Longitudinal associations among smartphone addiction, loneliness, and depressive symptoms in college students: Disentangling between– And within–person associations

Smartphone addiction and depressive symptoms are two prevalent and highly correlated problems among college students worldwide. However, the causal relationships and potential mechanisms (e.g., loneliness) between them remain controversial. Thus, the present study investigated the dynamic longitudinal relations between smartphone addiction and depressive symptoms including loneliness as a possible mediator in Chinese college students. A total of 3,827 college students (52.8% males, 47.2% females; Mage = 18.87 years, SD = 1.48) participated in a four-wave longitudinal study across two years, and the interval between waves was 6 months except for the second and the third wave (12 months). Smartphone Addiction Scale-Short Version, University of California Los Angeles Loneliness Scale-8 and Patient Health Questionnaire-9 were used to assess participants’ smartphone addiction, loneliness, and depressive symptoms, respectively. Random intercept cross-lagged panel models (RI-CLPM) were utilized to separate between- and within-person effects. The results of RI-CLPM demonstrated a bidirectional association between smartphone addiction and depressive symptoms (from T3 to T4), and loneliness (T3) mediated the association between smartphone addiction (T2) and depressive symptoms (T4) at the within-person level (indirect effect = 0.008, 95%CI = 0.002–0.019). Given that loneliness served as a mediator in the relation between smartphone addiction and depressive symptoms, enhancing offline interpersonal communication may hold great promise for alleviating negative emotions and reducing the dependence on online communication.