Does childhood maltreatment affect hikikomori via traits of modern-type depression?

Background: In the 1990s, the concepts of hikikomori and modern-type depression (MTD) emerged in Japan. Hikikomori is a condition of social avoidance or isolation, characterized by staying at home and being physically isolated for at least six months. MTD is characterized by depressive symptoms—mainly in stressful work or school situations during adolescence and early adulthood—which tend to rapidly reduce or disappear after leaving the stressful situation. We hypothesized that childhood maltreatment can form MTD traits that lead to hikikomori. Methods: As a first step, we conducted a multigroup path analysis between childhood maltreatment, MTD traits, and physical isolation in the hikikomori group. This study utilized the nine-item Patient Health Questionnaire (PHQ-9), Home Environment Questionnaire (HEQ), 22-item Tarumi Modern-Type Depressive Trait Scale (TACS-22), 25-item Hikikomori Questionnaire (HQ-25), and Hamilton Depression Rating Scale (HDRS). The HQ-25 contains three factors: physical isolation, lack of socialization, and lack of emotional support. Results: The hikikomori group included 92 patients and the control group comprised 137 healthy individuals. All total and subscale scores of PHQ-9, HEQ, TACS-22, HQ-25, and HDRS were significantly higher in the hikikomori group than in the control group. The risk model of childhood maltreatment for physical isolation via MTD traits obtained good fit with a goodness-of-fit index of.982. Limitations: The study's limitations were its sample selection bias, cross-sectional design, and use of self-report scales. Conclusions: Our findings support the hypothesis that childhood maltreatment is an important risk factor for hikikomori via MTD traits.