A Randomized Controlled Trial Testing the Effectiveness of an Indicated Depression Prevention Program ('Op Volle Kracht') Among Adolescent Girls with Elevated Depressive Symptoms.

In this randomized controlled trial (RCT with 2 conditions, intervention and control group) the effectiveness of an indicated depression prevention program for adolescent girls with elevated depressive symptoms (12-14 years of age) will be tested. Adolescents in the intervention condition receive the program consisting of the first 8 lessons of 50 minutes that will be implemented after schooltime. Measurements of primary and secondary outcomes will be conducted in the intervention and control group at baseline, immediately after each lesson and one month after the last lesson.

The effectiveness of a school-based indicated depression prevention program ('Op Volle Kracht') will be tested in a Dutch sample of adolescent girls with elevated depressive symptoms (aged 12-14 years). It is expected that the adolescent girls who receive the intervention will show lower levels of depressive symptoms during follow-up, compared to the control group. Moreover, we will examine whether implicit self-esteem predicts or mediates treatment outcome.

1. 0 (start);

2. Immediately after each lesson;

3. One month after last lesson (follow-up);

4. Six months after last lesson.

The girls with elevated depressive symptoms of the participating schools are at random assigned to the intervention or control condition. The participating girls in the intervention condition receive the program, consisting of the first 8 lessons of 50 minutes that will be implemented after schooltime. They will also fill in questionnaires after each lesson. The participating girls in the control condition will only fill in the questionnaires at the same time points. After the study, they will also get the chance to follow the lessons.