This study utilized data from the 2024 Korea Youth Risk Behavior Web-based Survey (KYRBS), an annual representative cross-sectional survey conducted on Korean adolescents (middle to high school aged) since 2005 by the Korea Disease Control and Prevention Agency and the Ministry of Education [3]. Samples were extracted using stratified colony sampling methods. A total of 54,653 students from 799 schools participated in the study (participation rate, 94.9%). All items surveyed were self-reported, and responses were collected using an online questionnaire. We decided to perform this study on a cohort of 45,847 students residing with at least one non-divorced biological parent or living with both parents. Stepparents were excluded from the study due to their small representation (3.2% for stepfathers and 2.7% for stepmothers) and the heterogeneity of the underlying family dynamics. The study protocol was approved by the Institutional Review Board of Gachon University Gil Medical Center (No. GFIRB2025-014).

Students were assigned to two groups based on their responses to the question, “Do you live with your father or mother?” Mental health stressors included depression, loneliness, anxiety, and stress. Responses of “Feel very much” or “Feel a lot” to the question “To what extent do you usually feel stressed?” were categorized as indicating significant stress. Respondents who answered “Yes” to the question “Have you felt sad or hopeless to the extent it interfered with daily activities for 2 weeks within the past 12 month?” were classified as depressive. Answers of “Sometimes,” “Often,” or “Always” to the question “How often did you feel lonely in the last month?” were categorized as lonely. The Generalized Anxiety Disorder-7 (GAD-7) was employed to assess anxiety. Moreover, GAD-7 scores were calculated by summing the seven component scores for nervousness, anxiety, one-edge, uncontrollable worry, worry about different things, trouble relaxing, restlessness, irritability, and fear. The response options included “Not at all,” “Sometimes,” “More than 50% of days,” and “Nearly every day.” The GAD-7 scores of ≥10 were defined as “Anxious.”

Economic status was examined using the question “What is your family’s financial condition?” Five possible answers were recorded (“High,” “Mid-high,” “Middle,” “Mid-low,” and “Low”). Responses of “Middle” to “Low” were categorized as indicating poor status. Although objective data on family income were not included in the KYRBS, subjective self-reported economic status has been demonstrated to be a reliable indicator in studies of adolescent mental health. Subjective health status was categorized into two groups, good (very healthy or healthy) and not good (normal, unhealthy, or very unhealthy) based on responses to the question “How do you rate your current health?” Subjective body shape was dichotomized as either obese (including “Slightly obese” and “Very obese”) or non-obese (including “Very lean,” “Slightly lean,” and “Moderate”). Current smoking and drinking status were defined as having smoked at least one cigarette or consumed alcohol within the past 30 days. Fatigue recovery through sleep over the past 7 days was categorized as either sufficient (including “Very sufficient,” “Sufficient,” and “Moderate”) or insufficient (including “Insufficient” and “Very insufficient”). Academic performance was assessed using the question, “How have your grades been over the past 12 months?” with response options categorized as high, moderate to high, moderate, moderate to low, or low.

Descriptive statistics are presented as means±standard deviations or numbers (percentages) using the t-test or chi-squared test (Table 1). Multivariate logistic regression models adjusted for covariates and the other three mental health variables were employed in the analysis. Statistical analyses were performed using Stata/MP software version 17.0 (Stata Corporation, College Station, TX, USA). All the tests were two-sided. P-values <0.01 were considered significant.

This is the first Korean study to examine adolescents’ mental status in relation to parental separation. Prior KYRBS studies have investigated suicidal behaviors according to parental marital status, but primarily focused on the impact of parental remarriage [4,5]. In this large-scale nationwide study, we identified that a father’s absence was associated with increased feelings of loneliness in children regardless of the child’s gender (Table 2). This preliminary study highlights the aforementioned phenomenon. Further qualitative studies are required to elucidate the underlying mechanisms. Future studies should also consider mediating factors,2 such as the timing of separation, reasons for separation (i.e., preparing for divorce or maintaining a job), and grandparental childcare. In conclusion, the mental health of Korean adolescents with separated parents should be screened carefully, particularly the specific subpopulation of adolescents identified in this study.