Problematic internet use (PIU) and depression usually co-occur and are common among college students. According to network theory, it may be attributed to the interplay of symptoms that connect these two mental health problems. However, most studies have failed to examine complex and subtle connections at the symptom level and have not clarified how PIU and depression symptoms are intercorrelated, which symptoms serve as the source of comorbidity (i.e., the central symptoms), and whether such a comorbidity mechanism would change with higher grades. To explore these questions, this study examined four contemporaneous networks and three cross-lagged panel networks, visualizing the symptoms as nodes and the connections between symptoms as edges. A total of 2,420 college students (M = 18.35, SD = 0.84; 67.98 % girls) completed four annual surveys. Overall, the results of contemporaneous networks and cross-lagged panel networks indicated that (a) PIU and depression symptoms are intercorrelated; (b) the core symptoms responsible for comorbidity mostly belonged to PIU, and (c) the comorbidity mechanism would change with time. These findings explain the dynamic relation between PIU and depression and identify possible primary symptoms that comorbidity programs can mitigate at different stages of the college years. age
