a diverse cohort (approximately 50% Hispanic) with normal cognition, mild cognitive impairment, or dementia. METHODS: Levels of glial fibrillary acidic protein (GFAP), neurofilament light (NFL), total tau (T-tau), and ubiquitin carboxy-terminal hydrolase-L1 (UCHL1) were measured for participants across the cognitive spectrum. Participants were categorized based on presence and absence of a history of TBI with loss of consciousness, and study samples were derived through case-control matching. Multivariable general linear models compared concentrations of biomarkers in relation to a history of TBI and smoothing splines modelled biomarkers non-linearly in the cognitively impaired groups as a function of time since symptom onset. RESULTS: Each biomarker was higher across stages of cognitive impairment, characterized by clinical diagnosis and Mini-Mental State Examination performance, but these associations were not influenced by a history of TBI. However, modelling biomarkers in relation to duration of cognitive symptoms for ADRD showed differences by history of TBI, with only GFAP and UCHL1 being elevated. CONCLUSIONS: Serum GFAP, NFL, T-tau, and UCHL1 were higher across stages of cognitive impairment in this diverse clinical cohort, regardless of TBI history, though longitudinal investigation of the timing, order, and trajectory of the biomarkers in relation to prior TBI is warranted.

Episodic stuttering as the presenting manifestation of acute ischemic stroke: A case report and systematic literature review.

BACKGROUND: Acquired episodic stuttering in adulthood represents a rare condition, which has been infrequently described in the literature. CASE PRESENTATION: We describe the case of a 62-year-old male who presented to the emergency room with three episodes of new-onset brief isolated stuttering with no other speech impairment or associated focal neurologic deficits. His brain magnetic resonance imaging was notable for the presence of a small acute ischemic stroke involving the left precuneus cortex. SYSTEMATIC LITERATURE REVIEW: We performed a systematic literature review to evaluate the association between stroke and acquired neurogenic stuttering. The evidence published to this date suggests that the underlying pathophysiology of acquired stutter does not localize to an isolated or focal region. The development of stuttering secondary to strokes may be the result of a disruption at any level in a cortico-striato-cortical integrative pathway mediating speech execution. CONCLUSION: Here we aimed to emphasize the importance of carefully evaluating new-onset recurrent episodic stuttering to rule out an underlying stroke or another neurogenic etiology. We provide a comprehensive review of acquired stuttering, its differential diagnosis, and its evaluation.

Limb myorhythmia treated with chemodenervation: a case report.

We describe a case of limb myorhythmia successfully palliated with botulinum toxin injections. The patient is a 30-year-old male evaluated for abnormal movements of the left lower foot that began after an ankle injury for which the patient underwent Achilles tendon scar tissue debridement without improvement. On examination, he had near-constant involuntary, slow, rhythmic flexion/extension tremor of toes 2-4 that was diminished during active movement. Needle electromyography (EMG) revealed a rhythmic, 2-3 Hz tremor isolated to the flexor digitorum brevis. After failure of medical management with muscle relaxants, gabapentin, and levodopa trials, the patient underwent two EMG-guided chemodenervation procedures with incobotulinum toxin A injections of the left flexor digitorum brevis. At 3-month follow-up, he had achieved a sustained 50% reduction in the intensity of the movements and improved quality of life. Myorhythmia is a rare condition characterized by a repetitive, rhythmic, slow frequency (1-4 Hz) movement affecting the cranial and limb muscles. The most common causes include stroke, demyelinating disorders, drug or toxin intake, trauma, and infections. The management of this condition is very limited with pharmacologic agents such as anticholinergics, antispasmodics, anticonvulsants, or dopaminergic agents showing limited efficacy. The use of botulinum toxin chemodenervation aided by EMG muscle targeting can be a useful therapeutic intervention in cases of medication-refractory regionally distributed myorhythmia involving accessible muscles.

Microglia as a cellular target of diclofenac therapy in Alzheimer's disease.

Alzheimer's disease (AD) is an untreatable cause of dementia, and new therapeutic approaches are urgently needed. AD pathology is defined by extracellular amyloid plaques and intracellular neurofibrillary tangles. Research of the past decades has suggested that neuroinflammation plays a critical role in the pathophysiology of AD. This has led to the idea that anti-inflammatory treatments might be beneficial. Early studies investigated non-steroidal anti-inflammatory drugs (NSAIDS) such as indomethacin, celecoxib, ibuprofen, and naproxen, which had no benefit. More recently, protective effects of diclofenac and NSAIDs in the fenamate group have been reported. Diclofenac decreased the frequency of AD significantly compared to other NSAIDs in a large retrospective cohort study. Diclofenac and fenamates share similar chemical structures, and evidence from cell and mouse models suggests that they inhibit the release of pro-inflammatory mediators from microglia with leads to the reduction of AD pathology. Here, we review the potential role of diclofenac and NSAIDs in the fenamate group for targeting AD pathology with a focus on its potential effects on microglia.

The validity of animal models to explore the pathogenic role of the complement system in multiple sclerosis: A review.

Animal models of multiple sclerosis (MS) have been extensively used to characterize the disease mechanisms in MS, as well as to identify potential pharmacologic targets for this condition. In recent years, the immune complement system has gained increased attention as an important effector in the pathogenesis of MS. Evidence from histological, serum, and CSF studies of patients supports an involvement of complement in both relapsing-remitting and progressive MS. In this review, we discuss the history and advances made on the use of MS animal models to profile the effects of the complement system in this condition. The first studies that explored the complement system in the context of MS used cobra venom factor (CVF) as a complement depleting agent in experimental autoimmune encephalomyelitis (EAE) Lewis rats. Since then, multiple mice and rat models of MS have revealed a role of C3 and the alternative complement cascade in the opsonization and phagocytosis of myelin by microglia and myeloid cells. Studies using viral vectors, genetic knockouts and pharmacologic complement inhibitors have also shown an effect of complement in synaptic loss. Antibody-mediated EAE models have revealed an involvement of the C1 complex and the classical complement as an effector of the humoral response in this disease. C1q itself may also be involved in modulating microglia activation and oligodendrocyte differentiation in these animals. In addition, animal and in vitro models have revealed that multiple complement factors may act as modulators of both the innate and adaptive immune responses. Finally, evidence gathered from mice models suggests that the membrane attack complex (MAC) may even exert protective roles in the chronic stages of EAE. Overall, this review summarizes the importance of MS animal models to better characterize the role of the complement system and guide future therapeutic approaches in this condition.

The role of the complement system in Multiple Sclerosis: A review.

The complement system has been involved in the pathogenesis of multiple neuroinflammatory and neurodegenerative conditions. In this review, we evaluated the possible role of complement activation in multiple sclerosis (MS) with a focus in progressive MS, where the disease pathogenesis remains to be fully elucidated and treatment options are limited. The evidence for the involvement of the complement system in the white matter plaques and gray matter lesions of MS stems from immunohistochemical analysis of post-mortem MS brains, in vivo serum and cerebrospinal fluid biomarker studies, and animal models of Experimental Autoimmune Encephalomyelitis (EAE). Complement knock-out studies in these animal models have revealed that this system may have a "double-edge sword" effect in MS. On the one hand, complement proteins may aid in promoting the clearance of myelin degradation products and other debris through myeloid cell-mediated phagocytosis. On the other, its aberrant activation may lead to demyelination at the rim of progressive MS white matter lesions as well as synapse loss in the gray matter. The complement system may also interact with known risk factors of MS, including as Epstein Barr Virus (EBV) infection, and perpetuate the activation of CNS self-reactive B cell populations. With the mounting evidence for the involvement of complement in MS, the development of complement modulating therapies for this condition is appealing. Herein, we also reviewed the pharmacological complement inhibitors that have been tested in MS animal models as well as in clinical trials for other neurologic diseases. The potential use of these agents, such as the C5-binding antibody eculizumab in MS will require a detailed understanding of the role of the different complement effectors in this disease and the development of better CNS delivery strategies for these compounds.

[18F]-AV-1451 binding profile in chronic traumatic encephalopathy: a postmortem case series.

INTRODUCTION: Chronic traumatic encephalopathy (CTE) is a tauopathy associated to repetitive head trauma. There are no validated in vivo biomarkers of CTE and a definite diagnosis can only be made at autopsy. Recent studies have shown that positron emission tomography (PET) tracer AV-1451 (Flortaucipir) exhibits high binding affinity for paired helical filament (PHF)-tau aggregates in Alzheimer (AD) brains but relatively low affinity for tau lesions in other tauopathies like temporal lobal degeneration (FTLD)-tau, progressive supranuclear palsy (PSP) or corticobasal degeneration (CBD). Little is known, however, about the binding profile of this ligand to the tau-containing lesions of CTE. OBJECTIVE: To study the binding properties of [18F]-AV-1451 on pathologically confirmed CTE postmortem brain tissue samples. METHODS: We performed [18F]-AV-1451 phosphor screen and high resolution autoradiography, quantitative tau measurements by immunohistochemistry and Western blot and tau seeding activity assays in brain blocks containing hippocampus, superior temporal cortex, superior frontal cortex, inferior parietal cortex and occipital cortex from 5 cases of CTE, across the stages of disease: stage II-III (n = 1), stage III (n = 3), and stage IV (n = 1). Importantly, low or no concomitant classic AD pathology was present in these brains. RESULTS: Despite the presence of abundant tau aggregates in multiple regions in all CTE brains, only faint or no [18F]-AV-1451 binding signal could be detected by autoradiography. The only exception was the presence of a strong signal confined to the region of the choroid plexus and the meninges in two of the five cases. Tau immunostaining and Thioflavin-S staining ruled out the presence of tau aggregates in those regions. High resolution nuclear emulsion autoradiography revealed the presence of leptomeningeal melanocytes as the histologic source of this off-target binding. Levels of abnormally hyperphosphorylated tau species, as detected by Western Blotting, and tau seeding activity were both found to be lower in extracts from cases CTE when compared to AD. CONCLUSION: AV-1451 may have limited utility for in vivo selective and reliable detection of tau aggregates in CTE. The existence of disease-specific tau conformations may likely explain the differential binding affinity of this tracer for tau lesions in different tauopathies.

[F-18]-AV-1451 binding correlates with postmortem neurofibrillary tangle Braak staging.

[F-18]-AV-1451, a PET tracer specifically developed to detect brain neurofibrillary tau pathology, has the potential to facilitate accurate diagnosis of Alzheimer's disease (AD), staging of brain tau burden and monitoring disease progression. Recent PET studies show that patients with mild cognitive impairment and AD dementia exhibit significantly higher in vivo [F-18]-AV-1451 retention than cognitively normal controls. Importantly, PET patterns of [F-18]-AV-1451 correlate well with disease severity and seem to match the predicted topographic Braak staging of neurofibrillary tangles (NFTs) in AD, although this awaits confirmation. We studied the correlation of autoradiographic binding patterns of [F-18]-AV-1451 and the stereotypical spatiotemporal pattern of progression of NFTs using legacy postmortem brain samples representing different Braak NFT stages (I-VI). We performed [F-18]-AV-1451 phosphor-screen autoradiography and quantitative tau measurements (stereologically based NFT counts and biochemical analysis of tau pathology) in three brain regions (entorhinal cortex, superior temporal sulcus and visual cortex) in a total of 22 cases: low Braak (I-II, n = 6), intermediate Braak (III-IV, n = 7) and high Braak (V-VI, n = 9). Strong and selective [F-18]-AV-1451 binding was detected in all tangle-containing regions matching precisely the observed pattern of PHF-tau immunostaining across the different Braak stages. As expected, no signal was detected in the white matter or other non-tangle containing regions. Quantification of [F-18]-AV-1451 binding was very significantly correlated with the number of NFTs present in each brain region and with the total tau and phospho-tau content as reported by Western blot and ELISA. [F-18]-AV-1451 is a promising biomarker for in vivo quantification of brain tau burden in AD. Neuroimaging-pathologic studies conducted on postmortem material from individuals imaged while alive are now needed to confirm these observations.