A Single Case Evaluation of an Emotion Regulation Training in Adolescents

Towards a Transdiagnostic Approach

Adolescence is a critical developmental phase in which 75% of all mental disorders manifest before the age of 24 (Wilson, 2020). Although current research is inconsistent in terms of determining the prevalence of adolescent mental health problems, one thing is not up for debate: over the past decade the numbers of both internalizing and externalizing disorders remained consistently high (i.e., ranging from 7.6% to 27,2%) with a recent peek during the COVID-19 pandemic (Kauhanen et al., 2022; Kovess-Masfety et al., 2016; Luijten et al., 2021; Waddell et al., 2014; Whitney & Peterson, 2019).

Simultaneously, perspectives on the classification, development and maintenance of psychopathology have shifted in the last decade (Wu et al., 2021). Moving forward from a categorical point of view, research is now more and more focused on a dimensional perspective such as the Hierarchical Taxonomy Of Psychopathology (HiTOP) and the Research Domain Criteria (RDoC) (Casey et al., 2013; Cuthbert, 2014; DeYoung et al., 2022; Insel et al., 2010; Kotov et al., 2018; Kotov et al., 2017). These approaches are more in line with clinical reality, as they provide a strong framework to research and to understanding for example comorbidity and symptom shifts. Especially with regard to comorbidity, youth rarely present themselves with one delineated problem raising the question on what may be the common ground between different disorders (Jacobi et al., 2014; Lehmann et al., 2013; Newman et al., 1996; Teplin et al., 2021).

This question has initiated research on transdiagnostic factors (i.e., factors underlying various types of psychopathology) (Dalgleish et al., 2020; Krueger & Eaton, 2015; Schaeuffele et al., 2021). One central transdiagnostic factor that is currently of high interest is emotion regulation (Fernandez et al., 2016).

Emotion Regulation

Emotion regulation (ER) or ‘the process by which individuals influence what emotions they have, when they have them, and how they experience and express them’ (Gross, 1998, p. 275), has been implicated in a wide range of psychopathological problems. Research suggests that difficulties in ER contribute to approximately 75% of disorders including anxiety disorders, depressive disorders, conduct disorder, and eating disorders (Kring & Sloan, 2009).

To understand the processes of ER in all its facets, the integrated Adaptive Coping with Emotions model (ACE model, Berking & Whitley, 2014) was developed. In the ACE-model, ER is considered a situationally-dependent interplay between seven ER skills, namely: (1) being aware of the emotion, (2) identifying/labeling the emotion and interpreting body sensations related to the emotion, (3) unravelling the causes and maintenance of the emotion, (4) actively and adaptively modifying the emotion using specific strategies, (5) accepting the emotion when needed and tolerating it when it cannot be changed, (6) confronting and approaching the situation that causes distress and (7) supporting oneself when facing the situation and undesired emotion.

According to the ACE model, modification of negative emotions (4) and acceptance and tolerance of emotions (5) are the central ER skills and problems with these skills are directly related to psychopathology. The other skills, such as awareness (1) and effective self-support (7) are considered facilitators that promote the use of the two central ER skills (Aldao et al., 2016; Berking & Lukas, 2015).

Emotion Regulation Interventions

Based on the ACE model the Affect Regulation Training (ART) was developed to improve adaptive ER in adults with a wide range of clinical problems (Berking et al., 2008; Berking & Lukas, 2015; Berking & Schwarz, 2014). The ART is founded on the ACE model and includes seven modules targeting various ER skills. The techniques employed are derived from cognitive behavioral therapy, acceptance and commitment therapy, emotion-focused therapy, solution-focused therapy and positive therapy. ART has been evaluated multiple times in both convenient samples (i.e., adults with a stressful occupation) and clinical samples (i.e., adults with depression) and proven to be effective in both improving ER skills and mental well-being (Berking et al., 2008; Berking et al., 2013; Berking et al., 2010).

Emotion Regulation Interventions in Youth

Adolescence is a period of heightened demands on ER processes. Cracco et al. (2017) found evidence for a maladaptive shift in the application of adaptive and maladaptive ER strategies. In literature adaptive ER strategies are described as strategies that lead to adequate ER as they reduce negative affect and have the possibility to increase positive affect. Moreover, they have been associated with a greater level of psychological well-being in both youth and adult samples (Aldao et al., 2014; Cicchetti et al., 1995; Werner & Gross, 2010). Examples of well-studied adaptive ER strategies are cognitive reappraisal, problem solving and distraction (Gross, 1999). In contrast, research shows that maladaptive ER strategies may in the short term lead to brief positive effects on experienced emotions but have been linked to persistent negative affect and emotional problems in the long term in both adults and youth (Aldao & Nolen-Hoeksma, 2010; Werner & Gross, 2010). Examples of maladaptive ER strategies that have been extensively researched are rumination and suppression (Aldao & Nolen-Hoeksma, 2010; Dryman & Heimberg, 2018; Moore et al., 2008).

Around the age of 12 to 15 years, during the maladaptive shift, research suggests the use of adaptive ER strategies decreases, and the use of maladaptive ER strategies increases compared to children and adolescents in younger and older age groups. This maladaptive shift provides a potential explanation for the spike in psychological problems (Cracco et al., 2017; Zimmermann & Iwanski, 2014) and emphasizes the need for specific attention for ER training within this age group.

Based on both the ART for adults (Berking & Lukas, 2015) and research evaluating the effects of the separate ER skills included in the ACE model in children and adolescents (Boelens et al., 2022; Volkaert et al., 2020; Wante et al., 2018), the Emotion Regulation Training for Children and Adolescents (EuREKA) was developed (Braet & Berking, 2019; Debeuf et al., 2020; Verbeken et al., 2019), for children and adolescents between 10 and 16 years old. The training is a child-friendly version of the ART and focuses on training facilitating ER skills (i.e., emotional awareness) and specific ER strategies (e.g., problem solving) in a fixed sequence (see procedure below; Verbeken et al., 2019). EuREKA is designed as a transdiagnostic ER training, both in a prevention and an intervention format.

Currently, the EuREKA prevention protocol has been evaluated in a randomized controlled trial (RCT) in community youth (aged 12–13) going through the transition from primary to secondary school (Volkaert et al., 2018). The school-based training was evaluated as feasible and showed significant improvements on depressive symptoms, self-esteem and indirect bullying immediately posttreatment compared to youth who did not follow the program (Volkaert et al., 2022).

Furthermore, the EuREKA intervention protocol has been evaluated in an RCT in children and adolescents with obesity enrolled in an inpatient multidisciplinary obesity treatment program. In this specific sample, the EuREKA intervention resulted in an increase in several ER skills (i.e., emotional awareness, problem solving and evoking a positive mood) posttreatment and effective self-support at 3-month follow-up compared to a control group of youth within the same treatment center only receiving TAU (Boelens et al., 2022; Debeuf et al., 2022).

Participants and Trainers

The current study included data from adolescents and trainers. Six adolescents between 11 and 15 years old (M = 12.50, SD = 1.52; 50% girls) participated in the study. All adolescents were patients in an inpatient multi-functional treatment center (MFC) for adolescents with behavioral (i.e., externalizing) and/or emotional (i.e., internalizing) problems (see Table 1 for a detailed overview). Two similar MFC’s participated in the current study. Adolescents were included when they (a) were between 11 and 15 years old, (b) had not yet received any ER training, (c) were evaluated as eligible through clinical observations by the psychologist of the treatment center and (d) had a normal intelligence. Treatment as usual (TAU) in the center involves weekly individual sessions mainly focused on pedagogical and basic psychological support (e.g., personal goals, following rules and agreements within the center, anger management, behavioral activation). On top of TAU, participants completed the EuREKA training delivered in a group format. The EuREKA training was administered by two of four trainers. The trainers were female students in the final year of their master in clinical psychology and were 23 years old. Prior to the study, they were trained in the EuREKA protocol and during the study they participated in weekly supervision meetings with the first author.

The study was submitted to and approved by the ethics committee of the faculty of psychology and psychological sciences (2020/58; Ghent University). Caregivers and trainers gave written active consent and adolescents gave written assent. After participating in the study, adolescents received a gift voucher for an online webstore.

Measurements

Design

Procedure

Assessment prior to and during EuREKA

At the start of the study (see Figure 1) pretraining assessment took place (duration 2h). Both adolescents and their caregiver (i.e., a parent or educator of the treatment center depending on the closest relationship) filled out questionnaires on psychopathology and ER via an online platform. Subsequently, participants started in the baseline phase and were asked to fill out a weekly ER questionnaire during the baseline phase.

Figure 1

Immediately after the baseline phase, the treatment/training phase (i.e., 12 weekly sessions EuREKA) started. At the start of each session, weekly assessment (i.e., ER questionnaire) took place and at the end the session rating scale with regard to feasibility was filled out by the adolescents.

General information on EuREKA

EuREKA consists of 12 sessions of one and a half hours. EuREKA aims to improve ER skills on top of TAU. The EuREKA program can be divided into 2 phases (see Figure 2). The first phase (session 2–7) is focused on training ER facilitating skills (e.g., relaxation; emotional awareness) and the second phase (session 8–11) is focused on training specific ER strategies (e.g., cognitive reappraisal, problem solving). Each session has a fixed structure to promote predictability and safety. More specifically, every session starts with a short recapitulation of the previous session and a discussion regarding the homework assignment (see EuREKA-time). Next, the content of the current session is introduced after which new skills are trained using psychoeducation and exercises. At the end of each session participants are informed about the upcoming homework assignments and receive a little incentive for their cooperation and motivation during the session (e.g., stress ball, emoji key chain).

Figure 2

Feasibility

Individual outcomes

Figures 3a, 3b, 3c, 3d, 3e, 3f present weekly scores on the ERSQ-J during the baseline phase (A) and treatment phase (B). Baseline scores show low initial values for four out of six youth. More specifically, two participants (PP5 and PP6) score ≤50 and two participants (PP1 and PP2) score ≤60 leaving room for improvement. Only participant 4 (PP4) scores consistently above 60 at baseline. Individual outcomes on the weekly ERSQ-J questionnaire showed pretraining to post training changes of +22%, –20%, +10%; –40%, +71%, +66% that will be discussed for each participant below.

Figure 3a

Figure 3b

Figure 3c

Figure 3d

Figure 3e

Figure 3f

Group outcomes

Next to the individual outcomes, pretraining and post training group outcomes were investigated (see Table 5). First, regarding internalizing problems, there was an 18% decline of depressive symptoms (CDI) reported by the adolescents. In addition, as reported by the caregivers, a 42% decline in internalizing problems (CBCL) and a 28% decline in externalizing problems was observed (CBCL). Second, ER outcomes show a 24% increase in ER skills (ERSQ-J) and a 17% increase in adaptive ER strategies (Feel-KJ SR) as reported by the adolescents. Similarly, a 32% increase in adaptive ER strategies (Feel-KJ CR) reported by caregivers was detected.

Wilcoxon Signed-Rank Test showed one significant effect for pretraining and post training change on the adaptive ER strategies (Feel-KJ SR). However, in addition, some notable effect sizes were observed. More specifically, (1) small effects were found for internalizing problems (YSR) and maladaptive ER strategies (Feel-KJ SR); (2) small-to-medium effects were found for ER skills (ERSQ-J); (3) medium-to-large effects were found for depressive symptoms (CDI), internalizing and externalizing problems (CBCL) and adaptive ER strategies (Feel-KJ SR) and (4) large effects were found for adaptive ER strategies (Feel-KJ CR) (see Table 5).

Feasibility

With regard to the feasibility outcomes as reported by the adolescents, the weekly session rating scale indicated no substantial treatment barriers. On average, participants evaluated the interactions with the trainer, the materials used (i.e., workbook) and the added value of the sessions (i.e., both in terms of content and personal value) positively. A closer look at the individual scores adds nuance to these general findings and shows that three participants gave more neutral responses on some of the items.

Next, based on the overall session scores, participants were, on average, moderately to very satisfied with each session. Half of the participants reported being very satisfied, one reported moderate satisfaction, and two participants provided mixed evaluations, with scores ranging from ‘not satisfied at all’ to ‘very satisfied’. One possible explanation is tied to the trainers’ feedback, which highlighted the crucial role of group atmosphere in the session’s quality. Another explanation could be the significant influence of the session’s topic on participants’ satisfaction.

The aforementioned feasibility outcomes support the use of individual feedback (i.e., routine outcome measurement), for example through a standardized questionnaire (e.g., Session Rating Scale), to monitor both the therapeutic relationship and content of therapy, in order to maintain or adjust the therapeutic approach as needed. (Campbell & Hemsley, 2009; Lambert et al., 2018).

With regard to the feasibility outcomes as reported by the trainers, feedback during the weekly supervision sessions could be categorized in five overarching themes: (1) treatment integrity and self-efficacy; (2) structural feedback on EuREKA, (3) session specific feedback, (4) external factors, and (5) research related feedback. With regard to ‘treatment integrity and self-efficacy’ trainers reported to have reached all goals and felt capable to use the manualized EuREKA protocol. Second, ‘structural feedback on EuREKA’ showed that session length, the long introduction of each session and homework assignments were seen as treatment barriers. Third, with respect to ‘session specific feedback’, the mindfulness exercises were experienced as too lengthy and overly frequent. Several factors may contribute to this perception, including limited attention spans often associated with psychopathology and comorbidities such as a ADHD (Günther et al., 2011). Additionally, negative attitudes toward psychoeducation and tasks resembling schoolwork, particularly for those with a history of academic difficulties, may play a role. A recent review by Herrera et al. (2023) noted that existing meta-analyses have yet to determine whether, and in what ways, variations in session length and format influence the effectiveness of psychoeducation, highlighting the need for further research in this area. Not surprisingly, with regard to ‘external factors’, difficulties with sustained attention and group atmosphere were reported. Finally, ‘research related feedback’ indicated that while the weekly supervision was perceived as valuable, the weekly questionnaires and rating scales were experienced as overly demanding by the adolescents.

Effectiveness

Overall, the results on the ERSQ-J (completed weekly) indicate variability in individual responses to EuREKA, with the majority of participants reporting improvements in ER skills. Notably, different response patterns emerged: some participants demonstrated stable improvements from the start of the training, while others exhibited more fluctuating trajectories, with key changes occurring in the second phase, after acquiring general ER skills. However, while four out of six participants showed an increase in ERSQ-J scores from pre- to posttraining, two participants reported a decline. These individual variations should be interpreted with caution. For instance, one participant with an initially high baseline score had limited room for further improvement, while another showed highly unstable response patterns, complicating interpretation.

Furthermore, within the current heterogeneous group of adolescents with internalizing and/or externalizing problems, different patterns in changes from pre- to posttraining were observed (see Table 6). First, four out of six participants showed decreases in internalizing problems (i.e;, CDI, YSR or CLBL), with adolescent-caregiver agreement in two cases. Nonetheless, one of these participants showed discrepancy between two measurements (i.e;, CDI and YSR). In addition, one participant reported more internalizing problems after completing EuREKA.

Next, half of the participants showed decreases in externalizing problems with adolescent-caregiver agreement in two cases. Generally, parent-child correspondence is often higher for more overt than covert behaviours (Achenbach et al., 2002; Achenbach et al., 1987), However, this was not the case in the current study. Moreover, one participant reported experiencing more externalizing problems after completing EuREKA. A possible explanation for the deterioration in internalizing or externalizing problems reported by three participants could be that they did not (yet) fully adopt and automatize the learned ER skills immediately after treatment.

Lastly, with respect to the overall group scores, a significant pre-post change in adaptive ER strategies, based on self-report, was observed. In addition, several notable effect sizes were observed across measures. Small effects were found for internalizing problems and self-reported maladaptive ER strategies, small-to-medium effects for ER skills, medium-to-large effects for depressive symptoms, internalizing and externalizing problems, self-reported adaptive ER strategies and large effects for caregiver-report adaptive ER strategies.

Strengths & Limitations

This study is one of the first to investigate the feasibility and effectiveness of a group training on ER in a clinical sample of referred adolescents with internalizing and/or externalizing problems. Although research on ER as a transdiagnostic treatment is mushrooming, most of the existing research has focused on homogeneous groups, mainly targeting anxiety or depression (i.e., internalizing problems), and have not yet included or evaluated the effects on participants with externalizing problems (Carlucci et al., 2021; Ehrenreich-May et al., 2017). Although research suggests that the association between internalizing problems and ER is stronger compared to that between externalizing problems and ER (Hankin, 2008), our study adds to the literature by providing evidence for the association between ER and both internalizing and externalizing problems, (Beauchaine & McNulty, 2013). In addition, given the considerable co-morbidity between internalizing and externalizing problems, addressing both simultaneously is seen as an added value (Krueger & Markon, 2006; Van der Ende et al., 2016). However, since not all strategies are associated with both problems, it is important to include more than one ER strategy or skill and to treat ER as a multicomponent factor (Aldao et al., 2016; Beauchaine & McNulty, 2013).

Next, this research employed two approaches to gain insight into treatment effectiveness: (1) the traditional approach, in which general results of the sample can be used to make generalizations to the population (however, in this case there is only a very small sample), and (2) an idiographic single-case approach in which the variability within a unique participant is observed (Hersen, 1990; Molenaar & Valsiner, 2009). This approach is supported by the American Psychological Association (APA, (Chambless, 1995) and provides complementary insights compared to a traditional RCT approach. The design allows for a thorough investigation of the processes responsible for intervention induced changes, while controlling for potential confounders (e.g., maturation, repeated testing), and also indirectly monitor adverse reactions or notable distress through weekly measurements (i.e., participants) and supervision (i.e., trainers). Therefore, this approach is considered a scientificly valuable method for increasing confidence that change is attributable to the intervention, while also enhancing generalizability beyond the individual cases studied (Hersen, 1990; Hilliard, 1993; Kazdin & Tuma, 1982).

Nonetheless, some limitations have to be taken into account. First, given the small sample size, the heterogeneous group, and mixed results, it is challenging to draw solid conclusions regarding the general effectiveness of EuREKA. To strenghten the case, the research should be replicated multiple times (Molenaar & Valsiner, 2009). Adding a simplified (i.e., fewer and shorter questionnaires) standardized single case research protocol to EuREKA could lower the threshold to psychologists to participate in research, which in turn could help build a large data base of single cases to abstract central features of EuREKA. In the next phase, once feasibility and effectiveness have been thoroughly evaluated and the training has been refined based on the generated insights, its effectiveness and efficacy could be further tested through a randomized controlled trial (RCT), which remains the gold standard for evidence-based practice (Chambless & Hollon, 1998). In addition, to obtain insight into long-term post training outcomes, follow-up measurements could provide important information (Kazdin & Weisz, 1998).

Next, particularly within this training, where specific ER strategies are introduced only during the last sessions, there is a possibility that adolescents have not yet internalized these competencies, which could lead to an underestimation of post training effects. Based on the instructional hierarchy for learning new skills (Haring & Eaton, 1978), it can be assumed that participants in the current study completed the acquisition phase of learning (i.e., phase 1: obtaining adequate competency of the content), but did not reach the fluency phase of skill mastery (i.e., phase 2: becoming fluent in the learned skills). The inclusion of multiple booster sessions—sessions delivered at a later time following the completion of training—has been identified as a critical factor in successful skill acquisition. These sessions facilitate the generalization of learned skills to everyday life and contribute positively to the long-term effectiveness of training (e.g., Durlak et al., 2011; Sanchez et al., 2018). For future research, we recommend systematically evaluating the impact of booster sessions by implementing them at various randomized time points to determine the optimal dose-response for this training.

Another notable limitation is the difficulty participants often face in completing homework assignments, as reported in previous research (e.g., Helbig & Fehm, 2004). Homework is considered a crucial component for facilitating the application of learned skills to real-life situations, with both the quantity and quality of homework completion serving as significant predictors of therapeutic success (Mausbach et al., 2010). To address this issue, the present study incorporated video clips and an engaging workbook to increase the appeal of the assignments. However, we recognize that a traditional workbook format may be perceived as outdated and less accessible or engaging compared to a mobile application on participants’ personal smartphones (Tang & Kreindler, 2017). Ongoing research is currently exploring the potential of a mobile application to support the EuREKA training.

Another limitation to adress is the lack of formal assessment of therapist adherence to the protocol, using for example structured measures such as session recordings or fidelity checklists. However, sessions were conducted in accordance with institutional guidelines for psycho-pedagogical support, and no deviations from the protocol were reported during weekly supervision meetings. Additionally, all participants were provided with individual workbooks, which served as an indirect tool to support adherence to the established protocol.

Lastly, with respect to the ERSQ-J questionnaire, some shortcomings can be noticed. The questionnaire was rather extensive (i.e., 28 items) to be filled oud on a weekly basis. Moreover, adolescents were asked to reflect on the past week when answering the questions, making the questionnaire (overly) sensitive to fluctuations. A shorter questionnaire focusing on the general perception of their own ER skills might provide more accurate weekly outcomes in future research. In addition, tracking personal goals and self-efficacy during training could also added value to this single case research design (Warren & Salazar, 2015). To assess this, ecological momentary assessment (EMA) could be used, in which adolescents repeatedly report on their ER skills and personal goals/self-efficacy in real-time outside therapy (Shiffman et al., 2008).

Clinical implications

First, this study sheds new light on both research and treatment of youth with internalizing and/or externalizing problems. The current approach suggests that it is feasible and beneficial to train ER within (a) a clinical referred heterogeneous group of youth, and (b) those diagnosed with internalizing and/or externalizing problems. The therapist protocol and participants’ workbook, which provide a step-by-step outline of the training, along with the detailed findings of the training in scientific work (i.e., Braet & Berking, 2024; Boelens et al., 2024), can be widely shared through workshops, white papers, and publications. This dissemination will enhance evidence-based practice in the short term and support improved mental health outcomes for adolescents in the long term.

The findings of this study provide valuable insights for future research aimed at developing and refining evidence-based transdiagnostic treatments for adolescents with internalizing and externalizing problems. Key considerations include addressing challenges related to session length, group formats, the inclusion of booster sessions, and enhancing the appeal of homework assignments. Some of these issues are already being explored in ongoing projects. For instance, a new program featuring shorter sessions spread over a longer period, with a particular focus on improving homework compliance, is currently under development. Building on previous research, it is anticipated that integrating eHealth solutions, such as a mobile app, into psychotherapy could significantly enhance homework adherence (Månsson et al., 2013). Especially, when classic offline face-to-face therapy is combined with online components in a blended care approach (Wentzel et al., 2016), the advantages of both treatment modalities are maximized (e.g., Wolters et al., 2017). An APP that supports the EUREKA training in a blended care format, is expected to have a surplus value making the training (and especially the homework) even more attractive and significantly helpful for adolescents with internalizing or externalizing problems.