Trends in health inequalities in childhood and adolescence in Germany: Results of the HBSC study 2009/10 - 2022.

Background: Many studies have identified health inequalities in childhood and adolescence. However, it is unclear how these have developed in recent years, particularly since the COVID-19 pandemic. Methods: Analyses are based on the German data from the international Health Behaviour in School-aged Children (HBSC) study from 2009/10 (n = 5,005), 2013/14 (n = 5,961), 2017/18 (n = 4,347), and 2022 (n = 6,475). A total of 21,788 students aged approximately between 11 and 15 years were included. Socioeconomic status (SES) was assessed using the Family Affluence Scale (FAS). Several health indicators were analysed stratified by gender using bivariate and multivariate analysis methods. Results: In 2022, there are clear socioeconomic inequalities in life satisfaction, self-rated health, fruit and vegetable consumption, and physical activity. These inequalities remained largely constant or increased between 2009/10 and 2022. Between 2017/18 and 2022, no significant changes in inequalities were found. Conclusions: Health inequalities are persistent and reduce the chances of growing up healthy. There is no evidence that inequalities in the analysed outcomes have changed during the pandemic period (between 2017/18 and 2022). Rather, the changes in the health indicators seem to affect all adolescents in a similar way.

Concept and methodology of the Health Behaviour in School-aged Children (HBSC) study - Insights into the current 2022 survey and trends in Germany.

Background: Health Behaviour in School-aged Children (HBSC) is one of the largest international studies on child and adolescent health and cooperates with the World Health Organization (WHO). In Germany, adolescents aged 11, 13 and 15 are surveyed every four years about their health, health behaviour and social conditions. This article describes the HBSC study and in particular the methodology of the current 2022 survey and prior surveys conducted between 2009/10 and 2017/18. Method: 174 schools with a total of 6,475 students participated in the 2022 survey. The survey was conducted using questionnaires and covered a wide range of topics (including mental health, physical activity, bullying experiences, social determinants of health and experiences related to COVID-19). The 2022 survey was complemented by a school principal survey (N = 160). In addition to the current sample, the samples of the three previous surveys with representative data for Germany are presented: 2009/10 (N = 5,005), 2013/14 (N = 5,961) and 2017/18 (N = 4,347). Discussion: The health of children and adolescents is of great public health importance. The HBSC study makes a substantial contribution by providing internationally comparable results, analysing trends, and providing stakeholders with comprehensive and representative health monitoring data.

Subjective health and psychosomatic complaints of children and adolescents in Germany: Results of the HBSC study 2009/10 - 2022.

Background: Subjective health and well-being are important health indicators in childhood and adolescence. This article shows current results and trends over time between 2009/10 and 2022. Methods: The Health Behaviour in School-aged Children (HBSC) study examined subjective health, life satisfaction and psychosomatic complaints of N = 21,788 students aged 11 to 15 years in the school years 2009/10, 2013/14, 2017/18 and in the calendar year 2022. Multivariate regression analyses show the associations between sociodemographic characteristics and well-being in 2022, as well as trends since 2009/10. Results: The majority of children and adolescents indicate a good subjective health and high life satisfaction. About half of the girls and one third of the boys report multiple psychosomatic health complaints, with a clear increase over time. Older adolescents, girls and gender diverse adolescents are at an increased risk of poor well-being. Subjective health and life satisfaction varied between 2009/10 and 2022, with a significant deterioration between 2017/18 and 2022. Conclusions: The high proportion of children and adolescents with psychosomatic complaints, as well as the observed gender and age differences, underline the need for target group-specific prevention, health promotion and continuous health monitoring.

Gender and Age Differences in ADHD Symptoms and Co-occurring Depression and Anxiety Symptoms Among Children and Adolescents in the BELLA Study.

Attention-deficit/hyperactivity disorder (ADHD) is one of the most diagnosed neurodevelopmental disorders of childhood. Current studies addressing gender and age differences in ADHD are lacking. The present study aims to fill this research gap by dimensionally evaluating gender and age differences in ADHD symptoms, as measured by a DSM-5-based parent rating scale, in children and adolescents who participated in the two-year follow-up of the community-based BELLA study (n = 1326). Associations between ADHD symptoms and depression symptoms and anxiety symptoms were also examined. Multiple linear regressions revealed significant associations between gender and all ADHD symptoms. Age was significantly associated with hyperactive/impulsive symptoms. Additional multiple linear regressions demonstrated significant positive associations between depression and anxiety symptoms and ADHD symptoms. Further, female gender was found to be positively associated with both depression and anxiety symptoms. These findings may suggest a need for more gender-specific approaches to ADHD diagnosis and treatment, as well as more research into the intersections of ADHD and depression and anxiety symptoms in children and adolescents.

Socioeconomic Status, Protective Factors, and Mental Health Problems in Transition from Adolescence to Emerging Adulthood: Results of the Longitudinal BELLA Study.

Lower familial socioeconomic status (SES) is associated with more mental health problems in adolescence. The aim of this study was to identify factors that may protect adolescents from families with lower SES from developing mental health problems in emerging adulthood. Data of the population-based longitudinal BELLA study included n = 426 participants aged 13 to 17 years at t0 (2009-2012) and 18 to 24 years at t1 (2014-2017). Hierarchical multiple linear regressions with interaction terms were conducted, examining three selected protective factors (self-efficacy, family climate, and social support). Self-efficacy had a small protective effect for adolescents from families with lower SES for mental health problems in emerging adulthood. However, social support had a small protective effect for adolescents from families with higher SES. No moderating effect was found for family climate. Instead, better family climate in adolescents predicted fewer mental health problems in emerging adulthood with a small effect regardless the SES in adolescence. Results indicate the need for prevention measures for adolescents from families with lower SES for becoming mentally healthy emerging adults.

Three years into the pandemic: results of the longitudinal German COPSY study on youth mental health and health-related quality of life.

Purpose: For the past three years, the German longitudinal COPSY (COVID-19 and PSYchological Health) study has monitored changes in health-related quality of life (HRQoL) and the mental health of children and adolescents during the COVID-19 pandemic. Methods: A nationwide, population-based survey was conducted in May-June 2020 (W1), December 2020-January 2021 (W2), September-October 2021 (W3), February 2022 (W4), and September-October 2022 (W5). In total, n = 2,471 children and adolescents aged 7-17 years (n = 1,673 aged 11-17 years with self-reports) were assessed using internationally established and validated measures of HRQoL (KIDSCREEN-10), mental health problems (SDQ), anxiety (SCARED), depressive symptoms (CES-DC, PHQ-2), psychosomatic complaints (HBSC-SCL), and fear about the future (DFS-K). Findings were compared to prepandemic population-based data. Results: While the prevalence of low HRQoL increased from 15% prepandemic to 48% at W2, it improved to 27% at W5. Similarly, overall mental health problems rose from 18% prepandemic to W1 through W2 (30-31%), and since then slowly declined (W3: 27%, W4: 29%, W5: 23%). Anxiety doubled from 15% prepandemic to 30% in W2 and declined to 25% (W5) since then. Depressive symptoms increased from 15%/10% (CES-DC/PHQ-2) prepandemic to 24%/15% in W2, and slowly decreased to 14%/9% in W5. Psychosomatic complaints are across all waves still on the rise. 32-44% of the youth expressed fears related to other current crises. Conclusion: Mental health of the youth improved in year 3 of the pandemic, but is still lower than before the pandemic.

[The COVID-19 pandemic-How did it affect the mental health of children?] / Die COVID-19-Pandemie ­ Wie hat sie die Kinderpsyche beeinflusst?

Background: The COVID-19 pandemic has had a substantial impact on the daily life of children and adolescents due to lockdowns, contact restrictions, closings of childcare, schools and leisure facilities. Objective: This article examines the impact of the pandemic on the mental health of children and adolescents in Germany. Material and methods: In the population-based longitudinal COPSY study (COVID-19 and Psychological Health) 1600 parents of children aged 7-17 years old and 1000 children and adolescents aged 11-17 years old completed established questionnaires at 5 online survey points (t1: May and June 2020 to t5: September and October 2022). For comparison, pre-pandemic data were obtained from the representative BELLA study. Results: During the pandemic the portion of children and adolescents, who reported a low health-related quality of life, increased from pre-pandemic 15% to 48% in the first year of the pandemic and improved in year 3 to 27%. This is still substantially above pre-pandemic levels. Similar trajectories were found for mental health problems which rose from 18% (pre-pandemic) to 31% and improved in year 3 to 23%. For anxiety and depression, the changes were similar except that depressive symptoms returned to pre-pandemic levels in year 3. The physical activity of almost one third of the youth was still very low in year 3. Conclusion: The mental health of children and adolescents was ignored during the pandemic for a long time. Now support and allocation of funding is urgently needed to mitigate the negative mental health effects and prevent further impairment by new crises.

[Epidemiology of mental well-being in childhood and adolescence. Results from three epidemiological studies before and during the COVID-19 pandemic]. / Epidemiologie seelischen Wohlbefindens von Kindern und Jugendlichen in Deutschland. Ergebnisse aus 3 Studien vor und während der COVID-19-Pandemie.

BACKGROUND: Continuous nationwide health monitoring is important to track the well-being of children and adolescents and to map developmental trajectories. Based on the results of three selected epidemiological studies, developments in child well-being over the past 20 years are presented. METHODS: Data are based on (1) the mental health module of the German National Health Interview and Examination Survey among Children and Adolescents (BELLA study, 2003-2017, N = 1500 to 3000), which is a module of the KiGGS study; (2) the COvid-19 and PSYchological Health Study (COPSY, 2020-2022, N = 1600-1700), which is based on the BELLA Study; and (3) the International Health-Behaviour in School-aged Children Study (HBSC, 2002-2018, N = 4300-7300). Well-being was assessed in 7­ to 17-year-olds using indicators of health-related quality of life (KIDSCREEN-10), life satisfaction (Cantril Ladder), and mental health problems (Strenghts and Difficulties Questionnaire (SDQ), Screen for Child Anxiety Related Emotional Disorders (SCARED), and Center for Epidemiological Studies Depression Scale for Children (CES-DC)). RESULTS: Overall, children and adolescents show consistently high health-related quality of life and high overall life satisfaction pre-pandemic (2002-2018), which initially worsened with the onset of the 2020 COVID-19-pandemic. Two years later, improvements are evident but have not yet reached baseline levels. Psychological problems, as well as symptoms of anxiety and depression, increased by up to 12 percentage points at the beginning of the pandemic and are still higher two years after the onset of the pandemic compared to pre-pandemic studies. CONCLUSION: The epidemiology of child well-being provides a necessary data basis to assess the support needs of children and adolescents and to use this as a basis for developing measures of health promotion, prevention, and intervention.

[Prevention perspective: mental health of schoolchildren in Germany]. / Perspektive Prävention: Psychische Gesundheit von Schülerinnen und Schülern in Deutschland.

BACKGROUND: The COVID-19 pandemic has impacted the learning and health of children and adolescents. The aim of this paper is to examine school students' mental health problems, family burden, and support needs during the pandemic depending on the type of school. Approaches to school-based prevention and health promotion are discussed. METHODS: Findings are based on data from the population-based COPSY study (T1: 05/2020 - T4: 02/2022) and the BELLA study (T0, pre-pandemic comparison). Approximately 1600 families with children aged 7 to 19 years were surveyed at each measurement point (T). Mental health problems were assessed using the SDQ, while family burden and support needs were captured with individual items in the parent report. RESULTS: Mental health problems increased among students in all school types at the beginning of the pandemic and have stabilized at a high level. Elementary school students are particularly affected (increase from 16.9% pre-pandemic to 40.0% at T2), especially in behavioral problems (11.7% to 24.6%) and hyperactivity (13.9% to 34.0%). Secondary school students also show higher levels of mental health problems (21.4% to 30.4%). Pandemic-related burden is consistently high, as is the need for family support received from schools/teachers and experts. DISCUSSION: There is a high need for mental health promotion and prevention measures in the school setting. These should start at primary school age in the sense of a "whole school approach" at different levels and include external stakeholders. In addition, binding legal requirements are needed in all federal states to create framework conditions and structures for school-based health promotion and prevention, including access to necessary resources.

Systematic Review of Gender-Specific Child and Adolescent Mental Health Care.

Gender differences in mental health emerge as early as in childhood and adolescence, highlighting the potential need for gender-specific child and adolescent mental health care. However, it is unclear how gender-specific child and adolescent mental health care is implemented and whether its' approaches are useful. Therefore, this study reviews gender-specific interventions and their effectiveness for child and adolescent mental health. Five databases were searched for articles published between 2000 and 2021. In total, 43 studies were included. Most interventions were conducted in school (n = 15) or community settings (n = 8). Substance-related disorders (n = 13) and eating disorders (n = 12) were addressed most frequently. Most interventions targeted girls (n = 31). Various gender-specific aspects were considered, including gender-specific risk and protective factors (n = 35) and needs (n = 35). Although most interventions yielded significant improvements in mental health outcomes (n = 32), only few studies reported medium or large effect sizes (n = 13). Additionally, there was a lack of strong causal evidence derived from randomized controlled trials, calling for more rigorous trials in the research field. Nevertheless, our findings indicate that gender-specific mental health care can be a promising approach to meet gender-specific mental health needs.

Mental health and quality of life in children and adolescents during the COVID-19 pandemic: a systematic review of longitudinal studies.

Background: The COVID-19 pandemic has significantly impacted the mental health of children and families, i.e., due to measures like social distancing and remote schooling. While previous research has shown negative effects on mental health and health-related quality of life (HRQoL), most studies have focused on pre-post comparisons in the early pandemic stages. This systematic review aims to examine longitudinal studies to understand the long-term impacts of the pandemic on children and adolescents. Methods: This systematic review adhered to the PRISMA guidelines and was preregistered in the international prospective register of systematic reviews (Record ID: CRD42022336930). We systematically searched PubMed/MEDLINE, Web of Science, PsycINFO, PSYNDEX, and the WHO-COVID-19 database and included studies published up to August 30, 2022. Based on pre-defined eligibility criteria, longitudinal and prospective studies that assessed the mental health or quality of life of children or adolescents (0-19 years) in the general population over a longer time span (at two or more measurement points) during the COVID-19 pandemic were included in the review. The methodological quality of the included studies was assessed using an adapted version of the Effective Public Health Practice Project (EPHPP) checklist. Narrative data synthesis was used to summarize the findings. Results: A total of 5,099 results were obtained from literature searches, with 4,935 excluded during title/abstract screening. After reviewing 163 full-text articles, 24 publications were included in the review. Sample sizes ranged between n = 86 and n = 34,038. The length of the investigated time periods and the number of assessment points, as well as outcomes, varied. The majority of studies were of moderate methodological quality. Mental health outcomes were more frequently studied compared to measures of HRQoL. The findings from these studies mostly suggest that children and adolescents experienced heightened mental health problems, specifically internalizing symptoms like anxiety and depression. Further, there was a decline in their overall HRQoL over the course of the COVID-19 pandemic that did not necessarily subside when lockdowns ended. Conclusion: It is crucial to continue monitoring the mental health and well-being of children and adolescents following the pandemic to identify groups at risks and plan interventions. This should ideally be conducted by large systematic studies, using validated instruments, and encompassing representative samples to obtain reliable and comprehensive insights with the aim of improving youth mental health care.

Child and Adolescent Mental Health During the COVID-19 Pandemic: Results of the Three-Wave Longitudinal COPSY Study.

PURPOSE: The German population-based longitudinal COVID-19 andPsychological Health study monitors changes in health-related quality of life (HRQoL) and mental health of children and adolescents during the COVID-19 pandemic and identifies vulnerable groups. METHODS: A nationwide, population-based survey was conducted in May 2020 to June 2020 (Wave 1), December 2020 to January 2021 (Wave 2), and September 2021 to October 2021 (Wave 3). In total, n = 2,097 children and adolescents aged 7-17 years were investigated using measures to assess HRQoL (KIDSCREEN-10), mental health problems (SDQ), anxiety (SCARED), depressive symptoms(PHQ-2), and psychosomatic complaints(HBSC-SCL). RESULTS: The prevalence of low HRQoL increased from 15% prepandemic to 40% and 48% in Waves 1 and 2 and improved slightly to 35% in Wave 3 (all differences significant). Similarly, overall mental health problems increased from 18% prepandemic to 29% in Wave 1 and 31% in Wave 2 to 28% in Wave 3 (all differences significant, except Wave 3 vs. 2), anxiety increased from 15% prepandemic to 24% and 30% in Waves 1 and 2 and was still 27% in Wave 3. Depressive symptoms increased from 10% prepandemic to 11% and 15% in Waves 1 and 2 and were 11% in Wave 3. A group with low parental education, restricted living conditions, migration background, and parental mental health problems was at significantly increased risk of HRQoL and mental health impairments. DISCUSSION: The prevalence of low HRQoL, mental health problems, and anxiety has been elevated throughout the pandemic. Thus, mental health promotion, prevention, and intervention strategies need to be implemented to support adolescents-particularly those at risk.

[The Role of the Socioeconomic Status in Mental Health Care Utilization by Children and Adolescents in Germany: Results of the BELLA Study]. / Zur Rolle des sozioökonomischen Status bei der Inanspruchnahme fachspezifischer Versorgung von psychisch auffälligen Kindern und Jugendlichen in Deutschland: Ergebnisse der BELLA-Studie.

OBJECTIVE: Children and adolescents with a low socioeconomic status (SES) are significantly more often affected by mental health problems than their peers with a high SES. So far, little is known about the association between family's SES and utilization of mental health care. This study examines the mental health care utilization by children and adolescents depending on their SES and symptoms of mental health problems as well as the impact of mental health problems. METHODS: The analysis comprisesd data from the population-based BELLA-study, which investigates mental health in a representative subsample of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS). Between 2014 and 2017, 1,580 participants aged 7 to 17 years were examined. SES was measured by the indicators of household income, parental educational attainment and parental occupation status. Symptoms and impairment of mental health problems were measured using the Strength and Difficulties Questionnaire (SDQ and SDQ-Impact). To investigate mental health care, the consultation of child and adolescent psychiatrists, medical and psychological psychotherapists and psychologists was considered. A hierarchic binary logistic regression model was calculated predicting mental health care use. In addition, effects of SES-indicators on associations between symptoms and impairment as well as mental health care utilization (moderator analysis) were investigated. RESULTS: Children and adolescents with a low SES were more likely to utilize mental health care services than their peers with a high SES. Mental health care utilization was significantly predicted by symptoms of mental health problems (OR=1.15, p≤0.001) as well as by the impairment caused by these problems (OR=1.68, p≤0.001); we found no significant moderation effects for household income, parental education or parental occupation. CONCLUSION: The probability of mental health care utilization by children and adolescents is significantly predicted by the symptoms and the impairments caused by mental health problems, but not by household income, parental education or parental occupation.

Risk and resource factors for depressive symptoms during adolescence and emerging adulthood - A 5-year follow-up using population-based data of the BELLA study.

INTRODUCTION: Depression is one of the most common mental disorders in adolescents and young adults worldwide, and causes a high burden for both individuals and society. The present study aims to investigate the role of risk and resource factors for depressive symptoms during adolescence and emerging adulthood in a German population-based cohort. METHODS: Within the longitudinal BELLA study, data on risk and resource factors were collected among n = 632 children and adolescents aged 11 to 17 years. Depressive symptoms were measured five years later. Multivariate linear regression models served to investigate effects of risk and resource factors on depressive symptoms. Regression models were stratified by gender. Moreover, we explored potential interaction effects. RESULTS: A negative mother-child relationship predicted depressive symptoms in girls, whereas school stress served as a risk factor in boys. Peer competence was associated with fewer depressive symptoms in girls, and family cohesion was identified as a resource factor in boys. In addition, few moderating effects of resource factors on the association between risk factors and depressive symptoms were found. LIMITATIONS: As the BELLA study is a population-based observational study, we only identified associations between risk and resource factors and no cause-effect relationships. CONCLUSIONS: Findings provide evidence of gender-specific risk and resource factors for depression. Individuals who are exposed to risk factors must be monitored during the transition into adulthood. Gender-sensitive prevention and early intervention programs are needed.

Mental health and well-being from childhood to adulthood: design, methods and results of the 11-year follow-up of the BELLA study.

Mental health and well-being are of great interest in health policy and research. Longitudinal surveys are needed to provide solid population-based data. We describe the design and methods of an 11-year follow-up of the German BELLA study in children, adolescents and young adults, and we report on age- and gender-specific courses of general health and well-being, long-term health-related outcomes of mental health problems, and mental health care use. The BELLA study is the module on mental health and well-being within the German Health Interview and Examination Survey for Children and Adolescents (KiGGS). Standardised measures were used at each of the five measurement points of the BELLA study. In the 11-year follow-up, young people aged 7-31 years participated (n = 3492). Individual growth modelling, linear regression and descriptive analyses were conducted. Self-reported general health and well-being were both better in younger (vs. older) and in male (vs. female) participants according to the data from all five measurement points. Mental health problems in childhood and adolescence (measured at baseline) predicted impaired health outcomes at 6-year and 11-year follow-ups. Approximately one out of four children with a diagnosed mental disorder was not undergoing mental health treatment. With its 11-year follow-up, the prospective longitudinal BELLA study provides new and solid data on mental health and well-being from childhood to adulthood in Germany, and these data are important for health promotion and prevention practices. These results are consistent with previous findings. Promising future analyses are planned.

Peer Relationships and Depressive Symptoms Among Adolescents: Results From the German BELLA Study.

Background: Poor mental health affects adolescent development and is associated with health and social outcomes in later life. The current study uses cross-sectional data to explore the understudied aspects of peer relationships as a predictor of depressive symptom severity of adolescents in Germany. Method: Data from the German BELLA study were analyzed. We focused on the most recent measurement point of the BELLA study and analyzed data of 446 adolescents (aged 14-17 years). Peer relationship was measured using four items from the internationally established Patient-Reported Outcome Measurement Information System (PROMIS). Depressive symptoms were assessed via seven items of the German version of the Centre for Epidemiological Studies Short Depression Scale (CES-D). Hierarchical linear regression models were computed to explore the association between depressive symptoms and peer relationships. Hierarchical linear regression models served to determine the added predictive effects of each aspect of peer relationships. Result: The regression model showed that 22% of the variance of the severity of depressive symptoms could be explained by the quality of adolescents' peer relationships (F(1,444) = 125.65, p < 0.001). Peer acceptance has the most substantial unique contribution to peer relationship as a predictor of depressive symptom severity (Change in R 2 = 0.05; Change in F = 27.01, p < 0.001). The gender-specific analysis shows different trends for boys and girls. Conclusion: The quality of peer relationships is a significant predictor of adolescents' depressive symptoms severity. Improved peer acceptance, dependability, and ease of making new friends are significantly associated with reduced depression symptoms for Germany's adolescent population.

Socioeconomic status, stressful life situations and mental health problems in children and adolescents: Results of the German BELLA cohort-study.

AIM: Children and adolescents with low socioeconomic status (SES) suffer from mental health problems more often than their peers with high SES. The aim of the current study was to investigate the direct and interactive association between commonly used indicators of SES and the exposure to stressful life situations in relation to children's mental health problems. METHODS: The prospective BELLA cohort study is the mental health module of the representative, population-based German National Health Interview and Examination Survey for children and adolescents (KiGGS). Sample data include 2,111 participants (aged 7-17 years at baseline) from the first three measurement points (2003-2006, 2004-2007 and 2005-2008). Hierarchical multiple linear regression models were conducted to analyze associations among the SES indicators household income, parental education and parental unemployment (assessed at baseline), number of stressful life situations (e.g., parental accident, mental illness or severe financial crises; 1- and 2-year follow-ups) and parent-reported mental health problems (Strength and Difficulties Questionnaire; 2-year follow-up). RESULTS: All indicators of SES separately predicted mental health problems in children and adolescents at the 2-year follow-up. Stressful life situations (between baseline and 2-year follow-up) and the interaction of parental education and the number of stressful life situations remained significant in predicting children's mental health problems after adjustment for control variables. Thereby, children with higher educated parents showed fewer mental health problems in a stressful life situation. No moderating effect was found for household income and parental employment. Overall, the detected effect sizes were small. Mental health problems at baseline were the best predictor for mental health problems two years later. CONCLUSIONS: Children and adolescents with a low SES suffer from multiple stressful life situations and are exposed to a higher risk of developing mental health problems. The findings suggest that the reduction of socioeconomic inequalities and interventions for families with low parental education might help to reduce children's mental health problems.

The BELLA study - the mental health module of KIGGS Wave 2.

The BELLA study is the module on mental health and health-related quality of life within the German Health Interview and Examination Survey for Children and Adolescents (KiGGS). Baseline data collection took place together with KiGGS baseline data collection between 2003 and 2006. This article discusses the fourth follow-up of the BELLA study (BELLA Wave 4), which was surveyed between 2014 and 2017. The aims of the BELLA Wave 4 are to enable longitudinal analyses of health-related quality of life and mental health problems. Dynamic measurement instruments were used to enable a user-friendly and precise assessment of mental health among children, adolescents and young adults. The study's participants were a sub-sample of around 3,500 KiGGS respondents aged 7 to 29 years. For the first time, in BELLA Wave 4 data were collected exclusively online. The BELLA study targeted both the parents of younger children (aged 7 to 13 years) and adolescents and young adults themselves (aged 11 years and above). Study instruments surveying mental health problems and the use of mental health care services were supplemented by a dynamic measurement tool in the form of a computer adaptive test (CAT) to record data on health-related quality of life.