To investigate the relationship between adaptive, maladaptive, and pathological Internet use and mental health problems, in particular depression, self-harm and suicidal behavior among a representative sample of adolescents from different European countries.

A total of 7.000 students from different European countries were recruited for the SEYLE study, a European school-based intervention study, and completed a self-report questionnaire for baseline assessment. Internet behaviors were evaluated by the Young Diagnostic Questionnaire, depression by the BDI-II, self-harm by the Deliberate Self-Harm Inventory and suicidal behavior by the Paykel Suicide Scale.

Pathological Internet users, who met the criteria for Internet addiction, showed significantly higher rates of depression, self-harm and suicidal behavior compared to students with adaptive Internet use. Remarkably, there were no significant differences in depression as well as self-harm and suicidal behavior between students suffering from Internet addiction and students presenting maladaptive Internet behaviors.

These results clearly demonstrate that students presenting either Internet addiction as well as maladaptive Internet use are more likely to suffer from depression as well as self-harm and suicidal behaviour. However, the group of students with Internet addiction and the students presenting maladaptive Internet use did not significantly differ from each other. These results suggest that not only Internet addiction, but also maladaptive Internet use, is associated with symptoms of depression, self-harm and suicidal behavior. Therefore, more attention should be paid to adolescents with maladaptive Internet use in order to early recognize depression, self-harm and suicidality in adolescence.