Evaluating an Online Wellness Intervention for Greek Adolescents

National and Kapodistrian University of Athens, Greece, University Mental Health, Neurosciences and Precision Medicine Research Institute "Costas Stefanis," Greece

The investigators are evaluating the effects of an online single-session mental health intervention (the Common Elements Toolbox; COMET). To evaluate COMET, the investigators are conducting a randomized controlled trial with Greek adolescents attending high school in the Attica region in Greece. Students will be randomized to the COMET condition or to an active control condition. Primary outcome measures (depressive symptoms, anxiety symptoms, subjective well-being) will be measured at two weeks post-intervention and four weeks post-intervention. The investigators will evaluate COMET as a universal intervention (using the full sample) and as a targeted intervention (analyzing those who reported elevated depressive symptoms or anxiety symptoms at baseline).

The active control condition includes an online self-awareness program that lasts approximately 40-50 minutes. Participants in the control condition will receive access to the intervention after data collection for the study has been completed.

Subjective Well-being questionnaire. Total scores range from 7 to 35. Higher values indicate higher well-being scores.

Questionnaire measuring the acceptability of an intervention. Acceptability refers to the perception that a given treatment is agreeable or satisfactory. The total score ranges from 4 to 20. Higher scores indicate higher acceptability ratings.

Questionnaire measuring the appropriateness of an intervention. Appropriateness refers to the perceived fit or relevance of an intervention. The total score ranges from 4 to 20. Higher scores indicate higher appropriateness.

The investigators will ask participants three items to assess secondary control (Weisz et al., 2010). The items are scored on a 4-point Likert scale, ranging from 0 ("Very false") to 3 ("Very true"). The three items are: When something bad happens, I can find a way to think about it that makes me feel better. After a really hard day, I can make myself feel better by remembering some good things that happened. When bad things happen to me that I can't control, there are lots of things I can do to feel better. Higher scores indicate greater secondary control.

Participants will be asked to rate three items relating to the perceived utility of each module. Specifically, the investigators asked participants: How helpful the module was; How engaging the module was; How much they will continue applying content from the module. If items are at least moderately correlated (r > .5) the investigators will combine them in a single measure of perceived utility. Higher scores indicate greater perceived utility.

Questionnaire measuring positive affect and negative affect. Scores on the positive affect subscale range from 10-50, with higher scores representing higher levels of positive affect. Scores on the negative affect subscale range from 10-50, with lower scores representing lower levels of negative affect.

Inclusion Criteria: Between 13 and 20 years old and a student at a participating Greek high school. Access to the internet.