Depressive symptoms precede and drive problematic smartphone use in Chinese medical students: a longitudinal network analysis

Background: Depression and problematic smartphone use (PSU) frequently co-occur in Chinese medical students and are increasingly attracting significant attention. Although the link between PSU and depression is well recognized, patterns of longitudinal dynamic associations at the symptom level remain poorly understood, particularly in the context of Chinese medical students. Methods: A total of 584 medical graduate students (mean age = 30.47 years, SD = 3.57; 65.2% males) completed the Smartphone Addiction Scale-Short Version and the 9-item Patient Health Questionnaire at two time points separated by 6 months. This study examined contemporaneous networks and cross-lagged panel network (CLPN) for both waves of data. Results: Network comparison test revealed that the two contemporaneous networks including PSU and depressive symptoms were consistent in global strength and network structure, with PHQ7 ("concentration difficulties") and PHQ4 ("fatigue") identified as bridging symptoms in both networks. The CLPN results indicated that the comorbidity was primarily driven by depressive symptoms at T1 triggering the development of PSU symptoms at T2. Among these, PHQ7 and PHQ4 exerted the greatest influence on other symptoms within the network and served as critical factors in activating the progression of PSU symptoms at T2. PSU4 ("can't stand not having a phone") and PSU7 ("never give up using a phone") were the most susceptible subsequent symptoms. Conclusions: Our findings provide empirical evidence supporting the comorbidity between PSU and depression, while elucidating their directional relationships at the symptom level. Crucially, we have identified antecedent bridge symptoms as effective intervention targets for simultaneously mitigating the development of co-occurring disorders.