Research master thesis | Psychology (research) (MSc)
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Research into Dutch substance-dependent youths who have committed crimes (age 16-22) is scarce, even though this population might benefit from more targeted treatment (e.g., addition of anger...Show moreResearch into Dutch substance-dependent youths who have committed crimes (age 16-22) is scarce, even though this population might benefit from more targeted treatment (e.g., addition of anger management to treatment for youths who have committed violent crimes) and is more likely to exhibit recidivism. Therefore, the aim of this study was to investigate the relation between different types of drugs (alcohol, cannabis, and hard drugs) and different types of crime (violent, drug-related, and property). It was expected that (1) alcohol users were more likely to commit violent crimes than cannabis or hard drug users, (2) cannabis users were less likely to commit drug-related crimes than alcohol or hard drugs users, and (3) hard drug users were more likely to commit property crimes than alcohol or cannabis users. Gender, SES, education, polydrug use, and conduct disorder were also taken into account. All variables were assessed using a structured interview in a sample of 209 youths who came into treatment for SUD at different treatment centers across the Netherlands. The key finding of this study was that the majority of this sample had committed multiple types of crime and were using multiple types of drugs, which made confirmatory analyses impossible. Exploratory analyses indicated that cannabis users were more likely to commit drug-related crimes than non-cannabis users and that there was no specific type of drug that increased the likeliness that a youth would commit multiple crimes.Show less
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
