Environmental risk factors and amyotrophic lateral sclerosis (ALS): A case-control study of ALS in China

•Risk factors of ALS include head trauma, drinking, smoking, low BMI, workers or famers.•Current evidence of protective factors of ALS is still weak and controversial, which needs further discussion.•The onset of ALS should be explained by mixed effect of trauma, exercise, smoking, occupation, and education level etc. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease mainly involving central and peripheral motor neurons. The etiology of ALS is not clear. In China, there is a preliminary exploration of genetic factors, but the study on environmental factors is relatively inadequate, which needs to be further clarified. To investigate the protective or harmful effects of different environmental factors on ALS, and explore the possible etiology of ALS of the Chinese for further study. Case-control study were used in 123 patients and 239 healthy controls from 2013 to 2016. Statistical analysis and description were performed with SPSS24.0. The risk factors of ALS include head trauma (OR = 3.397, 95% [1.298, 8.893], P = 0.013), drinking (OR = 1.760, 95% CI [1.110,2.790], p = 0.016), smoking (OR = 3.196, 95% [1.375, 7.427], P = 0.351), low BMI (OR = 1.231, 95% CI [1.115, 1.319], P = 0.000), workers or famers (OR = 2.539, 95% [1.441,4.475], P = 0.001, 30–34 yrs); factors that reduce incidence of ALS including hypertension (OR = 0.526, 95% [0.313, 0.883], P = 0.015), severe physical activities (OR = 0.808, 95% [0.711, 0.918], P = 0.001), longer duration of education (OR = 0.183, 95% [0.078, 0.428], P = 0.000, >12 yrs), reading (OR = 0.225, 95% [0.126, 0.516], P = 0.000, 13–30 yrs), retirement or unemployment (OR = 0.040, 95% [0.005, 0.291], P = 0.000, 30–34 yrs); family history of neurologic disorder, general trauma, years and numbers of smoking, artistic activities, and other occupational factors did not show correlation with ALS. Head trauma, alcohol consumption, smoking, low BMI, workers or farmers are risk factors for ALS; high blood pressure, severe physical activity, longer duration of education, reading, retirement or unemployment are protective factors for ALS; whether there is a connection between ALS and family history, general trauma, years or numbers of smoking, artistic activities, and other occupational factors need to be confirmed by further study.