Examining the Causal Relationship Between Hikikomori and Psychological Features of New-Type Depression: A Longitudinal Study on Male Individuals With Hikikomori Condition

AIMS: New-type depression, which exhibits characteristics that are different from those of traditional depression, is thought to be associated with hikikomori. However, a causal relationship has yet to be established. Thus, this study examined the causal relationship between the psychological characteristics of new-type depression (interpersonal sensitivity and privileged self) and hikikomori. METHOD: The analysis included 393 male individuals with hikikomori, with longitudinal data collected from participants by asking them to respond 3 times at 3-month intervals. Participants responded to scales to measure the psychological characteristics of new-type depression and the severity of hikikomori symptoms. We analyzed the data using a random-intercept cross-lagged panel model. RESULTS: Our results showed significant cross-lag effects. In particular, our findings revealed that the extent of hikikomori at Time 1 increased IS and PS at Time 2, whereas IS and PS at Time 2 increased the extent of hikikomori at Time 3. Our data fit the model. These results suggest a self-reinforcing pattern in which hikikomori tendencies intensify with increasing IPS over time. CONCLUSION: We propose that it is important to address both new types of depression and hikikomori rather than addressing one or the other in the treatment of these two disorders. However, this study focused exclusively on individuals who were hikikomori, men, unemployed, and non-disabled. Future studies should include individuals without hikikomori infections or new types of depression.