Trauma and amyotrophic lateral sclerosis: a case-control study from a population-based registry

Physical Activity, Fitness, and Long-Term Risk of Amyotrophic Lateral Sclerosis: A Prospective Cohort Study

BACKGROUND AND OBJECTIVES

Observational studies have demonstrated an increased amyotrophic lateral sclerosis (ALS) risk among professional athletes in various sports. For moderately increased levels of physical activity and fitness, the results are diverging. Through a cohort study, we aimed to assess the relationship between indicators of physical activity and fitness (self-reported physical activity and resting heart rate) and long-term ALS risk.

METHODS

From a large Norwegian cardiovascular health survey (1985-1999), we collected information on self-reported physical activity in leisure time, resting heart rate, and other cardiovascular risk factors. Patients with ALS were identified through health registries covering the whole population. We fitted Cox proportional hazard models to assess the risk of ALS according to levels of self-reported physical activity in 3 categories (1: sedentary; 2: minimum 4 hours per week of walking or cycling; 3: minimum 4 hours per week of recreational sports or hard training), and resting heart rate modeled both on the continuous scale and as quartiles of distribution.

RESULTS

Out of 373,696 study participants (mean 40.9 [SD 1.1] years at inclusion), 504 (41.2% women) developed ALS during a mean follow-up time of 27.2 (SD 5.0) years. Compared with participants with the lowest level of physical activity, the hazard ratio was 0.71 (95% CI 0.53-0.95) for those with the highest level. There were no clear associations between resting heart rate and ALS in the total sample. In men, the hazard ratio of ALS was 0.71 (95% CI 0.53-0.95) for those reporting moderate levels of physical activity and 0.59 (95% CI 0.42-0.84) for those reporting high levels, compared with those reporting low levels. Men with resting heart rate in the lowest quartile had 32% reduced risk of ALS (hazard ratio 0.68, 95% CI 0.49-0.94) compared with those in the second highest quartile. In women, no association was detected between neither self-reported levels of physical activity nor resting heart rate and ALS risk.

DISCUSSION

Indicators of high levels of physical activity and fitness are associated with a reduced risk of ALS more than 30 years later in men, but not in women.

Analysis of the spatial distribution of amyotrophic lateral sclerosis in Virginia

Objective: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that is usually fatal. Environmental exposures have been posited in the etiology of ALS, but few studies have modeled the spatial risk of ALS over large geographic areas. In this paper, our goal was to analyze the spatial distribution of ALS in Virginia and identify any areas with significantly elevated risk using Virginia ALS Association administrative data. Methods: We used Bayesian hierarchical spatial regression models to estimate the relative risk for ALS in Virginia census tracts, adjusting for several covariates posited to be associated with the disease. We used an intrinsic conditional autoregressive prior to allow for spatial correlation in the risk estimates and stabilize estimates over space. Results: Considerable variation in ALS risk existed across Virginia, with greater relative risk found in the central and western parts of the state. We identified significantly elevated relative risk in a number of census tracts. In particular, Henrico, Albemarle, and Botetourt counties all contained at least four census tracts with significantly elevated risk. Conclusions: We identified several areas with significantly elevated ALS risk across Virginia census tracts. These results can inform future studies of potential environmental triggers for the disease, whose etiology is still being understood.

Sports and trauma as risk factors for Motor Neurone Disease: New Zealand case-control study

Objectives

To assess whether sports, physical trauma and emotional trauma are associated with motor neurone disease (MND) in a New Zealand case–control study (2013–2016).

Methods

In total, 321 MND cases and 605 population controls were interviewed collecting information on lifetime histories of playing sports, physical trauma (head injury with concussion, spine injury) and emotional trauma (14 categories). ORs were estimated using logistic regression adjusting for age, sex, ethnicity, socioeconomic status, education, smoking status, alcohol consumption and mutually adjusting for all other exposures.

Results

Head injury with concussion ≥3 years before diagnosis was associated with MND (OR 1.51, 95% CI: 1.09–2.09), with strongest associations for two (OR 4.01, 95% CI: 1.82–8.86), and three or more (OR 2.34, 95% CI: 1.00–5.45) head injuries. Spine injury was not associated with MND (OR 0.81, 95% CI: 0.48–1.36). Compared to never playing sports, engaging in sports throughout childhood and adulthood increased MND risk (OR 1.81, 95% CI: 1.01–3.25), as was more than 12 years playing football/soccer (OR 2.35, 95% CI: 1.19–4.65). Reporting emotionally traumatic events in more than three categories was associated with MND (OR 1.88, 95% CI: 1.17–3.03), with physical childhood abuse the only specific emotional trauma associated with MND (OR 1.82, 95% CI: 1.14–2.90), particularly for those reporting longer abuse duration (OR_{(5–8 years)} 2.26, 95% CI: 1.14–4.49; OR_(>8 years) 3.01, 95% CI: 1.18–7.70). For females, having witnessed another person being killed, seriously injured or assaulted also increased MND risk (OR 2.68, 95% CI: 1.06–6.76).

Conclusions

This study adds to the evidence that repeated head injury with concussion, playing sports in general, and playing football (soccer) in particular, are associated with an increased risk of MND. Emotional trauma, that is physical abuse in childhood, may also play a role.

Environmental risk factors for amyotrophic lateral sclerosis: a case-control study in Canada and France

Objective: To evaluate the association between amyotrophic lateral sclerosis (ALS) and potential environmental risk factors, especially head traumas and pesticides, in two populations from Canada and France.Methods: A case-control study was performed in tertiary-care centers. Consecutive ALS cases were recruited along with a control group from the same age distribution and region. Participants answered a phone-administered questionnaire. Head trauma exposure was censored at age of symptom onset, and a sensitivity analysis considering old head traumas that occurred more than 3 years before onset was performed. Univariate and multivariate logistic regression were used to estimate odds ratios (ORs) and their 95% confidence intervals (CIs).Results: A total of 404 ALS cases and 381 controls completed the questionnaire. Previous head trauma was more frequently reported by cases (adjusted OR 1.50 (1.05-2.18)) with a dose-response relationship. This association was driven by a strong effect in men (adjusted OR 2.06 (1.22-3.55)) and was consistent for old traumas, but there was no association in women. For pesticides, a previous high-risk occupation was associated with ALS (adjusted OR 2.08 (1.36-3.24)), although reported occupational exposure to pesticides was not statistically significant in the multivariate model (adjusted OR 1.67 (0.97-2.97)). Past electrocution was associated with ALS (adjusted OR 1.79 (CI 1.13-2.87)), especially spinal-onset ALS. Residential exposure to pesticides, neck trauma, and welding were not associated with ALS.Conclusions: Head trauma is a risk factor for ALS in men only. Previous occupation at high risk for pesticides exposure and electrocution are also risk factors for ALS.

Examining the Relationship between Concussion and Neurodegenerative Disorders: A Review on Amyotrophic Lateral Sclerosis (ALS) and Alzheimer’s Disease (AD)

Background Current epidemiological studies have examined the associations between moderate and severe traumatic brain injury (TBI) and their risks of developing neurodegenerative diseases. Concussion, also known as mild TBI (mTBI), is however quite distinct from moderate or severe TBIs. Only few studies in this burgeoning area have examined concussion—especially repetitive episodes—and neurodegenerative diseases. Thus, no definite relationship has been established between them.

Objectives This review will discuss the available literatures linking concussion and amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD).

Materials and Methods Given the complexity of this subject, a realist review methodology was selected which includes clarifying the scope and developing a theoretical framework, developing a search strategy, selection and appraisal, data extraction, and synthesis. A detailed literature matrix was set out in order to get relevant and recent findings on this topic.

Results Presently, there is no objective clinical test for the diagnosis of concussion because the features are less obvious on physical examination. Absence of an objective test in diagnosing concussion sometimes leads to skepticism when confirming the presence or absence of concussion. Intriguingly, several possible explanations have been proposed in the pathological mechanisms that lead to the development of some neurodegenerative disorders (such as ALS and AD) and concussion but the two major events are deposition of tau proteins (abnormal microtubule proteins) and neuroinflammation, which ranges from glutamate excitotoxicity pathways and inflammatory pathways (which leads to a rise in the metabolic demands of microglia cells and neurons), to mitochondrial function via the oxidative pathways.

Conclusion mTBI constitutes majority of brain injuries. However, studies have focused mostly on moderate-to-severe TBI as highlighted above with inconclusive and paucity of studies linking concussion and neurodegenerative disorders. Although, it is highly probable that repetitive concussion (mTBI) and subconcussive head injuries may be risk factors for ALS) and AD from this review. It will be imperative therefore to conduct more research with a focus on mTBI and its association with ALS and AD.

Trauma and amyotrophic lateral sclerosis: a systematic review and meta-analysis

Background: Trauma especially head trauma is considered a potential risk factor of amyotrophic lateral sclerosis (ALS), but their association has not been well established. We aimed to determine the association of prior trauma with ALS risk. Methods: This study was performed according to the Meta-Analysis of Observational Studies in Epidemiology guideline to assess related literatures, and a random-effects model was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Results: Twenty-nine eligible articles involving 18,390 cases and 6,519,391 controls were included in this meta-analysis. The results showed that trauma was associated with an increased risk of ALS (pooled OR = 1.51, 95% CI: 1.32-1.73). Besides, patients with trunk trauma, head trauma and lower limb trauma had an increased risk of ALS, whereas no evidence suggested that upper limb trauma and spine trauma could increase ALS risk. Considering the number of traumatic events, the association between trauma and ALS risk was significant for patients with repeated trauma events (pooled OR = 1.21, 95% CI: 1.07-1.38). The results showed that individuals with a history of trauma within 5 years were more likely to be diagnosed with ALS (pooled OR = 1.84, 95% CI: 1.56-2.17). Importantly, both old trauma and very old trauma were found to be associated with an increased risk of ALS (pooled OR = 1.24, 95% CI: 1.12-1.38; pooled OR = 1.28, 95% CI: 1.10-1.49; respectively). Conclusions: This meta-analysis indicated that trauma could increase ALS risk, which may be applied for the clinicians to tailor targeted treatment regimens and make prophylactic strategies for ALS in traumatic patients.

Poor Bone Quality in Patients With Amyotrophic Lateral Sclerosis

Objective: Musculoskeletal functional deterioration in Amyotrophic lateral sclerosis (ALS) is associated with an increase in bone fractures. The purpose of this study was to evaluate the influence of sex, ALS type, on bone quality in patients with ALS compared to healthy controls. The impact on bone health of the clinical status and some metabolic parameters was also analyzed in ALS patients.

Methods: A series of 33 voluntary patients with ALS, and 66 healthy individuals matched in sex and age underwent assessment of bone mass quality using quantitative ultrasound (QUS) of the calcaneus. Ultrasonic broadband attenuation (BUA), the speed of sound (SOS), stiffness index and T-score were measured. Bone mineral density (BMD) was estimated using standard equations. Apart from fat and muscle mass percentage determinations, clinical baseline measures in ALS patients included ALSFRS-R score, Barthel index for activities of daily living, pulmonary function measured using FVC, and muscular strength assessed by a modified MRC grading scale. Laboratory tests included serum calcium, 25-HO-cholecalciferol (Vitamin D), alkaline phosphatase (ALP), T4 and TSH.

Results: All bone parameters evaluated were statistically significant lower in ALS patients than in healthy controls. ALS females showed significantly lower bone parameters than healthy females. According to the estimated BMD, there were 25 ALS patients (75.8%) and 36 (54.5%) healthy individuals showing an osteoporotic profile (BMD <0.700 g/cm²). Only 16.7% of the ALS females had T-scores indicative of healthy bones. There was no correlation between any of the clinical parameters analyzed and the bone QUS measurements. Vitamin D and TSH levels positively correlated with all the bone parameters.

Conclusions: This study confirms that ALS patients, particularly females, exhibited deteriorated bone health as compared to healthy individuals. These structural bone changes were independent of ALS subtype and clinical status. Bone health in ALS patients seems to be related to certain metabolic parameters such as Vitamin D and TSH levels.

Military service and related risk factors for amyotrophic lateral sclerosis

BACKGROUND

The cause of amyotrophic lateral sclerosis (ALS) is unknown, but occupations have been explored as a potential proxy measure of risk. There is a substantial body of literature connecting military service to ALS. We aimed to summarize and assess the quality of this evidence.

METHODS

Systematic review of the literature, including observational studies which explored one of the following exposures: general military service (army, air force, marines, or navy); or specific exposures associated with military service measured among military personnel. The outcome of interest was ALS incidence, which could include onset, diagnosis, or death from ALS.

RESULTS

A total of 2642 articles were screened. Following exclusion, 19 articles remained for inclusion in the systematic review, including 1 meta-analysis and 18 original observational studies. Most studies were of moderate quality. In general, the relationship between military service was suggestive of an increased risk, particularly among Gulf War and WWII veterans. Exposure to pesticides (including Agent Orange) certain chemicals (exhaust, burning agents), heavy metals, and head trauma appeared to increase the risk of ALS among military personnel.

CONCLUSIONS

There is a possible association between military service and the subsequent development of ALS; however, the evidence was limited. Studies were generally hindered by small sample sizes and inadequate follow-up time. Future studies should endeavor to objectively measure specific exposures, or combinations thereof, associated with military service, as this will be of vital importance in implementing preventative strategies into military organizations.

Increased risk and early onset of ALS in professional players from Italian Soccer Teams

Objective: Since the observation of several deaths from amyotrophic lateral sclerosis (ALS) among Italian professional soccer players, an association between ALS and soccer has been postulated. The objective of the study is to investigate the association between professional soccer and the risk of ALS in a large cohort of former professional soccer players with prolonged follow-up. Methods: All professional soccer players practicing in the period 1959-2000 were identified through the archives of an Italian soccer cards publisher. For each player, date and place of birth, playing role, and team history were recorded. Each player was followed since 15 years of age. Incident ALS cases were all soccer players first diagnosed during the period 1959-2018. The expected incidence rate was the number of ALS cases/100,000 person-years expected in the cohort. SIR was the ratio between observed and expected incidence rate. Results: 34 ALS cases were detected. The number of expected cases was 17.8. The SIR was 1.91 (95% CI 1.32-2.67) in the entire sample and 4.66 (95% CI 2.66-7.57) in subjects aged less than 45 years. The mean age at diagnosis was 45.0 years. Compared to the mean age of onset of ALS in the general population (65.2 years), the disease in former soccer players occurred 20.2 years earlier. Conclusions: Professional soccer players are at higher risk of developing ALS than the general population. Soccer players with ALS develop the disease at a younger than expected age.

Chronic Traumatic Encephalopathy and Neurodegeneration in Contact Sports and American Football

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease characterized by the presence of abnormally phosphorylated tau protein in the depths of one or more cortical sulci. Controversy over the risk of CTE and neurologic disorders later in life among contact sport athletes has taken hold in the public spotlight, most notably in American football. Players, parents, coaches, and legislators have taken action based on the commonly held notion that contact sports invariably lead to neurodegenerative disorders. However, to fully understand the science behind this assumed association, a critical appraisal of the evidence is warranted. With regards to CTE in sports, the objectives of the current report are to: 1) describe the history of CTE, 2) review current CTE definitions, 3) critically evaluate the empiric data, divided into all contact sports and exclusively American football, and 4) summarize notable themes for future research.

Impairment between Oxidant and Antioxidant Systems: Short- and Long-term Implications for Athletes' Health

The role of oxidative stress, an imbalance between reactive oxygen species production (ROS) and antioxidants, has been described in several patho-physiological conditions, including cardiovascular, neurological diseases and cancer, thus impacting on individuals' lifelong health. Diet, environmental pollution, and physical activity can play a significant role in the oxidative balance of an organism. Even if physical training has proved to be able to counteract the negative effects caused by free radicals and to provide many health benefits, it is also known that intensive physical activity induces oxidative stress, inflammation, and free radical-mediated muscle damage. Indeed, variations in type, intensity, and duration of exercise training can activate different patterns of oxidant-antioxidant balance leading to different responses in terms of molecular and cellular damage. The aim of the present review is to discuss (1) the role of oxidative status in athletes in relation to exercise training practice, (2) the implications for muscle damage, (3) the long-term effect for neurodegenerative disease manifestations, (4) the role of antioxidant supplementations in preventing oxidative damages.

Contact Sports as a Risk Factor for Amyotrophic Lateral Sclerosis: A Systematic Review

STUDY DESIGN

Systematic review.

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease, ultimately resulting in paralysis and death. The condition is considered to be caused by a complex interaction between environmental and genetic factors. Although vast genetic research has deciphered many of the molecular factors in ALS pathogenesis, the environmental factors have remained largely unknown. Recent evidence suggests that participation in certain types of sporting activities are associated with increased risk for ALS.

OBJECTIVE

To test the hypothesis that competitive sports at the highest level that involve repetitive concussive head and cervical spinal trauma result in an increased risk of ALS compared with the general population or nonsport controls.

METHODS

Electronic databases from inception to November 22, 2017 and reference lists of key articles were searched to identify studies meeting inclusion criteria.

RESULTS

Sixteen studies met the inclusion criteria. Sports assessed (professional or nonprofessional) included soccer (n = 5), American football (n = 2), basketball (n = 1), cycling (n = 1), marathon or triathlon (n = 1), skating (n = 1), and general sports not specified (n = 11). Soccer and American football were considered sports involving repetitive concussive head and cervical spinal trauma. Professional sports prone to repetitive concussive head and cervical spinal trauma were associated with substantially greater effects (pooled rate ratio [RR] 8.52, 95% CI 5.18-14.0) compared with (a) nonprofessional sports prone to repetitive concussive head and cervical spinal trauma (pooled RR 0.60, 95% CI 0.12-3.06); (b) professional sports not prone to repetitive head and neck trauma (pooled RR 1.35, 95% CI 0.67-2.71); or (c) nonprofessional sports not prone to repetitive concussive head and cervical spinal trauma (pooled RR 1.17, 95% CI 0.79-1.71).

CONCLUSIONS

Our review suggests that increased susceptibility to ALS is significantly and independently associated with 2 factors: professional sports and sports prone to repetitive concussive head and cervical spinal trauma. Their combination resulted in an additive effect, further increasing this association to ALS.

Traumatic injury induces stress granule formation and enhances motor dysfunctions in ALS/FTD models

Traumatic brain injury (TBI) has been predicted to be a predisposing factor for amyotrophic lateral sclerosis (ALS) and other neurological disorders. Despite the importance of TBI in ALS progression, the underlying cellular and molecular mechanisms are still an enigma. Here, we examined the contribution of TBI as an extrinsic factor and investigated whether TBI influences the susceptibility of developing neurodegenerative symptoms. To evaluate the effects of TBI in vivo, we applied mild to severe trauma to Drosophila and found that TBI leads to the induction of stress granules (SGs) in the brain. The degree of SGs induction directly correlates with the level of trauma. Furthermore, we observed that the level of mortality is directly proportional to the number of traumatic hits. Interestingly, trauma-induced SGs are ubiquitin, p62 and TDP-43 positive, and persistently remain over time suggesting that SGs might be aggregates and exert toxicity in our fly models. Intriguingly, TBI on animals expressing ALS-linked genes increased mortality and locomotion dysfunction suggesting that mild trauma might aggravate neurodegenerative symptoms associated with ALS. Furthermore, we found elevated levels of high molecular weight ubiquitinated proteins and p62 in animals expressing ALS-causing genes with TBI, suggesting that TBI may lead to the defects in protein degradation pathways. Finally, we observed that genetic and pharmacological induction of autophagy enhanced the clearance of SGs and promoted survival of flies in vivo. Together, our study demonstrates that trauma can induce SG formation in vivo and might enhance neurodegenerative phenotypes in the fly models of ALS.

Toward a Reasoned Classification of Diseases Using Physico-Chemical Based Phenotypes

Background: Diseases and health conditions have been classified according to anatomical site, etiological, and clinical criteria. Physico-chemical mechanisms underlying the biology of diseases, such as the flow of energy through cells and tissues, have been often overlooked in classification systems.

Objective: We propose a conceptual framework toward the development of an energy-oriented classification of diseases, based on the principles of physical chemistry.

Methods: A review of literature on the physical chemistry of biological interactions in a number of diseases is traced from the point of view of the fluid and solid mechanics, electricity, and chemistry.

Results: We found consistent evidence in literature of decreased and/or increased physical and chemical forces intertwined with biological processes of numerous diseases, which allowed the identification of mechanical, electric and chemical phenotypes of diseases.

Discussion: Biological mechanisms of diseases need to be evaluated and integrated into more comprehensive theories that should account with principles of physics and chemistry. A hypothetical model is proposed relating the natural history of diseases to mechanical stress, electric field, and chemical equilibria (ATP) changes. The present perspective toward an innovative disease classification may improve drug-repurposing strategies in the future.

Lack of an association between attention-deficit/hyperactivity disorder (ADHD) and amyotrophic lateral sclerosis (ALS)

BACKGROUND

Lulé, Ludolph, and Ludolph (2008) hypothesized that there may be a pathophysiological link between attention-deficit/hyperactivity disorder (ADHD) and amyotrophic lateral sclerosis (ALS). They summarized common clinical features, specifically enhanced physical and psychological activity, which have been described typically for ADHD patients and also as common personality traits before disease onset in patients with ALS.

METHODS

We assessed the lifetime prevalence rate of ADHD in 104 patients with ALS using valid self-report instruments for ADHD symptoms in childhood (WURS-k) and adulthood (ADHD-SB). Results were compared with a population-based sample (n=2069) and with patients with Parkinson's disease (PD, n=52) using regression analyses and adjusting for sociodemographic differences. Physical activity was assessed by the 21-item exercise dependency scale (EDS-21).

RESULTS

ALS patients reported a lower prevalence of childhood ADHD compared to the general population. Both clinical groups reported significantly lower scores on the WURS-k scale and the attention deficit subscale of the ADHD-SB. The EDS-21 showed significantly longer exercise times in ALS and PD patients.

CONCLUSIONS

We could not show that ADHD is more common in ALS patients. However, our results revealed shared personality traits in ALS and PD with lower rates of premorbid attention deficit symptoms and increased physical activity.

Military service and the risk of amyotrophic lateral sclerosis: A meta-analysis

To explore the relationship between the risk of amyotrophic lateral sclerosis and exposure to overall military service, we conducted a search of articles relevant to military service and the risk of ALS that used human subjects and were published in English through 20 May 2016, using Ovid Medline and Embase databases. Studies specially investigating the risk of ALS for Gulf war veterans were excluded. Quality of the cohort and case-control studies was assessed according to the Newcastle-Ottawa Scale (NOS). Analysis of data and publication bias were performed with Review Manager 5.3. A total of 8 case-control studies and 3 cohort studies were included in the meta-analysis. Only two case-control studies were conducted in Japan, comparing to 9 studies conducted in Europe/USA. The NOS scores of all studies were ≥6/9. The risk of ALS was significantly increased in military personnel compared to non-military personnel (pooled OR=1.29, 95% CI: 1.08-1.54, by random-effects model), with a moderate heterogeneity (P=0.01, I²=55%) due to some studies with lower quality, conformed by subgroup and sensitivity analysis. The present meta-analysis supports a positive association between overall military service and the risk of ALS. Additional studies are needed to find out related factors influencing the ALS risk of veterans, especially by gender and for specific geographic regions such as Asia. That would also do some favor to explore the etiology and mechanism of ALS.

Occupational formaldehyde and amyotrophic lateral sclerosis

Prior studies have yielded inconsistent evidence regarding the association between formaldehyde exposure and amyotrophic lateral sclerosis (ALS). We conducted a population case-control study in the Danish National Registries on the relationship between occupationally-derived formaldehyde exposure and ALS. Occupational history was obtained from a comprehensive and prospectively recorded pension database of all paid work in Denmark since 1964, and was linked to a job-exposure matrix to derive individual exposure estimates. Each case was matched to 4 age- and sex-matched population controls alive on the date of the case diagnosis via risk set sampling, and odds ratios and confidence intervals (CI) were calculated via conditional logistic regression, adjusting for potential confounders. There were 3650 incident cases of ALS in the Danish National Patient Register from 1982 to 2009. Among controls, 25% were ever employed in jobs with a positive prevalence of formaldehyde exposure. Exposure to formaldehyde was associated with a 1.3-fold increased rate of ALS (95% CI 1.2-1.4). This study suggests that formaldehyde exposure, or employment in formaldehyde-exposed occupations, is related to the risk of ALS.

Decreased Levels of Foldase and Chaperone Proteins Are Associated with an Early-Onset Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by a progressive upper and lower motor neuron degeneration. One of the peculiar clinical characteristics of ALS is the wide distribution in age of onset, which is probably caused by different combinations of intrinsic and exogenous factors. We investigated whether these modifying factors are converging into common pathogenic pathways leading either to an early or a late disease onset. This would imply the identification of phenotypic biomarkers, that can distinguish the two populations of ALS patients, and of relevant pathways to consider in a therapeutic intervention. Toward this aim a differential proteomic analysis was performed in peripheral blood mononuclear cells (PBMC) from a group of 16 ALS patients with an age of onset ≤55 years and a group of 16 ALS patients with an age of onset ≥75 years, and matched healthy controls. We identified 43 differentially expressed proteins in the two groups of patients. Gene ontology analysis revealed that there was a significant enrichment in annotations associated with protein folding and response to stress. We next validated a selected number of proteins belonging to this functional group in 85 patients and 83 age- and sex-matched healthy controls using immunoassays. The results of the validation study confirmed that there was a decreased level of peptidyl-prolyl cis-trans isomerase A (also known as cyclophilin A), heat shock protein HSP 90-alpha, 78 kDa glucose-regulated protein (also known as BiP) and protein deglycase DJ-1 in PBMC of ALS patients with an early onset. Similar results were obtained in PBMC and spinal cord from two SOD1^G93A mouse models with an early and late disease onset. This study suggests that a different ability to upregulate proteins involved in proteostasis, such as foldase and chaperone proteins, may be at the basis of a different susceptibility to ALS, putting forward the development of therapeutic approaches aiming at boosting the protein quality control system.

Prevalence of potential sports-associated risk factors in Swiss amyotrophic lateral sclerosis patients

OBJECTIVES

Amyotrophic lateral sclerosis (ALS) has been reported to occur with increased incidence amongst physically active people. The role of extrinsic risk factors as physical activity, head trauma and drug/pesticide-exposure in the pathophysiology of ALS and especially in the context of practising sports remains controversial.

MATERIALS AND METHODS

We retrospectively studied exposure to extrinsic factors in 92 ALS patients in the presymptomatic stage. Metabolic equivalents (METs) were calculated and the association of physical activity, drug intake, head trauma and participation in specific sports (football [soccer], ice hockey) with age at symptom-onset was evaluated.

RESULTS

Ninety-five percent of patients considered themselves physically active before symptom-onset. Total MET-values varied broadly and there was no correlation between vigorous physical activity and age at symptom-onset. Mild traumatic brain injury (prevalence = 16.7%) was the most frequent diagnosis after head/neck injury. A history of ≥1 head/neck injuries was associated with a younger age at symptom-onset (61.8 ± 11.0 vs. 54.1 ± 13.0, p = .013). In former football and ice hockey players the rate of vigorous physical activities was increased (p < .05), whereas total MET-values, frequency of head injuries and analgesic intake were not different compared to other ALS patients.

CONCLUSIONS

History of head injuries was the only extrinsic risk factor associated with accelerated neurodegeneration in ALS. There was no evidence for extrinsic factors predisposing former football and ice hockey players to ALS. Our data therefore support the hypothesis that not increased physical activity per se, but other unknown environmental factors and/or genetic profile or lifestyle-promoting physical fitness increases ALS susceptibility.

Association of fractures with the incidence of amyotrophic lateral sclerosis

OBJECTIVE

Elevated bone turnover observed in ALS patients suggests poor bone health and increased fracture risk. We therefore evaluated the relationship of fracture to subsequent ALS risk.

METHODS

We followed 4,529,460 Swedes from 1987 to 2010 and identified ALS and fractures from the Swedish National Patient Register. We examined associations of ALS risk with all fractures, osteoporotic and non-osteoporotic fractures, and traumatic and non-traumatic fractures among individuals aged 30-80 years. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). We analysed the association of ALS with time since fracture using a Poisson regression model.

RESULTS

All fractures (HR: 1.51, 95% CI 1.39-1.65) as well as osteoporotic (HR: 1.59, 95% CI 1.41-1.79), non-osteoporotic (HR: 1.46, 95% CI 1.31-1.63), traumatic (HR: 1.50, 95% CI 1.37-1.63), and non-traumatic (HR: 1.80, 95% CI 1.35-2.40) fractures were associated with a higher incidence of ALS. Increased ALS incidence was associated with fractures occurring from one (HR: 2.33, 95% CI 2.04-2.66) to 18 (HR: 1.19, 95% CI 1.01-1.43) years before ALS diagnosis.

CONCLUSIONS

Poor bone health may be related to ALS. These findings may offer insight into ALS pathophysiology.

Environmental and Occupational Exposures and Amyotrophic Lateral Sclerosis in New England

BACKGROUND

Recent data provide support for the concept that potentially modifiable exposures are responsible for sporadic amyotrophic lateral sclerosis (ALS).

OBJECTIVE

To evaluate environmental and occupational exposures as risk factors for sporadic ALS.

METHODS

We performed a case-control study of ALS among residents of New England, USA. The analysis compared questionnaire responses from 295 patients with a confirmed ALS diagnosis to those of 225 controls without neurodegenerative illness.

RESULTS

Self-reported job- or hobby-related exposure to one or more chemicals, such as pesticides, solvents, or heavy metals, increased the risk of ALS (adjusted OR 2.51; 95% CI 1.64-3.89). Industries with a higher toxicant exposure potential (construction, manufacturing, mechanical, military, or painting) were associated with an elevated occupational risk (adjusted OR 3.95; 95% CI 2.04-8.30). We also identified increases in the risk of ALS associated with frequent participation in water sports, particularly waterskiing (adjusted OR 3.89; 95% CI 1.97-8.44). Occupation and waterskiing both retained independent statistical significance in a composite model containing age, gender, and smoking status.

CONCLUSIONS

Our study contributes to a growing body of literature implicating occupational- and hobby-related toxicant exposures in ALS etiology. These epidemiologic study results also provide motivation for future evaluation of water-body-related risk factors.

Motoneuron Disease: Basic Science

ALS is a relentless neurodegenerative disease in which motor neurons are the susceptible neuronal population. Their death results in progressive paresis of voluntary and respiratory muscles. The unprecedented rate of discoveries over the last two decades have broadened our knowledge of genetic causes and helped delineate molecular pathways. Here we critically review ALS epidemiology, genetics, pathogenic mechanisms, available animal models, and iPS cell technologies with a focus on their translational therapeutic potential. Despite limited clinical success in treatments to date, the new discoveries detailed here offer new models for uncovering disease mechanisms as well as novel strategies for intervention.

Drivers: A Biologically Contextualized, Cross-Inferential View of the Epidemiology of Neurodegenerative Disorders

Background:

Sutherland et al. (2011) suggested that, instead of risk factors for single neurodegenerative disorders (NDDs), there was a need to identify specific “drivers”, i.e., risk factors with impact on specific deposits, such as amyloid-β, tau, or α-synuclein, acting across entities.

Objectives and Methods:

Redefining drivers as “neither protein/gene- nor entity-specific features identifiable in the clinical and general epidemiology of conformational NDDs (CNDDs) as potential footprints of templating/spread/transfer mechanisms”, we conducted an analysis of the epidemiology of ten CNDDs, searching for patterns.

Results:

We identified seven potential drivers, each of which was shared by at least two CNDDs: 1) an age-at-exposure-related susceptibility to Creutzfeldt-Jakob disease (CJD) and several late-life CNDDs; 2) a relationship between age at onset, survival, and incidence; 3) shared genetic risk factors for CJD and late-life CNNDs; 4) partly shared personal (diagnostic, educational, behavioral, and social risk factors) predating clinical onset of late-life CNDDs; 5) two environmental risk factors, namely, surgery for sporadic CJD and amyotrophic lateral sclerosis, and Bordetella pertussis infection for Parkinson’s disease; 6) reticulo-endothelial system stressors or general drivers (andropause or premenopausal estrogen deficiency, APOEɛ4, and vascular risk factors) for late-life CNDDs such as dementia/Alzheimer’s disease, type-2 diabetes mellitus, and some sporadic cardiac and vascular degenerative diseases; and 7) a high, invariant incidence ratio of sporadic to genetic forms of mid- and late-life CNDDs, and type-2 diabetes mellitus.

Conclusion:

There might be a systematic epidemiologic pattern induced by specific proteins (PrP, TDP-43, SOD1, α-synuclein, amyloid-β, tau, Langerhans islet peptide, and transthyretin) or established combinations of these.

Pharmacological targeting of the PDGF-CC signaling pathway for blood-brain barrier restoration in neurological disorders

Neurological disorders account for a majority of non-malignant disability in humans and are often associated with dysfunction of the blood-brain barrier (BBB). Recent evidence shows that despite apparent variation in the origin of neural damage, the central nervous system has a common injury response mechanism involving platelet-derived growth factor (PDGF)-CC activation in the neurovascular unit and subsequent dysfunction of BBB integrity. Inhibition of PDGF-CC signaling with imatinib in mice has been shown to prevent BBB dysfunction and have neuroprotective effects in acute damage conditions, including traumatic brain injury, seizures or stroke, as well as in neurodegenerative diseases that develop over time, including multiple sclerosis and amyotrophic lateral sclerosis. Stroke and traumatic injuries are major risk factors for age-associated neurodegenerative disorders and we speculate that restoring BBB properties through PDGF-CC inhibition might provide a common therapeutic opportunity for treatment of both acute and progressive neuropathology in humans. In this review we will summarize what is known about the role of PDGF-CC in neurovascular signaling events and the variety of seemingly different neuropathologies it is involved in. We will also discuss the pharmacological means of therapeutic interventions for anti-PDGF-CC therapy and ongoing clinical trials. In summary: inhibition of PDGF-CC signaling can be protective for immediate injury and decrease the long-term neurodegenerative consequences.

Potential Environmental Factors in Amyotrophic Lateral Sclerosis

The causes of amyotrophic lateral sclerosis (ALS) are largely unknown, and may always be multiple, including environmental factors. Monogenetic determinants of ALS are involved in roughly 20% of all cases (including 10% familial cases). Less well understood multigenetic causes may contribute to another 20% to 80%. Environmental factors likely play a role in the development of ALS in susceptible individuals, but proved causation remains elusive. This article discusses the possible factors of male gender (males are selectively exposed to different influences, or genetically predisposed to be susceptible), smoking, military service, exercise, electrical exposure, heavy metals, agricultural chemicals, and geographic clusters.

Traumatic brain injury history is associated with earlier age of onset of frontotemporal dementia

OBJECTIVE

We retrospectively examined whether a history of traumatic brain injury (TBI) is associated with an earlier age of symptom onset and diagnosis in a large sample of patients with behavioural variant frontotemporal dementia (bvFTD).

METHODS

Data on patients with bvFTD (n=678) were obtained from the National Alzheimer's Coordinating Center Uniform Data Set. TBI was categorised based on reported lifetime history of TBI with loss of consciousness (LOC) but no chronic deficits occurring more than 1 year prior to diagnosis of bvFTD. Analysis of covariance (ANCOVA) was used to determine if clinician-estimated age of symptom onset and age at diagnosis of bvFTD differed between those who reported a history of TBI with LOC (TBI+) and those who did not (TBI-).

RESULTS

Controlling for sex, the TBI+ bvFTD group had an age of symptom onset and age of diagnosis that was on average 2.8 and 3.2 years earlier (p<0.01) than the TBI- bvFTD group.

CONCLUSIONS

TBI history with LOC occurring more than 1 year prior to diagnosis is associated with an earlier age of symptom onset and diagnosis in patients with bvFTD. TBI may be related to the underlying neurodegenerative processes in bvFTD, but the implications of age at time of injury, severity and repetitive injuries remain unclear.

Recent advances in amyotrophic lateral sclerosis

ALS is a relentlessly progressive and fatal disease, with no curative therapies available to date. Symptomatic and palliative care, provided in a multidisciplinary context, still remains the cornerstone of ALS management. However, our understanding of the molecular mechanisms underlying the disease has advanced greatly over the past years, giving new hope for the development of novel diagnostic and therapeutic approaches. Here, we have reviewed the most recent studies that have contributed to improving both clinical management and our understanding of ALS pathogenesis.

Military service, deployments, and exposures in relation to amyotrophic lateral sclerosis etiology

BACKGROUND

Factors underlying a possible excess of amyotrophic lateral sclerosis (ALS) among military veterans remain unidentified. Limitations of previous studies on this topic include reliance on ALS mortality as a surrogate for ALS incidence, low statistical power, and sparse information on military-related factors.

OBJECTIVES

We evaluated associations between military-related factors and ALS using data from a case-control study of U.S. military veterans.

METHODS

From 2005 to 2010, we identified medical record-confirmed ALS cases via the National Registry of Veterans with ALS and controls via the Veterans Benefits Administration's Beneficiary Identification and Records Locator System database. In total, we enrolled 621 cases and 958 frequency-matched controls in the Genes and Environmental Exposures in Veterans with Amyotrophic Lateral Sclerosis study. We collected information on military service and deployments and 39 related exposures. We used unconditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). We used inverse probability weighting to adjust for potential bias from confounding, missing covariate data, and selection arising from a case group that disproportionately included long-term survivors and a control group that may or may not differ from U.S. military veterans at large.

RESULTS

The odds of ALS did not differ for veterans of the Air Force, Army, Marines, and Navy. We found higher odds of ALS for veterans whose longest deployment was World War II or the Korean War and a positive trend with total years of all deployments (OR=1.27; 95% CI: 1.06, 1.52). ALS was positively associated with exposure to herbicides for military purposes, nasopharyngeal radium, personal pesticides, exhaust from heaters or generators, high-intensity radar waves, contaminated food, explosions within one mile, herbicides in the field, mixing and application of burning agents, burning agents in the field, and Agent Orange in the field, with ORs between 1.50 and 7.75.

CONCLUSIONS

Although our results need confirmation, they are potentially important given the large number of U.S. military veterans, and they provide clues to potential factors underlying the apparent increase of ALS in veteran populations.

Physical activity, and physical activity related to sports, leisure and occupational activity as risk factors for ALS: A systematic review

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is considered a multifactorial, multisystem neurodegenerative disease due to an interaction between environmental and genetic factors. This systematic review aims at gathering all available evidence on the association between physical activity (PA) and the risk of ALS.

METHODS

Relevant literature published up to January 2015 was gathered through structured searches on Medline, The Cochrane Library, and the ISI Web of Science databases. Studies considering any type of PA as the main exposure and a diagnosis of ALS or motor neuron disease were selected. Data were extracted in standardized forms, and the quality of included studies was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

Bibliographic searches yielded 3168 records. Nineteen case control studies and 7 cohort studies met the inclusion criteria, and were included in the analysis. Evidence on cumulative measures of PA as a risk factor for ALS remain inconclusive. However, cohort studies report a significantly higher number of cases of ALS in professional soccer and American football players, and a slightly increased risk of ALS in varsity athletes.

Physical Trauma and Amyotrophic Lateral Sclerosis: A Population-Based Study Using Danish National Registries

Prior studies have suggested that physical trauma might be associated with the development of amyotrophic lateral sclerosis (ALS). We conducted a population-based, individually matched case-control study in Denmark to assess whether hospitalization for trauma is associated with a higher risk of developing ALS. There were 3,650 incident cases of ALS in the Danish National Patient Register from 1982 to 2009. We used risk-set sampling to match each case to 100 age- and sex-matched population controls alive on the date of the case's diagnosis. Odds ratios and 95% confidence intervals were calculated using a conditional logistic regression model. History of trauma diagnosis was also obtained from the Danish Patient Register. When traumas in the 5 years prior to the index date were excluded, there was a borderline association between any trauma and ALS (odds ratio (OR) = 1.09, 95% confidence interval (CI): 0.99, 1.19). A first trauma before age 55 years was associated with ALS (OR = 1.22, 95% CI: 1.08, 1.37), whereas first traumas at older ages were not (OR = 0.97, 95% CI: 0.85, 1.10). Our data suggest that physical trauma at earlier ages is associated with ALS risk. Age at first trauma could help explain discrepancies in results of past studies of trauma and ALS.

A look into the future of ALS research

Although amyotrophic lateral sclerosis (ALS), also referred as 'Lou Gehrig's Disease,' was first described in 1869 and the first disease-associated gene was discovered almost 20 years ago, the disease etiology is still not fully understood and treatment options are limited to one drug approved by the US Food and Drug Administration (FDA). The slow translational progress suggests that current research models are not ideal to study such a complicated disease and need to be re-examined. Progress will require greater insight into human genes and biology involved in ALS susceptibility, as well as a deeper understanding of disease phenotype at the histological and molecular levels. Improving human disease outcome will require directing focus toward improved assessment technologies and innovative approaches.

Risk factors for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease. It is typically fatal within 2-5 years of symptom onset. The incidence of ALS is largely uniform across most parts of the world, but an increasing ALS incidence during the last decades has been suggested. Although recent genetic studies have substantially improved our understanding of the causes of ALS, especially familial ALS, an important role of non-genetic factors in ALS is recognized and needs further study. In this review, we briefly discuss several major genetic contributors to ALS identified to date, followed by a more focused discussion on the most commonly examined non-genetic risk factors for ALS. We first review factors related to lifestyle choices, including smoking, intake of antioxidants, physical fitness, body mass index, and physical exercise, followed by factors related to occupational and environmental exposures, including electromagnetic fields, metals, pesticides, β-methylamino-L-alanine, and viral infection. Potential links between ALS and other medical conditions, including head trauma, metabolic diseases, cancer, and inflammatory diseases, are also discussed. Finally, we outline several future directions aiming to more efficiently examine the role of non-genetic risk factors in ALS.

Epidemiological characteristics of motor neuron disease in Chinese patients

BACKGROUND

The epidemiology, diagnosis, and treatment of motor neuron disease (MND) in Chinese patients are ill known.

METHODS

A registered study of 461 MND patients was conducted across 10 facilities in 7 Chinese cities from February 2009 to March 2010.

RESULTS

Patients were classified as amyotrophic lateral sclerosis (ALS) (84.4%), progressive bulbar palsy (PBP) (4.1%), progressive muscular atrophy (PMA) (10.4%), or primary lateral sclerosis (PLS) (0.9%). MND was predominant in men (men/women; 1.6:1.0). Mean onset age was 52.6 years, with the highest incidence being observed between 51 and 60 years. Notably, 26.0% of MND patients were employed in forestry, fishery, or animal husbandry industries. Ten cases (2.7%) reported family history of MND, and 54.2% exhibited cervical onset. MND was also associated with head/neck trauma. Non-invasive positive pressure ventilation was the most common supportive therapy.

CONCLUSION

As a novel comprehensive report of a Chinese population, this study reveals that epidemiological characteristics of MND patients were similar to those observed in international populations. MND is age-related, male gender predominant, and may be associated with both environmental and genetic risk factors.

Prior medical conditions and the risk of amyotrophic lateral sclerosis

Sporadic amyotrophic lateral sclerosis (ALS) is believed to be a complex disease in which multiple exogenous and genetic factors interact to cause motor neuron degeneration. Elucidating the association between medical conditions prior to the first symptoms of ALS could lend support to the theory that specific subpopulations are at risk of developing ALS and provide new insight into shared pathogenic mechanisms. We performed a population-based case-control study in the Netherlands, including 722 sporadic ALS patients and 2,268 age and gender matched controls. Data on medical conditions and use of medication were obtained through a structured questionnaire. Multivariate analyses showed that hypercholesterolemia (OR 0.76, 95% CI 0.63-0.92, P = 0.006), the use of statins (OR 0.45, 95% CI 0.35-0.59, P = 1.86 × 10(-9)) or immunosuppressive drugs (OR 0.26, 95% CI 0.08-0.86, P = 0.03) were associated with a decreased risk of ALS. Head trauma was associated with an increased ALS susceptibility (OR 1.95, 95% CI 1.11-3.43, P = 0.02). No association was found with autoimmune diseases, cancer, psychiatric disorders or cardiovascular diseases, or survival. The lower frequency of hypercholesterolemia and less use of statins in ALS patients indicate a favorable lipid profile prior to symptom onset in at least a subpopulation of ALS. Prior head trauma is a risk factor for ALS and the significantly lower use of immunosuppressive drugs in ALS patients could suggest a protective effect. The identification of specific subpopulations at risk for ALS may provide clues towards possible pathogenic mechanisms.

Does surgery accelerate progression of amyotrophic lateral sclerosis?

BACKGROUND

Surgery is not a recognised potential amyotrophic lateral sclerosis (ALS) risk factor that might modify the onset or course of ALS.

METHODS

We studied our database of ALS patients, which includes questions concerning surgical procedures. We defined surgery as an operative procedure requiring general or regional anaesthesia, but not local anaesthesia. Patients were classified as G1-no surgery; G2-surgery performed ≥3 months before disease onset; G3-surgery <3 months before disease onset; and G4-surgery after disease onset. The ALS-FRS score was evaluated every 3 months from presentation. The maximal ALS-FRS score was ascribed to disease onset, itself defined as symptom onset.

RESULTS

657 patients with ALS were studied. In G3 there was a positive correlation between onset-region and surgery-region (p=0.032). In G4, 35 (57.6%) patients had surgery, probably due to initial misdiagnosis. The rate of functional change (%) in G4 was significantly greater in the 3-month period immediately after surgery as compared with the 3-month period before (1.46%±1.35 vs. 6.30%±8.10, p=0.005) and the following 3 months (3.30%±3.10, p=0.006).

CONCLUSIONS

The site of surgery before ALS onset correlates with the region of onset of ALS. Patients with slower disease progression are at an increased risk of undergoing surgery, probably as part of initial difficulty in diagnosis. We noted accelerated disease progression during the 3-month period after surgery. Definite diagnosis is important to avoid unnecessary surgical trauma and subsequent more rapid deterioration.

Chronic traumatic encephalopathy: where are we and where are we going?

Chronic traumatic encephalopathy (CTE, previously called punch drunk and dementia pugilistica) has a rich history in the medical literature in association with boxing, but has only recently been recognized with other contact sports, such as football and ice hockey, as well as with military blast injuries. CTE is thought to be a neurodegenerative disease associated with repeated concussive and subconcussive blows to the head. There is characteristic gross and microscopic pathology found in the brain, including frontal and temporal atrophy, axonal degeneration, and hyperphosphorylated tau and TAR DNA-binding protein 43 pathology. Clinically, there are characteristic progressive deficits in cognition (memory, executive dysfunction), behavior (explosivity, aggression), mood (depression, suicidality), and motor function (parkinsonism), which correlate with the anatomic distribution of brain pathology. While CTE shares clinical and neuropathological traits with other neurodegenerative diseases, the clinical syndrome and the neuropathology as a whole are distinct from other neurodegenerative diseases. Here we review the CTE literature to date. We also draw on the literature from mild traumatic brain injury and other neurodegenerative dementias, particularly when these studies provide guidance for future CTE research. We conclude by suggesting seven essential areas for future CTE research.

Examining the relationship between head trauma and neurodegenerative disease: A review of epidemiology, pathology and neuroimaging techniques

Traumatic brain injuries (TBI) are induced by sudden acceleration-deceleration and/or rotational forces acting on the brain. Diffuse axonal injury (DAI) has been identified as one of the chief underlying causes of morbidity and mortality in head trauma incidents. DAIs refer to microscopic white matter (WM) injuries as a result of shearing forces that induce pathological and anatomical changes within the brain, which potentially contribute to significant impairments later in life. These microscopic injuries are often unidentifiable by the conventional computed tomography (CT) and magnetic resonance (MR) scans employed by emergency departments to initially assess head trauma patients and, as a result, TBIs are incredibly difficult to diagnose. The impairments associated with TBI may be caused by secondary mechanisms that are initiated at the moment of injury, but often have delayed clinical presentations that are difficult to assess due to the initial misdiagnosis. As a result, the true consequences of these head injuries may go unnoticed at the time of injury and for many years thereafter. The purpose of this review is to investigate these consequences of TBI and their potential link to neurodegenerative disease (ND). This review will summarize the current epidemiological findings, the pathological similarities, and new neuroimaging techniques that may help delineate the relationship between TBI and ND. Lastly, this review will discuss future directions and propose new methods to overcome the limitations that are currently impeding research progress. It is imperative that improved techniques are developed to adequately and retrospectively assess TBI history in patients that may have been previously undiagnosed in order to increase the validity and reliability across future epidemiological studies. The authors introduce a new surveillance tool (Retrospective Screening of Traumatic Brain Injury Questionnaire, RESTBI) to address this concern.

Advances in cellular models to explore the pathophysiology of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disorder, is fatal for most patients less than 3 years from when the first symptoms appear. The aetiologies for sporadic and most familial forms of ALS are unknown, but genetic factors are increasingly recognized as causal in a subset of patients. Studies of disease physiology suggest roles for oxidative stress, glutamate-mediated excitotoxicity or protein aggregation; how these pathways interact in the complex pathophysiology of ALS awaits elucidation. Cellular models are being used to examine disease mechanisms. Recent advances include the availability of expanded cell types, from neuronal or glial cell culture to motoneuron-astrocyte co-culture genetically or environmentally modified. Cell culture experiments confirmed the central role of glial cells in ALS. The recent adaptation of induced pluripotent stem cells (iPSC) for ALS modeling could allow a broader perspective and is expected to generate new hypotheses, related particularly to mechanisms underlying genetic factors. Cellular models have provided meaningful advances in the understanding of ALS, but, to date, complete characterization of in vitro models is only partially described. Consensus on methodological approaches, strategies for validation and techniques that allow rapid adaptation to new genetic or environmental influences is needed. In this article, we review the principal cellular models being employed in ALS and highlight their contribution to the understanding of disease mechanisms. We conclude with recommendations on means to enhance the robustness and generalizability of the different concepts for experimental ALS.

Are professional soccer players at higher risk for ALS?

Since the observation of several deaths from amyotrophic lateral sclerosis (ALS) among Italian professional soccer players, an association between ALS and soccer has been postulated, supported by high rates of morbidity and mortality risks in large cohorts of professionals. Several factors may explain this. A history of repeated (head) injuries is reported more frequently by ALS patients than by individuals with other clinical conditions. An association between exercise and ALS has also been suggested, but results in animals and humans are conflicting. Some clinical and experimental observations suggest a relation between ALS and use of substances such as non-steroidal anti-inflammatory agents, and dietary supplements including branched-chain amino acids. Although Italian soccer players may be at higher risk of ALS than players in other countries, and higher than expected disease frequency seems soccer-specific, increased attention by the Italian lay press is an explanation that cannot be excluded. However, growing evidence points to the possibility that soccer players with ALS are susceptible individuals who develop the disease in response to combinations of environmental factors. Only cohort and case-control studies carried out with the same design in different European countries can provide a definite answer to this suspected but still unconfirmed association.