Structural brain and spinal cord damage in symptomatic and pre-symptomatic VAPB-related ALS

Distinct patterns of cerebral and spinal pathology along the spectrum of ATXN2-related disorders

BACKGROUND

The ATXN2 gene contains a polymorphic CAG-rich region encoding a polyglutamine tract in ataxin- 2. Normal alleles have fewer than 27 CAG repeats, 27-34 repeats pose a risk for ALS (ATXN2-ALS), and > 34 repeats cause spinocerebellar ataxia type 2 (SCA2). The striking phenotypic differences between these two ATXN2-related conditions are not yet fully understood.

OBJECTIVE

To characterize and compare the distinguishing radiological signatures of ATXN2-ALS, SCA2, sporadic ALS (sALS) and healthy controls in vivo using quantitative computational neuroimaging techniques.

METHODS

Four groups were defined: healthy controls (n = 34), sALS (n = 17), ATXN2-ALS (n = 16), and SCA2 (n = 17). Cortical, subcortical, brainstem, cerebellar and spinal regions were segmented based on T1-weighted data using validated segmentation tools and their volumes estimated. Group-specific morphometric data were correlated with cerebral ATXN2 expression maps from the Allen Human Brain Atlas.

RESULTS

Study groups were age and sex-matched. sALS, ATXN2-ALS and SCA2 have distinct structural CNS signatures, with disease burden restricted to the precentral gyri in the sALS group, to the spinal cord and brainstem in the ATXN2-ALS group and more diffusely distributed in the subcortical structures in the SCA2 group. Brain ATXN2 expression correlated with the structural signature of SCA2, but not with that of ATXN2-ALS.

CONCLUSIONS

Neuroimaging signatures differ in ATXN2-ALS and SCA2, indicating distinct mechanisms of ATXN2-mediated neurodegeneration. sALS and ATXN2-ALS also exhibit distinct patterns of CNS involvement. The unique imaging signatures and clinical profiles along the spectrum of ATXN2-related disorders raise important questions regarding the pathophysiology of the disease and have practical clinical ramifications.

Quantitative and Computational Spinal Imaging in Neurodegenerative Conditions and Acquired Spinal Disorders: Academic Advances and Clinical Prospects

Introduction: Quantitative spinal cord imaging has facilitated the objective appraisal of spinal cord pathology in a range of neurological conditions both in the academic and clinical setting. Diverse methodological approaches have been implemented, encompassing a range of morphometric, diffusivity, susceptibility, magnetization transfer, and spectroscopy techniques. Advances have been fueled both by new MRI platforms and acquisition protocols as well as novel analysis pipelines. The quantitative evaluation of specific spinal tracts and grey matter indices has the potential to be used in diagnostic and monitoring applications. The comprehensive characterization of spinal disease burden in pre-symptomatic cohorts, in carriers of specific genetic mutations, and in conditions primarily associated with cerebral disease, has contributed important academic insights. Methods: A narrative review was conducted to examine the clinical and academic role of quantitative spinal cord imaging in a range of neurodegenerative and acquired spinal cord disorders, including hereditary spastic paraparesis, hereditary ataxias, motor neuron diseases, Huntington's disease, and post-infectious or vascular disorders. Results: The clinical utility of specific methods, sample size considerations, academic role of spinal imaging, key radiological findings, and relevant clinical correlates are presented in each disease group. Conclusions: Quantitative spinal cord imaging studies have demonstrated the feasibility to reliably appraise structural, microstructural, diffusivity, and metabolic spinal cord alterations. Despite the notable academic advances, novel acquisition protocols and analysis pipelines are yet to be implemented in the clinical setting.

A comprehensive review of electrophysiological techniques in amyotrophic lateral sclerosis research

Amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease, is characterized by progressive motor neuron degeneration, leading to widespread weakness and respiratory failure. While a variety of mechanisms have been proposed as causes of this disease, a full understanding remains elusive. Electrophysiological alterations, including increased motor axon excitability, likely play an important role in disease progression. There remains a critical need for non-animal disease models that can integrate electrophysiological tools to better understand underlying mechanisms, track disease progression, and evaluate potential therapeutic interventions. This review explores the integration of electrophysiological technologies with ALS disease models. It covers cellular and clinical electrophysiological tools and their applications in ALS research. Additionally, we examine conventional animal models and highlight advancements in humanized models and 3D organoid technologies. By bridging the gap between these models, we aim to enhance our understanding of ALS pathogenesis and facilitate the development of new therapeutic strategies.

Language impairment in sporadic and familial (type 8) amyotrophic lateral sclerosis: A comparative study

INTRODUCTION/AIMS

Language is frequently affected in patients with sporadic amyotrophic lateral sclerosis (sALS), with reduced performance in naming, syntactic comprehension, grammatical expression, and orthographic processing. However, the language profile of patients with familial type 8 ALS (ALS8), linked to p.P56S VAPB mutation, remains unclear. We investigated language in patients with ALS8 by examining their auditory comprehension and verbal production.

METHODS

We included three groups of participants: (1) patients with sALS (n = 20), (2) patients with familial ALS8 (n = 22), and (3) healthy controls (n = 21). The groups were matched for age, sex, and education level. All participants underwent a comprehensive language battery, including the Boston Diagnostic Aphasia Examination, the reduced Token test, letter fluency, categorical fluency (animals), word definition from the Cambridge Semantic Memory Research Battery, and a narrative discourse analysis. Participants also were evaluated using Addenbrooke's Cognitive Exam-Revised Version, the Hospital Anxiety and Depression Scale, and the ALS Functional Rating Scale-Revised.

RESULTS

Compared to controls, sALS and ALS8 patients had impaired performance on oral (syntactic and phonological processing) comprehension and inappropriate discourse cohesion. sALS and ALS8 did not differ in any language measure. There was no correlation between language scores and functional and psychiatric scales.

DISCUSSION

ALS8 patients exhibit language deficits that are independent of motor features. These findings are consistent with the current evidence suggesting that ALS8 has prominent non-motor features.

A comparative study of cognitive and behavioral profiles between sporadic and type 8 amyotrophic lateral sclerosis

INTRODUCTION/AIMS

Amyotrophic lateral sclerosis (ALS) type 8 (ALS8) is caused by VAPB gene mutations. The differences between neuropsychological and behavioral profiles of patients with sporadic ALS (sALS) and those with ALS8 are unclear. We aimed to compare cognitive performance and behavioral aspects between sALS and ALS8 patients.

METHODS

Our study included 29 symptomatic ALS8 patients (17 men; median age 49 years), 20 sALS patients (12 men; median age 55 years), and 30 healthy controls (16 men; median age 50 years), matched for sex, age, and education. Participants underwent neuropsychological assessments focused on executive functions, visual memory, and facial emotion recognition. Behavioral and psychiatric symptoms were evaluated using the Hospital Anxiety and Depression Scale and the Cambridge Behavioral Inventory.

RESULTS

Clinical groups (sALS and ALS8) exhibited lower global cognitive efficiency and impaired cognitive flexibility, processing speed, and inhibitory control compared with controls. ALS8 and sALS showed similar performance in most executive tests, except for poorer verbal (lexical) fluency in those with sALS. Apathy, anxiety, and stereotypical behaviors were frequent in both clinical groups.

DISCUSSION

sALS and ALS8 patients demonstrated similar deficits in most cognitive domains and had comparable behavioral profiles. These findings should be considered in the care of patients.

Basal ganglia alterations in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) has traditionally been associated with brain damage involving the primary motor cortices and corticospinal tracts. In the recent decades, most of the research studies in ALS have focused on extra-motor and subcortical brain regions. The aim of these studies was to detect additional biomarkers able to support the diagnosis and to predict disease progression. The involvement of the frontal cortices, mainly in ALS cases who develop cognitive and/or behavioral impairment, is amply recognized in the field. A potential involvement of fronto-temporal and fronto-striatal connectivity changes in the disease evolution has also been reported. On this latter regard, there is still a shortage of studies which investigated basal ganglia (BG) alterations and their role in ALS clinical manifestation and progression. The present review aims to provide an overview on the magnetic resonance imaging studies reporting structural and/or functional BG alterations in patients with ALS, to clarify the role of BG damage in the disease clinical evolution and to propose potential future developments in this field.

VAP Proteins - From Organelle Tethers to Pathogenic Host Interactors and Their Role in Neuronal Disease

Vesicle-associated membrane protein (VAMP)-associated proteins (VAPs) are ubiquitous ER-resident tail-anchored membrane proteins in eukaryotic cells. Their N-terminal major sperm protein (MSP) domain faces the cytosol and allows them to interact with a wide variety of cellular proteins. Therefore, VAP proteins are vital to many cellular processes, including organelle membrane tethering, lipid transfer, autophagy, ion homeostasis and viral defence. Here, we provide a timely overview of the increasing number of VAPA/B binding partners and discuss the role of VAPA/B in maintaining organelle-ER interactions and cooperation. Furthermore, we address how viruses and intracellular bacteria hijack VAPs and their binding partners to induce interactions between the host ER and pathogen-containing compartments and support pathogen replication. Finally, we focus on the role of VAP in human disease and discuss how mutated VAPB leads to the disruption of cellular homeostasis and causes amyotrophic lateral sclerosis.