Maladaptive social interaction and its related-psychopathology have been highlighted in psychiatry especially among younger generations. “Hikikomori” defined as a syndrome with six months or longer of severe social withdrawal was initially reported in Japan, and the prevalence rate has been reported as 1.2% in Japanese population. The majority of hikikomori patients are adolescents and young adults who become recluses in their parents’ homes for months or years. They withdraw from contact with family, rarely have friends, and do not attend school or hold a job. An international vignette-used questionnaire survey indicates the spread of hikikomori in many other countries (Kato et al. Lancet, 2011; Kato et al. Soc Psychiatry Psychiatr Epidemiol, 2012). In addition, our international clinical studies have revealed the prevalence of hikikomori outside Japan (Teo et al., 2015). On the other hand, a novel form of maladaptive psychopathology, called modern-type depression has emerged in Japan (Kato et al. J Affect Disord, 2011; Kato et al. Psychiatry Clin Neurosci, 2016).

In this presentation, I will introduce “Hikikomori” and “modern-type depression” in Japan, and also propose novel diagnostic/therapeutic approach against them.