Background: The potential mechanisms underlying the association between online social networking use intensity and depressive symptoms are unclear and underresearched.

Objective: We aimed to investigate the potential roles of interpersonal psychosocial factors on the association between online social networking use intensity and depressive symptoms among early adolescents.

Methods: A total of 4237 adolescents from a 9-month longitudinal study were included. Score changes (indicated as Delta) for the social function use intensity (SFUI) and entertainment function use intensity (EFUI) subscales of the Online Social Networking Activity Intensity Scale and for friendship quality, perceived family support, perceived friend support, parent-adolescent conflict, social nonconfidence, and depressive symptoms were analyzed. The potential mediation effects of unfavorable psychosocial factors and suppression effects of favorable psychosocial factors on the association of Delta SFUI with Delta CES-D and the association of Delta EFUI with Delta CES-D were tested using hierarchical regression models.

Results: The association between Delta SFUI and Delta CES-D was partially mediated by Delta mother-adolescent conflict (mediation effect size 5.11%, P=.02) and Delta social nonconfidence (mediation effect size 20.97%, P<.001) but partially suppressed by.friendship quality, Delta perceived family support, and Delta perceived friend support, with suppression effects of -0.011 (P=.003), -0.009 (P=.003), and -0.022 (P<.001), respectively. The association between Delta EFUI and Delta CES-D was partially mediated by.social nonconfidence (mediation effect size 30.65%, P<.001) but partially suppressed by.perceived family support and Delta perceived friend support, with suppression effects of -0.036 (P<.001) and -0.039 (P<.001), respectively.

Conclusions: The association between online social networking use intensity and depressive symptoms was partially mediated through the indirect increase in social nonconfidence and mother-adolescent conflict; however, better perceived social support and friendship quality would partially compensate for the harmful impact of online social networking use intensity on depressive symptoms among early adolescents.