Research master thesis | Psychology (research) (MSc)
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Objective: The Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) is the gold standard to assess post-traumatic stress disorder (PTSD). Although the CAPS-5 was developed and validated in Western...Show moreObjective: The Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) is the gold standard to assess post-traumatic stress disorder (PTSD). Although the CAPS-5 was developed and validated in Western populations, many clinicians and researchers also use it to assess PTSD in non-Western refugee populations. In this study we investigated whether PTSD as assessed with the CAPS-5 has the same structure and meaning across trauma-exposed, treatment-seeking individuals with either a Dutch (i.e. Western) background or a non-Western refugee background. Method: We evaluated commonly accepted DSM-5 PTSD factor models and tested different levels of measurement invariance (configural and scalar invariance) in a clinical sample of non-Western refugee patients (N = 710) and Dutch patients (N = 1162) suffering from prolonged complaints of psychotrauma, using confirmatory factor analyses (CFA). Results: CFAs showed that the Hybrid model of PTSD fit the data best in the Dutch and non-Western refugee subsample, as well as in the combined sample, indicating that configural invariance was met. The model representing scalar invariance showed a worse fit compared to the model representing configural invariance, indicating that factor loadings and/or symptom severity differed between the subsamples. Further investigation showed that this result could mainly be attributed to non-Western refugee patients often manifesting higher scores on the CAPS-5 items than Dutch patients. Conclusions: Non-Western refugee patients showed a similar structure of DSM-5 PTSD symptoms as Dutch patients. Furthermore, the relative contribution of the majority of symptoms to its belonging symptom cluster was similar between non-Western refugee patients and Dutch patients. This meant that both groups understood these symptoms in the same way. However, non-Western refugee patients often manifested a higher symptom severity than Dutch patients.Show less
Research master thesis | Developmental Psychopathology in Education and Child Studies (research) (MSc)
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Both youth with a substance use disorder (SUD) and youth who have experienced adverse childhood experiences (ACEs) show heightened vulnerability to psychopathology. We aimed to quantify the risk of...Show moreBoth youth with a substance use disorder (SUD) and youth who have experienced adverse childhood experiences (ACEs) show heightened vulnerability to psychopathology. We aimed to quantify the risk of comorbid disorders in SUD youth with ACE-history. Additionally, we aimed to examine relations between ACEs, overall household experience, and general distress. We used cross-sectional YIT-study data from interviews with Dutch youth (aged 16-22) upon SUD treatment entry for cannabis, alcohol, or stimulant use. We measured ACE-types experienced up until 15 years of age, past-year DSM-5 disorders, general distress (DASS-21), and overall household experience rating. Logistic regressions quantified relations between ACE sum score and anxiety, depressive, behavior, and any disorder. Higher ACE sum scores related to increased risks for a(n) anxiety (OR = 1.12, highest odds = 2.84; χ2(1) = 6.71, p < .010; Nagelkerke R2 = 0.2), depressive (OR = 1.21, highest odds = 5.43; χ2(1) = 18.11, p < .001; Nagelkerke R2 = 0.6), behavior (OR = 1.20, highest odds = 5.24; χ2(1) = 17.41, p < .001; Nagelkerke R2 = 0.6), and any (OR = 1.25, highest odds = 7.58; χ2(1) = 17.26, p < .001; Nagelkerke R2 = 0.7) disorder. Exploratory analyses revealed that frequency of parental fighting, being hit/abused, getting belittled, emotional neglect, physical neglect, insufficient household income, long parental sickness, and overall household experience positively related to DASS-21. In a hierarchical regression analysis with all ACEs and overall household experience, only emotional neglect related to DASS-21 (B = 3.68, t(373) = 2.41, p = .017). Overall household experience did not improve the model (F(12) = 3.51, p < .001; R2change < .001). In hierarchical regression analyses containing ACE sum score and overall household experience, overall household experience was not uniquely related to DASS-21 (t = -0.22, p = .824; R2change < .01). In conclusion, ACEs relate to comorbid disorders in SUD youth. Our exploratory research suggests that ACE frequency might influence this relation, while overall household experience does not further explain this relation. Further research should investigate which ACE measures (a.o., type, frequency) strongly relate to SUDs and psychopathology and examine improved treatment options.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Objective: This study aimed to clarify the relationship between the course of core depressive symptoms and the course of insomnia symptoms in older adults with a depressive disorder, and to...Show moreObjective: This study aimed to clarify the relationship between the course of core depressive symptoms and the course of insomnia symptoms in older adults with a depressive disorder, and to identify predictors of an unfavorable versus a favorable course of core depressive symptoms and insomnia symptoms. Method: We examined 329 older adults (median age 69 (IQR 65-75), 66.9% women) with a depressive disorder within the Netherlands Study of Depression in Older persons (NESDO), a naturalistic cohort study with a six-year follow-up and assessments every six months in between. Core depressive symptoms and insomnia symptoms were assessed with 14 and 3 items, respectively, from the Inventory of Depressive Symptomatology (IDS). We applied growth mixture modelling to identify classes of participants with similar trajectories of core depressive symptoms and insomnia symptoms. The association between core depressive and insomnia symptom trajectories was examined with a chi-squared test. Finally, we investigated predictors of class membership for core depressive symptoms and for insomnia symptoms using multinomial logistic regression. Results: We identified three trajectories of core depressive symptoms: high and stable (22.2% of participants were assigned to this class), moderate and declining (37.4%), and low and declining (40.4%). We identified four trajectories of insomnia symptoms: high and stable (23.1%), moderate and stable (55.6%), low and increasing (7.6%), and moderate and declining (13.7%). There was a significant association between core depressive and insomnia symptom trajectories, in particular for the most and least favorable trajectories. Number of chronic diseases, a comorbid anxiety disorder, and functional limitations predicted less favorable core depressive symptom trajectories. We found no predictors for insomnia symptom trajectories. Conclusion: Persistent insomnia symptoms are highly prevalent in older adults with depression, even in those with improving core depressive symptoms. This highlights the need for separate treatment of insomnia symptoms in addition to depression interventions.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Adolescents’ future expectations (FE) regarding the attainability of desired life goals are variable, and, compared to allistic peers (i.e., non-autistics), are often more pessimistic. One reason...Show moreAdolescents’ future expectations (FE) regarding the attainability of desired life goals are variable, and, compared to allistic peers (i.e., non-autistics), are often more pessimistic. One reason may be that autistic adolescents have more difficulties on the social domain, and therefore perceive their own social competence as poorer than allistic peers. Importantly, FE may inform adolescents goal-directed actions, such that expectations for the future influence actual future outcomes. Thus, the importance of assessing which factors influence future expectations is evident. This study assessed the extent to which autistic and allistic adolescents differ on self-perceived social competence (SPSC), and FE (on the romantic and self-development domains); and the extent to which autistic adolescents’ SPSC was related to their FE compared to allistic peers, controlled for global self-esteem. Autistic adolescents’ were expected to have lower FE than allistic peers’, related to lower SPSC. Preliminarily, the uni-dimensionality and reliability of constructs was tested with factor analyses. Mediation analyses on a total of 142 adolescents, 88 allistic and 54 autistic (Mrange 12-21; Mage = 16.31, SD = 1.94), revealed that, though autism was not directly related to having less optimistic FE for either romantic or self-development goals, SPSC mediated the relationship between autism and FE for self-development (i.e., having a job/career, or continuing their education). That is, autistic adolescents’ lower SPSC was related to poorer FE for self-development compared to allistic peers, when controlled for global self-esteem. Clinical implications and future directions for research are discussed.Show less
Research master thesis | Psychology (research) (MSc)
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Adolescent’s prosocial behaviour is likely related to their social context and relationships. This social context drastically changes during adolescence, with peers becoming more important relative...Show moreAdolescent’s prosocial behaviour is likely related to their social context and relationships. This social context drastically changes during adolescence, with peers becoming more important relative to parents. This pilot study therefore investigated the relative contribution and interaction of adolescents’ quality of parental and peer attachment in predicting their prosocial behaviour towards unknown peers. Forty-two adolescents aged 9-12 completed the brief Inventory of Parent and Peer Attachment and an adapted version of the Prosocial Effort Task. In this task, participants choose whether to earn rewards for themselves and others by exerting physical effort. Computational modelling was used to quantify the rate at which rewards lose subjective value to adolescents when effort increases, both when earning rewards for others and for themselves. The difference in this effort discounting rate for others and for themselves was used as measure of prosocial behaviour, as well as the difference between the number of times participants chose to exert high effort for others and for themselves. We show that adolescents are generally less willing to exert effort for others than for themselves, and that their willingness to exert effort for a reward is more strongly affected by the effort needed to obtain it when someone else will receive this reward. These findings support the cost-benefit framework of prosocial motivation. Linear models fitted using nonparametric bootstrapping show nonsignificant trends in the expected directions, namely higher quality parental and peer attachment being related to more prosocial behaviour and peer attachment generally being a stronger predictor than parental attachment. We found some evidence that girls show significantly more prosocial behaviour than boys. Future research should further investigate these potential effects using larger samples with a broader age range across adolescence, to also study developmental effects.Show less
Research master thesis | Psychology (research) (MSc)
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Childhood maltreatment (CM) is a public health issue affecting mental and physical well-being of individuals across the lifespan. The literature so far suggests that CM is a risk factor for the...Show moreChildhood maltreatment (CM) is a public health issue affecting mental and physical well-being of individuals across the lifespan. The literature so far suggests that CM is a risk factor for the development and severity of EDs in adulthood. This study aims to build upon and update the findings of Molendijk et al. (2017) by integrating both pre-2016 and post-2016 literature on the relationship between all types of CM (physical, sexual, and emotional) and all types of EDs. A random-effects meta-analysis with moderator analyses was performed to assess the associations between all types of CM and all types of ED, focusing on their prevalence, severity, and related comorbid conditions. The prevalence of CM was consistently and significantly higher in ED patients (18.4- 57.7%) than in healthy controls (7.2-29.2%) and mostly higher compared to psychiatric controls (21.2 - 31.1%). The odds of developing EDs were significantly elevated in individuals exposed to CM, with ORs ranging from 2.81 to 4.60. CM exposure was associated with greater severity of EDs (r = .21, 95% CI [0.10, 0.32], p < .001) and was also associated with higher levels of depression and anxiety (r = .19, 95% CI [0.11, 0.26], p < .001). Additionally, we found that CM exposure significantly increased the likelihood of comorbid mental health disorders in patients with EDs compared to non-exposed counterparts (ORs 1.15 to 3.96), with the strongest associations observed for Axis I disorders, especially depression and anxiety. Moderator analyses revealed that recent studies reported slightly higher CM prevalence in AN samples. Sample size influenced the sexual CM-BED relationship (R2 =0.42, p =.04), and higher study quality was linked to lower prevalence rates (R2 = 0.07, p < .001), though these factors explained only a small part of the heterogeneity. Our findings highlight that all types of childhood maltreatment (physical, sexual, and emotional) are associated with a range of EDs in adulthood and influence both the severity and course of EDs.Show less
Research master thesis | Psychology (research) (MSc)
open access
Bullying victimization is a major public health concern, because victims often experience long-term negative mental health outcomes. Longitudinal brain structure research in children is needed to...Show moreBullying victimization is a major public health concern, because victims often experience long-term negative mental health outcomes. Longitudinal brain structure research in children is needed to understand the possible mechanisms underlying the relation between bullying victimization and negative mental health outcomes. Previous research has shown that the fusiform gyrus, amygdala and vmPFC are impaired in victims. Therefore, this thesis examined the relation between victimization and fusiform gyrus, amygdala and vmPFC volume over time. We hypothesized that victims of bullying, compared to children uninvolved in bullying, would have a larger fusiform gyrus volume and a steeper volume increase. Furthermore, we hypothesized that victims of bullying, compared to children uninvolved in bullying, would have a smaller amygdala and vmPFC volume and a steeper volume decrease. The sample consisted of 156 children (62% female), aged between 7 and 9 years old at baseline, from the Leiden Consortium on Individual Development. At the beginning of the study, the Revised Olweus Bully/Victim Questionnaire was administered to measure bullying victimization and high-resolution structural MRI scans were taken. This was done again two years later. Children were classified as victims if they had been bullied regularly in the past two months. We did not find an effect of victimization on fusiform gyrus, amygdala and vmPFC volume. Future research examining the influence of victimization on both structural and functional brain development is needed to provide further insights, which can help inform the design of interventions to reduce the negative consequences of bullying victimization. The current findings emphasize the importance of protective factors that make a victim’s brain development resilient against victimization. This indicates a need for interventions targeting the development of social-emotional skills or the increase of family support.Show less
Research master thesis | Psychology (research) (MSc)
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Transcutaneous vagus nerve stimulation (tVNS) together with mindful acceptance hold promise for pain management, yet their combined efficacy remains largely unstudied. This study investigates...Show moreTranscutaneous vagus nerve stimulation (tVNS) together with mindful acceptance hold promise for pain management, yet their combined efficacy remains largely unstudied. This study investigates whether this combination can effectively reduce pain perception in healthy participants. We exposed 52 participants to two types of heat stimuli by using a Medoc pain device: Warm temperature of 47 °C and hot temperature of 51 °C. Subsequently, participants were divided into receiving either active tVNS (n = 26), or sham tVNS (n = 26). During the experiment, on alternating blocks, we asked participants to exercise mindful acceptance or to react naturally towards the experimentally induced heat pain. Participants rated their subjective pain by using a visual analogue slider and underwent EEG recordings to assess Contact-Heat Evoked Potentials (CHEPs). After performing several rmANOVAs, the results indicated that tVNS combined with mindful acceptance did not significantly reduce reported pain perception and neurophysiological responses, compared to the control group. However, mindful acceptance alone was associated with reduced subjective pain ratings, both for the affective (p < .001, np2 = .45) and sensory (p < .001, np2 = .39) aspects of pain, though it did not significantly reduce CHEPs (p = .82, np2 = .001). Lastly, tVNS alone did not significantly influence subjective pain ratings, both affective (p = .13, ηp² = .045) and sensory (p = .42, ηp² = .013), nor CHEPs (p = .31, np2 = .021). Overall, these findings suggest a positive effect of mindful acceptance on subjective pain perception, but future studies assessing objective measures of neurophysiological correlates during tVNS with mindful acceptance are warranted.Show less
Research master thesis | Developmental Psychopathology in Education and Child Studies (research) (MSc)
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The failure to speak of children with selective mutism (SM) has been conceptualized as a specific emotion regulation strategy to avoid extreme arousal in stressful (social) situations. However, the...Show moreThe failure to speak of children with selective mutism (SM) has been conceptualized as a specific emotion regulation strategy to avoid extreme arousal in stressful (social) situations. However, the underlying psychophysiological mechanisms of their failure to speak, and the development of these children over time, are still not well understood. The current study examined the arousal (heart rate and heart rate variability) of 33 children with SM and 42 typically developing children (comparison group, CG), aged 4 to 8 years, during rest and during a verbal and non-verbal social evaluation stress paradigm. Moreover, 18 children with SM participated in a follow-up measurement after almost all of them had received treatment. Children with SM had a significantly higher arousal during rest. However, their reactivity arousal (performance minus baseline) during a verbal and non-verbal stress task did not differ from the CG. Moreover, at the follow-up measurement, children with SM showed significantly lower baseline arousal compared to the first measurement, and no difference in verbal and non-verbal reactivity arousal. The results indicate that children with SM have elevated stress levels compared to typically developing children, even in a non-verbal situation. Over time, after treatment, their stress levels tend to ‘normalize’. These findings do not support the avoidance hypothesis and might indicate a more inflexible stress response to a stressful situation in children with SM compared to typically developing children.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Many situations in daily life require the simultaneous performance of motor and cognitive tasks, such as reaching for items in the supermarket while recalling a shopping list. For patients with...Show moreMany situations in daily life require the simultaneous performance of motor and cognitive tasks, such as reaching for items in the supermarket while recalling a shopping list. For patients with Parkinson’s Disease (PwPD), who already suffer from distinct motor and cognitive symptoms, these situations can be even more challenging. While deep brain stimulation (DBS) provides a promising option for symptom management in the advanced stages of the disease, its effect on everyday life situations has not been explored as much. Thus, using a dual-task paradigm, this study aimed to address this gap by investigating the effects of varying levels of cognitive load and DBS on motor and cognitive performance in PwPD. Eight PwPD with DBS were tested twice: once with DBS turned on and once off. Motor performance was assessed with a custom-designed motor task that required the patients to perform consecutive goal-directed reaching movements. These movements were recorded with a markerless hand-tracking module to capture broad motor performance measures and detailed kinematic data. Cognitive performance was assessed with a serial subtraction task, including high and low levels of cognitive load (subtracting by seven and one, respectively). Finally, linear mixed-effect models were used to statistically compare the effects of DBS, high, and low cognitive load on overall motor and cognitive performance and relevant kinematic features. The results show that high cognitive load negatively affected overall motor and cognitive performance, while low cognitive load only affected cognitive performance. On the other hand, DBS improved overall motor performance while not affecting cognitive performance. Furthermore, high cognitive load and DBS had a significant, yet opposite, effect on the same kinematic features: deceleration time, movement time, reaction time, peak velocity, and coefficient of variation of trajectory error. In conclusion, this study highlights the feasibility of administering more naturalistic experimental designs with a dual-task paradigm and detailed kinematic analyses in PwPD. We show that the dual-task effect is dependent on the amount of cognitive load and that Deep Brain Stimulation can significantly improve motor performance in dual-tasking scenarios. Finally, our detailed kinematic analyses reveal specific components of a reaching movement responsible for changes in motor performance, providing valuable insights for future research and clinical practice.Show less
Research master thesis | Developmental Psychopathology in Education and Child Studies (research) (MSc)
closed access
Child maltreatment is highly prevalent among juvenile delinquents and can result in numerous negative life outcomes, one of which could be violent delinquency. The current study aimed to provide...Show moreChild maltreatment is highly prevalent among juvenile delinquents and can result in numerous negative life outcomes, one of which could be violent delinquency. The current study aimed to provide new insights into the relation between child maltreatment and violent delinquency, as well as the mediating roles of working memory (WM) and three aspects of social information processing (SIP) on this relation. This was done using a cross-sectional design with a questionnaire, WM task, SIP task and file analysis. In total, 58 Dutch juvenile delinquents were included in the study. No relation was found between child maltreatment and violent delinquency in a juvenile delinquent population. In addition, WM and SIP did not mediate the relation between child maltreatment and violent delinquency. Child maltreatment was however related with more hostile attribution bias and more aggressive response evaluation, indicating that juvenile delinquents who have experienced child maltreatment have more hostile attributions in social situations and see aggressive responses as more appropriate than their non-maltreated peers. Furthermore, all three aspects of SIP were related to each other, and WM was related to more hostile attributions. This study highlights the fact that hostile attributions and aggressive response evaluations can be targeted in interventions that aim to improve social skills and reduce recidivism for maltreated juvenile delinquents. Further research is needed to unravel the consequences and underlying mechanisms of child maltreatment and violent delinquency in juvenile delinquent populations.Show less
Research master thesis | Psychology (research) (MSc)
under embargo until 2025-07-31
2025-07-31T00:00:00Z
We tested the effects of audit probability (high, low, ambiguous) and audit probability change (increase, decrease) on compliance in a simplified tax return task. Participants were asked to report...Show moreWe tested the effects of audit probability (high, low, ambiguous) and audit probability change (increase, decrease) on compliance in a simplified tax return task. Participants were asked to report correct returns, faced with either a high (40%), low (10%) or ambiguous (10-40%) audit probability. In addition, audit probabilities of each participant were either increased or decreased by five percentage points after half of all trials were completed. Results showed that, in line with our predictions, high audit probability yielded significantly higher compliance than low audit probability and that high and ambiguous audit probability yielded similar compliance. Contrary to our expectations, audit probability change in the form of increases or decreases did not yield significant effects on compliance. The present study indicates that an ambiguous audit probability can yield increased compliance akin to a high audit probability. Our findings provide a starting point for further investigation into the effects of information about audit probability on tax compliance. Suggestions for replication studies and further research are provided.Show less
Research master thesis | Psychology (research) (MSc)
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Adolescence is characterized by the onset of puberty. Puberty, in turn is shown to be a driver of brain development and has been related to the onset and increase of internalizing symptoms. However...Show moreAdolescence is characterized by the onset of puberty. Puberty, in turn is shown to be a driver of brain development and has been related to the onset and increase of internalizing symptoms. However, the relationship between puberty, brain development, and internalizing symptoms has not been studied using multiple pubertal measures in both sexes. Here we examine the mediating role of brain development on the relationship between puberty and internalizing symptoms. Pubertal status, timing, age at menarche, and internalizing symptoms were assessed based on self-reports in 160 adolescents between 10 and 25 using a three-wave accelerated longitudinal design. Structural MRI scans were only obtained in the first wave. Subsequently, the relations between the pubertal measures (status, timing, age at menarche) and internalizing symptoms were tested as well as their relations with grey matter thickness and volume in frontal, cingulate, and subcortical areas. Only age at menarche as a timing variable had a significant effect on internalizing symptoms at T1 in girls (ß = -.36, p = .002, 95% CI [-.68, -.17]). Mediation models revealed no significant mediation of grey matter thickness and volume in our ROIs. Other effects did not reach significance or became non-significant after Bonferroni corrections. These findings indicate that menstruating before one’s peers is a risk factor for developing internalizing symptoms. This highlights the importance of supporting early menstruating girls to possibly prevent them from developing internalizing symptoms. Replication studies are needed to assess the accuracy of our results.Show less
Research master thesis | Developmental Psychopathology in Education and Child Studies (research) (MSc)
closed access
Theory of Mind (ToM) is a central topic in psychology and neuroscience. Nevertheless, debates persist regarding the validity and reliability of ToM measurement. Recent documentation of numerous...Show moreTheory of Mind (ToM) is a central topic in psychology and neuroscience. Nevertheless, debates persist regarding the validity and reliability of ToM measurement. Recent documentation of numerous failed replications in ToM research, involving both children and adults, highlights the need for establishing effective methods for measuring ToM across the lifespan. In response to this challenge, an international multi-lab collaboration named Many Babies 2 (MB2) has been launched, with Leiden University Babylab participating in this project. This thesis discusses preliminary findings related to the 16 adults tested at our lab. Following the MB2 protocol, an eye-tracker attached to a screen recorded participants’ looking behavior (first look [FL] and differential looking scores [DLS]) in an anticipatory looking task. We had two main goals. First, we aimed to find evidence of an automatic and implicit form of ToM in adults, by investigating whether participants’ looking behavior varied depending on a character’s mental state (i.e. whether the character was knowledgeable (condition 1) or ignorant (condition 2) about a specific situation). Contrary to our expectations, neither FL nor DLS differed between the experimental conditions. Second, we examined whether participants’ looking behavior was affected by (a) the selection of the anticipatory period, and (b) participants’ simultaneous activation of a conscious and explicit form of ToM, which had been measured with a debriefing questionnaire. We concluded that none of these factors significantly impacted participants’ looking behavior at a group level. However, FL and DLS of individual participants randomly varied when processed with different anticipatory periods; therefore, further research is needed to determine which anticipatory period minimizes the presence of noise in the data. While recognizing the preliminary nature of our findings, our insights contribute to the ongoing efforts to refine ToM assessment methods, underscoring the importance of addressing challenges in measuring this fundamental aspect of human cognition.Show less
