Although Amyotrophic Lateral Sclerosis Research Articles

Sensory Involvement in Amyotrophic Lateral Sclerosis.

Although amyotrophic lateral sclerosis (ALS) is pre-eminently a motor disease, the existence of non-motor manifestations, including sensory involvement, has been described in the last few years. Although from a clinical perspective, sensory symptoms are overshadowed by their motor manifestations, this does not mean that their pathological significance is not relevant. In this review, we have made an extensive description of the involvement of sensory and autonomic systems described to date in ALS, from clinical, neurophysiological, neuroimaging, neuropathological, functional, and molecular perspectives.

The frequency of ALSFRS-R reversals and plateaus in patients with limb-onset amyotrophic lateral sclerosis: a cohort study.

Although amyotrophic lateral sclerosis (ALS) is a relentlessly progressive neurodegenerative disorder, ALS patients might show reversals or plateaus of ALS Functional rating scale-revised (ALSFRS-R) scores during follow-up, which might cast the doubt on the diagnosis. The study aims to determine the frequency of reversals and plateaus of ALSFRS-R score in patients with limb-onset ALS. One hundred and fifty four patients with limb-onset ALS were prospectively recruited. ALSFRS-R scores were followed up every 3 months for at least 1year. The changes between two follow-up points in ALSFRS-R score were compared. Totally 95 (61.7%) participants showed 85 times plateau and 69 times reversal in ALSFRS score during the 12-month follow-up when compared the ALSFRS-R score between two adjacent follow-up points. Reversal and plateau in ALSFRS-R score were detected in 31.8% patients between initial and 3 months, 18.8% between 3 and 6 months, 22.7% between 6 and 9 months, 22.7% between 9 and 12 months, respectively. When comparing with the ALSFRS-R score in the baseline, reversal and plateau in ALSFRS-R score were detected in 31.8% patients at 3 months, 14.9% at 6 months, 6.5% at 9 months, 5.8% at 12 months, respectively. Plateaus and reversals in ALSFRS-R score were common in limb-onset ALS patients during follow-up. A relatively stable or reversal in the ALS-FRS-R score does not exclude the diagnosis of ALS. Limitations of ALSFRS-R score as an outcome parameter in clinical trial should be further evaluated.

Time Course of Alterations in Adult Spinal Motoneuron Properties in the SOD1(G93A) Mouse Model of ALS.

Although amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease, motoneuron electrical properties are already altered during embryonic development. Motoneurons must therefore exhibit a remarkable capacity for homeostatic regulation to maintain a normal motor output for most of the life of the patient. In the present article, we demonstrate how maintaining homeostasis could come at a very high cost. We studied the excitability of spinal motoneurons from young adult SOD1(G93A) mice to end-stage. Initially, homeostasis is highly successful in maintaining their overall excitability. This initial success, however, is achieved by pushing some cells far above the normal range of passive and active conductances. As the disease progresses, both passive and active conductances shrink below normal values in the surviving cells. This shrinkage may thus promote survival, implying the previously large values contribute to degeneration. These results support the hypothesis that motoneuronal homeostasis may be “hypervigilant” in ALS and a source of accumulating stress.

Lifetime Risk and Heritability of Amyotrophic Lateral Sclerosis

Heritability describes the proportion of variance in the risk of developing a condition that is explained by genetic factors. Although amyotrophic lateral sclerosis (ALS) is known to have a complex genetic origin, disease heritability remains unclear. To determine the extent of ALS heritability and assess the association of sex with disease transmission. A prospective population-based parent-offspring heritability study was conducted from January 1, 2008, to December 31, 2017 to assess ALS heritability, and was the first study to assess heritability in the context of known gene mutations of large effect. A total of 1123 incident cases of ALS, diagnosed according to the El Escorial criteria and recorded on the Irish ALS register, were identified. Ninety-two individuals were excluded (non-Irish parental origin [n = 86] and familial ALS [n = 6]), and 1117 patients were included in the final analysis. Annual age-specific and sex-specific standardized ALS incidence and mortality-adjusted lifetime risk were determined. Sex-specific heritability estimates were calculated for the overall study cohort, for those known to carry the C9orf72 (OMIM 614260) variant, and for those with no known genetic risk. A total of 32 parent-child ALS dyads were identified during the study period. Affected offspring were younger at the onset of disease (mean age, 52.0 years; 95% CI, 48.8-55.3 years) compared with their parents (mean age, 69.6 years; 95% CI, 62.4-76.9 years; P = .008). Lifetime risk of developing ALS in first-degree relatives of individuals with ALS was increased compared with the general population (1.4% [32 of 2234] vs 0.3% [2.6 of 1000]; P < .001). Mean lifetime heritability of ALS for the overall study cohort was 52.3% (95% CI, 42.9%-61.7%) and 36.9% (95% CI, 19.8%-53.9%) for those with no known genetic risk. Heritability estimates were highest in mother-daughter pairings (66.2%; 95% CI, 58.5%-73.9%). This population-based study confirms that up to 50% of variance in ALS has a genetic basis, and that the presence of the C9orf72 variant is an important determinant of heritability. First-degree relatives of individuals with ALS without a known genetic basis remain at increased risk of developing ALS compared with the general population. A higher heritability estimate in mother-daughter pairings points to a sex-mediated effect that has been previously unrecognized.

The Peripheral Nervous System in Amyotrophic Lateral Sclerosis: Opportunities for Translational Research.

Although amyotrophic lateral sclerosis (ALS) has been considered as a disorder of the motor neuron (MN) cell body, recent evidences show the non-cell-autonomous pathogenic nature of the disease. Axonal degeneration, loss of peripheral axons and destruction of nerve terminals are early events in the disease pathogenic cascade, anticipating MN degeneration, and the onset of clinical symptoms. Therefore, although ALS and peripheral axonal neuropathies should be differentiated in clinical practice, they also share damage to common molecular pathways, including axonal transport, RNA metabolism and proteostasis. Thus, an extensive evaluation of the molecular events occurring in the peripheral nervous system (PNS) could be fundamental to understand the pathogenic mechanisms of ALS, favoring the discovery of potential disease biomarkers, and new therapeutic targets.

Very late-onset amyotrophic lateral sclerosis in a Portuguese cohort

Objective: Although amyotrophic lateral sclerosis (ALS) incidence has been stable among Western countries, population-ageing effect will probably increase the proportion of very-old ALS patients. We aim to study this population.Methods: A retrospective study was performed, including 1083 ALS patients followed longitudinally in our ALS unit from January 1995 to December 2017. The patients were divided in two groups, according to age at disease onset (</≥80 years). Demographic, clinical, and survival data were compared between groups.Results: Fifty out of 1083 (4.62%) patients were aged 80 or over. Mean onset age in this group was 82.9 ± 2.59 years and 28 (56%) were men. Contrasting with the younger group, bulbar-onset was remarkably the most common presentation form (54%, p < 0.001), but with no gender preference (p = 0.52) and so was significantly shorter disease duration before first visit (13.41 ± 9.42 versus 18.84 ± 21.66 months, p = 0.001). Survival after disease onset (31.87 ± 25.45 versus 45.61 ± 39.93 months, respectively for older and younger groups, p = 0.001) was significantly dependent on age of onset, disease duration and onset form in the younger group while it was only dependent on onset form in the older group. No significant differences were observed regarding cognitive dysfunction, ALS/FTD familial history, non-invasive ventilation (NIV) or riluzole prescription.Conclusions: Very-old patients represent a minor but distinctive ALS group. A predominant bulbar presentation was disclosed and it could probably explain the shorter disease duration before first visit as well as survival. Older age was not an exclusion factor for good health care practices, in particular NIV and riluzole prescription.

Exploring the genetics and non-cell autonomous mechanisms underlying ALS/FTLD.

Although amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, was first described in 1874, a flurry of genetic discoveries in the last 10 years has markedly increased our understanding of this disease. These findings have not only enhanced our knowledge of mechanisms leading to ALS, but also have revealed that ALS shares many genetic causes with another neurodegenerative disease, frontotemporal lobar dementia (FTLD). In this review, we survey how recent genetic studies have bridged our mechanistic understanding of these two related diseases and how the genetics behind ALS and FTLD point to complex disorders, implicating non-neuronal cell types in disease pathophysiology. The involvement of non-neuronal cell types is consistent with a non-cell autonomous component in these diseases. This is further supported by studies that identified a critical role of immune-associated genes within ALS/FTLD and other neurodegenerative disorders. The molecular functions of these genes support an emerging concept that various non-autonomous functions are involved in neurodegeneration. Further insights into such a mechanism(s) will ultimately lead to a better understanding of potential routes of therapeutic intervention. Facts ALS and FTLD are severe neurodegenerative disorders on the same disease spectrum. Multiple cellular processes including dysregulation of RNA homeostasis, imbalance of proteostasis, contribute to ALS/FTLD pathogenesis. Aberrant function in non-neuronal cell types, including microglia, contributes to ALS/FTLD. Strong neuroimmune and neuroinflammatory components are associated with ALS/FTLD patients. Open Questions Why can patients with similar mutations have different disease manifestations, i.e., why do C9ORF72 mutations lead to motor neuron loss in some patients while others exhibit loss of neurons in the frontotemporal lobe? Do ALS causal mutations result in microglial dysfunction and contribute to ALS/FTLD pathology? How do microglia normally act to mitigate neurodegeneration in ALS/FTLD? To what extent do cellular signaling pathways mediate non-cell autonomous communications between distinct central nervous system (CNS) cell types during disease? Is it possible to therapeutically target specific cell types in the CNS?

Identification of risk factors associated with onset and progression of amyotrophic lateral sclerosis using systematic review and meta-analysis

Although amyotrophic lateral sclerosis (ALS) was identified as a neurological condition 150 years ago, risk factors related to the onset and progression of ALS remain largely unknown. Monogenic mutations in over 30 genes are associated with about 10% of ALS cases. The age at onset of ALS and disease types has been found to influence ALS progression. The present study was designed to identify additional putative risk factors associated with the onset and progression of ALS using systematic review and meta-analysis of observational studies. Risk factors that may be associated with ALS include: 1) genetic mutations, including the intermediate CAG repeat expansion in ATXN2; 2) previous exposure to heavy metals such as lead and mercury; 3) previous exposure to organic chemicals, such as pesticides and solvents; 4) history of electric shock; 5) history of physical trauma/injury (including head trauma/injury); 6) smoking (a weak risk factor for ALS in women); and 6) other risk factors, such as participating in professional sports, lower body mass index, lower educational attainment, or occupations requiring repetitive/strenuous work, military service, exposure to Beta-N-methylamino-l-alanin and viral infections. Risk factors that may be associated with ALS progression rate include: 1) nutritional status, including vitamin D deficiency; 2) comorbidities; 3) ethnicity and genetic factors; 4) lack of supportive care; and 4) smoking. The extent to which these associations may be causal is discussed, with further research recommended to strengthen the evidence on which determinations of causality may be based.

Respiratory failure as the presenting manifestation of amyotrophic lateral sclerosis

Although amyotrophic lateral sclerosis (ALS) does not directly affect the lung parenchyma, it can jeopardize the mechanical function of the respiratory system. About one-quarter of ALS patients have had at least one prior misdiagnosis. Therefore, a high clinical suspicion, and careful correlation of physical examination and electromyography (EMG) are needed to reach the correct diagnosis. We report a 65-year-old man who presented with a progressive exertional dyspnea. He was subsequently found to have a diaphragmatic paralysis that was felt to be secondary to spinal cord stenosis. However, his subsequent EMG showed evidence of muscle fasciculation and he was ultimately diagnosed with ALS.

Increased Frequency of Pathologic Findings on Transcranial B-Mode Parenchymal Sonography in Patients with Sporadic Amyotrophic Lateral Sclerosis

Although amyotrophic lateral sclerosis (ALS) is characterized by involvement of motor neurons in the motor cortex, brainstem and spinal cord, there is accumulating evidence that it is a multisystem degenerative disease, with dysfunction of the striatonigral dopaminergic system as well. Transcranial B-mode sonography of the parenchyma enables depiction of the differing tissue echogenicity of midbrain and basal ganglia structures in various movement disorders. Transcranial B-mode sonography was performed in the standard manner in 101 patients with sporadic newly diagnosed ALS and 60 age- and gender-matched controls. Increased frequencies of pathologic substantia nigra hyper-echogenicity (p = 0.027), interrupted brainstem raphe (p = 0.003) and increased third ventricle diameter (p < 0.0001) were detected in ALS patients as compared with healthy controls. Only four ALS patients exhibited some features of parkinsonism. Pathologic findings on transcranial B-mode sonography of parenchyma did not correlate with clinical presentation, functional status or disease subtype. Our study provides additional evidence of multisystem involvement in ALS patients, particularly in subcortical areas.

Human glial progenitor engraftment and gene expression is independent of the ALS environment

Although Amyotrophic Lateral Sclerosis (ALS) is a motor neuron disease, basic research studies have highlighted that astrocytes contribute to the disease process. Therefore, strategies which replace the diseased astrocyte population with healthy astrocytes may protect against motor neuron degeneration. Our studies have sought to evaluate astrocyte replacement using glial-restricted progenitors (GRPs), which are lineage-restricted precursors capable of differentiating into astrocytes after transplantation. The goal of our current study was to evaluate how transplantation to the diseased ALS spinal cord versus a healthy, wild-type spinal cord may affect human GRP engraftment and selected gene expression. Human GRPs were transplanted into the spinal cord of either an ALS mouse model or wild-type littermate mice. Mice were sacrificed for analysis at either the onset of disease course or at the endstage of disease. The transplanted GRPs were analyzed by immunohistochemistry and NanoString® gene profiling which showed no gross differences in the engraftment or gene expression of the cells. Our data indicate that human glial progenitor engraftment and gene expression is independent of the neurodegenerative ALS spinal cord environment. These findings are of interest given that human GRPs are currently in clinical development for spinal cord transplantation into ALS patients.

Embryonic alteration of motoneuronal morphology induces hyperexcitability in the mouse model of amyotrophic lateral sclerosis

Although amyotrophic lateral sclerosis (ALS) is an age-dependent fatal neurodegenerative disease in which upper and lower motoneurons (MNs) are targeted for death in adults, increasing lines of evidence indicate that MNs display physiological and morphological abnormalities during postnatal development, long before disease onset. Here, using transgenic mice overexpressing the G93A mutation of the human Cu/Zn superoxide dismutase gene (SOD1), we show that SOD1G93A embryonic lumbar E17.5 MNs already expressed abnormal morphometric parameters, including a deep reduction of their terminal segments length. Whole-cell patch-clamp recordings from acute spinal cord preparations were made to characterize functional changes in neuronal activity. SOD1G93A E17.5 MNs displayed hyperexcitability compared to wild-type MNs. Finally, we performed realistic simulations in order to correlate morphometric and electrophysiological changes observed in embryonic SOD1G93A MNs. We found that the reduced dendritic elongation mainly accounted for the hyperexcitability observed in SOD1G93A MNs. Altogether, our results emphasize the remarkable early onset of abnormal neural activity in the commonly used animal model for ALS, and suggest that embryonic morphological changes are the primary compensatory mechanisms, the physiological adjustments being only secondary to morphological alterations.

Hyperexcitability and amyotrophic lateral sclerosis

Although amyotrophic lateral sclerosis (ALS) was described some 150 years ago, there remain critical questions about the origin and progression of the disease. A recent focus of clinical research has been the potential role of excitotoxicity underlying the pathophysiology of ALS.[1][1] Several

Postsynaptic Alteration of NR2A Subunit and Defective Autophosphorylation of alphaCaMKII at Threonine-286 Contribute to Abnormal Plasticity and Morphology of Upper Motor Neurons in Presymptomatic SOD1G93A Mice, a Murine Model for Amyotrophic Lateral Sclerosis

Although amyotrophic lateral sclerosis (ALS) has long been considered as a lower motor neuron (MN) disease, degeneration of upper MNs arising from a combination of mechanisms including insufficient growth factor signaling and enhanced extracellular glutamate levels is now well documented. The observation that these mechanisms are altered in presymptomatic superoxide dismutase (SOD1) mice, an ALS mouse model, suggests that defective primary motor cortex (M1) synaptic activity might precede the onset of motor disturbances. To examine this point, we assessed the composition of AMPAR and NMDAR subunits and of the alphaCa²(+)/calmodulin-dependent kinase autophosphorylation at threonine-286 in the triton insoluble fraction from the M1 in postnatal P80-P85 SOD1(G93A) and wild-type mice. We show that presymptomatic SOD1(G93A) exhibit a selective decrease of NR2A subunit expression and of the alphaCa²(+)/calmodulin-dependent kinase autophosphorylation at threonine-286 in the triton insoluble fraction of upper MNs synapses. These molecular alterations are associated with synaptic plasticity defects, and a reduction in upper MN dendritic outgrowth revealing that abnormal neuronal connectivity in the M1 region precedes the onset of motor symptoms. We suggest that the progressive disruption of M1 corticocortical connections resulting from the SOD1(G93A) mutation might extend to adjacent regions and promote development of cognitive/dementia alterations frequently associated with ALS.

Tau phosphorylation at threonine‐175 leads to fibril formation and enhanced cell death: implications for amyotrophic lateral sclerosis with cognitive impairment

Although amyotrophic lateral sclerosis (ALS) can be associated with cognitive impairment (ALSci) as a reflection of frontotemporal lobar degeneration, the basis of this process is unknown. The observation of neuronal and extraneuronal tau deposition in ALSci in addition to a unique tau phosphorylation at Thr175 has suggested that ALSci can be associated with alterations in tau metabolism. We have examined the association between phosphorylation at Thr175 and tau fibril formation. Both soluble and insoluble tau was purified from control, patients with Alzheimer's disease (AD), ALS without cognitive impairment, and ALSci and the tendency to fibril formation assayed ex vivo using the thioflavin S fluorescence assay. The extent of fibril formation was significantly greater in tau derived from ALSci, with ALS-derived tau being intermediate between control and AD-derived tau. Using both Neuro2A and human embryonic kidney (HEK293T) cells, we expressed full-length tau constructs harboring either a pseudophosphorylation at Thr175 (Thr175-Asp-tau), inhibition of Thr175 phosphorylation (Thr175-Ala-tau) or intact tau (wild-type tau). Both tau fibril formation and cell death were significantly enhanced in the presence of Thr175-Asp-tau, regardless of the tau isoform, suggesting that phosphorylation of Thr175 is associated with tau fibril formation in ALSci.

Predictors of long survival in amyotrophic lateral sclerosis: A population-based study

Although amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder, some ALS cases can survive beyond 10 years. However, the predictors of long survival in ALS patients remain uncertain. To define clinical predictors of long survival in a cohort of ALS incident cases. One hundred-thirty incidents cases, diagnosed in 1998--1999 and classified according to the El Escorial criteria (EEC), were enrolled from a prospective population-based registry established in Puglia, Italy. All but two cases were followed-up until death or November 30, 2006. Thirteen patients (high 10% of the survivors) were classified as long survivors (LS), 13 as short survivors (SS) (low 10%), and 102 as average survivors (AS). LS presented a lower frequency of bulbar onset (8% versus 29% of AS and 39% of SS; p=0.1) and a significantly longer time between symptom onset to diagnosis [(ODI): 13 months versus 10 and 6; p=0.0005]. In multivariate analysis, predictors of long survival were younger age at diagnosis (>65 compared to < or =45 years: odds ratio (OR):18.9; 95%CI: 1.8-194.7; p=0.04), longer interval onset-diagnosis (< or =9 months compared to >9 months, OR: 7.9; 95%CI: 1.3-47; p=0.02) and clinical features with predominant upper motor neuron signs (OR: 8.5; 95%CI: 1.1-64.2; p=0.04). In this population-based study, younger age, longer interval onset to diagnosis, and clinical features with predominance of upper motor signs predicted long survival, while EEC category at diagnosis did not.

Therapeutic targets for amyotrophic lateral sclerosis: current treatments and prospects for more effective therapies

Although amyotrophic lateral sclerosis (ALS) was described more than 130 years ago, the cause(s) of most cases of this adult motor neuron disease remains a mystery. With the discovery of mutations in one gene (Cu/Zn superoxide dismutase) as a primary cause of some forms of ALS, model systems have been developed that have helped us begin to understand mechanisms involved in motor neuron death and enabled testing of potential new therapies. Several other genes have been implicated as risk factors in motor neuron diseases, including neurofilaments, cytoplasmic dynein and dynactin, vascular endothelial growth factor, and angiogenin. With advances in the basic research of the disease, many hypotheses accounting for motor neuron death are being explored, including loss of trophic support, protein mishandling, mitochondrial dysfunction, excitotoxicity, axonal abnormalities and inflammation. Many of these mechanisms are the focus of research in other neurodegenerative disorders, such as Parkinson’s, Alzheimer’s and Huntington’s disease.

Molecular and synaptic changes in the hippocampus underlying superior spatial abilities in pre-symptomatic G93A+/+ mice overexpressing the human Cu/Zn superoxide dismutase (Gly 93 → ALA) mutation

Although amyotrophic lateral sclerosis (ALS) is mainly considered as a motor disease, extramotor neural and cognitive alterations have also been reported in ALS patients. There is evidence that mutations in the Cu/Zn superoxide dismutase (SOD1) gene are implicated in about 20% of familiar ALS and transgenic mice overexpressing the human Cu/Zn superoxide dismutase (GLY 93 → ALA) mutation show an ALS-like phenotype. However, while motor behavior has been extensively analyzed in these mutants, little is known on their cognitive abilities. To characterize the pre-symptomatic cognitive profile of G93A+/+ mice, we estimated their capability to detect spatial novelty and examined several indexes of their hippocampal function. We found an enhancement of spatial abilities in mutant mice associated with (1) a higher expression of hippocampal AMPA subunit GluR1 mRNA and of GluR1 protein levels, and (2) an increased induction and maintenance of long-term potentiation (LTP) at Schaffer collateral-CA1 synapses. Thus, before leading to extensive neuronal excitotoxicity, the high endogenous levels of glutamate present in the brain of pre-symptomatic G93A+/+ mice could mediate site-specific molecular and synaptic changes providing favorable conditions to spatial information processing. These findings suggest that identification of pre-symptomatic behavioral changes in murine models of ALS may point to early neural abnormalities selectively associated with mutations in the Cu/Zn superoxide dismutase (SOD1) gene.