Research master thesis | Psychology (research) (MSc)
closed access
Introduction: The default mode network (DMN) is a large intrinsic network in the brain, which seems to be affected in depressed patients. Also, aberrant heart rate variability (HRV) is often found...Show moreIntroduction: The default mode network (DMN) is a large intrinsic network in the brain, which seems to be affected in depressed patients. Also, aberrant heart rate variability (HRV) is often found in this population. Ketamine is thought to be a fast-acting antidepressant and has shown to have an effect on HRV and intrinsic brain connectivity. In this study, the effect of HRV on resting-state functional connectivity of the DMN and brain activity of areas within the DMN that were significantly correlated with HRV was examined. Also, it was investigated whether ketamine moderated this relationship. Method: Twelve healthy men received an intravenous ketamine or placebo infusion on two occasions. Resting-state functional connectivity and HRV were measured before, during, and after infusion. Dual-regression was used to obtain DMN connectivity scores, while a whole brain analysis was done to determine which brain areas were correlated with HRV. Raw digitized electrocardiogram (EKG), obtained with a pulse oximeter, was analyzed in order to extract HRV data. Multilevel analysis was used to determine the effect of HRV and ketamine on resting-state functional connectivity in the DMN and brain activity in the subgenual anterior cingulate cortex (sgACC), right dorsolateral prefrontal cortex (dlPFC), and the left postcentral gyrus. Results: DMN connectivity strength was negatively related to HRV, but positively related to activity of the right dlPFC and the left postcentral gyrus for the placebo condition. Ketamine was associated with a more profound effect of HRV on DMN connectivity and brain activity within the postcentral gyrus. Discussion: The present results complement recent studies that show that HRV is associated with connectivity strength in the DMN. Implications for the relevance of using ketamine in depressed patients are discussed. Initial increases of DMN connectivity are followed by a decrease in the DMN, which may be beneficial for depressed patients who generally show hyperconnectivity within the DMN. Results thus imply that ketamine has a moderating role in this.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Patients that suffer from posttraumatic stress disorder (PTSD) may respond less well to existing PTSD therapies if their PTSD was caused by childhood trauma. A relatively novel treatment, Narrative...Show morePatients that suffer from posttraumatic stress disorder (PTSD) may respond less well to existing PTSD therapies if their PTSD was caused by childhood trauma. A relatively novel treatment, Narrative Exposure Therapy (NET), has shown promising outcomes for refugee and veteran PTSD patients that suffered from multiple and continuous trauma, as is often the case for those with childhood trauma-related PTSD (CTR-PTSD). We aimed to investigate whether NET could be effective for the treatment of CTR-PTSD. Methods: We followed the treatment trajectories of nine adult CTR-PTSD patients in an outpatient setting. A non-concurrent multiple baseline design was used, with a baseline of 4 weeks before treatment started. Participants responded to weekly online questionnaires that assessed their PTSD symptoms (i.e., the Posttraumatic Diagnostic Scale; PDS) and their experienced quality of life (QOL; i.e. the Manchester Short Assessment of quality of life; MANSA). Data were analyzed using visual inspection and a mixed model analysis. Results: Results revealed no significant reduction of PTSD symptoms during NET treatment, nor an increase in QOL, as compared to baseline. Of the nine participants, one lost her PTSD diagnosis after treatment with NET. During the procedure, several participants dropped out due to medical, practical or unknown reasons. Conclusion: Results of this study indicate that NET is not effective for the treatment of CTR-PTSD, in contrast to previous literature.Show less
