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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
A mindfulness prevention program based on acceptance and commitment therapy for adolescents: A feasibility study
Scientific title
A mindfulness prevention program for anxiety and depressive symptoms based on acceptance and commitment therapy for adolescents: A feasibility study
Secondary ID [1] 290248 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
depression 300457 0
anxiety 300458 0
Condition category
Condition code
Mental Health 300317 300317 0 0
Mental Health 300351 300351 0 0

Study type
Description of intervention(s) / exposure
The study was a quasi-randomised controlled study. Randomisation was conducted by a staff member of the school who was independent of the study using cluster randomisation based on their Tutorial groups of which there were eight in the Year group. Tutorial groups had a name and these were listed alphabetically and the first assigned to the mindfulness condition and the last four to the control condition. Randomisation was completed before enrolment in the study because attendance to the workshops was a required curricular activity for students. It was for this reason that there were disproportionate numbers in each condition and the randomisation was considered ‘quasi’. The control condition received the mindfulness workshops 5 months after the intervention group.

The intervention is a mindfulness prevention program that utilises the ACT components of: Values, Committed Action, Contact with Present Moment, Acceptance of Emotions, and Thought Defusion. It was delivered in an amphitheatre at the school. The aim of each session was to educate the students on a particular concept (e.g. Values) and encourage them to apply the concepts to their everyday life. To achieve this aim in each session, verbal explanations, personal stories, metaphors, PowerPoint slides, videos, and experiential exercises were used. An example of an experiential exercise was the mindful eating of a sultana to help teach the concept of Contact with Present Moment. The lecture-style presentations were supported by four teacher-led exercises between the presentations, during class time and in a smaller group (approximately 15 students). Teacher exercises were based on the ACT components of Thought Defusion, Contact with Present Moment, and Values. All workshops and teacher-led classes were 25 minutes in duration. In total, students received 4.6 hours of the intervention. Workshops were delivered once per week for 7 weeks.

A clinical psychologist delivered each session of the mindfulness program face-to-face to participants. The mindfulness workshop facilitator had 6 years of university training in psychology, including 2 years in a clinical master’s program. He had also received specialist training and supervision in ACT and had previously delivered the same material to a similar sized group of students in the same school. At the time of workshop delivery, he had approximately 2 years’ experience using ACT in both an individual and group context.

Intervention code [1] 296034 0
Intervention code [2] 296061 0
Comparator / control treatment
The control condition comprised ‘Pastoral Care’, which was their usual class activity during the time slot that the mindfulness workshops were being delivered. In these classes of around 15 to 20 students, material on social justice and cyber-safety was presented by a schoolteacher who had been assigned to the tutorial at the start of the semester, prior to the study commencing. Duration of both programs was equivalent – all Pastoral Care classes were 25 minutes in duration and students received 4.6 hours of Pastoral Care. The control condition received the mindfulness workshops 5 months after the intervention group.
Control group

Primary outcome [1] 299784 0
Depression symptoms, assessed by Depression Anxiety Stress Scale (DASS-21).
Timepoint [1] 299784 0
5 month follow-up
Primary outcome [2] 299809 0
Anxiety symptoms, assessed by Depression Anxiety Stress Scale (DASS-21)
Timepoint [2] 299809 0
5 month follow-up
Secondary outcome [1] 328106 0
Wellbeing, assessed by the Flourishing Scale (FS).
Timepoint [1] 328106 0
5 month follow-up
Secondary outcome [2] 328107 0
Program evaluation questionnaire, specifically designed for this study
Timepoint [2] 328107 0

Key inclusion criteria
Year 10 student at selected high school; self-consent; parental consent if under 16 years of age.
Minimum age
13 Years
Maximum age
18 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
The present study sought to investigate an ACT-based mindfulness intervention as a school universal prevention program. One problem in the evaluation of a new prevention program is the issue of statistical power. Given there is a low rate of emergence of new cases of anxiety and depression over any given period, it has been estimated that over 30,000 participants are needed to adequately power a prevention program evaluation study. Measuring symptom reduction rather than cases can reduce this figure but still almost 1,000 would be required to demonstrate a statistically significant difference between conditions. However to justify investment in a trial of this size, preliminary evidence, obtained in a feasibility study, is required. The aims of this study were to: a) examine the feasibility and acceptability of using an ACT-based prevention program that targets anxiety and depressive symptoms in a non-clinical sample of adolescents; and b) to compare the impact of the ACT-based program on wellbeing and symptoms of depression and anxiety. It was expected that there would be a trend for the mindfulness participants to demonstrate improvements on a range of measures compared to participants in the control condition. Given the underpowered nature of feasibility studies, this trial sought to use effect sizes as an indication of effectiveness and to provide the evidence required for a large-scale study.

Statistical analysis was completed using SPSS 22.0. For baseline and drop-out comparisons, t-tests were used for continuous variables and Chi-squared tests for independence with Yates Continuity Correction for categorical variables. In the universal analysis comparing outcome scores between the mindfulness and control conditions an intention-to-treat analysis was used. Mixed Models with Repeated Measures (MMRM) is considered to be particularly appropriate for school-based studies or when the dropout rate is above 5% as it accounts for all the available data under the missing-at-random assumption. A single analysis examined the outcome scores across the three time-points. To select the covariance structure, the best fitting model using Akaike’s Information Criterion (AIC) was retained. The parameters of the model were estimated using restricted maximum likelihood as the evidence suggests it is preferable over maximum likelihood when the sample is small. The dppc2, formula was used to estimate Cohen’s d effect sizes were interpreted using Cohen’s standards. A positive number for the DASS-21 and FS scales represents an improvement in symptoms and wellbeing, respectively.
For clinical significance analysis, binary mixed modelling was used to examine if the number of participants in the Normal range compared to those in the clinical range differed significantly between the mindfulness and control conditions. The clinical significance effect sizes were calculated using the Cox Logit method.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 294615 0
Name [1] 294615 0
University of NSW Australian Postgraduate Award
Address [1] 294615 0
University of NSW
Kensington, NSW, 2052
Country [1] 294615 0
Primary sponsor type
University of NSW
University of NSW
Kensington, NSW, 2052
Secondary sponsor category [1] 293478 0
Name [1] 293478 0
Address [1] 293478 0
Country [1] 293478 0

Ethics approval
Ethics application status
Ethics committee name [1] 296056 0
University of New South Wales Human Research Ethics Committee
Ethics committee address [1] 296056 0
University of NSW
Kensington, NSW, 2052
Ethics committee country [1] 296056 0
Date submitted for ethics approval [1] 296056 0
Approval date [1] 296056 0
Ethics approval number [1] 296056 0

Brief summary
Mindfulness is an important emotion regulation strategy that has shown promise as a prevention program for anxiety and depressive symptoms. Acceptance and commitment therapy (ACT), a mindfulness-based therapy, has yet to be evaluated in this capacity. This study examines the feasibility of using an ACT-based prevention program in a sample of Year 10 (aged 14 to 16 years) high school students from Sydney, Australia. Participants were allocated to either their usual classes or to the ACT-based mindfulness condition. Participants were followed for a period of 5 months post-intervention and completed the Flourishing Scale, Depression Anxiety Stress Scale, and a program evaluation questionnaire.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 69386 0
Mr Rowan Burckhardt
Address 69386 0
Black Dog Institute
Hospital Rd
Randwick NSW 2031
Country 69386 0
Phone 69386 0
Fax 69386 0
Email 69386 0
Contact person for public queries
Name 69387 0
Mr Rowan Burckhardt
Address 69387 0
Black Dog Institute
Hospital Rd
Randwick NSW 2031
Country 69387 0
Phone 69387 0
Fax 69387 0
Email 69387 0
Contact person for scientific queries
Name 69388 0
Mr Rowan Burckhardt
Address 69388 0
Black Dog Institute
Hospital Rd
Randwick NSW 2031
Country 69388 0
Phone 69388 0
Fax 69388 0
Email 69388 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary