[Internet addiction].

Internet technologies have made a rapid progress, bringing convenience to daily life. On the other hand, internet use disorder and internet addiction (IA) have become reportedly serious health and social problems. In 2013, internet gaming disorder criteria have been proposed in the section of Conditions for Further Study of DSM-5. Existing epidemiological studies by questionnaire methods have reported that the prevalence of IA ranges between 2.8% and 9.9% among youths in Japan. Attention deficit hyperactivity disorder (ADHD), sleeping disorders, depression, obsessive compulsive disorder, and phobic anxiety disorder are extremely common comorbid mental disorders with IA. Some psychotherapies (e.g., cognitive behavioral therapy, motivational interviewing) and medical treatments (e.g., antidepressant drugs, methylphenidate) for comorbid mental disorders as well as rehabilitation (e.g., treatment camp) are effective for IA remission. However, some serious cases of IA may be difficult to treat, and prevention is very important. In future, the prevention, rehabilitations and treatments for IA will be more required in Japan.