Social Media Use and Adolescent Depressive Symptoms: A Critical Review of Patterns, Mechanisms, and Individual Differences

Social media has become an important environment for teenagers to communicate, obtain information, and interact with peers, but its psychological impact is not the same for all teenagers. One of the main limitations of existing research is that it often relies on the total usage time, that is, the number of hours teenagers spend on the Internet every day. This measurement method regards highly different digital experiences as equivalent, so it may mask the psychological processes that affect individual outcomes. This critical review shifts the research focus from the simple "dose effect" to the "process effect" and examines how different social media usage patterns are experienced and psychologically processed. This article discusses active use and passive browsing, and then analyzes three core paths: social comparison, rumination, and online social support and sense of belonging. Next, this article emphasizes individual susceptibility to explain why the same digital experience may have different consequences for different teenagers. In particular, characteristics such as self-esteem, comparative tendencies and offline support may affect how teenagers interpret and respond to online experiences. In general, the existing evidence shows that social media itself is neither necessarily harmful nor necessarily beneficial. The psychological consequences depend on what teenagers experience on the Internet, how they interpret and process these experiences, and who these experiences are more important to them. Therefore, future research should give priority to empirical sampling, ecological instantaneous assessment, digital log data, longitudinal research design and individual-specific models to better understand these individual-level processes.