In this dissertation, we aimed to identify the influence of cortisol exposure and cognitive performance on the clinical course of bipolar disorder. Data regarding sociodemographics, disease... Show moreIn this dissertation, we aimed to identify the influence of cortisol exposure and cognitive performance on the clinical course of bipolar disorder. Data regarding sociodemographics, disease characteristics and genetic analysis of the cortisol receptors, were collected of 366 patients with bipolar disorder (BD). Part of this cohort participated in the longitudinal study, including the Test for Attentional Performance, prospectively registration of mood, and the collection of hair samples to assess long term cortisol. The main findings are as follows: 1) Several Glucocorticoid Receptor (GR) gene polymorphisms, in particular the 9β polymorphism (rs6198), relate with clinical characteristics of BD. The most important relations were with the number of (hypo)manic episodes, and second, with seasonal patterns of mood episodes, especially hypomania. 2) Higher long term cortisol exposure is associated with more psychiatric co morbidity in BD patients., and with an older age at onset, indicating a subgroup of patients. 3) Medication as potential confounder on cognitive performance, appeared to relate with the type (mainly antipsychotics) and the number of different types of medication used. Summarizing, cortisol exposure is associated with several clinically relevant phenomena defining course of BD and give insight in possible subgroups of patients with higher cortisol exposure. Show less
Fluorescence bias in in signals from individual SNP arrays can be calibrated using linear models. Given the data, the system of equations is very large, so a specialized symbolic algorithm was... Show moreFluorescence bias in in signals from individual SNP arrays can be calibrated using linear models. Given the data, the system of equations is very large, so a specialized symbolic algorithm was developed. These models are also used to illustrate that genomic waves do not exist, but are merely an artifact of commonly used methods. Furthermore, a new semi-parametric, single array, approach to SNP genotyping is introduced and shown to be both effective and efficient. A refined algorithm for copy number estimation, using a zero-exponent norm is proposed, which performs well, as is illustrated by thorough comparisons with other methods. Indications that the signal calibration can improve (genotyping) results from lower quality samples are also discussed. A software suite that implements the above is described and illustrated. Show less
The aim was to provide more insight in people's nonverbal reactions to and perceptions of nonverbal behavior in interactions. We argue that nonverbal reactions are not simply linked to nonverbal... Show moreThe aim was to provide more insight in people's nonverbal reactions to and perceptions of nonverbal behavior in interactions. We argue that nonverbal reactions are not simply linked to nonverbal expressions of others, but that social context influences how people react to and perceive such expressions. In Chapter 2 it was examined whether information of a target's status influenced nonverbal reactions. In Chapter 3 we examined whether the legitimacy of such status positions also influenced nonverbal reactions. Finally, in Chapter 4 we investigated whether nonverbal reactions influence the perceptions of dominance, conflict avoidance, and conflict in the interaction. Results demonstrate that social contexts influence people's nonverbal reactions. People mimic or complement a target's expanded or constricted posture depending on the relative status position and on whether or not this status position was obtained in a legitimate way. Furthermore, the contrast between the postures of interaction partners influence the degree to which people perceive postures as dominant and conflict avoidant. Also, the contrast influences the degree to which people perceive conflict in the interaction. Overall, it can be concluded that nonverbal reactions are influenced by the social context. The reactions influence the perceptions people have about the behavior and situation. Show less
Background As maintenance of lifestyle change and risk factor modification following completion of cardiac rehabilitation (CR) has been shown to be notoriously difficult, we developed a brief self... Show moreBackground As maintenance of lifestyle change and risk factor modification following completion of cardiac rehabilitation (CR) has been shown to be notoriously difficult, we developed a brief self-regulation lifestyle program for post-CR patients. Design Randomized-controlled trial. Method Following completion of CR 210 patients were randomized to receive either a lifestyle maintenance program (n=112) or standard care (n=98). The program was based on self-regulation principles and consisted of a motivational interview, 7 group sessions and home assignments. Risk factors and health behaviors were assessed at baseline (end of CR), and 6 and 15 months thereafter. Results ANCOVAs showed a significant effect of the lifestyle program after 6 months on blood pressure, waist circumference and exercise behavior, only the latter of which remained significant at follow-up (15 months). Mediation analysis demonstrated that the treatment effect on exercise behavior could be explained by an effect on self-regulation skills. Furthermore, the lifestyle intervention program was associated with a 12% reduction in self-reported cardiac hospital admission rates. In addition, patients in the intervention group had significantly fewer uncontrolled risk factors as compared to the control group. However, there was only a long-term beneficial intervention effect on obesity and physical inactivity, but not on other individual risk factors (increased waist circumference, raised blood pressure, raised TC/HDLC-ratio and smoking). Conclusion This trial indicates that a relatively brief, theory-based lifestyle program is capable of inciting and maintaining improvements in exercise adherence. It is suggested that patients may need ongoing attention and guidance, for example in the form of (internet-based) booster sessions, as long-term consolidation of changes is arduous. Show less
Assessment procedures are frequent in children's school careers; however, measuring potential for learning has remained a puzzle. Dynamic testing is a method to assess cognitive potential that... Show moreAssessment procedures are frequent in children's school careers; however, measuring potential for learning has remained a puzzle. Dynamic testing is a method to assess cognitive potential that includes training in the assessment process. The goal of this thesis project was to develop a new dynamic test of analogical reasoning for school children. The main aims were to (1) investigate factors that influence children’s differences in performance and change during dynamic testing and (2) examine the predictive value of dynamic measures on children’s school performance. Children showed great variation in cognitive potential. Higher ability children generally required less training and showed greater transfer to other problem sets. Yet, lower ability children tended to improve more during dynamic testing. Performance change during testing appears to be a unique predictor of math and reading achievement, but was unrelated to working memory or cultural background, providing evidence that this may be a separate construct important in the assessment of cognitive potential – especially in culturally diverse schools. This performance change measure, often criticized within classical test theory, has demonstrated its worth when estimated using item response theory models and will hopefully find its place again among the valuable measurement outcomes of children’s potential for learning. Show less
Between 150 and 200 deaf children are born in the Netherlands each year. Deafness has major consequences for these children’s development, as it deprives them of access to spoken language. Since... Show moreBetween 150 and 200 deaf children are born in the Netherlands each year. Deafness has major consequences for these children’s development, as it deprives them of access to spoken language. Since the 1990s, deaf children have been able to have a cochlear implant (CI), which enables them to experience sound. The questions central to this thesis concern the way in which a CI affects children’s development, and the factors that play an important role in this. The framework for this thesis is provided by Bronfenbrenner’s social-ecological model, which proposes that children’s development is influenced by the quality and quantity of their interpersonal interactions. These interactions are influenced indirectly by the environment in which children live. In young children with a CI, language development and the social-emotional development are both delayed compared to their hearing peers. However, it is not yet cl ear how these children will develop in the future. The children who participated in this study were still very young, and a number of them received their CI relatively late. It is possible that they will catch up with hearing children when they are older and have had a longer period of access to spoken language Show less
The principal aim of this thesis was to develop an outcome monitoring feedback model for Dutch outpatient mental health care in the Netherlands and to test whether providing feedback to therapists... Show moreThe principal aim of this thesis was to develop an outcome monitoring feedback model for Dutch outpatient mental health care in the Netherlands and to test whether providing feedback to therapists and patients can improve treatment outcomes. Data on patient progress collected in outpatient centers in the Netherlands were used to predict the functioning of patients at the end of treatment and the rate of change. In addition, two feedback studies were conducted. In the first study the effect of therapist feedback was compared with no feedback. The results showed no significant effect of feedback for the full group, but did show an effect for therapists that actively used the feedback in therapy. Therapist factors mediated the effectiveness of feedback: in therapists with higher self-efficacy the feedback had a more positive effect. The second study had three treatment conditions, a control group, a group with feedba ck to therapists alone and a group in which both therapists and patients received feedback about the patient’s progress. The results showed that feedback to both therapists and patients was more effective than feedback to therapists alone. The feedback effect was strongest in short-term therapy, for cases that were not progressing well. Show less
In this dissertation I investigate how individuals respond to collective disadvantage from the perspective of regulatory focus theory. Regulatory focus theory distinguishes between two motivational... Show moreIn this dissertation I investigate how individuals respond to collective disadvantage from the perspective of regulatory focus theory. Regulatory focus theory distinguishes between two motivational systems: promotion focus, the system in charge of the approach of positive end-states, and prevention focus, the system in charge of the avoidance of negative end-states. In 7 studies I investigate the effects of promotion and prevention focus on 1) low status group members’ choice between seeking individual or group status improvement, 2) their level of commitment to collective status improvement and 3) the extent to which they see hostile forms of collective action (e.g. riots, sabotage) as justified. The results showed that activation of the prevention system (compared to activation of the promotion system) causes members of low status groups 1) to prefer collective status improvement over individual status improvement, 2) to commit to collective action when they value its goal, even when the likelihood of achieving this goal is low and 3) to come to see hostile forms of collective action as justified in order to reach group status improvement. I conclude that activation of the prevention system is more conducive to collective action than activation of the promotion focus. Show less
The studies described in this thesis aimed to investigate how affect and motivation impact cognitive control, in terms of both behavior and brain activation. Six out of the eight empirical studies... Show moreThe studies described in this thesis aimed to investigate how affect and motivation impact cognitive control, in terms of both behavior and brain activation. Six out of the eight empirical studies found support for indirect effects on cognitive control, as measured with sequential trial-to-trial adaptations in cognitive control tasks. Only two studies resulted in evidence for a direct modulation of cognitive control (Chapter 4 and 9). Indirect effects occurred on trial-to-trial adaptation in cognitive control tasks involving a random presentation of compatible and incompatible trials. We found that conflict adaptation, the transient improvement of behavioral control after incompatible in comparison to compatible trials, was subject to affective regulation. In particular, we found that after incompatible trials, positive emotional states reduced and negative emotional states increased adaptation. These effects occurred for both short-term (Chapters 2 and 3) and long-term affect manipulations (Chapters 5, 6, and 7). Motivation and task difficulty also interacted with conflict adaptation (Chapter 8). The neuroimaging studies described in Chapter 3 and 6 demonstrate the role of fronto-striatal interactions in this affective regulation of cognitive control. Taken together, this thesis demonstrates the role that positive and negative emotions play in the adaptation of behavior and mental effort. Show less
