Depression is a common, debilitating mental disorder. Due to its frequency and negative effects, there is a strong need for the development of efficient treatments. Especially since a large...Show moreDepression is a common, debilitating mental disorder. Due to its frequency and negative effects, there is a strong need for the development of efficient treatments. Especially since a large percentage of people is resistant to commonly prescribed antidepressant interventions. Rumination is an important symptom and predictor of depression, and it has been linked to dysfunctional default mode network (DMN) connectivity in depression. A better understanding of the relationship between the DMN and rumination may help us understand depression better, which may support the development of new interventions. This study focuses on rumination and its effects on the DMN during a working memory (WM) task in healthy participants. This was tested by inducing rumination in participants before the WM task, where DMN and DMN subsystem connectivity were compared to participants who did not receive rumination induction. Results showed that inducing rumination during tasks requiring external focus does not increase functional connectivity of the DMN. Both the overall DMN connectivity and subsystem connectivity did not show any significant differences between groups. Furthermore, time-related changes in DMN connectivity were explored, but results indicated no significant changes either. Studies with depression showed that DMN connectivity is increased during WM tasks which was linked to rumination. But in this study with healthy participants DMN connectivity was suppressed during the WM task, even after inducing rumination. Therefore, these findings suggest that inducing rumination does not lead to insufficient DMN suppression in healthy participants, and that insufficient depression may be exclusive to depression.Show less
Research master thesis | Psychology (research) (MSc)
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Atomoxetine is a prescription drug often used to restore executive (or cognitive) functioning in patients with attention-deficit/hyperactivity disorder and other neuropsychiatric conditions....Show moreAtomoxetine is a prescription drug often used to restore executive (or cognitive) functioning in patients with attention-deficit/hyperactivity disorder and other neuropsychiatric conditions. Moreover, this drug may potentially be ingested by healthy individuals who seek to improve their cognitive performance. However, the effect of atomoxetine on healthy brain functioning remains largely unclear. Network approaches have become useful for studying how the functional connectivity between brain regions may enhance or hinder executive functioning. Accordingly, to further examine the underlying mechanisms of action of atomoxetine, it is relevant to explore how this drug influences the functional connectivity of a large-scale brain network involved in the control of top-down processes: the executive control network (ECN). The aim of this study was thus to investigate the effect of atomoxetine (40 mg) on the functional connectivity of the ECN in healthy volunteers (n = 15). Network analyses were conducted on unpublished functional magnetic resonance (fMRI)-data collected by Chamberlain and colleagues (2009) in a double-blind, placebo-controlled, within-subjects, crossover design in which participants completed a goal-directed fMRI-task (i.e., the temporal discounting task), probing the ECN. Contrary to expectations, a paired-samples permutation test, corrected for multiple comparisons by means of a threshold free cluster enhancement, revealed that the functional connectivity of the participants’ ECN does not increase significantly after ingesting atomoxetine as compared to placebo (p > .05 corrected). Nevertheless, exploratory analyses indicated that, relative to placebo, atomoxetine significantly strengthens the functional connectivity of a frontoparietal network highly associated with cognition and language paradigms (t(14) = 7.61, p = .003). Together, these results suggest that, in healthy individuals, atomoxetine might not have enhancing effects on the processes supported by the ECN but (potentially) on those supported by a frontoparietal network. Atomoxetine might thus have beneficial effects in the cognitive performance of healthy individuals by facilitating certain processes associated with both cognition and language. Further research is however warranted to corroborate these findings in confirmatory studies and enhance the understanding of the underlying mechanisms of action of atomoxetine in healthy brain functioning.Show less
Background. Anxiety disorders are considered to be the most common psychiatric disorder. Knowing underlying mechanisms can help to improve treatment effectiveness. Thus, the study researches the...Show moreBackground. Anxiety disorders are considered to be the most common psychiatric disorder. Knowing underlying mechanisms can help to improve treatment effectiveness. Thus, the study researches the association of anxiety, rumination, heart rate variability (HRV) and the Default Mode Network (DMN). Previous studies indicate a relationship between the factors. The DMN has been found to be essential for self-related cognitive activity. Its functional connectivity (FC) has been shown to be impaired in major psychiatric disorders. Research Question. The study investigates described associations within a population of high trait ruminators, rumination being experimentally manipulated. It is hypothesized that an increase in rumination is associated with lower HRV. High anxiety levels are expected to be related to lower HRV. The FC within the DMN is expected to be affected by rumination. The resulting DMN effect size is predicted to be associated with HRV and anxiety. Methods. A cross-sectional, within-subject experimental design was implemented. The sample consists of 33 female healthy participants who filled out the Penn State Worry Questionnaire and Ruminative Responses Scale. The FC within the DMN was assessed carrying out a working memory task and being cued with memories inducing rumination. Results. Solely a significant positive correlation has been found between anxiety and rumination. Brain areas of the DMN showed an increase in FC during rumination induction compared to rest condition. This effect was significantly negatively related to HRV. Conclusion. The significant relationship between rumination and anxiety should be considered in mental healthcare institutions. The FC of the DMN needs further research to derive practical value.Show less
Het is een terugkerende discussie of de winter- of zomertijd wel of niet afgeschaft moet worden. Uit onderzoek blijkt dat mensen lichamelijke, psychische en cognitieve problemen ervaren na het...Show moreHet is een terugkerende discussie of de winter- of zomertijd wel of niet afgeschaft moet worden. Uit onderzoek blijkt dat mensen lichamelijke, psychische en cognitieve problemen ervaren na het verzetten van de klok. Om een beter beeld te krijgen van welke factoren invloed hebben op de mate van last die mensen hebben gaat dit onderzoek in op de rol van persoonlijkheid. Er is specifiek gekeken of mensen die relatief lager scoren op de eigenschap ‘nauwgezetheid’ meer last hebben van de transitie van winter- naar zomertijd dan mensen die relatief hoger scoren op de eigenschap ‘nauwgezetheid’. 33 participanten hebben een week voor het verzetten van de klok tot en met een week erna hun tijden van opstaan en van naar bed gaan bijgehouden. Daarnaast hebben ze eenmalig de subschaal voor het meten van de karaktereigenschap ‘nauwgezetheid’ van de Big Five Inventory ingevuld. Vervolgens werd aan de hand van de ingevulde tijden berekend na hoeveel dagen de participanten na het verzetten van de klok weer terug waren in hun normale ritme. Het aantal dagen werd vergeleken met de BFI scores door middel van een regressieanalyse. De resultaten waren niet significant. Desondanks waren er wel lichte trends te zien die in overeenstemming waren met de hypothese dat chaotische mensen meer moeite hebben met aanpassen aan de zomertijd dan ordelijke mensen. Dit aspect van persoonlijkheid speelt hier dus mogelijk een rol, maar meer onderzoek is nodig om dit te bevestigen.Show less
