The main purpose of this dissertation was to highlight and address seven challenges related to the measurement of youth cognition, understanding the role of cognitive constructs in anxiety and... Show moreThe main purpose of this dissertation was to highlight and address seven challenges related to the measurement of youth cognition, understanding the role of cognitive constructs in anxiety and school refusal, and the examination of cognitive mediators of cognitive-behavioural treatment outcomes. The studies presented in this dissertation contributed to the empirically valid assessment of constructs of cognitive processing in youth which were until now only present in cognitive theories of Aron Beck. Now, constructs of cognitive processing coming from the cognitive theories of depression and anxiety of Beck and colleagues can be assessed in youth using one single measure. Further, cognitive dimensions of cognitive products and cognitive processes from Beck and colleagues cognitive theories of emotional disorders were found to be important in the etiology of school refusal. The belief that positive treatment outcomes can be achieved through changes in cognition received support. Using innovative statistical approaches to mediation, it was found that enhanced levels of self-efficacy following cognitive-behavioural treatment for school refusal were associated with increased levels of school attendance and decreased levels of school fear. Show less
Doublecortin (DCX) and DCX-domain containing Doublecortin-Like Kinase (DCLK) gene splice variants function during embryonic development, where they play a role in microtubule binding. Although a... Show moreDoublecortin (DCX) and DCX-domain containing Doublecortin-Like Kinase (DCLK) gene splice variants function during embryonic development, where they play a role in microtubule binding. Although a role for the DCLK gene during embryogenesis is clearly established, it encodes multiple, different transcripts, some of which are expressed in the adult brain or in response to neuronal activity. This suggests that the DCLK gene may have additional functions beyond neuronal development. Strikingly, the roles of two DCLK gene products, DCLK-short and CaMK-related peptide (CARP), remain largely elusive. Therefore, we have generated transgenic mice with over-expression of either CARP or a constitutively active form of DCLK-short, called _C-DCLK-short, in the brain. This has opened up the possibility to study the effect of over-expression of these DCLK transcripts in the brain during adulthood. To gain more insight in DCLK gene function in the adult brain we aimed to study and describe the phenotypes of these transgenic mice at different functional levels, such as the genetic, network and behavioural level. Show less
School refusal is an attendance problem characterized by a young person’s difficulty in going to school, accompanied by emotional distress on the part of the young person and parental attempts to... Show moreSchool refusal is an attendance problem characterized by a young person’s difficulty in going to school, accompanied by emotional distress on the part of the young person and parental attempts to return the young person to regular school attendance. Prolonged absence from school has serious short- and long-term consequences for young people, their families, and schools. Therefore, effective treatment of school refusal is essential. Numerous treatment outcome studies provide evidence for the efficacy of cognitive-behavioural therapy (CBT) for school refusal. Previous research has however indicated that adolescent school refusers may be particularly disturbed and harder to treat. An existing treatment for school-refusing children and adolescents was modified to better account for the impact of developmental variables on engagement in treatment. The studies presented in this dissertation describe the preparation, implementation, and evaluation of the resulting developmentally-appropriate CBT for adolescent school refusal. The treatment was associated with increased school attendance, reduced emotional symptoms, and increased adolescent and parental self-efficacy. Exploratory analyses revealed that several developmental factors were related to treatment outcomes, namely clinician developmental appropriateness, insight, and autonomy. Recommendations for research and clinical practice are made on the basis of these findings, and on the methodological strengths and limitations of the current research. Show less
For a majority of people worries about upcoming stressful events are a common experience in daily life. The aim of this thesis was to examine the effects of common worries on somatic health. In... Show moreFor a majority of people worries about upcoming stressful events are a common experience in daily life. The aim of this thesis was to examine the effects of common worries on somatic health. In particular, the effects of worry on somatic health complaints, like headache and back pain, and on cardiac activity after stressful events were tested. Furthermore, the mechanisms by which worry was hypothesized to affect somatic health were investigated. The studies in this thesis add to the accumulating number of studies testing the perseverative cognition hypothesis stating that only perseverative cognitive representations of stressful events (worries) lead to prolonged stress-related physiological activity which, in turn, can lead to somatic disease. Taken together, the studies reported in this thesis provide evidence for the perseverative cognition hypothesis, that is, worry predicted adverse somatic health outcomes. In addition, the results of the studies presented in the second part of this thesis yielded several new and more specific hypotheses concerning the mechanisms behind the health effects of worry and the effects of worry on stress management therapies. All in all, evidence from real life and laboratory studies makes clear that worry might play a substantial role in somatic health. Show less
