Cognitive flexibility as a bridge between depressive symptoms and problematic smartphone use in adolescents: A two-wave network analysis across depression-severity groups.

The co-occurrence of depressive symptoms and problematic smartphone use (PSU) in adolescents poses a growing public health concern, but its component-level conditional associations, cross-wave patterns, and variation across depression-severity groups remain insufficiently understood. Using a two-wave observational design with a 12-month interval (N = 1200 students from one high school in a county of Gansu Province, China), this study integrated Gaussian graphical modeling (GGM), network comparison testing (NCT), and latent profile analysis (LPA). Cognitive Flexibility showed the largest absolute bridge expected influence at both waves, and the ranking was unchanged when the comparison was restricted to nodes measured at the same level of aggregation. NCT detected no significant global difference between the T1 and T2 contemporaneous networks, although several local cross-community edges differed between the two estimates. LPA retained four nearly parallel, severity-ordered classes at both waves, interpreted as depression-severity groups rather than qualitatively distinct profiles. Subgroup bootstrap analyses showed acceptable edge-weight accuracy; expected-influence CS coefficients ranged from 0.286 to 0.750, whereas all bridge-expected-influence CS coefficients were below 0.25, so the subgroup findings are confined to cross-community connectivity. Between-group differences in cross-community connectivity persisted after equal-n down-sampling. These findings should be interpreted in light of the observational design, single-school convenience sample, and reliance on self-report measures. Cognitive flexibility nevertheless emerged as a consistent cross-community correlate in the overall networks and warrants further longitudinal and intervention evaluation rather than being regarded as an established intervention target.