Abstract
BACKGROUND: Mental health disorders are a major public health challenge, and problematic internet use (PIU) may play an important role in this issue. However, the underlying mechanisms of PIU and its effects on mental health have not yet been elucidated. OBJECTIVE: This study examines the mediating effect of loneliness on the relationship between PIU and mental health, as well as the moderating effect of social media identity on the relationships among PIU, loneliness, and mental health. METHODS: A cross-sectional questionnaire survey was conducted on 21,292 participants recruited using a multistage stratified sampling strategy from 31 provinces/regions in mainland China from June 20 to August 31, 2022. This study assesses PIU (PIU questionnaire-short form-6), depression (9-item Patient Health Questionnaire [PHQ-9]), anxiety (7-item Generalized Anxiety Disorder scale [GAD-7]), loneliness (3-item loneliness scale), and social media identity (identity bubble reinforcement scale). Additionally, we collected the sociodemographic characteristics of the participants. Participants whose total score of PHQ-9≥15 or total score of GAD-7≥10 were considered to have moderate or severe symptoms of depression or anxiety, respectively. A moderated mediation model was established to examine the mediating effect of loneliness on the association between PIU and mental health outcomes (depression and anxiety), moderated by social media identity. RESULTS: Approximately 22.80% (4854/21,292) and 14.20% (3023/21,292) of the respondents reported moderate or severe symptoms of depression and anxiety, respectively. Loneliness significantly mediated the association between PIU and mental health outcomes, explaining 42.53% and 45.48% of the total effect of PIU on depression and anxiety, respectively. Social media identity significantly moderated the associations between PIU and depression (β=0.002, 95% CI 0.001-0.002), PIU and anxiety (β=0.001, 95% CI 0.000-0.002), loneliness and depression (β=0.010, 95% CI 0.007-0.013), and loneliness and anxiety (β=0.007, 95% CI 0.004-0.010), but not between PIU and loneliness (β=0.000, 95% CI -0.003 to 0.003). Higher levels of social media identity were significantly associated with lower levels of loneliness (β=-0.018, 95% CI -0.020 to -0.016). CONCLUSIONS: Addressing loneliness may serve as a valuable approach to mitigate the impact of PIU on mental health outcomes. However, social media identity poses a significant challenge in addressing health issues linked to PIU.