AUTHOR=Zhu Qiaochu , Zhou Jing , Zhang Yijie , Huang Hai , Han Jie , Cao Biwei , Xu Dandan , Zhao Yan , Chen Gang 

TITLE=Risk factors associated with amyotrophic lateral sclerosis based on the observational study: a systematic review and meta-analysis

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 17 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1196722

DOI=10.3389/fnins.2023.1196722

ISSN=1662-453X

ABSTRACT=Objective: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder affecting the upper and lower motor neurons. Though the pathogenesis of ALS is still unclear, exploring the associations between risk factors and ALS can provide reliable evidence to find the pathogenesis. This meta-analysis aims to synthesize all related risk factors of ALS to understand this disease comprehensively.
Methods: We searched the following databases: PubMed, EMBASE, Cochrane library, Web of Science, and Scopus. Moreover, observational studies, including cohort studies and case-control studies, were included in this meta-analysis. 
Results: The results of this meta-analysis showed that head trauma (OR = 1.26, 95% CI = 1.13, 1.40), physical activity (OR = 1.06, 95% CI = 1.04, 1.09), electric shock (OR = 2.72, 95% CI = 1.62, 4.56), military service (OR = 1.34, 95% CI = 1.11, 1.61), pesticides (OR = 1.96, 95% CI = 1.7, 2.26), and lead exposure (OR = 2.31, 95% CI = 1.44, 3.71) were risk factors for ALS onset and progression. Interestingly, DM (OR = 0.74, 95% CI = 0.66, 0.84) was a protective factor for the disease. However, cerebrovascular disease (OR = 0.99, 95% CI = 0.75, 1.29), occupation (OR = 1.03, 95% CI = 0.66, 1.62), smoking (OR = 1.25, 95% CI = 0.5, 3.09), chemicals (OR = 2.45, 95% CI = 0.89, 6.77), and heavy metal (OR = 1.5, 95% CI = 0.47, 4.84) were not risk factors for ALS according to statistical analyses.
Conclusions: Head trauma, physical activity, electric shock, military service, pesticides, and lead were risk factors for ALS onset and progression. But DM was a protective factor. This finding provides a better understanding of ALS risk factors with strong evidence for clinicians to rationalize clinical intervention strategies.