Efficacy of a Group Intervention Grounded in Acceptance and Commitment Therapy (ACT) to Address Problem Gambling in Youth: A Randomized Clinical Trial
Phase: NA
Conditions: Problem Gambling
Sponsor: Universidad Europea de Madrid

 
 
 
 
 
 
 
Efficacy of a Group Intervention Grounded in Acceptance and 
Commitment Therapy (ACT) to Address Problem Gambling in Youth: A 
Randomized Clinical Trial 
 
ID: CEIm25/04 
Document date: February 23, 2025 
Principal Investigators: Francisco Montesinos, Ph.D.- David Lobato, Ph.D. 
Study Protocol and Statistical Analysis Plan 
 
 

Study Protocol 
Objective 
To examine the efficacy of a brief group-based psychological intervention grounded in 
Acceptance and Commitment Therapy (ACT), aimed at young individuals exhibiting 
problematic gambling behaviors. 
Design 
Randomized clinical trial 
Methods 
After being informed about the objectives and characteristics of the study and after all 
participants have signed the informed consent form, they will be assessed to determine 
their suitability. Those who meet the criteria will be randomly assigned to one of two 
groups: 
• 
Immediate intervention group 
• 
Control group (waiting list) 
Both groups will be assessed using standardized questionnaires before and after treatment, 
and at follow-up at three and six months. Participants in the intervention group will receive 
an online group psychological intervention protocol consisting of eight sessions, each 
lasting approximately 90 minutes. 
Participants in the control group will remain on the waiting list during the intervention 
period and will receive treatment after completing the eight sessions in the immediate 
intervention group. 
Intervention Protocol 
Session 1: Introduction to ACT and Values Clarification 
Through metaphors and experiential exercises, such as the “garden” metaphor, participants 
will explore meaningful life domains (e.g., family, relationships, health, education/work, 
leisure) that may have been overshadowed by gambling behavior. 
Session 2: Acceptance and Cognitive Defusion 
Participants will be trained in cognitive defusion and acceptance strategies using exercises 
such as “the mind narrator,” aimed at altering their relationship with automatic gambling-
related thoughts. 
Session 3: Mindfulness 
Mindfulness practices focused on present-moment awareness, such as the “body scan” and 
“conscious breathing,” will be introduced to help participants observe their thoughts, 
emotions, and bodily sensations without immediate reaction. This skill is expected to 
enhance recognition of gambling-related impulses and improve emotional regulation. 

Session 4: Establishing the Observer Self Perspective 
The session will address how individuals identify with self-labels and narratives that foster 
hopelessness. Experiential exercises will be used to cultivate a more flexible and expansive 
perspective, reducing the influence of these narratives on behavior. 
Session 5: Committed Action and Goal Setting 
Participants will work on identifying and formulating concrete personal goals aligned with 
their values. Strategies will be developed to support deliberate action toward these goals, 
even in the presence of emotional discomfort or gambling urges. 
Session 6: The Trap of Experiential Avoidance and Psychological Flexibility 
The session will explore how gambling may serve as an escape from difficult emotions such 
as sadness, anxiety, or guilt. Through metaphors and experiential exercises, participants 
will be trained to remain in contact with these complex emotions without avoidance, 
thereby expanding their repertoire for coping with distress. 
Session 7: Committed Action and Overcoming Barriers 
Internal and external barriers to value-consistent action—such as gambling urges, fear of 
failure, or aversive thoughts (e.g., “there’s no point in trying,” “I’m sure I can’t do it”)—will 
be identified. Practical exercises will be used to train flexible responses to these barriers. 
Session 8: Consolidation and Maintenance Planning 
Key learnings will be reviewed, and an individualized action plan will be developed to 
sustain commitment to value-driven actions in the medium and long term. Potential risk 
situations that may trigger gambling urges will be identified, and coping strategies will be 
practiced. 
Statistical Analysis Plan (SAP) 
The demographic and clinical characteristics of the sample in each treatment group will be 
described, using measures of central tendency (mean and median) and dispersion (standard 
deviation, range). 
The results will be analyzed using nonparametric techniques, comparing the group means 
at pre-treatment, post-treatment, and follow-up. 
An analysis of variance will be performed to estimate the specific weight of each 
independent variable, as well as potential interactions between factors. 
For the comparative analysis between groups, the most appropriate statistical tests will be 
used depending on the type of variable: Student's t-test or Wilcoxon signed-rank test for 
continuous data, and the chi-square test for categorical variables. 
The Jacobson and Truax (1991) statistic will be used to estimate the clinical significance of 
the effect, thus completing the statistical efficacy analyses.