Kimberly Young, an American psychologist, initially proposed provisional diagnostic criteria for subjects with problematic internet use with her naming of “internet addiction” in reference to Diagnostic and Statistical Manual of Mental Disorders (DSM) IV (6) criteria for substance dependence in 1996 (7).Two years later, Young revised her definition of internet addiction, which made it more similar to an impulse control disorder in DSM-IV (8).
With more people using smartphones, problems regarding smartphone overuse become more serious.
However, after thorough discussion, some regard it as one type of behavioral addiction and this attitude seems to be the majority (3, 14–16).
In recent years, internet access has been changing.
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).