Hikikomori symptoms, depressive symptoms, and frontal beta activity in young adult males with gaming disorder.

Gaming disorder (GD) is a clinically heterogeneous condition that frequently co-occurs with hikikomori symptoms, depressive symptoms, and reduced resilience. The interrelationships between psychological characteristics and resting-state electroencephalography (EEG) features were investigated. In this cross-sectional study, 59 males with GD and corresponding age-matched healthy controls were recruited. The diagnoses were made through face-to-face psychiatric interviews. The participants completed the Hikikomori Questionnaire-25 (HQ-25), Center for Epidemiologic Studies Depression Scale, and 14-Item Resilience Scale. Resting-state EEG (eyes closed) was recorded for 5 min. In the GD group, subgroup analyses were performed according to high (≧42-points) and low (<42-points) HQ-25 symptom levels. Group comparisons, hierarchical logistic regressions, and correlation analyses were performed. In the hierarchical logistic regression analysis, depressive and total hikikomori symptoms were independently associated with GD, whereas resilience was not. When HQ-25 was decomposed into subscales, only the physical isolation subscale was independently associated with GD. In the GD group, participants with high hikikomori symptoms were more depressed and had lower resilience than those with low hikikomori symptoms. No significant differences in resting EEG were observed between the GD and control groups. Within the GD group, the high-hikikomori subgroup showed nominally higher frontal beta activity at Fz, F3, and F4; however, these differences were attenuated and no longer statistically significant after adjustment for depressive symptoms. Frontal beta power was positively correlated with depressive symptoms and hikikomori severity, whereas F4 beta power was associated with clinical severity. These findings suggest that depressive symptoms and isolation-related social withdrawal are important clinical dimensions in GD, while frontal beta activity may reflect overlapping depressive and social withdrawal-related burden rather than a hikikomori-specific biomarker.