Is a schools-based 8-week mindfulness programme more effective for younger versus older adolescents?

INTERVENTION: Adolescent mindfulness intervention: Mindful Teens (advance English translation from developer http://daviddewulf.be/en/mindfulness‐for‐life; also see Raes, F., Griffith, J., Van der Gucht, K., & Williams, J. (2014). School‐based prevention and Reduction of Depression in Adolescents: A Cluster‐Randomized Trial of a Mindfulness Group Program. Mindfulness, 5(5), 477‐486. ). Lesson duration 75‐ 100 minutes delivered face to face to school classes (Year 8, 10, 12) once weekly over a period of 8 weeks. Lesson length varies per school depending on the length of a standard double lesson. Attendance at lessons is recorded by classroom teacher. Lesson format is a mix of mindfulness meditation, real‐life applications, interactive activities and discussion. Students will receive a weekly handout with key messages and home activities. Home activities consist of (1) daily tips to apply short mindfulness strategies (a few minutes) (2) Formal guided meditations with an audioCD (building from 10 to 20 minutes with an invitation to listen daily) (3) exploration exercises eg noting thoughts and feelings associated with pleasant and unpleasant events (5‐15 minutes over a week). Students self‐report their home practice compliance in deidentified survey post course. Delivered by an external facilitator (15 years personal mindfulness experience, adult and youth mindfulness facilitator) with classroom teacher present. Classes will be audiorecorded and rated for competence and fidelity by programme developer. CONDITION: Anxiety Depression Eating disorders PRIMARY OUTCOME: Anxiety (DASS‐21 subscale and GAD‐7 Depression (DASS‐21 subscale and CES‐DC) weight and shape concerns (subscales of EDE‐Q) SECONDARY OUTCOME: mindfulness (eight subscales of CHIME‐A) INCLUSION CRITERIA: enrolled a selected school in Year 8, 10 or 12, with passive consent from parent and active assent from student