Since the 1990s the term “Hikikomori” has emerged as a way to describe a modern form of severe social withdrawal first described in Japan. Recently, there have been increasing reports of Hikikomori around the globe.

To describe operationalized research criteria for Hikikomori, as well as epidemiologic, diagnostic, and psychosocial features of the Hikikomori in international settings.

Participants were recruited from sites in India, Japan, Korea, and the US. Hikikomori was defined as a six-month or longer period of spending almost all time at home and avoiding social situations and social relationships, associated with significant distress/impairment. Lifetime history of psychiatric diagnosis was determined by the Structured Clinical Interview for the DSM-IV Axis-I and Axis-II Disorders. Additional measures included the Internet Addiction Test, UCLA Loneliness Scale, Lubben Social Network Scale (LSNS-6), and Sheehan Disability Scale (SDS).

Thirty-six participants meeting diagnostic criteria for Hikikomori were identified, with cases detected in all four countries. Avoidant personality disorder (41%), major depressive disorder (32%), paranoid personality disorder (32%), social anxiety disorder (27%), posttraumatic stress disorder (27%), and depressive personality disorder (27%) were the most common diagnoses. Sixty-eight percent had at least two psychiatric diagnoses. Individuals with Hikikomori had high levels of loneliness (UCLA Loneliness Scale M = 55.4, SD = 10.5), limited social networks (LSNS-6 M = 9.7, SD = 5.5), and moderate functional impairment (SDS M = 16.5, SD = 7.9).

Hikikomori exists cross-nationally and can be assessed with a standardized assessment tool. Individuals with Hikikomori have substantial psychosocial impairment and disability, and a history of multiple psychiatric disorders is common.

The author has not supplied his declaration of competing interest.