Predictors of internet addiction among adolescents in Japan: A two-year prospective cohort study

Internet addiction (IA) is a significant and growing concern for adolescents. However, there is a lack of longitudinal research on Japanese high school students to inform evidence-based prevention programs. This two-year prospective cohort study aimed to identify lifestyle and emotional predictors of IA development among Japanese adolescents. A self-administered questionnaire, including the Young Diagnostic Questionnaire (YDQ), was completed by 5673 first-year high school students (50 % girls) in 2016 and again in 2018. A generalized linear mixed model identified baseline predictors of IA at the two-year follow-up. The cumulative incidence of IA was 1.0 % for boys and 2.4 % for girls, with girls being more than twice as likely to develop IA. For boys, significant predictors of IA were sedentary time of two or more hours per day and social anxiety. For girls, the predictors were tardiness, social anxiety, and impulsivity. Social anxiety was a common predictor for both sexes. The study concludes that the predictors of IA in Japanese adolescents are linked to lifestyle and emotional factors and that they differ by sex. These findings highlight the need for sex-specific prevention strategies. For boys, interventions should focus on reducing sedentary behavior and promoting physical activity. For girls, interventions should address tardiness and impulsivity. Addressing social anxiety is a key preventative measure for all adolescents. These results provide a basis for developing targeted, evidence-based IA prevention programs in schools. • Sex differences were observed in the predictors of Internet addiction (IA). • Girls were more likely to develop IA, with a two-year incidence rate of 2.4 %, compared to 1.0 % in boys. • Sedentary behavior, tardiness, and social anxiety play a significant role in IA onset, requiring targeted prevention.