Recently, researchers have increasingly focused on understanding commonalities in
psychological processes underlying human suffering and psychopathology [1,2]. This has been
driven by multiple factors, namely: high comorbidity among mental health problems [e.g.,
3,4]; evidence for within-disorder and between-disorder prediction and cascading effects
throughout life [e.g., 5,6]; data suggesting that disorder-specific interventions produce
improvements in comorbid disorders [e.g., 7,8]; established efficacy of transdiagnostic
interventions in multiple disorders [e.g., 9,10]; and their equivalent efficacy to
diagnosis-specific interventions [11]. Taken together, research indicates the presence of
shared mechanisms, highlighting the need for treatments to target broader processes.
Accordingly, transdiagnostic approaches have emerged as promising frameworks, as they may
better reflect the complexity and dimensionality of the human experience and more accurately
represent the reality of mental health problems.
Acceptance and Commitment Therapy (ACT) is a transdiagnostic approach to behavior change that
proposes Psychological Inflexibility (PI) as the root of human suffering in general, and of
mental health disorders in particular [12]. PI is defined as rigid attempts to control, alter
or minimize unpleasant internal experiences at the expense of the ability to persist and/or
change behavior to pursue chosen values. PI steams from six interrelated processes: Cognitive
Fusion, Experiential Avoidance, Attachment to the Conceptualized Self, Dominance of the
Conceptualized Past/Feared Future, Lack of Values Clarity and Inaction, Impulsivity or
Avoidant Persistence [13]. ACT aims to reverse PI processes by cultivating Psychological
Flexibility (PF) which refers to the ability to be in contact with the present moment
regardless of unpleasant internal experiences while persisting in value-guided behaviors
[14]. PF entails six interrelated processes, opposing each PI processes: Cognitive Defusion,
Acceptance, Self as Context, Contact with the Present Moment, Values, and Committed Action
[12].
Evidence supports ACT's efficacy in adults with various disorders [e.g.,15, 16] as well as
the role of PI/PF components as mechanisms of change following ACT [17]. Some studies support
that role in adolescents' mental health [18,19] and promising results suggest ACT's efficacy
with this population [e.g.,20]. However, most studies did not consider all PI/PF processes
[e.g., 21] and there is a scarcity of methodologically robust designs (e.g., Randomized
Controlled Trials; RCTs) investigating ACT interventions in adolescents [e.g.,10]. Because
most studies did not include extended follow-ups and adolescence is marked by significant and
rapid psychological changes [22], ACT's utility to this age group has not been fully
assessed. This seems worrisome considering that between 10 to 20% of adolescents experience
mental health problems [23]. In youth, anxiety disorders are the most common disorders [24].
Particularly, Social Anxiety Disorder (SAD) and Generalized Anxiety Disorder (GAD) present
significant prevalence rates in adolescents [4,25] both typically presenting a chronic course
that may evolve into other mental health disorders in adulthood [6,26]. ACT has been proven
effective for SAD and GAD treatment in adults [27,28]. Preliminary findings point to ACT
being efficacious for treating anxiety in adolescence [23]. However, few studies examined
ACT's efficacy for adolescents' SAD [20,29], and only one included adolescents with GAD [20].
Research on the efficacy of ACT to adolescents' SAD and GAD is largely missing, and
mechanisms underlying change have not been reported. Increasing the understanding of the
common mechanisms underlying mental health problems in adolescents, and how these mechanisms
can be used to sustain efficacious psychological interventions, is a crucial research
concern.
Thus, this project intends to amplify the transdiagnostic application of ACT to adolescents
presenting SAD and GAD. A RCT will be conducted to explore the efficacy and processes of
change of ACT for SAD or GAD, considering adolescents' anxiety symptoms and flourishing as
outcomes. The research team will adapt, implement, and investigate the efficacy of an online
delivered (videoconference) ACT Intervention to adolescents presenting SAD or GAD via: : 1.
Changes in primary (i.e., anxiety symptoms) and secondary (i.e., flourishing and PI/PF
processes) outcomes following intervention - significant improvements are expected at
post-intervention only in the intervention groups (i.e., SAD intervention and GAD
intervention groups), in comparison with a clinical control group; 2. Examining the stability
of change over time (i.e., 3- and 6-months follow-up) - improvements are expected to
maintain; 3. Comparing the efficacy of the intervention between both intervention groups -
Similar effects on outcome measures for both clinical groups are expected; 4. Investigating
mechanisms of change following intervention in both intervention groups - Similar findings in
both intervention groups are expected, with changes in PI/PF predicting changes in outcome
variables.
All procedures involved in this project (described elsewhere in this form) were approved by
the Ethics Committee of the Faculty of Psychology and Educational Sciences, University of
Coimbra and the General Directorate of Education authorized the data collection protocol to
be implemented in school contexts. Informed consent from adolescents and their parents/legal
guardians will be required for all potential participants prior to any data collection.
Adolescents and their parents/legal guardians will be informed that the participation is
voluntary and that they can decline to participate at any time during the project without any
negative consequence. Moreover, they will be informed that the confidentiality of responses
will be assured in all moments.