Maartje Boer

SMU AND MENTAL HEALTH 155 6 Social Media Use Intensity, Social Media Use Problems, and Mental Health among Adolescents: Investigating Directionality and Mediating Processes Socialmedia, suchas InstagramandSnapchat, are immenselypopular among adolescents (Anderson & Jiang, 2018; Vannucci & McCauley Ohannessian, 2019). Concerns have been raised about adolescents’ social media use (SMU) and its impact on their mental health, in particular on their life satisfaction and depressive symptoms (Primack & Escobar-Viera, 2017; Underwood & Ehrenreich, 2017). The present study investigated the relationship between SMU and mental health in adolescents. In doing so, we distinguished SMU intensity from SMU problems as two separate dimensions of SMU . SMU intensity refers to the frequency of SMU, whereas SMU problems indicate addiction-like SMU, such as loss of control over SMU or neglecting hobbies or other activities due to SMU (Van den Eijnden et al., 2016). Although adolescents with SMU problems tend to also display high SMU intensity, high SMU intensity does not necessarily imply loss of control over SMU or interference with important life domains. Yet, research suggests that both types of SMU are negatively related to adolescents’ mental health, including their life satisfaction, happiness, and other emotional problems (Mérelle et al., 2017; Twenge, Martin, et al., 2018). Given that SMU intensity and SMU problems differ conceptually, they may have differential associations with mental health. However, research that investigates this hypothesis is scarce. Also, we know little about the directionality of these associations and their underlying processes. Using three waves of longitudinal data among adolescents, the present study addressed these gaps in the literature by investigating bidirectional associations between both types of SMU andmental health, and possible mediators in these associations. The study thereby aims to advance current knowledge on the potential link between social media behaviors and mental health, which is essential given the prominent role social media play into the daily lives of adolescents. SMU Intensity and Mental Health Cross-sectional research suggests that adolescents’ SMU intensity is