The purpose of this research is to assess whether a short-term group intervention can enhance the emotion regulation skills of adolescents, when the family environment experiences stressful situations, psychopathology or substance abuse. This study aims to increase intervention effectiveness by examining effective approaches to train a crucial mechanism involved in emotional and behavior problems, which is emotion regulation. This research aims to develop a prevention program focused on the enhancement of adolescents' emotion regulation. Before and after the prevention program, participants will answer questionnaires and do a 5 minute psychophysiology experiment to evaluate their emotion regulation ability with both subjective and objective approaches. This prevention program, which is short-term, entailing 7 sessions, synthesizes techniques from three therapeutic models: Cognitive-Behavioral Therapy, Dialectical-Behavioral Therapy and Acceptance and Commitment Therapy. A short-term intervention was formulated and will be tested in the current study, with which is considered an advancement from previous similar interventions because of this synthesis and specific focus on emotion regulation skills, the lack of which can be considered a transdiagnostic risk factor across many psychological conditions and outcomes, including substance use. The main purpose is to help adolescents to enhance their emotion regulation, with the ultimate goal to decrease their risk of developing addictions and other psychopathology.

According to some classic theories of emotion, each emotion triggers a discrete pattern of behaviour, physiology, thoughts and feelings (Mauss \& Robinson, 2009; Russell, 2003). This research will assess adolescents' emotion regulation through three dimensions: a) self-reported emotion reactivity (e.g. sensitivity, arousal/intensity and persistence), b) self-reported emotion regulation (e.g. self-blame, other-blame, rumination, catastrophizing, putting into perspective, positive refocusing, positive reappraisal, acceptance, planning, impulsivity, awareness and emotional clarity) and c) physiological (heart rate and skin conductance). These three dimensions will be assessed before and after the prevention program using relevant questionnaires and an experiment. The prevention program will focus on the enhancement of emotion regulation. However, it is expected that differences in the other two dimensions will also be found parallel to enhancement of emotion regulation skills.

Regarding the randomized control trial study, half of participants will take part in the intervention group and the other half in the waiting-list group. Participants will be divided into groups; each group of 5-10 adolescents (mixed male and female). Participants in the waiting-list group will receive the intervention when the intervention group finish the intervention. The questionnaires will be answered by all participants before and after the intervention and by those in the waiting list group. All participants will answer the questionnaires before and after a five week time interval during which the intervention will take place for the intervention group.

Physiological assessment of emotion processing will be of a 5 minutes duration, during an emotional imagery task, and participants participate twice -before and after the intervention for the intervention group, and two times with 5 weeks in between for the waiting-list group. The experiment will begin after a rest period which includes relaxation in the absence of any stimuli for 2 minutes (baseline) during which heart rate (HR) and skin conductance (SC) will be measured. Afterwards, participants will be asked to imagine six pre-standardized emotional scenarios, which three of them focusing on anger and three on fear situations, appropriate for their age. Participants will be given specific instructions on how to regulate their emotional responses to each scenario. Participants are given written instructions as to how they are to regulate elicited emotions during the different scenarios. Three different sets of emotion regulation instructions will be given to all participants: no guidance, acceptance and cognitive reappraisal. Participants will memorize each scenario prior to engaging in imagery and have to recall the scene as vividly as possible when each trial begins as prompted by the researcher. The duration of each imagery trial for each scenario is 30 seconds. Physiological measurements will be recorded during each scenario. More specifically, heart rate and skin conductance will be measured. Once this pre-intervention assessment is completed, the 7 sessions of group intervention will follow. In addition, at the end of each session participants will set a goal relevant to the skills which they have just learnt to practice at home as homework. For example, if the content of the session is the anger management, participants goal will be to start recognize their emotions and try to calm using different ways, and then when they are ready to express their emotions and try to find a functional solution.