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The possible effects of violent video gameplay on adolescents are intensely debated, highlighting the difficulties in the violent media research. The current dissertation posits that media may sort effects in more subtle and less direct ways than thus far studied. It employed a novel perspective to investigate the possible effects of violent video games on adolescents’ social outcomes, by looking beyond aggression and by focusing on four social-cognitive skills: emotion recognition, inhibitory control, perspective-taking, and empathy for pain. The development of these skills is particularly salient during early adolescence. If such development would be disturbed by exposure to violent video games, it may underlie antisocial behavior. Integration of insights from media psychology, developmental psychology, and neuroscience led to an expectation that exposure to violent video games would be negatively related to and would have a negative impact on the four social-cognitive skills. To investigate how exposure to violent video games may influence these social-cognitive skills, we took a multi-level approach, by investigating possible effects on a self-report level (questionnaires), a behavioral level (reaction times), and a brain level (ERP responses). To test our hypotheses, we performed four studies employing various study designs: correlational, experimental, and quasi-experimental in different adolescent samples and in one young adult sample. The outcomes of this project indicated that the possible impact of violent video game exposure on adolescents’ social-cognitive skills is limited and may be observed only in terms of short-term effects: less accurate perspective-taking and lower empathy for pain reactions measured immediately after the game. Further, habitual exposure to violent video games was related to lower empathy for pain reactions, but only in young adults, not in adolescents. Contrary to our expectations, more frequent habitual exposure to violent video games was related to better inhibitory control over emotional expressions in adolescents. Moreover, we also tested the possible effects of exposure to antisocial content in other media, beyond video games, and found that it was related to less accurate emotion recognition and lower empathy for pain reactions in adolescents. While this project brings new insights which could enrich scientific and public debates on violent media effects on youth, future longitudinal studies are needed to better understand possible ‘traces’ of violent video games in adolescent development, considering individual developmental trajectories and differences between young people.

The possible effects of violent video gameplay on adolescents are intensely debated, highlighting the difficulties in the violent media research. The current dissertation posits that media may sort effects in more subtle and less direct ways than thus far studied. It employed a novel perspective to investigate the possible effects of violent video games on adolescents’ social outcomes, by looking beyond aggression and by focusing on four social-cognitive skills: emotion recognition, inhibitory control, perspective-taking, and empathy for pain. The development of these skills is particularly salient during early adolescence. If such development would be disturbed by exposure to violent video games, it may underlie antisocial behavior. Integration of insights from media psychology, developmental psychology, and neuroscience led to an expectation that exposure to violent video games would be negatively related to and would have a negative impact on the four social-cognitive skills. To investigate how exposure to violent video games may influence these social-cognitive skills, we took a multi-level approach, by investigating possible effects on a self-report level (questionnaires), a behavioral level (reaction times), and a brain level (ERP responses). To test our hypotheses, we performed four studies employing various study designs: correlational, experimental, and quasi-experimental in different adolescent samples and in one young adult sample. The outcomes of this project indicated that the possible impact of violent video game exposure on adolescents’ social-cognitive skills is limited and may be observed only in terms of short-term effects: less accurate perspective-taking and lower empathy for pain reactions measured immediately after the game. Further, habitual exposure to violent video games was related to lower empathy for pain reactions, but only in young adults, not in adolescents. Contrary to our expectations, more frequent habitual exposure to violent video games was related to better inhibitory control over emotional expressions in adolescents. Moreover, we also tested the possible effects of exposure to antisocial content in other media, beyond video games, and found that it was related to less accurate emotion recognition and lower empathy for pain reactions in adolescents. While this project brings new insights which could enrich scientific and public debates on violent media effects on youth, future longitudinal studies are needed to better understand possible ‘traces’ of violent video games in adolescent development, considering individual developmental trajectories and differences between young people.

Purpose: This case study is presented to inform the reader of potential speech, language, cognitive, and emotional characteristics in preadolescent cluttering. Method: This case study describes a 10-year-old boy who started to clutter during preadolescence. The case illustrates that, in some adolescents, cluttering can co-occur with temporary stuttering-like behavior. In this case, signs of disturbances in speech-language production associated with behavioral impulsiveness as a young child were noted. Speech, language, cognitive, and emotional results of the case are reported in detail. Results: The changes in fluency development are reported and discussed within the context of changes in the adolescent brain as well as adolescent cognitive and emotional development. While being unaware of their speech condition before adolescence, during preadolescence, the changes in brain organization lead to an increase in rate and a decrease in speech control. Given that the client had limited understanding of what was occurring, they were at risk of developing negative communication attitudes. Speech-language therapists are strongly advised to monitor children with cluttering signals in the early years of their adolescence. Supplemental Material: https://doi.org/10.23641/asha.21318072

The thesis is nested within a larger research programme in India which developed a suite of low-intensity psychological interventions for addressing common mental health problems among school going adolescents in low income urban communities in India – PRIDE (PRemIum for aDolEscents, 2016-2022 (Sangath, 2017)) at Indian’s leading not for-profit, non-governmental mental health research organization, Sangath. Chapters 2-6 summarise the studies included in this thesis. Chapter 2 presents a summary of salient context-specific factors that influence stress and coping among school-going adolescents based on focus group discussions undertaken with 191 school-going adolescent boys and girls aged 11-17 years (New Delhi and Goa). Salient social stressors included academic pressure, difficulties in romantic relationships, negotiating parental and peer influences, and exposure to violence and other threats to personal safety. Additionally, girls highlighted stress from having to conform to normative gender roles and in managing the risk of sexual harassment, especially in Delhi. Adolescents primarily used emotion-focused coping strategies (e.g., distraction, escape-avoidance, emotional support seeking). Problem-focused coping (e.g., instrumental support seeking) was less common. Examples of harmful coping (e.g., substance use) were also reported. Chapter 3 summarizes the views of diverse stakeholders (New Delhi and Goa) about their priorities and preferences for SBMHS. Semi-structured interviews and focus group discussions were conducted with adolescents (n=191), parents (n=9), teachers (n=78), school counsellors (n=15), clinical psychologists/psychiatrists (n=7) across the two sites. All stakeholders indicated the need for and acceptability of SBMHS. Adolescents prioritized resolution of life problems. Parents and teachers however, emphasized functional outcomes. Problem solving was suggested as a component of SBMHS. Face-to-face counselling and practical guidance was preferred while self-help was less frequently endorsed. Concerns about confidentiality were raised. Structured sensitisation was recommended to promote adolescent's engagement. Chapter 4 outlines the detailed protocols of evaluation of the sensitisation interventions and the first-line problem solving interventions in the school settings in New Delhi through interlinked randomised controlled trials. The effects of the classroom-based sensitisation intervention involving a brief video presentation and moderated group discussion on the demand for counselling services (Intervention Condition, IC) over and above the whole-school sensitisation interventions (Control Condition, CC) were evaluated through an embedded recruitment trial which adopted a stepped-wedge, cluster randomized controlled trial (SWCRCT) design involving 70 classes that were randomly selected across grades 9th-12th in six Government-run secondary schools in Delhi (Trial registration number: NCT03633916). Chapter 5 includes the findings of this trial. Between 20 August 2018 and 9 December 2018, 835 students (23.3% of all students) were referred into the host trial. The proportion of students referred was significantly higher in the IC (IC=21.7%, CC=1.5%, OR=111.36, 95%CI 35.56 to 348.77, p

The thesis is nested within a larger research programme in India which developed a suite of low-intensity psychological interventions for addressing common mental health problems among school going adolescents in low income urban communities in India – PRIDE (PRemIum for aDolEscents, 2016-2022 (Sangath, 2017)) at Indian’s leading not for-profit, non-governmental mental health research organization, Sangath. Chapters 2-6 summarise the studies included in this thesis. Chapter 2 presents a summary of salient context-specific factors that influence stress and coping among school-going adolescents based on focus group discussions undertaken with 191 school-going adolescent boys and girls aged 11-17 years (New Delhi and Goa). Salient social stressors included academic pressure, difficulties in romantic relationships, negotiating parental and peer influences, and exposure to violence and other threats to personal safety. Additionally, girls highlighted stress from having to conform to normative gender roles and in managing the risk of sexual harassment, especially in Delhi. Adolescents primarily used emotion-focused coping strategies (e.g., distraction, escape-avoidance, emotional support seeking). Problem-focused coping (e.g., instrumental support seeking) was less common. Examples of harmful coping (e.g., substance use) were also reported. Chapter 3 summarizes the views of diverse stakeholders (New Delhi and Goa) about their priorities and preferences for SBMHS. Semi-structured interviews and focus group discussions were conducted with adolescents (n=191), parents (n=9), teachers (n=78), school counsellors (n=15), clinical psychologists/psychiatrists (n=7) across the two sites. All stakeholders indicated the need for and acceptability of SBMHS. Adolescents prioritized resolution of life problems. Parents and teachers however, emphasized functional outcomes. Problem solving was suggested as a component of SBMHS. Face-to-face counselling and practical guidance was preferred while self-help was less frequently endorsed. Concerns about confidentiality were raised. Structured sensitisation was recommended to promote adolescent's engagement. Chapter 4 outlines the detailed protocols of evaluation of the sensitisation interventions and the first-line problem solving interventions in the school settings in New Delhi through interlinked randomised controlled trials. The effects of the classroom-based sensitisation intervention involving a brief video presentation and moderated group discussion on the demand for counselling services (Intervention Condition, IC) over and above the whole-school sensitisation interventions (Control Condition, CC) were evaluated through an embedded recruitment trial which adopted a stepped-wedge, cluster randomized controlled trial (SWCRCT) design involving 70 classes that were randomly selected across grades 9th-12th in six Government-run secondary schools in Delhi (Trial registration number: NCT03633916). Chapter 5 includes the findings of this trial. Between 20 August 2018 and 9 December 2018, 835 students (23.3% of all students) were referred into the host trial. The proportion of students referred was significantly higher in the IC (IC=21.7%, CC=1.5%, OR=111.36, 95%CI 35.56 to 348.77, p

Dutch schools increasingly work towards stimulating healthy choices among adolescents through the Dutch Healthy School-approach. However, interventions and programs are difficult to sustainably embed and maintain in every day practice, and long term effects remain limited. In order to achieve (sustainable) implementation of Healthy School initiatives, it is advocated that the dynamic nature and the complexity of real-life practice needs to be embraced rather than avoided. Two central themes seem to arise when looking at indicators for successful implementation: a) contextualization is key to ensure that local initiatives are tailored to the dynamic and unique context of the school, and b) stakeholders in a school need to feel ownership and need to be empowered by means of leadership, collaboration and community involvement. In order for stakeholders to address these themes, a focus on the concept of ‘building community capacity’ can be an interesting strategy. This pertains ‘the development of knowledge, skills, ownership, leadership, structures and systems to enable effective health promotion’. Despite the fact that community capacity has long been recognized as an important indicator of program success, there is no simple, clear approach available to translate this into a strategy for practice, and to measure the development and impact of such a strategy. This dissertation aims to explore whether and how building community capacity can work as a strategy to (sustainably) implement a context-specific a broadly supported Healthy School-initiative in Dutch secondary schools. In the Fit Lifestyle at School and at Home (FLASH) intervention four prevocational schools in the Netherlands were encouraged to create a Healthy School community that specifically stimulated physical activity and healthy dietary behavior among pupils. The theoretical principles of FLASH are based on the Community Readiness to Change-method, resulting in four capacity-building strategies: 1) identifying and motivating leaders; 2) promoting a participatory school culture; 3) designing and implementing tailored health-promotion activities; and 4) creating a local network of collaborations and resources. Findings illustrated that these strategies, as explored in FLASH, can provide a reference to translate the concept of building community capacity to the real-life practice of Dutch secondary schools. By focusing on capacity-building, schools put more emphasis on the process of becoming a Healthy School that suits their unique and dynamic context. Engaging in continuous conversations about where to go and who and what is needed to get there, enabled stakeholders to move beyond organizing health-topic-specific activities and realize change is also needed on an organizational level. As a result, schools particularly increased their use of strategies concerning leadership and participatory school culture. At the same time, these efforts did not (yet) lead to improved health and health behavior among adolescents, and we observed a stagnation on the "initiation" stage of readiness in all capacity-building strategies. A contributing factor to this observation is that experiences of stakeholders in FLASH show that building community capacity is a long-term process and new focus for stakeholders, and therefore requires time to understand and grow. Because community capacity-building activities initially focus on organizational processes rather than directly stimulating healthy behavior through health promotion activities, delays in the system of a Healthy School community on health-related outcomes can occur. Nevertheless, it is worth engaging in a continued capacity-building process of a "Plan-Do-Check-Act" cycle that can potentially be sustained. By building on the expertise of professionals, the opportunities in and around the school system, and the needs and wants of community members, continuous improvement can be evoked so that schools get into an upward spiral. This can help stakeholders build a strong and professional Healthy School based on an integral approach that is embedded in the school's DNA.

Children and adolescents treated with antipsychotic drugs can experience severe and bothersome adverse drug reactions (ADRs), which can have a physical as well as an emotional impact on their lives. It is important to monitor these children and adolescents closely so that ADRs are identified early. The aim of this thesis was to assess the daily clinical practice of monitoring for ADRs of antipsychotic drugs in children and adolescents, including the facilitators for and barriers to monitoring. First, the need for monitoring was assessed. The frequencies of spontaneously reported ADRs in children and adolescents treated with antipsychotic drugs were determined using data from the worldwide database VigiBase. Many different ADRs were reported by young people and healthcare professionals, including weight gain, breast enlargement, and movement disorders. Second, monitoring in daily clinical practice was examined. How ADRs were monitored was studied in various ways: questionnaires were completed by Dutch child and adolescent psychiatrists, medical records of an organization for child and adolescent psychiatry were examined, and prescription data from British general practitioners were analyzed. In none of these studies monitoring was optimal. The monitoring frequencies as well as what was monitored varied between healthcare professionals. Healthcare professionals rarely reported the reason for not monitoring and guidelines were most often not completely followed. Third, the support provided during antipsychotic drug treatment was assessed. There are clinical guidelines available for healthcare professionals on how to monitor for ADRs. The clarity of presentation and the applicability of ADR-related monitoring instructions in six clinical practice guidelines for children and adolescents treated with antipsychotic drugs were assessed. These guidelines were clearly presented but differed in what and how often to monitor and were not always easily applicable in daily practice. Given the ADRs that might occur, not only the healthcare professionals need support on how to monitor, but also the children, adolescents, parents, and caregivers should be provided with clear instructions and information. Therefore, adolescents treated with antipsychotic drugs were interviewed and asked about their experiences, needs, preferences, and suggestions for improvement. The preliminary results emphasized the importance of personal guidance and involvement in decision-making. Better monitoring is of importance so ADRs can be detected early and the antipsychotic drug treatment can be adjusted according to the individual needs and preferences of the child or adolescent, ensuring a safe and effective antipsychotic drug treatment for this vulnerable population.

Suicidal behavior is a major public health problem in adolescents. Worldwide, about one-third of adolescents report lifetime suicidal thoughts, one in ten adolescents have attempted suicide and almost 46,000 adolescents end their own lives every year. In the Netherlands, one adolescent dies by suicide every week. Adolescents with suicidal behavior also have a higher risk of problems later in life. Therefore, early screening and prevention of suicidal behavior is important. Although much epidemiological evidence on suicidal behavior is available, there are still gaps in our understanding of suicidal behavior in adolescents. The general aim of the research presented in this dissertation was therefore to contribute to a better understanding of suicidal behavior among adolescents (aged 13-16 years) in Amsterdam and vicinity. We used data from the school-based screening questionnaires and from the Digital Child Health Care Registry, which is a registration system for the outcomes of health assessments. Both of these sources are part of the routine health assessments of the Public Health Service (GGD) of Amsterdam. We considered the data to be representative of all adolescents 13-16 years old living in Amsterdam and vicinity. Part I of this dissertation describes time trends for emotional and behavioral problems and suicidal behavior. An important finding was that sociodemographic risk groups for emotional and behavioral problems and suicidal behavior changed over time. The prevalence of total difficulties in adolescents increased by 19% between school years 2004-2005 and 2013-2014 and the time trends differed by sex. The prevalence of suicidal thoughts decreased between 2010-2011 and 2014-2015 from 18% to 13% and of suicide attempts from 3% to 2%. Time trends differed between subgroups according to ethnicity and educational level. Part II of this dissertation describes possible risk factors of suicidal behavior during adolescence. Adolescents with overweight or obesity were more likely to have emotional and behavioral problems and suicidal behavior than their non-overweight peers, which is probably because they were also victimized more often. These associations were stronger for adolescents with obesity than those with overweight. Adolescents who reported physical abuse, emotional neglect, emotional abuse or victimization had an increased risk of suicidal thoughts and suicide attempts. This risk was higher when maltreatment or victimization was more frequent or when several forms of maltreatment were involved simultaneously. For physical abuse, emotional neglect and multiple forms of maltreatment, the risk of suicidal behavior was higher for girls than for boys. Part III presents longitudinal research into the course of suicidal behavior and the possibilities of prediction. Relative to their peers without suicidal behavior, adolescents with suicidal thoughts reported suicidal thoughts five times more often (26% versus 5%) and suicidal attempts six times more often (3% versus 0.5%) two years later. Adolescents who reported a suicide attempt also reported suicidal thoughts four times more often (22% versus 5%) and suicide attempts 25 times more often (12.5% versus 0.5%). Persistent suicidal behavior two years later was associated with sex, education level, family situation, reporting emotional and behavioral problems and abuse. We also investigated whether machine learning techniques improved the prediction of future suicidal behavior in adolescents compared to usual practice, i.e. risk based on previous suicidal behavior. Random Forest achieved slightly higher sensitivity, with the same specificity. With Lasso Regression, sensitivity increased significantly but at the expense of specificity. In conclusion, recommendations for future research and policy are the following: (i) account for different risk groups and the fact that these risk groups can change over time; (ii) focus on modifiable environmental risk factors; (iii) ensure early screening and early treatment; and (iv) improve prediction of increased risk of adolescent suicidal behavior.

Suicidal behavior is a major public health problem in adolescents. Worldwide, about one-third of adolescents report lifetime suicidal thoughts, one in ten adolescents have attempted suicide and almost 46,000 adolescents end their own lives every year. In the Netherlands, one adolescent dies by suicide every week. Adolescents with suicidal behavior also have a higher risk of problems later in life. Therefore, early screening and prevention of suicidal behavior is important. Although much epidemiological evidence on suicidal behavior is available, there are still gaps in our understanding of suicidal behavior in adolescents. The general aim of the research presented in this dissertation was therefore to contribute to a better understanding of suicidal behavior among adolescents (aged 13-16 years) in Amsterdam and vicinity. We used data from the school-based screening questionnaires and from the Digital Child Health Care Registry, which is a registration system for the outcomes of health assessments. Both of these sources are part of the routine health assessments of the Public Health Service (GGD) of Amsterdam. We considered the data to be representative of all adolescents 13-16 years old living in Amsterdam and vicinity. Part I of this dissertation describes time trends for emotional and behavioral problems and suicidal behavior. An important finding was that sociodemographic risk groups for emotional and behavioral problems and suicidal behavior changed over time. The prevalence of total difficulties in adolescents increased by 19% between school years 2004-2005 and 2013-2014 and the time trends differed by sex. The prevalence of suicidal thoughts decreased between 2010-2011 and 2014-2015 from 18% to 13% and of suicide attempts from 3% to 2%. Time trends differed between subgroups according to ethnicity and educational level. Part II of this dissertation describes possible risk factors of suicidal behavior during adolescence. Adolescents with overweight or obesity were more likely to have emotional and behavioral problems and suicidal behavior than their non-overweight peers, which is probably because they were also victimized more often. These associations were stronger for adolescents with obesity than those with overweight. Adolescents who reported physical abuse, emotional neglect, emotional abuse or victimization had an increased risk of suicidal thoughts and suicide attempts. This risk was higher when maltreatment or victimization was more frequent or when several forms of maltreatment were involved simultaneously. For physical abuse, emotional neglect and multiple forms of maltreatment, the risk of suicidal behavior was higher for girls than for boys. Part III presents longitudinal research into the course of suicidal behavior and the possibilities of prediction. Relative to their peers without suicidal behavior, adolescents with suicidal thoughts reported suicidal thoughts five times more often (26% versus 5%) and suicidal attempts six times more often (3% versus 0.5%) two years later. Adolescents who reported a suicide attempt also reported suicidal thoughts four times more often (22% versus 5%) and suicide attempts 25 times more often (12.5% versus 0.5%). Persistent suicidal behavior two years later was associated with sex, education level, family situation, reporting emotional and behavioral problems and abuse. We also investigated whether machine learning techniques improved the prediction of future suicidal behavior in adolescents compared to usual practice, i.e. risk based on previous suicidal behavior. Random Forest achieved slightly higher sensitivity, with the same specificity. With Lasso Regression, sensitivity increased significantly but at the expense of specificity. In conclusion, recommendations for future research and policy are the following: (i) account for different risk groups and the fact that these risk groups can change over time; (ii) focus on modifiable environmental risk factors; (iii) ensure early screening and early treatment; and (iv) improve prediction of increased risk of adolescent suicidal behavior.

Suicidal behavior is a major public health problem in adolescents. Worldwide, about one-third of adolescents report lifetime suicidal thoughts, one in ten adolescents have attempted suicide and almost 46,000 adolescents end their own lives every year. In the Netherlands, one adolescent dies by suicide every week. Adolescents with suicidal behavior also have a higher risk of problems later in life. Therefore, early screening and prevention of suicidal behavior is important. Although much epidemiological evidence on suicidal behavior is available, there are still gaps in our understanding of suicidal behavior in adolescents. The general aim of the research presented in this dissertation was therefore to contribute to a better understanding of suicidal behavior among adolescents (aged 13-16 years) in Amsterdam and vicinity. We used data from the school-based screening questionnaires and from the Digital Child Health Care Registry, which is a registration system for the outcomes of health assessments. Both of these sources are part of the routine health assessments of the Public Health Service (GGD) of Amsterdam. We considered the data to be representative of all adolescents 13-16 years old living in Amsterdam and vicinity. Part I of this dissertation describes time trends for emotional and behavioral problems and suicidal behavior. An important finding was that sociodemographic risk groups for emotional and behavioral problems and suicidal behavior changed over time. The prevalence of total difficulties in adolescents increased by 19% between school years 2004-2005 and 2013-2014 and the time trends differed by sex. The prevalence of suicidal thoughts decreased between 2010-2011 and 2014-2015 from 18% to 13% and of suicide attempts from 3% to 2%. Time trends differed between subgroups according to ethnicity and educational level. Part II of this dissertation describes possible risk factors of suicidal behavior during adolescence. Adolescents with overweight or obesity were more likely to have emotional and behavioral problems and suicidal behavior than their non-overweight peers, which is probably because they were also victimized more often. These associations were stronger for adolescents with obesity than those with overweight. Adolescents who reported physical abuse, emotional neglect, emotional abuse or victimization had an increased risk of suicidal thoughts and suicide attempts. This risk was higher when maltreatment or victimization was more frequent or when several forms of maltreatment were involved simultaneously. For physical abuse, emotional neglect and multiple forms of maltreatment, the risk of suicidal behavior was higher for girls than for boys. Part III presents longitudinal research into the course of suicidal behavior and the possibilities of prediction. Relative to their peers without suicidal behavior, adolescents with suicidal thoughts reported suicidal thoughts five times more often (26% versus 5%) and suicidal attempts six times more often (3% versus 0.5%) two years later. Adolescents who reported a suicide attempt also reported suicidal thoughts four times more often (22% versus 5%) and suicide attempts 25 times more often (12.5% versus 0.5%). Persistent suicidal behavior two years later was associated with sex, education level, family situation, reporting emotional and behavioral problems and abuse. We also investigated whether machine learning techniques improved the prediction of future suicidal behavior in adolescents compared to usual practice, i.e. risk based on previous suicidal behavior. Random Forest achieved slightly higher sensitivity, with the same specificity. With Lasso Regression, sensitivity increased significantly but at the expense of specificity. In conclusion, recommendations for future research and policy are the following: (i) account for different risk groups and the fact that these risk groups can change over time; (ii) focus on modifiable environmental risk factors; (iii) ensure early screening and early treatment; and (iv) improve prediction of increased risk of adolescent suicidal behavior.

Suicidal behavior is a major public health problem in adolescents. Worldwide, about one-third of adolescents report lifetime suicidal thoughts, one in ten adolescents have attempted suicide and almost 46,000 adolescents end their own lives every year. In the Netherlands, one adolescent dies by suicide every week. Adolescents with suicidal behavior also have a higher risk of problems later in life. Therefore, early screening and prevention of suicidal behavior is important. Although much epidemiological evidence on suicidal behavior is available, there are still gaps in our understanding of suicidal behavior in adolescents. The general aim of the research presented in this dissertation was therefore to contribute to a better understanding of suicidal behavior among adolescents (aged 13-16 years) in Amsterdam and vicinity. We used data from the school-based screening questionnaires and from the Digital Child Health Care Registry, which is a registration system for the outcomes of health assessments. Both of these sources are part of the routine health assessments of the Public Health Service (GGD) of Amsterdam. We considered the data to be representative of all adolescents 13-16 years old living in Amsterdam and vicinity. Part I of this dissertation describes time trends for emotional and behavioral problems and suicidal behavior. An important finding was that sociodemographic risk groups for emotional and behavioral problems and suicidal behavior changed over time. The prevalence of total difficulties in adolescents increased by 19% between school years 2004-2005 and 2013-2014 and the time trends differed by sex. The prevalence of suicidal thoughts decreased between 2010-2011 and 2014-2015 from 18% to 13% and of suicide attempts from 3% to 2%. Time trends differed between subgroups according to ethnicity and educational level. Part II of this dissertation describes possible risk factors of suicidal behavior during adolescence. Adolescents with overweight or obesity were more likely to have emotional and behavioral problems and suicidal behavior than their non-overweight peers, which is probably because they were also victimized more often. These associations were stronger for adolescents with obesity than those with overweight. Adolescents who reported physical abuse, emotional neglect, emotional abuse or victimization had an increased risk of suicidal thoughts and suicide attempts. This risk was higher when maltreatment or victimization was more frequent or when several forms of maltreatment were involved simultaneously. For physical abuse, emotional neglect and multiple forms of maltreatment, the risk of suicidal behavior was higher for girls than for boys. Part III presents longitudinal research into the course of suicidal behavior and the possibilities of prediction. Relative to their peers without suicidal behavior, adolescents with suicidal thoughts reported suicidal thoughts five times more often (26% versus 5%) and suicidal attempts six times more often (3% versus 0.5%) two years later. Adolescents who reported a suicide attempt also reported suicidal thoughts four times more often (22% versus 5%) and suicide attempts 25 times more often (12.5% versus 0.5%). Persistent suicidal behavior two years later was associated with sex, education level, family situation, reporting emotional and behavioral problems and abuse. We also investigated whether machine learning techniques improved the prediction of future suicidal behavior in adolescents compared to usual practice, i.e. risk based on previous suicidal behavior. Random Forest achieved slightly higher sensitivity, with the same specificity. With Lasso Regression, sensitivity increased significantly but at the expense of specificity. In conclusion, recommendations for future research and policy are the following: (i) account for different risk groups and the fact that these risk groups can change over time; (ii) focus on modifiable environmental risk factors; (iii) ensure early screening and early treatment; and (iv) improve prediction of increased risk of adolescent suicidal behavior.

Adolescence is a period of increased sensitivity to stress and increased risk of developing mental health problems. However, the majority of adolescents do not receive treatment for these problems. To reach and support adolescents with psychological needs, it is important to provide accessible and effective mental health care. School-based intervention programs targeting (school or social) stress may be a promising way to promote adolescents’ mental health. The results of this dissertation showed the potential of school-based stress-reduction and targeted skills-training programs. That is, the meta-analyses and the performance anxiety program indicated promising results for selected groups on reducing (psychological and physiological) stress and performance anxiety, respectively. Yet, the social skills program was not effective, possibly because the program was not intensive enough, was too broad, or the target group was too heterogenous. Despite the challenges, it was possible to successfully implement and evaluate targeted skills-training programs within schools in a diverse sample of adolescents. In addition, our findings regarding the impact of the COVID-19 pandemic revealed that adolescents with prepandemic vulnerabilities were at risk for experiencing problems during the pandemic, stressing the need of providing help and support for adolescents with psychological needs. Schools and governments should be aware of the existence and potential of school-based intervention programs and should offer and implement them in the first years of secondary school to reduce stress and performance anxiety in adolescents.

Adolescence is a period of increased sensitivity to stress and increased risk of developing mental health problems. However, the majority of adolescents do not receive treatment for these problems. To reach and support adolescents with psychological needs, it is important to provide accessible and effective mental health care. School-based intervention programs targeting (school or social) stress may be a promising way to promote adolescents’ mental health. The results of this dissertation showed the potential of school-based stress-reduction and targeted skills-training programs. That is, the meta-analyses and the performance anxiety program indicated promising results for selected groups on reducing (psychological and physiological) stress and performance anxiety, respectively. Yet, the social skills program was not effective, possibly because the program was not intensive enough, was too broad, or the target group was too heterogenous. Despite the challenges, it was possible to successfully implement and evaluate targeted skills-training programs within schools in a diverse sample of adolescents. In addition, our findings regarding the impact of the COVID-19 pandemic revealed that adolescents with prepandemic vulnerabilities were at risk for experiencing problems during the pandemic, stressing the need of providing help and support for adolescents with psychological needs. Schools and governments should be aware of the existence and potential of school-based intervention programs and should offer and implement them in the first years of secondary school to reduce stress and performance anxiety in adolescents.

In chapter 2, we assessed the acute effects of a single methylphenidate administration on amygdala reactivity during fear learning and fear reversal learning. As hypothesized, DBD-patients in the placebo condition (DBD-PCB) showed lower amygdala reactivity during the acquisition of fear compared to healthy controls (HCs) and to DBD patients in the MPH condition (DBD-MPH). These findings suggest a normalizing effect of MPH on amygdala functioning during the acquisition of fear in DBD. Contrary our hypothesis, at the group level there was no difference in reactivity between the groups in the vmPFC during fear reversal learning. In exploratory subgroup analyses it was found that amygdala hypoactivation and the subsequent normalizing effect of MPH seemed to be driven by a subgroup of DBD-patients without comorbid ADHD. In chapter 3, we assessed whether brain activity during the extinction of previously acquired fear was associated with the persistence or desistence of DBD and psychopathic traits. As hypothesized, DBD-P and DBD-D were both associated with increased reactivity of ACC and insula during fear extinction, compared to HCs. Furthermore, impulsive-irresponsible psychopathic traits were positive associated with hyperreactivity in the amygdala, insula and ACC. Moreover, these impulsive-irresponsible traits mediated the association of neural reactivity in the ACC and persisting and desisting of DBD. The acute effect of methylphenidate administration on reward and punishment sensitivity was investigated in chapter 4. We hypothesized that - compared to HCs – DBD-patients have deviancies in both reward and punishment processing and that a single dose of methylphenidate could (temporary) normalize these deviancies. DBD-PCB showed - compared to HCs - significantly lower amygdala responsiveness during reward receipt or omission. DBD-MPH showed, compared to HCs, similar amygdala responsiveness during omission of a reward suggesting normalization of amygdala reactivity during reward omission. In contrast to our hypotheses, there was no suggested normalization of amygdala responsiveness during reward receipt. Furthermore, compared to DBD-MPH, DBD-PCB showed higher nucleus accumbens reactivity when anticipating a potential reward. In chapter 5, we assessed the effects of a single dose of methylphenidate on resting state connectivity of the nucleus accumbens (NAcc), amygdala and ventral tegmental area (VTA) with other brain areas. We hypothesized that DBD-PCB, compared to HCs, would show aberrances in resting state connectivity and a normalizing effect of methylphenidate. Compared to HCs, DBD-PCB showed higher connectivity between the NAcc seed and the occipital cortex, posterior cingulate cortex (PCC), precuneus and inferior parietal lobule (IPL). Furthermore, compared to HCs, DBD-PCB had higher connectivity of the amygdala seed with the precuneus and PCC. Compared to DBD-MPH, DBD-PCB had higher connectivity between NAcc seed and occipital cortex, IPL, and medial frontal gyrus. Both NAcc and amygdala seeds showed no connectivity differences in the DBD-MPH compared to the HCs group, suggesting that MPH normalizes the increased functional connectivity between mesolimbic seed regions and areas involved in moral decision making, visual processing and attention. In chapter 6 we assessed gray matter volume (GMV), white matter volume (WMV), and WM integrity of DBD-patients and HCs. In line with previous studies, DBD-patients had decreased GMV of the amygdala, insula, and inferior frontal cortex (IFG). While the previous literature of white matter integrity in DBD adolescents was inconsistent, with some studies reporting higher WM integrity and others reporting lower WM integrity, in this thesis we reported both higher and lower WM integrity in DBD-patients. Compared to HCs, DBD-patients had a cluster with higher WM integrity and a cluster with lower WM integrity within the uncinate fasciculus (UF), the white matter tract connecting the amygdala, insula and IFG.

In chapter 2, we assessed the acute effects of a single methylphenidate administration on amygdala reactivity during fear learning and fear reversal learning. As hypothesized, DBD-patients in the placebo condition (DBD-PCB) showed lower amygdala reactivity during the acquisition of fear compared to healthy controls (HCs) and to DBD patients in the MPH condition (DBD-MPH). These findings suggest a normalizing effect of MPH on amygdala functioning during the acquisition of fear in DBD. Contrary our hypothesis, at the group level there was no difference in reactivity between the groups in the vmPFC during fear reversal learning. In exploratory subgroup analyses it was found that amygdala hypoactivation and the subsequent normalizing effect of MPH seemed to be driven by a subgroup of DBD-patients without comorbid ADHD. In chapter 3, we assessed whether brain activity during the extinction of previously acquired fear was associated with the persistence or desistence of DBD and psychopathic traits. As hypothesized, DBD-P and DBD-D were both associated with increased reactivity of ACC and insula during fear extinction, compared to HCs. Furthermore, impulsive-irresponsible psychopathic traits were positive associated with hyperreactivity in the amygdala, insula and ACC. Moreover, these impulsive-irresponsible traits mediated the association of neural reactivity in the ACC and persisting and desisting of DBD. The acute effect of methylphenidate administration on reward and punishment sensitivity was investigated in chapter 4. We hypothesized that - compared to HCs – DBD-patients have deviancies in both reward and punishment processing and that a single dose of methylphenidate could (temporary) normalize these deviancies. DBD-PCB showed - compared to HCs - significantly lower amygdala responsiveness during reward receipt or omission. DBD-MPH showed, compared to HCs, similar amygdala responsiveness during omission of a reward suggesting normalization of amygdala reactivity during reward omission. In contrast to our hypotheses, there was no suggested normalization of amygdala responsiveness during reward receipt. Furthermore, compared to DBD-MPH, DBD-PCB showed higher nucleus accumbens reactivity when anticipating a potential reward. In chapter 5, we assessed the effects of a single dose of methylphenidate on resting state connectivity of the nucleus accumbens (NAcc), amygdala and ventral tegmental area (VTA) with other brain areas. We hypothesized that DBD-PCB, compared to HCs, would show aberrances in resting state connectivity and a normalizing effect of methylphenidate. Compared to HCs, DBD-PCB showed higher connectivity between the NAcc seed and the occipital cortex, posterior cingulate cortex (PCC), precuneus and inferior parietal lobule (IPL). Furthermore, compared to HCs, DBD-PCB had higher connectivity of the amygdala seed with the precuneus and PCC. Compared to DBD-MPH, DBD-PCB had higher connectivity between NAcc seed and occipital cortex, IPL, and medial frontal gyrus. Both NAcc and amygdala seeds showed no connectivity differences in the DBD-MPH compared to the HCs group, suggesting that MPH normalizes the increased functional connectivity between mesolimbic seed regions and areas involved in moral decision making, visual processing and attention. In chapter 6 we assessed gray matter volume (GMV), white matter volume (WMV), and WM integrity of DBD-patients and HCs. In line with previous studies, DBD-patients had decreased GMV of the amygdala, insula, and inferior frontal cortex (IFG). While the previous literature of white matter integrity in DBD adolescents was inconsistent, with some studies reporting higher WM integrity and others reporting lower WM integrity, in this thesis we reported both higher and lower WM integrity in DBD-patients. Compared to HCs, DBD-patients had a cluster with higher WM integrity and a cluster with lower WM integrity within the uncinate fasciculus (UF), the white matter tract connecting the amygdala, insula and IFG.

Jongeren ervaren de laatste jaren steeds meer schoolstress en druk door school. Om goed inzicht te krijgen in de factoren die ten grondslag liggen aan deze toename en mogelijk een schakel zijn voor verandering, is het van belang om dit maatschappelijke probleem vanuit verschillende perspectieven te bekijken. In dit onderzoek verbinden we wetenschappelijke kennis (systematisch literatuuronderzoek) met praktijk- en ervaringskennis van professionals, beleidsmedewerkers, ouders en jongeren (diepte-interviews, n = 60). De resultaten van dit onderzoek laten zien dat de beschermende factoren op verschillende niveaus (systeem, directe omgeving, individu) met elkaar interacteren. De maatschappij legt veel nadruk op resultaat en prestaties, wat invloed heeft op de verwachtingen van jongeren en ouders, en de inrichting van ons onderwijssysteem. Scholen kunnen jongeren ondersteunen bij hun ontwikkeling door aandacht te besteden aan bredere talentontwikkeling, alternatieve beoordelingsvormen, goed mentorschap en de sociaal-emotionele ontwikkeling. Om de ervaren schoolstress en druk door school te verminderen is het belangrijk om niet alleen het individu weerbaarder te maken, maar ook de directe omgeving en de school/maatschappij mee te nemen in preventieve maatregelen om schoolstress en ervaren druk te minderen.

Achtergrond: Langketige meervoudige onverzadigde vetzuren (LCPUFA) zijn belangrijk voor hersenontwikkeling en -functioneren bij adolescenten. Onderzoek naar het effect van LCPUFA-suppletie op schoolprestaties bij adolescenten ontbreekt. Enkele observationele studies toonden een positief verband tussen visconsumptie en schoolprestaties; en één interventiestudie vond een significant positief effect van visconsumptie (bron van LCPUFA) op schoolprestaties. Doel: Onderzoek naar het effect van één jaar krilloliesuppletie (bron van LCPUFA) op schoolprestaties bij adolescenten van voortgezet middelbaar beroepsonderwijs theoretische leerweg (VMBO-TL) met een lage omega-3 index (O3I). Design: Dubbelblind, gerandomiseerde, placebo-gecontroleerde interventie met herhaalde metingen bij start, drie, zes en twaalf maanden. 256 participanten moesten dagelijks krilloliesupplementen (in totaal 520mg EPA en 280mg DHA) of placebosupplementen nemen gedurende 12 maanden met als doel de O3I van de krilloliegroep te laten stijgen tot 8-11%. O3I werd op alle meetmomenten gemeten via een vingerprik. Schoolcijfers van Nederlands, Engels en wiskunde werden verzameld en een gestandaardiseerde rekentoets werd afgenomen bij start onderzoek en na 12 maanden. Hiërarchische multilevel analyses werden uitgevoerd om de data te analyseren. Resultaten: O3I is na twaalf maanden significant gestegen tot 4,86% bij de krilloliegroep. Er zijn geen significante effecten gevonden van krilloliesuppletie op schoolprestaties en gestandaardiseerde rekentoets. Conclusie: Krilloliesuppletie gedurende één jaar heeft de O3I verhoogd, maar niet tot de streefwaarde. Er zijn geen significante effecten gevonden van krilloliesuppletie op schoolprestaties en gestandaardiseerde rekentoets bij adolescenten. Een mogelijke verklaring hiervoor is hoge uitval en niet innemen van capsules bij participanten. Meer onderzoek naar het effect van LCPUFA-suppletie op schoolprestaties bij adolescenten is nodig.

Jongeren ervaren de laatste jaren steeds meer schoolstress en druk door school. Om goed inzicht te krijgen in de factoren die ten grondslag liggen aan deze toename en mogelijk een schakel zijn voor verandering, is het van belang om dit maatschappelijke probleem vanuit verschillende perspectieven te bekijken. In dit onderzoek verbinden we wetenschappelijke kennis (systematisch literatuuronderzoek) met praktijk- en ervaringskennis van professionals, beleidsmedewerkers, ouders en jongeren (diepte-interviews, n = 60). De resultaten van dit onderzoek laten zien dat de beschermende factoren op verschillende niveaus (systeem, directe omgeving, individu) met elkaar interacteren. De maatschappij legt veel nadruk op resultaat en prestaties, wat invloed heeft op de verwachtingen van jongeren en ouders, en de inrichting van ons onderwijssysteem. Scholen kunnen jongeren ondersteunen bij hun ontwikkeling door aandacht te besteden aan bredere talentontwikkeling, alternatieve beoordelingsvormen, goed mentorschap en de sociaal-emotionele ontwikkeling. Om de ervaren schoolstress en druk door school te verminderen is het belangrijk om niet alleen het individu weerbaarder te maken, maar ook de directe omgeving en de school/maatschappij mee te nemen in preventieve maatregelen om schoolstress en ervaren druk te minderen.

Mental health literacy (MHL) interventions in secondary schools may help to improve competencies that adolescents require to stay mentally healthy and seek help if mental health problems arise. These MHL interventions should be tailored to the needs of adolescents and educational professionals (EPs) to reach sustainable implementation and long-term effectiveness. However, evidence is lacking on these needs. Thus, our aim was to explore their experiences with, and perspectives on, mental health help seeking and needs regarding MHL interventions. We performed online focus group discussions and interviews with adolescents (n = 21; 13–19 years) and EPs (n = 12) and analyzed the data using directed content analysis. We identified three themes related to mental health help seeking: (1) Limited MHL competencies of adolescents, (2) Limited competencies of EP to provide mental health support, and (3) Limited mental health promotion in the school environment. We further identified three themes regarding MHL interventions: (1) Addressing basic mental health knowledge and skills, (2) Interactive and easily accessible, and (3) Sustainable implementation. Improving the MHL competencies of adolescents and EPs, and creating a mental health-literate school environment can promote adolescents’ mental health help seeking. Our findings highlight the importance of developing MHL interventions that are tailored to both adolescents’ and EPs needs.

The overall goal of this dissertation was to investigate the complex interplay between person-related factors (i.e., status and behaviors) and multiple contextual effects on status-related behaviors in adolescents. The behaviors of adolescents are clearly associated with the behaviors of their peers in multiple overlapping contexts. In each context, individual characteristics (e.g., popularity), group characteristics (e.g., the distribution of status in a classroom, mean levels of alcohol use, relational aggression norms), and their interactions play a role. On the outcome side, the story varies depending on whether one wishes to predict, for example, adolescents’ health-risk behaviors, their achievement of status, or the process of conformity to peers. Associations varied considerably, but in all studies the group co-facilitated individual influence. Interventions are therefore likely to benefit from targeting individuals within groups rather than individuals in isolation. Furthermore, the set of research questions across the six studies led to four noteworthy contributions to peer influence and sociometric research: (a) investigating peer influence effects in multiple peer contexts and including multiple individual and contextual characteristics simultaneously as interacting sources of influence, (b) improving the sociometric measurement of peer status, (c) using ecologically valid field experiments to determine specific peer influence effects, and (d) investigating multiple group composition effects simultaneously using a new methodological framework, the GAPIM (Kenny & Garcia, 2012). Unraveling associations between individual and group-level characteristics is a fascinating enterprise. Yet, it is also a challenging endeavor. Fortunately, this will be increasingly possible thanks to the further development of new methods and analyses, such as those used in our studies (e.g., Group Actor-Partner Interdependence Model) and others (e.g., Stochastic Actor-Based Modelling). There is an exciting time ahead of us in the study of adolescent peer influence processes.

Mental health problems in adolescence can have a profound influence on school functioning, educational attainment and thus future societal participation. Supported education (SEd) is a potentially useful method for educational professionals to help adolescents with mental health problems in secondary school improve their functioning by stimulating collaboration, ownership, and participation. In this study, we examined the feasibility of SEd in secondary education by examining its acceptability, implementation, and preliminary effectiveness. We performed a mixed-methods study using quantitative data (questionnaires) and qualitative data (interviews) from educational professionals (EP) and adolescents, aged 13–17, about their experiences with a SEd intervention. Regarding the acceptability of the intervention, three main themes emerged: (a) structure, (b) autonomy, and (c) applicability of the intervention. Themes regarding the implementation were: (a) lack of time, (b) personal attitude, (c) mastery, and (d) complexity of the school environment. The findings show that, for those that followed the intervention, SEd is a promising approach to support adolescents with mental health problems to improve their functioning and participation in school. Further research is needed on the effectiveness of the intervention. This article belongs to the Special Issue Children and Young People’s Participation in Health and Well-Being.

Purpose: Adolescents are the least likely to seek help for their mental health problems. School may be an important route to improve early recognition of adolescents with mental health problems in need for support, but little is known about the barriers to school support. Materials and methods: Data were collected in a longitudinal cohort study of Dutch adolescents (age 12–16) in secondary school (n = 956). We assessed the relation between level of psychosocial problems at the beginning of the school year (T1) and the support used in school at the end of that school year (T2), whether the willingness to talk to others (measured at T1) mediates this relation, and whether stigma towards help-seeking (T1) moderates this mediation. Results: Adolescents with more psychosocial problems were more likely to use support in school and were less willing to talk to others about their problems, but the willingness to talk to others was not a mediator. Stigma moderated the relationship between psychosocial problems and willingness to talk to others. Conclusions: Most adolescents with psychosocial problems get support in Dutch secondary school regardless of their willingness to talk to others about their problems. However, perceiving stigma towards help-seeking makes it less likely for someone to talk about their problems.

This dissertation had a twofold aim. The first was to generate greater knowledge about outpatients who are referred to more intensive mental healthcare in the form of Youth ACT. The second was to generate knowledge of the care needs of children and adolescents with mental health problems, such that mental healthcare could be better tailored to these needs. The motivation for the thesis was rooted in daily clinical practice, and the rationale for the research project lay in the following: (i) indications that, due to high rates of non-compliance, non-attendance at appointments, or drop-out, many patients referred to child and adolescent psychiatry are undertreated; (ii) the assumption that such non-compliance, non-attendance, or drop-out can be explained, at least in part, by the limited attention paid to the broad range of patients’ met and unmet care needs; and (iii) our identification of knowledge gaps with respect to these patients’ met and unmet care needs – needs that must be addressed if patients are to receive more personalized care, if adherence to treatment is to be optimized, and, ultimately, if better treatment outcomes are to be attained. To gain a comprehensive overview of these care needs, we examined children’s and adolescents’ perceptions of their care needs, and also the perceptions of their mental health professionals. In Chapter 2 of this thesis, we will describe the design and results of a systematic PRISMA review on youth ACT. In this review, the results of the existing studies are summarized with respect to the effects of Youth ACT on severity of psychiatric symptoms, general functioning, and frequency and duration of psychiatric hospital admissions. In Chapter 3, we will describe a cross-sectional study that investigated the patient, family and contextual variables that are associated with treatment intensification from regular outpatient care to Youth ACT. In Chapter 4, we will zoom in on the unmet care needs in children and adolescents with ADHD, in general outpatient clinics compared with those receiving Youth ACT. In Chapter 5, we will examine the extent to which children and adolescents agree or disagree with care providers on the broad range of met and unmet care needs. In Chapter 6, we describe the factors that are associated with concordance on needs for care between patients and mental healthcare providers in child and adolescent psychiatry. Finally, Chapter 7 provides a summary and a general discussion in which the main findings, methodological issues, and the implications for clinical practice and research are discussed.

This dissertation had a twofold aim. The first was to generate greater knowledge about outpatients who are referred to more intensive mental healthcare in the form of Youth ACT. The second was to generate knowledge of the care needs of children and adolescents with mental health problems, such that mental healthcare could be better tailored to these needs. The motivation for the thesis was rooted in daily clinical practice, and the rationale for the research project lay in the following: (i) indications that, due to high rates of non-compliance, non-attendance at appointments, or drop-out, many patients referred to child and adolescent psychiatry are undertreated; (ii) the assumption that such non-compliance, non-attendance, or drop-out can be explained, at least in part, by the limited attention paid to the broad range of patients’ met and unmet care needs; and (iii) our identification of knowledge gaps with respect to these patients’ met and unmet care needs – needs that must be addressed if patients are to receive more personalized care, if adherence to treatment is to be optimized, and, ultimately, if better treatment outcomes are to be attained. To gain a comprehensive overview of these care needs, we examined children’s and adolescents’ perceptions of their care needs, and also the perceptions of their mental health professionals. In Chapter 2 of this thesis, we will describe the design and results of a systematic PRISMA review on youth ACT. In this review, the results of the existing studies are summarized with respect to the effects of Youth ACT on severity of psychiatric symptoms, general functioning, and frequency and duration of psychiatric hospital admissions. In Chapter 3, we will describe a cross-sectional study that investigated the patient, family and contextual variables that are associated with treatment intensification from regular outpatient care to Youth ACT. In Chapter 4, we will zoom in on the unmet care needs in children and adolescents with ADHD, in general outpatient clinics compared with those receiving Youth ACT. In Chapter 5, we will examine the extent to which children and adolescents agree or disagree with care providers on the broad range of met and unmet care needs. In Chapter 6, we describe the factors that are associated with concordance on needs for care between patients and mental healthcare providers in child and adolescent psychiatry. Finally, Chapter 7 provides a summary and a general discussion in which the main findings, methodological issues, and the implications for clinical practice and research are discussed.