Plasticity is a central concept within the life-span approach of development and is defined as the ability of an individual to change and reorganize in response to environmental challenges (e.g., Baltes & Singer, 20019. Such intraindividual changes can be induced by systematic cognitive training. Recent studies suggest that substantial amounts of plasticity can be induced in executive control functions with a process-based training approach. These newer studies show that repeated practice on executive control tasks not only improved performance on these trained tasks, but also led to improvements in nontrained tasks (i.e., transfer; e.g., Jaeggi, Buschkuehl, Jonides, & Perrig, 2008; Karbach & Kray, 2009). Executive control processes are especially relevant from a developmental perspective because executive control is involved in a wide range of complex cognitive activities (e.g., van der Sluis, de Jong, & van der Leij, 2007) and is one of the most central areas of cognitive development (e.g., Craik & Bialystok, 2006). The current thesis aimed at elucidating several important questions concerning the plasticity of executive control functions induced by systematic cognitive training. Firstly, the amount, range, and stability of plasticity in adolescents and older adults were investigated. Secondly, studies explored if training design, age, and interindividual differences moderate the amount and range of plasticity. Furthermore, the current thesis aimed at exploring how process-based training specifically leads to transfer effects. To explore these questions, all studies employed a pretest-posttest-design comparing a group of participants that was trained with a process-based training approach to a group of control partici-pants that did not receive the training. Pretraining and posttraining sessions incorporated systematic assessment of transfer measures in different cognitive domains. The first study set out to investigate if executive control can be trained in adolescents with a task switching training. Additionally, the study explored what particular domains of executive control may underlie training and transfer effects, and if acute bouts of exercise directly prior to cognitive training enhance training effects. Analyses indicated substantial training effects for both training groups (with or without acute exercise) and near transfer to a similar switching task. Other findings of transfer were limited to a speed task and a tendency for faster reaction times in an updating task. Thus, findings indicate, for the first time, that executive control can be enhanced in adolescents through a short training. Furthermore, analyses suggest that updating may be of particular relevance for the effects of the task switching training. Analyses revealed no additional effects of the exercise intervention. The second study set out to explore, for the first time, the effects of a process-based training ap-proach in old-old age (above 80 years). After ten sessions of practice on working memory tasks, the training group improved in four of the five trained tasks, emphasizing the potential for plasticity even in old-old age. The gains in the training group were largely driven by individuals who started out with a low capacity in the training tasks. Thus, findings suggest that working memory can be improved with a short executive control training even in old-old age, particularly for low-capacity individuals. The absence of transfer effects in this study may point to the limits of plasticity in this age group. The third study aimed at further elucidating the mixed findings regarding the amounts of training and transfer effects induced by executive control training in older adults. For that purpose, a sample of older adults covering a wide range from young-old to old-old age (65 to 95 years) was either trained for nine sessions on a visuospatial and a verbal working memory as well as an executive control task; or served as controls. Analyses revealed significant training effects in all three trained tasks, as well as near transfer to verbal working memory and far transfer to a nonverbal reasoning task. Remarkably, all training effects and the transfer effect to verbal working memory were even stable at a nine-month follow-up. These findings suggest that cognitive plasticity is preserved over a large range of old age and that even a rather short training regimen can lead to (partly specific) training and transfer effects. However, analyses also revealed that there are a range of factors that may moderate the amount of plasticity, e.g., age and baseline performance in the training domain. To summarize, the current thesis explored effects of short executive control trainings on cognitive functions in adolescents and older adults. The findings suggest a high potential for intraindividual variability across the whole life-span. Plasticity was shown on the level of training and transfer tasks, as well as on the level of stability of effects. Furthermore, results support the notion that process-based training improves executive control processes that in turn lead to improvements in tasks that rely on these processes. The current thesis makes important contributions to the conceptual debate about the potentials and limits of training-induced plasticity across the life-span. It benefits the debate in that it specifically delineates factors that moderate the obtained effects.

Plasticity is a central concept within the life-span approach of development and is defined as the ability of an individual to change and reorganize in response to environmental challenges (e.g., Baltes & Singer, 20019. Such intraindividual changes can be induced by systematic cognitive training. Recent studies suggest that substantial amounts of plasticity can be induced in executive control functions with a process-based training approach. These newer studies show that repeated practice on executive control tasks not only improved performance on these trained tasks, but also led to improvements in nontrained tasks (i.e., transfer; e.g., Jaeggi, Buschkuehl, Jonides, & Perrig, 2008; Karbach & Kray, 2009). Executive control processes are especially relevant from a developmental perspective because executive control is involved in a wide range of complex cognitive activities (e.g., van der Sluis, de Jong, & van der Leij, 2007) and is one of the most central areas of cognitive development (e.g., Craik & Bialystok, 2006). The current thesis aimed at elucidating several important questions concerning the plasticity of executive control functions induced by systematic cognitive training. Firstly, the amount, range, and stability of plasticity in adolescents and older adults were investigated. Secondly, studies explored if training design, age, and interindividual differences moderate the amount and range of plasticity. Furthermore, the current thesis aimed at exploring how process-based training specifically leads to transfer effects. To explore these questions, all studies employed a pretest-posttest-design comparing a group of participants that was trained with a process-based training approach to a group of control partici-pants that did not receive the training. Pretraining and posttraining sessions incorporated systematic assessment of transfer measures in different cognitive domains. The first study set out to investigate if executive control can be trained in adolescents with a task switching training. Additionally, the study explored what particular domains of executive control may underlie training and transfer effects, and if acute bouts of exercise directly prior to cognitive training enhance training effects. Analyses indicated substantial training effects for both training groups (with or without acute exercise) and near transfer to a similar switching task. Other findings of transfer were limited to a speed task and a tendency for faster reaction times in an updating task. Thus, findings indicate, for the first time, that executive control can be enhanced in adolescents through a short training. Furthermore, analyses suggest that updating may be of particular relevance for the effects of the task switching training. Analyses revealed no additional effects of the exercise intervention. The second study set out to explore, for the first time, the effects of a process-based training ap-proach in old-old age (above 80 years). After ten sessions of practice on working memory tasks, the training group improved in four of the five trained tasks, emphasizing the potential for plasticity even in old-old age. The gains in the training group were largely driven by individuals who started out with a low capacity in the training tasks. Thus, findings suggest that working memory can be improved with a short executive control training even in old-old age, particularly for low-capacity individuals. The absence of transfer effects in this study may point to the limits of plasticity in this age group. The third study aimed at further elucidating the mixed findings regarding the amounts of training and transfer effects induced by executive control training in older adults. For that purpose, a sample of older adults covering a wide range from young-old to old-old age (65 to 95 years) was either trained for nine sessions on a visuospatial and a verbal working memory as well as an executive control task; or served as controls. Analyses revealed significant training effects in all three trained tasks, as well as near transfer to verbal working memory and far transfer to a nonverbal reasoning task. Remarkably, all training effects and the transfer effect to verbal working memory were even stable at a nine-month follow-up. These findings suggest that cognitive plasticity is preserved over a large range of old age and that even a rather short training regimen can lead to (partly specific) training and transfer effects. However, analyses also revealed that there are a range of factors that may moderate the amount of plasticity, e.g., age and baseline performance in the training domain. To summarize, the current thesis explored effects of short executive control trainings on cognitive functions in adolescents and older adults. The findings suggest a high potential for intraindividual variability across the whole life-span. Plasticity was shown on the level of training and transfer tasks, as well as on the level of stability of effects. Furthermore, results support the notion that process-based training improves executive control processes that in turn lead to improvements in tasks that rely on these processes. The current thesis makes important contributions to the conceptual debate about the potentials and limits of training-induced plasticity across the life-span. It benefits the debate in that it specifically delineates factors that moderate the obtained effects.:Abstract ..............................................................................................1 1 General Introduction .....................................................................3 1.1 Plasticity of cognitive functions ...................................................5 1.2 Executive control functions .........................................................6 1.3 Cognitive training of executive control functions .......................9 2 Outline and Central Questions ......................................................19 2.1 What amount of plasticity does executive control training induce in different age groups? .........................................................................19 2.2 Do training and transfer effects of executive control training remain stable over time? ....................................................................20 2.3 Do training design, age, and baseline performance moderate the amount of plasticity? ...........................................................................20 2.4 Are changes in trained tasks specifically related to changes in transfer tasks? .................................................................................21 3 Study 1 - Effects of a Task Switching Training in Adolescents .......22 3.1 Introduction ..............................................................................22 3.2 Methods ....................................................................................27 3.3 Results ......................................................................................33 3.4 Discussion .................................................................................43 4 Study 2 - Effects of a Working Memory Training in Old-Old adults .48 4.1 Introduction ...............................................................................48 4.2 Methods .....................................................................................51 4.3 Results .......................................................................................54 4.4 Discussion ..................................................................................59 5 Study 3 - Factors Moderating Effects of Working Memory Training in Older Adults .......................................................................63 5.1 Introduction ................................................................................63 5.2 Methods ......................................................................................67 5.3 Results .........................................................................................71 5.4 Discussion ...................................................................................78 6 General Discussion .........................................................................83 6.1 Summary of empirical findings .....................................................83 6.2 Integration of the main empirical findings ...................................85 6.3 Conclusion and Outlook ...............................................................95 6.4 Summary ......................................................................................98 References ..........................................................................................99 Appendix ............................................................................................112

Aims To estimate the national incidence rate and trend of type 1 diabetes (T1DM) in Germany from 1999 to 2008 and the national prevalence in 2008 in the age group 0–14 years. Methods Data were taken from a nationwide registry for incident cases of T1DM in the ages 0–4 years and 3 regional registries (North-Rhine-Westphalia, Baden-Wuerttemberg and Saxony) for incident cases of T1DM in the ages 0–14 years covering 41% of the child population in Germany. The degree of ascertainment was ≥ 97% in all registries. Incident and prevalent cases were grouped by region, sex, age (0–4, 5–9, 10–14 years), and, for incident data, additionally by two 5-year periods (1999–2003, 2004–2008). Poisson regression models were fitted to the data to derive national estimates of incidence rate trends and prevalence in the age groups 5–9, 10–14 and 0–14 years. We used direct age-standardization. Results The estimated national incidence rate in 0-14-year-olds increased significantly by 18.1% (95%CI: 11.6–25.0%, p<0.001) from 1999–2003 to 2004–2008, independent of sex, corresponding to an average annual increase of 3.4% (95%-CI: 2.2–4.6%). The overall incidence rate was estimated at 22.9 per 100,000 person-years and we identified a within-country west-east-gradient previously unknown. The national prevalence in the ages 0–14 years on 31/12/2008 was estimated to be 148.1 per 100,000 persons. Conclusions The national incidence rate of childhood T1DM in Germany is higher than in many other countries around the world. Importantly, the estimated trend of the incidence rate confirms the international data of a global increase of T1DM incidences.

Moral judgments and moral emotions are a ubiquitous feature of social interactions. Humans decide quickly and intuitively whether an action is morally right or wrong. Schadenfreude and sympathy, as emotional reactions to the misfortunes of others, are prototypical moral emotions. So far, however, little evidence exists concerning children’s understanding of schadenfreude. Within three studies, we investigated the experience of schadenfreude and sympathy among N = 364 children of different age groups. We interviewed the children while showing them picture stories. In the picture stories, we varied the behavior of the protagonist prior to a misfortune: (1) whether his behavior had been morally right or wrong, (2) whether the protagonist attained his goal, (3) whether the protagonist was responsible for the misfortune. In addition, in one study we varied (4) the emotional relationship of the interviewed children to the protagonist. Furthermore, we asked the children to decide whether they want to sit next to the protagonist or do him a favor. Results show that children experience sympathy as well as schadenfreude at the age of 4 years. Sympathy is more likely to arise when the protagonists of a story are likable, when these actors typically pursue morally positive goals, and if they are not responsible for their misfortune. In contrast, schadenfreude is more likely when the protagonist is disliked, when actors pursue immoral goals and if they are responsible for their misfortune. In addition, sympathy increases approach (helping behavior, sitting next to the agent and doing favors), whereas schadenfreude increases avoidance tendencies.

Aims The aim of this study was to analyze the incidence rates of type 1 diabetes in Saxony before and after the German reunification. Methods The study examined two registries: one until 1990 and one since 1999. Only patients under 15 years of age with type 1 diabetes and living in Saxony were included in the study. Standardized incidence rates were described based on direct age standardization procedures using the Standard European Population for each calendar year between the observation periods 1982–1989 and 1999–2014. Age was grouped into three classes: 0–4, 5–9 and 10–14 years of age. Incidence data were presented as age-standardized incidence rates per 100,000 person-years (PY) with 95% confidence intervals [CI]. Joinpoint regression was used for trend analyses and Poisson regression was used to adjust for the effects of age and sex on the incidence. Results A total number of 2,092 incident cases of type 1 diabetes (1,109 males; 983 females) were included. The age-standardized incidence rates of type 1 diabetes per 100,000 PY was 7.9 [95%CI 6.8; 8.9] in the period from 1982–1989 and 20.1 [95%CI 14.0; 26.1] in the period from 1999–2014. The yearly increase in incidence over the entire time period (1982–2014) was 4.3% according to the average annual percent change (AAPC) method, and estimated to be 4.4% [95% CI 4.0; 4.8%] using a Poisson regression model adjusting for sex and age group. Conclusion In this study, a significantly increasing incidence of type 1 diabetes was observed after reunification. In future studies it would be interesting to follow up on the question of which environmental and lifestyle factors could be causing the increasing type 1 diabetes incidence.

Aims To estimate the national incidence rate and trend of type 1 diabetes (T1DM) in Germany from 1999 to 2008 and the national prevalence in 2008 in the age group 0–14 years. Methods Data were taken from a nationwide registry for incident cases of T1DM in the ages 0–4 years and 3 regional registries (North-Rhine-Westphalia, Baden-Wuerttemberg and Saxony) for incident cases of T1DM in the ages 0–14 years covering 41% of the child population in Germany. The degree of ascertainment was ≥ 97% in all registries. Incident and prevalent cases were grouped by region, sex, age (0–4, 5–9, 10–14 years), and, for incident data, additionally by two 5-year periods (1999–2003, 2004–2008). Poisson regression models were fitted to the data to derive national estimates of incidence rate trends and prevalence in the age groups 5–9, 10–14 and 0–14 years. We used direct age-standardization. Results The estimated national incidence rate in 0-14-year-olds increased significantly by 18.1% (95%CI: 11.6–25.0%, p<0.001) from 1999–2003 to 2004–2008, independent of sex, corresponding to an average annual increase of 3.4% (95%-CI: 2.2–4.6%). The overall incidence rate was estimated at 22.9 per 100,000 person-years and we identified a within-country west-east-gradient previously unknown. The national prevalence in the ages 0–14 years on 31/12/2008 was estimated to be 148.1 per 100,000 persons. Conclusions The national incidence rate of childhood T1DM in Germany is higher than in many other countries around the world. Importantly, the estimated trend of the incidence rate confirms the international data of a global increase of T1DM incidences.

Aims The aim of this study was to analyze the incidence rates of type 1 diabetes in Saxony before and after the German reunification. Methods The study examined two registries: one until 1990 and one since 1999. Only patients under 15 years of age with type 1 diabetes and living in Saxony were included in the study. Standardized incidence rates were described based on direct age standardization procedures using the Standard European Population for each calendar year between the observation periods 1982–1989 and 1999–2014. Age was grouped into three classes: 0–4, 5–9 and 10–14 years of age. Incidence data were presented as age-standardized incidence rates per 100,000 person-years (PY) with 95% confidence intervals [CI]. Joinpoint regression was used for trend analyses and Poisson regression was used to adjust for the effects of age and sex on the incidence. Results A total number of 2,092 incident cases of type 1 diabetes (1,109 males; 983 females) were included. The age-standardized incidence rates of type 1 diabetes per 100,000 PY was 7.9 [95%CI 6.8; 8.9] in the period from 1982–1989 and 20.1 [95%CI 14.0; 26.1] in the period from 1999–2014. The yearly increase in incidence over the entire time period (1982–2014) was 4.3% according to the average annual percent change (AAPC) method, and estimated to be 4.4% [95% CI 4.0; 4.8%] using a Poisson regression model adjusting for sex and age group. Conclusion In this study, a significantly increasing incidence of type 1 diabetes was observed after reunification. In future studies it would be interesting to follow up on the question of which environmental and lifestyle factors could be causing the increasing type 1 diabetes incidence.

Aims An increasing number of children and adolescents worldwide suffer from inflammatory bowel disease (IBD) such as Crohn’s disease (CD) and ulcerative colitis (UC). The present work aims to investigate the incidence, prevalence and future trends of IBD in children and adolescents in Saxony, Germany. Methods The Saxon Pediatric IBD Registry collected data on patients up to 15 years of age from all 31 pediatric hospitals and pediatric gastroenterologists in Saxony over a 15-year period (2000–2014). In 2019, an independent survey estimated a registry completeness of 95.7%. Age-standardized incidence rates (ASR) per 100,000 person-years (PY) and prevalence per 100,000 children and adolescents were calculated. Evaluation was also been performed in sex and age subgroups. Joinpoint and Poisson regression were used for trend analyses and projections. Results 532 patients with confirmed IBD during 2000–2014 were included in the epidemiological evaluation. 63.5% (n = 338) patients had CD, 33.1% (n = 176) had UC and 3.4% (n = 18) had unclassified IBD (IBD-U). The 15-year IBD prevalence was 111.8 [95%-CI: 102.3–121.3] per 100,000. The incidence ASR of IBD per 100,000 PY over the whole observation period was 7.5 [6.9–8.1]. ASR for the subtypes were 4.8 [4.3–5.3] for CD, 2.5 [2.1–2.9] for UC and 0.3 [0.1–0.4] for IBD-U. The trend analysis of ASR using the joinpoint regression confirmed a significant increase for incidence of IBD as well as CD. For IBD, the ASR per 100,000 PY increased from 4.6 [2.8–6.3] in 2000 to 8.2 [7.5–13.6] in 2014; projected incidence rates for IBD in Germany are 12.9 [6.5–25.5] in the year 2025 and 14.9 [6.7–32.8] in 2030, respectively. Thus, the number of new IBD diagnoses in Germany would more than triple (325%) in 2030 compared to 2000. The increase is expected to be faster in CD than UC, and be more in males than in females. The expected number of newly diagnosed children with IBD in Germany is projected to rise to about 1,584 [1,512–1,655] in 2025, and to about 1,918 [1,807–2,29] in 2030. Conclusion The incidence of IBD in children and adolescents in Saxony increased at a similar rate as in other developed countries during the observation period. Given this trend, the health care system must provide adequate resources for the care of these young patients in the future.

Moral judgments and moral emotions are a ubiquitous feature of social interactions. Humans decide quickly and intuitively whether an action is morally right or wrong. Schadenfreude and sympathy, as emotional reactions to the misfortunes of others, are prototypical moral emotions. So far, however, little evidence exists concerning children’s understanding of schadenfreude. Within three studies, we investigated the experience of schadenfreude and sympathy among N = 364 children of different age groups. We interviewed the children while showing them picture stories. In the picture stories, we varied the behavior of the protagonist prior to a misfortune: (1) whether his behavior had been morally right or wrong, (2) whether the protagonist attained his goal, (3) whether the protagonist was responsible for the misfortune. In addition, in one study we varied (4) the emotional relationship of the interviewed children to the protagonist. Furthermore, we asked the children to decide whether they want to sit next to the protagonist or do him a favor. Results show that children experience sympathy as well as schadenfreude at the age of 4 years. Sympathy is more likely to arise when the protagonists of a story are likable, when these actors typically pursue morally positive goals, and if they are not responsible for their misfortune. In contrast, schadenfreude is more likely when the protagonist is disliked, when actors pursue immoral goals and if they are responsible for their misfortune. In addition, sympathy increases approach (helping behavior, sitting next to the agent and doing favors), whereas schadenfreude increases avoidance tendencies.