Effects of left-behind experience on the interplay between mental health, ecological factors, and problematic smartphone use: A network analysis in adolescents with major depressive disorder

Adolescence is a critical period for the onset of depression, yet the associated risks and developmental processes remain unclear. This study employed network analysis to examine the associations between mental health, ecological factors, and problematic smartphone use (PSU) in adolescents with major depressive disorder (MDD), while also investigating the potential role of left-behind experience in these associations. A total of 2341 adolescents (Mage = 14.99, 22.08% male, 19.99% with left-behind experience) diagnosed with MDD were recruited from 14 outpatient clinics across nine provinces in China. Participants completed validated measures of mental health (depression, anxiety, stress, sleep, self-esteem, loneliness), ecological factors (childhood trauma, peer victimization, social support), and PSU. Undirected network analysis was employed to explore key associations, while network comparisons were employed to assess differences between those with and without left-behind experience. In the full sample network, depression and loneliness demonstrated the highest strength centrality, while sleep exhibited the lowest. Both PSU and loneliness acted as bridges between mental health symptoms and ecological factors. Although no significant network differences were identified, childhood trauma and PSU appeared to have a more pronounced role in the left-behind group, whereas social support seemed more prominent in the non-left-behind group. The findings underscore the complex relationships among various mental health issues, ecological factors, and smartphone use in adolescents with MDD. By identifying the bridging and central nodes in both the full sample and subgroup networks, these results offer valuable targets for intervention studies.