Lifestyle factors and risk of amyotrophic lateral sclerosis: a case-control study in Japan.

Purpose We examined the associations between lifestyle factors and the risk of amyotrophic lateral sclerosis (ALS) using a case-control study in Aichi Prefecture, Japan. Methods The study comprised 183 ALS patients diagnosed by the El Escorial World Federation of Neurology criteria as well as 366 gender- and age-matched controls randomly selected from the general population with the use of the basic register of residents. Detailed information on lifestyle factors was obtained through a mailed self-administered questionnaire. The strength of association between ALS and a potential risk factor was assessed by calculating odds ratios (ORs) and 95% confidence intervals (CIs). Results Vigorous physical activity, self reported stress, a type A behavior pattern, and less frequent intakes of green-yellow vegetables were significantly associated with increased risk of ALS, whereas smoking and drinking habits were not. The greatest effect on risk for ALS was posed by the combination of a type A behavior pattern and less frequent intakes of green-yellow vegetables (adjusted OR, 11.2; 95% CI, 3.8 to 33.0). Conclusion These data suggested that imbalances between excessive productions of oxidants as patient-specific factors and a diminished or missing antioxidant defense system in motor neurons may increase the risk of ALS.