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Goutman SA, Savelieff MG, Jang DG, Hur J, Feldman EL. The amyotrophic lateral sclerosis exposome: recent advances and future directions. Nat Rev Neurol 2023; 19:617-634. [PMID: 37709948 PMCID: PMC11027963 DOI: 10.1038/s41582-023-00867-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2023] [Indexed: 09/16/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal disease of motor neuron degeneration with typical survival of only 2-5 years from diagnosis. The causes of ALS are multifactorial: known genetic mutations account for only around 70% of cases of familial ALS and 15% of sporadic cases, and heritability estimates range from 8% to 61%, indicating additional causes beyond genetics. Consequently, interest has grown in environmental contributions to ALS risk and progression. The gene-time-environment hypothesis posits that ALS onset occurs through an interaction of genes with environmental exposures during ageing. An alternative hypothesis, the multistep model of ALS, suggests that several hits, at least some of which could be environmental, are required to trigger disease onset, even in the presence of highly penetrant ALS-associated mutations. Studies have sought to characterize the ALS exposome - the lifetime accumulation of environmental exposures that increase disease risk and affect progression. Identifying the full scope of environmental toxicants that enhance ALS risk raises the prospect of preventing disease by eliminating or mitigating exposures. In this Review, we summarize the evidence for an ALS exposome, discussing the strengths and limitations of epidemiological studies that have identified contributions from various sources. We also consider potential mechanisms of exposure-mediated toxicity and suggest future directions for ALS exposome research.
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Affiliation(s)
- Stephen A Goutman
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA
| | - Masha G Savelieff
- Department of Biomedical Sciences, University of North Dakota, Grand Forks, ND, USA
| | - Dae-Gyu Jang
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA
| | - Junguk Hur
- Department of Biomedical Sciences, University of North Dakota, Grand Forks, ND, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
- NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI, USA.
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Yamakawa M, Dwyer S, Song X, Statland J. Demographics, clinical characteristics, and prognostic factors of amyotrophic lateral sclerosis in Midwest. Muscle Nerve 2022; 65:217-224. [PMID: 34708421 PMCID: PMC8849587 DOI: 10.1002/mus.27450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 10/19/2021] [Accepted: 10/23/2021] [Indexed: 02/03/2023]
Abstract
INTRODUCTION/AIMS The Midwest has the highest regional prevalence of self-reported amyotrophic lateral sclerosis (ALS) in the United States, but with limited epidemiological studies. We aimed to explore the characteristics of patients with ALS in the Midwest. METHODS This was a retrospective cohort study of participants with ALS deceased between January, 2010, and September, 2020, registered with the ALS Association Mid-America Chapter. Demographics and clinical variables included gender, race/ethnicity, military status, site of onset, interventions (gastrostomy, non-invasive ventilation, tracheostomy), and visits to ALS Association-registered clinics. Disease characteristics were compared to the National ALS Registry, and survival analysis was performed followed by sample augmentation with historical data to estimate survival with hypothetical censoring. RESULTS The database included 1447 participants with a mean age at diagnosis of 65.7 ± 11.9 y (>60 y at diagnosis: 72%). The median survival from symptom onset was 28.0 mo (95% confidence limit: 26.3, 29.7); sample augmentation increased this to 41.0 mo (38.5, 43.5). Bulbar onset disease and older age at diagnosis were associated with shorter survival. Participants not followed in ALS-Association registered clinics were more frequently male, had familial onset and tracheostomy. Veterans (N = 298) were older at diagnosis but had similar survival after adjustment for age. DISCUSSIONS Our cohort had an older age at onset and more frequent bulbar onset than the National ALS Registry, perhaps reflecting ascertainment biases in each registry. Prospective cohort studies with more clinical and functional data are needed to better characterize ALS in Midwest, veterans, and non-clinic populations, and to optimize care.
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Affiliation(s)
- Mai Yamakawa
- University of Kansas Medical Center, Department of Neurology, Kansas City, KS, USA
| | - Sally Dwyer
- The ALS Association Mid-America Chapter, Mission, KS, USA
| | - Xing Song
- University of Missouri, Health Management and Informatics, School of Medicine, Columbia, MO, USA
| | - Jeffrey Statland
- University of Kansas Medical Center, Department of Neurology, Kansas City, KS, USA
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McKay KA, Smith KA, Smertinaite L, Fang F, Ingre C, Taube F. Military service and related risk factors for amyotrophic lateral sclerosis. Acta Neurol Scand 2021; 143:39-50. [PMID: 32905613 PMCID: PMC7756624 DOI: 10.1111/ane.13345] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/27/2020] [Accepted: 09/02/2020] [Indexed: 12/13/2022]
Abstract
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.
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Affiliation(s)
- Kyla A. McKay
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
- Centre for Molecular Medicine Karolinska Institutet Stockholm Sweden
| | - Kelsi A. Smith
- Clinical Epidemiology Division Department of Medicine Solna, Karolinska Institutet Stockholm Sweden
| | - Lidija Smertinaite
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
| | - Fang Fang
- Unit of Integrative Epidemiology Insitute of Environmental Medicine Karolinska Institutet Stockholm Sweden
| | - Caroline Ingre
- Department of Clinical Neuroscience Karolinska Institutet Stockholm Sweden
| | - Fabian Taube
- School of Public Health and Community Medicine Sahlgrenska Academy at the University of Gothenburg Gothenburg Sweden
- Swedish Armed Forces Center for Defence Medicine Gothenburg Sweden
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Abstract
With age, the presence of multiple neuropathologies in a single individual becomes increasingly common. Given that traumatic brain injury and the repetitive head impacts (RHIs) that occur in contact sports have been associated with the development of many neurodegenerative diseases, including chronic traumatic encephalopathy (CTE), Alzheimer's disease, Lewy body disease, and amyotrophic lateral sclerosis, it is becoming critical to understand the relationship and interactions between these pathologies. In fact, comorbid pathology is common in CTE and likely influenced by both age and the severity and type of exposure to RHI as well as underlying genetic predisposition. Here, we review the major comorbid pathologies seen with CTE and in former contact sports athletes and discuss what is known about the associations between RHI, age, and the development of neuropathologies. In addition, we examine the distinction between CTE and age-related pathology including primary age-related tauopathy and age-related tau astrogliopathy.
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Affiliation(s)
- Thor D. Stein
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts,Boston University Alzheimer’s Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts,Departments of Research and Pathology & Laboratory Medicine, VA Boston Healthcare System, Boston, Massachusetts,Department of Veterans Affairs Medical Center, Bedford, Massachusetts
| | - John F. Crary
- Department of Pathology, Neuropathology Brain Bank & Research Core, Ronald M. Loeb Center for Alzheimer’s Disease, Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York
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Vlaar T, Elbaz A, Moisan F. Is the incidence of motor neuron disease higher in French military personnel? Amyotroph Lateral Scler Frontotemporal Degener 2019; 21:107-115. [DOI: 10.1080/21678421.2019.1675709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Tim Vlaar
- INSERM, Centre for Research in Epidemiology and Population Health, U1018, University Paris-Sud, Villejuif, France and
- Santé publique France, Saint-Maurice, France
| | - Alexis Elbaz
- INSERM, Centre for Research in Epidemiology and Population Health, U1018, University Paris-Sud, Villejuif, France and
- Santé publique France, Saint-Maurice, France
| | - Frédéric Moisan
- INSERM, Centre for Research in Epidemiology and Population Health, U1018, University Paris-Sud, Villejuif, France and
- Santé publique France, Saint-Maurice, France
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Tai H, Cui L, Shen D, Li D, Cui B, Fang J. Military service and the risk of amyotrophic lateral sclerosis: A meta-analysis. J Clin Neurosci 2017; 45:337-342. [PMID: 28864407 DOI: 10.1016/j.jocn.2017.08.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 06/18/2017] [Accepted: 08/10/2017] [Indexed: 12/12/2022]
Abstract
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.
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Affiliation(s)
- Hongfei Tai
- Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Liying Cui
- Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China; Neurosciences Center, Chinese Academy of Medical Sciences, Beijing, China.
| | - Dongchao Shen
- Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Dawei Li
- Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Bo Cui
- Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Jia Fang
- Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
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