La sindrome “Hikikomori”: prevalenza nella popolazione generale e psichiatrica. Una systematic review con meta-analisi [The “hikikomori” syndrome: Prevalence in the general and the psychiatric population. A systematic review and meta-analysis]

“Hikikomori” Syndrome is a condition observed in Japanese adolescents in the last decade, characterized by complete and prolonged social withdrawal and repetitive activities, such as the use of the computer at home, associated with loss of interest in school or work. It is not clear to what extent this phenomenon exists in other cultural contexts. In the international literature, there is no systematic review with meta-analysis, which summarizes its prevalence.The present work describes the first systematic review with meta-analysis on the prevalence of the syndrome in the general and the psychiatric population.A systematic search was conducted by using the electronic databases PubMed and Scopus. Nine studies (n = 8598) were included, 7 out of which were conducted in Asian countries. In the general population studies, a significant mean effect size of 0.015 was observed (p <0.001), showing 1.5% prevalence.A significant mean effect size of 0.26 (p <0.05) was observed in the psychiatric population, showing 26% prevalence. In the studies where the mean age was lower (B =-0.06, p <0.001) or with higher percentage of males (B = 0.18, p <0.001), prevalence was significantly higher. Prevalence was comparable to that of the other severe psychiatric disorders, such as personality disorders. It is possible that gender differences, associated with social support and help-seeking behaviours, mediate the role of the male gender. Further studies are requested in Western countries, particularly in Italy.