Prevalence rate of Internet addiction among Japanese college students: Two cross-sectional studies and reconsideration of cut-off points of Young's Internet Addiction Test in Japan.

AIM: Due to variation in estimates of the prevalence of Internet addiction (IA) in prior research, we conducted two cross-sectional studies over 2 years investigating the prevalence rate of IA in college students in Japan and reconsidered appropriate cut-off points of a self-rating scale to screen possible IA. METHODS: This study was composed of two parts: survey I in 2014 and survey II in 2016, which were conducted in the same schools with an interval of 2 years. The study questionnaire included questions about demographics and Internet use, and Young's Internet Addiction Test (IAT). Additionally, the subjects in survey II were asked about self-reported IA. RESULTS: There were 1005 respondents in total with a mean age (± SD) of 18.9 ± 1.3 years. The mean IAT scores remained stable between 2014 and 2016: 45.2 ± 12.6 in survey I and 45.5 ± 13.1 in survey II (overall mean IAT score of 45.4 ± 13.0). With respect to self-reported IA in survey II, a total of 21.6% admitted to having IA (score of 5 or 6 on a 6-point Likert scale). We categorized these subjects as IA, and the remainder as non-IA. The mean IAT score showed a significant difference between these two groups (57.8 ± 14.3 vs 42.1 ± 10.7, P < 0.001). CONCLUSION: The severity of IA symptoms among Japanese college students has appeared stable in recent years, with mean IAT scores of over 40. Our results suggest that a screening score cut-off of 40 on the IAT could be reconsidered and that 50 might be proposed for the cut-off.