Network structure of social withdrawal symptoms in Asian psychiatric patients at high risk of hikikomori: Findings from the REAP-AD3

Background: Hikikomori is a severe pathological form of social withdrawal that first emerged in Japan in the late 20th century and has since become a global phenomenon. This was recently added to the cultural concept of distress in the DSM-5-TR. Objective: This study aimed to examine the precise network structure of social withdrawal symptoms in Asian psychiatric patients at high risk of hikikomori using data from Phase 3 of the Research on Asian Psychotropic Prescription Patterns for Antidepressants. Methods: High risk of hikikomori was defined as a score ≥ 42 on the 1-month version of the 25-item Hikikomori Questionnaire (HQ-25M), a scale that measures social withdrawal symptoms. The HQ-25M network structures were estimated separately for patients at high and low risks of hikikomori. The differences in network structure invariance and global strength invariance between the two networks were evaluated. Data from 2993 participants were assessed, including 1939 and 1054 patients at high and low risk of hikikomori, respectively. Results: Network analysis revealed that enjoyment of social activities was the most central symptom among patients at high risk of hikikomori, whereas trust issues were the most central among those at low risk of hikikomori. In addition, although no significant differences were identified in the overall network structures, the global strength invariance differed significantly between networks. Conclusion: While the study has several limitations, the findings may point to potential differences in how social withdrawal symptoms are structured between individuals with high versus low risk of hikikomori, particularly with regard to the overall connectivity among symptoms. A notable finding is that low enjoyment of social interactions may be a main area for early intervention. However, given that the participants were all psychiatric patients receiving antidepressant medication and able to attend in-person evaluations, the applicability of these results to non-clinical groups or individuals with more severe social withdrawal may be restricted.