In this study, we investigated the relationship of internet addiction, smartphone addiction, and the risk of hikikomori, severe social withdrawal, in Japanese young adult.Methods: The subjects were 478 college/university students in Japan.On these backgrounds, the concept of smartphone addiction has attracted the attentions of researchers from several countries (17–22), while debate about whether it is one of the behavioral addictions or not has been lasting (23).Our previous study demonstrated that male internet users favored online gaming while female users were online for social networking services (SNSs) via their smartphones (24–26).Adolescents and youth may particularly be attracted to and preoccupied with various online activities.A nationwide survey conducted by the Ministry of Internal Affairs and Communications of Japan (MIAC) in 2017 demonstrated that 96.9% of teenagers in Japan use the internet on a daily basis (1).
Internet addiction has not been listed as a psychiatric disorder in the DSM-5 in 2013 (12) nor the International Classification of Diseases (ICD)-11, which was released in June 2018 (13).
It appears that adolescents and youth maintain their friendship primarily by communicating on the internet, especially young women.
Hikikomori phenomena, severe social withdrawal, is one of the most serious social concerns in Japan over the last two decades (28, 29).
Males often isolate themselves from the social community in order to engage in online gaming while females use the internet as to not be excluded from their communications online.
Mental health providers should be aware of the seriousness of internet addictions and hikikomori.