This research aims to investigate the topology of the brain during reward processing and the influence of dopamine and norepinephrine on this network. So far, most research about reward processing...Show moreThis research aims to investigate the topology of the brain during reward processing and the influence of dopamine and norepinephrine on this network. So far, most research about reward processing has concentrated on specific brain areas and connections between particular regions, rather than the brain's organization and architecture. By investigating this organisation, gaps in our understanding of the brain architecture can be addressed, which could in turn lead to a better understanding of pathologies that disrupt the brain’s architecture. It is hypothesized that the brain will be more integrated during reward processing, and that increased dopamine and norepinephrine activity will result in a more integrated brain organisation. To test this prediction, the Global Efficiency (GE) of a total of 132 Regions of Interest (ROIs) and BOLD- activity of the Substantia Nigra/Ventral Tegmental Area (SN/VTA) and the Locus Coeruleus (LC) were obtained during a reward processing task, which 38 participants completed. During a functional magnetic resonance imaging (fMRI) scan, participants completed a reward- emotion recognition test. As predicted, in the reward condition, the paired t-test showed a higher GE in comparison to the no-reward condition in several nodes, mostly in the default mode network. These findings imply that the brain is more integrated when processing reward than when it is not processing reward. However, the catecholamines showed no significant correlation with this integration. Future research is needed to investigate the topology and influence of different catecholamines in more detail. The implications of these findings will be discussed.Show less
Background Alzheimer's dementia (AD) and mild cognitive impairment (MCI) are neurodegenerative conditions associated with cognitive decline. Previous research suggests that motor impairments are...Show moreBackground Alzheimer's dementia (AD) and mild cognitive impairment (MCI) are neurodegenerative conditions associated with cognitive decline. Previous research suggests that motor impairments are also present in individuals with MCI and AD. This thesis study aims to evaluate motor sequence learning abilities in patients with amnestic MCI (aMCI) and AD compared to healthy controls. This thesis study also explores the relationship between amyloid-β burden, a known biomarker for MCI and AD, and motor sequence learning to study whether such motor learning could also be a behavioral biomarker. This is because measuring amyloid-β is very costly and invasive, and thus the search for other biomarkers is important. Methods A cross-sectional design was employed, and participants included 28 AD patients, 33 aMCI patients, and 53 healthy controls. Motor sequence learning was assessed using a computerized task measuring reaction time and accuracy per trial, and with this information the rate and final amount of learning was calculated, i.e. how fast and how much information the participants are able to learn, respectively. Amyloid-β burden was measured using PET imaging, with higher burden reflecting more severity of the symptoms of aMCI and AD. Results The final amount of learning was not different amongst the groups, and the rate of learning was only significantly different between the AD and aMCI groups, with the AD groups showing a faster rate of learning. The AD and healthy control group did not, however, differ significantly in terms of rate of learning. The amount of amyloid-β in the brain was not associated with motor sequence learning abilities. Conclusion The findings suggest that motor sequence learning abilities are preserved in individuals with aMCI and AD, both in terms of how fast and how much they learn. In fact, patients with AD showed a faster rate of learning than patients with aMCI, although this was not found when comparing the AD patients with the healthy individuals. It is possible that this finding is because patients had more to learn by the end of the task than the aMCI group given that their memory is worse, and displayed a faster rate of learning due to this. This thesis study also suggests that motor sequence learning is not a behavioral biomarker for aMCI and AD. The search for less invasive and more easily measurable biomarkers continues to be imperative.Show less
The current study examined to what extent the quality of the sibling relationship and the quality of the parent-child relationship is linked to aggressive behavior between siblings during conflicts...Show moreThe current study examined to what extent the quality of the sibling relationship and the quality of the parent-child relationship is linked to aggressive behavior between siblings during conflicts. In addition, it was examined whether the quality of the parent-child relationship would moderate the relation between the quality of the sibling relationship and aggressive behavior between siblings during conflict. These relations were examined with a sample of 26 families, of which two siblings aged 8-15 years old and one parent participated. The amount of aggressive behavior during conflicts between siblings, quality of the sibling relationship and the quality of the parent-child relationship were measured by questionnaires. The results of this study showed a negative relation between the sibling relationship quality and aggressive behavior during conflicts between siblings, a positive relation between the quality of the sibling relationship and the quality of the parent-child relationship and a negative relation between the quality of the parent-child relationship and aggressive behavior during conflicts between siblings. The quality of the parent-child relationship did not act as a moderator for the relationship between the quality of the sibling relationship and the degree of aggressive behavior in conflicts between siblings. These results indicate a possible indirect role of the parent-child relationship quality in the degree of aggressive behavior in conflicts between siblings.Show less
In a world of rising economic inequality, exploring factors that contribute to a more equal society is vital. The extent to which people are generous towards those around them can help reduce local...Show moreIn a world of rising economic inequality, exploring factors that contribute to a more equal society is vital. The extent to which people are generous towards those around them can help reduce local inequalities. While previous literature has established a link between economic mobility and preferences for redistribution, the impact on individual giving remains unclear. Therefore, this study examined the influence of economic mobility on giving behavior and whether meritocratic beliefs mediate this effect. The sample included 301 participants, predominantly from Global South countries. Participants were randomly assigned to ranks on a 5-rank ladder resembling socioeconomic classes and to conditions of low or high economic mobility. First, participants played a game in which they estimated the number of dots in a picture. Those with high economic mobility could earn 3 points, and those with low economic mobility could earn 1 point per round. In a dictator game, they could indicate how many points they want to give to reach rank. Results showed that the high economic mobility condition had significantly stronger meritocratic beliefs about the estimation game, aligning with the first hypothesis. However, contrary to the second hypothesis, participants in the high economic mobility condition gave significantly more to the ranks below them. Meritocratic beliefs about the estimation game did not mediate the effect. This suggests that inducing high economic mobility seems to increase generosity, particularly towards those with fewer resources. Policymakers and non-governmental organizations should promote high economic mobility to foster generosity in society.Show less
Autism spectrum disorder (ASD) is a developmental disorder that still holds many uncertainties regarding the etiology. In order to provide the most effective assistance to children with ASD,...Show moreAutism spectrum disorder (ASD) is a developmental disorder that still holds many uncertainties regarding the etiology. In order to provide the most effective assistance to children with ASD, understanding the cognitive foundation of this disorder is crucial. There are several theories on this subject, yet there is limited research delving deeper into the potential connections between these theories. This research focused on the Central Coherence Theory and the Executive Dysfunction Theory and investigated whether there is a relation between these factors in explaining ASD. For this purpose, the Rey-Osterrieth Complex Figure Task, Tower of Hanoi, Picture Span and Autism Spectrum Questionnaire were administered to 89 children aged between 8 and 11 from six different primary schools in the Netherlands. Correlation analyzes were conducted to examine whether performance on central coherence, planning, and working memory correlated with the level of ASD traits. Using the PROCESS Macro, a mediation analysis was conducted to investigate whether executive functions could mediate the relationship between central coherence and ASD characteristics. The results of this study indicated that neither central coherence nor planning nor working memory were associated with the number of ASD characteristics. Moreover, no mediating effect of planning or working memory could be found. The fact that the results were not in line with the expectations could possibly be related to the non-clinical sample used in the current study, among other things. Future research should continue to focus on further investigation into the relationship between central coherence and executive functions, carefully taking into account the heterogeneity of ASD.Show less
Social media has become a platform for sharing alcohol and other drug (AOD) recovery journeys, with #selflove as a prominent theme. This study explores the association of self- views, positive...Show moreSocial media has become a platform for sharing alcohol and other drug (AOD) recovery journeys, with #selflove as a prominent theme. This study explores the association of self- views, positive emotions, and social connections in the context of social media, particularly regarding #selflove and in AOD recovery. Specifically, social connections are examined as they are considered to be a relevant point of support during the recovery process. Positive emotions are examined, as employing a more positive outlook towards oneself is associated with a more positive self-view and a more sustained recovery process. The dataset comprises 902 posts from Instagram and Twitter in 2019 collected by Ziemer (2022). The present study addresses two research questions: (1) What is the association between positive and negative self-views in social media posts using chi-square analysis to identify a balanced self-view (discussing negative and positive self-views) during the recovery journey, (2) to what extent can positive self-view mentions be predicted through logistic regression, based on expressed connectedness with family/friends, the AOD recovery community, and positive emotions in the posts. Surprisingly, the results challenge the initial hypothesis of predominantly balanced self-views in these posts, as no association was found between mentioning positive and negative self-views within a single post. Contrary to expectations, mentioning positive self- views was not linked to references to connecting with others or positive emotions. Future research should employ more nuanced coding for emotions and social connections. Qualitative measures can help capture potential differences between sharing one's recovery journey online and the actual offline experience.Show less
Competency-based intervention is an approach in youth services focusing on enhancing skills aligned with age-appropriate developmental tasks. It is employed across various contexts and for diverse...Show moreCompetency-based intervention is an approach in youth services focusing on enhancing skills aligned with age-appropriate developmental tasks. It is employed across various contexts and for diverse target populations. However, the extent of evidence supporting this method in literature is unclear. This thesis synthesizes multiple sources to provide a comprehensive overview of to which extend this topic has been researched: What is known about this methodology, its strengths and weaknesses, and the specific target groups under investigation? Through a narrative review, ten evidence-based and seven non-evidence-based sources have been integrated to present a holistic perspective on the field of competency-based intervention. Several sources have indicated that the application of this model is effective in improving behavior and psychosocial conditions, including youth residing in residential facilities, high-risk families, adolescents with severe psychiatric/behavioral issues, and elementary school children with antisocial behavior. Although indications have been found that this method brings many advantages in practice, it was concluded that there is not enough evidence for competence-based work in the literature due to limitations in the studies. There is a need for further research to assess the effectiveness of this widely used approach.Show less
Aim: In recent years, a lot of attention has been paid to improving the care and support of people with intellectual disabilities. A consequence is that many studies have been conducted into the...Show moreAim: In recent years, a lot of attention has been paid to improving the care and support of people with intellectual disabilities. A consequence is that many studies have been conducted into the effects of support on the well-being of people with an intellectual disability. But research into groups that have improved, deteriorated or remained the same in terms of quality of life in combination with support needs was lacking. Therefore, the purpose of this study is to investigate the characteristics of the forward, backward and equal groups and to discover whether the groups differ in support needs. This is relevant because it can improve care and support. Method: Over a period of 4 years, 234 participants with an intellectual disability between the ages of 17 and 71 took part. To measure the quality of life of people with an intellectual disability, the San Martin Scale was used, completed by a supervisor. The support needs were identified with the Contextual Interview, this was done with the help of family, psychologist and supervisors. Both measuring instruments were administered three times in 4 years. Results: the results show that the quality of life differs over time. The forward, backward and equal groups differ in the domains: housing, communication, attachment, self-determination and physical needs. This research suggests that housing, communication, attachment and (physical) needs influence the progression of quality of life. Conclusion: the findings show that there are differences between the forward, backward and equal groups on domains of support needs. This research suggests that good support per domain leads to improvement or stabilization of the quality of life of people with an intellectual disability.Show less
Conduct Disorder (CD) is a common psychiatric disorder of childhood and adolescence characterized by severe aggressive and antisocial behaviors that often result in impaired social, academic, or...Show moreConduct Disorder (CD) is a common psychiatric disorder of childhood and adolescence characterized by severe aggressive and antisocial behaviors that often result in impaired social, academic, or occupational functioning. The subtype CD with callous-unemotional (CU) traits has been suggested to be part of the developmentary trajectory of psychopathy, with both being linked to amygdalar volume deficits. Research into the neurodevelopmental perspective of CD/CU+ has been inconsistent due to methodological, demographic and cultural factors. Therefore, the current study examined amygdala morphology in two matched juvenile groups: CD offenders (N = 51) and healthy control subjects (HC; N = 36). In an additional set of analyses, the CD group was divided in two subgroups: CD with CU traits (CD/CU+; N = 26), CD without CU traits (CD/CU-; N = 25), and compared to HC participants. Additionally, the influence of CU traits on brain morphology was assessed in a dimensional manner across all participants (N = 87). Analyses revealed significant lower left amygdalar volumes in all CD youth compared to HC youth, while no significant differences emerged in the right amygdalar volumes. Furthermore, no significant differences in amygdalar volumes emerged between CD/CU- vs. CD/CU+ vs. HC youths. Moreover, the severity of CU traits did not relate to brain morphology in a dimensional manner across all participants. The current findings reflect the complexity and inconsistency of research into the relationship between brain morphology and CD diagnosis, and add to the research into the neurodevelopmental perspective of CD/CU+Show less
Objective: Informal caregivers of palliative care patients face many challenges and are in need of support by healthcare providers. We aim to assess the care provided to informal caregivers, the...Show moreObjective: Informal caregivers of palliative care patients face many challenges and are in need of support by healthcare providers. We aim to assess the care provided to informal caregivers, the effects of healthcare providers’ background characteristics and actions undertaken to improve the care provided in healthcare organizations. Method: A cross-sectional mixed-method approach was applied. Questionnaires were used for statistical analysis. First, the care provided to informal caregivers (i.e. basic emotional care and specific care tasks) was examined using descriptive statistics. Second, the effects of healthcare providers’ background characteristics (i.e. healthcare setting, profession, age and work experience) on the care provided were examined using bivariable analyses and general linear model (GLM). Third, actions to improve the care provided in healthcare organizations were examined using qualitative conventional content analysis. Journey mapping workshops provided input for the 19 analyzed action plan reports. Results: 586 healthcare providers and volunteers of 19 Dutch healthcare organizations completed the questionnaire (response rate: 49%). First, participants had an average basic emotional care of 6.70 (SD = 3.33, 0-10 range) and an average of specific care tasks of 8.51 (SD = 2.89, 0-13 range). Second, volunteers and paramedics scored lower than other healthcare providers on basic emotional care (p = .003, p = .012) and volunteers scored lower on specific care tasks (p = .012). The age of healthcare providers and volunteers seemed to have a quadratic effect on the basic emotional care (p = .017) with an increase until 45-55 years. The same effect was found on specific care tasks (p = 0.042) after excluding the volunteers. Third, improvement categories were derived from the action plan reports. For individual healthcare providers: care and support for informal caregivers during the illness-trajectory, bereavement care for informal caregivers, cooperation with informal caregivers, interprofessional cooperation. For healthcare organizations: organizational support. Discussion: The care provided to informal caregivers is still in need of improvement. The age and profession of healthcare providers were found to affect the care provided. The actions found to improve the care provided to informal caregivers are promising and can be a source of inspiration for healthcare organizations.Show less
Changes in social cognition, encompassing all cognitive processes that underlie social interaction, have been noted in various types of dementia. Theory of Mind (ToM) is a key aspect of social...Show moreChanges in social cognition, encompassing all cognitive processes that underlie social interaction, have been noted in various types of dementia. Theory of Mind (ToM) is a key aspect of social cognition, defined as the ability to understand the mental state of another person, including their emotions, intentions and beliefs. Cartoon tests aim to adopt humour using cartoon jokes to assess ToM. In this study, a new Dutch cartoon test aimed to be applicable in clinical assessment of dementia was developed and validated. The test includes 12 cartoons (6 requiring ToM to understand the joke and 6 that do not), which were collected through an extensive search and were rated by experts (n = 17) on content and funniness. Normative data for the selected cartoons was obtained by control participants (n = 39), through annotation of these, scoring categories were formed. The test was then validated in a clinical sample, including patients referred to a memory clinic for cognitive complaints and suspected dementia (n = 9), in an observational cross-sectional study with a case-control type selection of participants. Patients were expected to score lower on the cartoon test than controls. An ANCOVA with demographic variables as covariates was performed: no significant differences between patients (n = 9) and control participants (n = 9) were found (p > .05). Further, the internal validity (Cronbach’s α of .864 for the total cartoon test) and convergent validity of test was good. Divergent validity was found to be questionable. Regarding demographics: females were expected to score higher than males; older participants were expected to score higher than younger participants; and higher educated participants were expected to score higher than lower educated participants on the cartoon test. A Mann-Whitney U analysis showed no gender differences (p > .05); assessment of Spearman-rank order correlation coefficients showed age was significant in its negative relation to cartoon test performance (p < .05); and education level significant in its positive relation to test performance (p < .05). Future investigation with a larger patient sample including differential dementia diagnoses is recommended to substantiate the results and make the test clinically applicable.Show less
Itch is a somatosensory stimulus and could potentially alter performance of daily activities. Since itch stimuli will signal potential danger, one might want to protect oneself from potential harm...Show moreItch is a somatosensory stimulus and could potentially alter performance of daily activities. Since itch stimuli will signal potential danger, one might want to protect oneself from potential harm by adapting ones behaviour. Pleading itch stimuli demands ones attention, which can be called the attentional bias (AB). Adapting ones behaviour might influence the effectiveness of treatment, due to not paying attention to the treatment. So far, an AB has been found in healthy individuals, but evidence is mixed. In addition, it is unclear if an AB is present in patients who experience chronic itch. Therefore, this study investigated attentional bias towards itch related visual stimuli in participants who suffer from chronic itch (N=34) compared to healthy controls (N=36). Attentional bias was measured in an online study with two attention tasks, the dot-probe paradigm and the spatial-cuing paradigm using itch-related pictures. During the dot-probe task, patients with chronic itch showed the presence of an AB. Yet, the results acquired from the spatial-cuing task showed the presence of an AB in every participant in disregard of the group they were in. This is not in line with previous research. However, previous research only investigated healthy individuals. Furthermore, all participants reacted faster on invalid trials once an itch cue was presented. One might interpret this as having an attentional avoidance of threat. Yet, also healthy participants seemed to react faster, which perhaps indicates that the itch cue is an overall negative cue regardless of having a past with itch. The discrepancy between the two attention tasks is remarkable, and could perhaps be ascribed to the different processing skills the two tasks ask from the participant. Therefore, future research should focus on the different components of attentional processing. This could eventually optimize current treatment/intervention options.Show less
Central coherence is the ability to perceive, process and integrate incoming information to put it in the right context and give it meaning. Central coherence is an important skill that aids people...Show moreCentral coherence is the ability to perceive, process and integrate incoming information to put it in the right context and give it meaning. Central coherence is an important skill that aids people in understanding situations they encounter in daily life but is also an important skill to support the process of learning. After all, new information has to be processed, organised and integrated, taking into account overall context and meaning. Research into autism spectrum disorders (ASD) in the past 4 decades has provided multiple findings that indicate that people with ASD have weak central coherence skills and therefore lack the ability to create meaningful or coherent wholes, but research findings have been mixed. In this study a process-oriented dynamic version of the Rey-Osterrieth Complex Figure (ROCF), in which the training part was built up according to the ‘graduated prompts’ method, was used to measure and train central coherence. Furthermore, the potential relationship between ASD characteristics of the children in this study and central coherence or improved central coherence following training was assessed. The participants in this study consisted of 49 pupils in grade 5 or 6 of regular Dutch primary school education (M = 8.96 years, SD = .76 years). The dynamic test, including training based on the ‘graduated prompts’ method, lead to significantly more progression in structuring the drawing of the complex figure compared to the unguided control group. Regarding a potential relationship between ASD characteristics and central coherence or improved central coherence, no relationship was found in this study.Show less
In this thesis the relative spectral energy density of stochastic primordial gravitational waves is investigated. Decoupling of Standard Model particles and neutrino free-streaming affect the...Show moreIn this thesis the relative spectral energy density of stochastic primordial gravitational waves is investigated. Decoupling of Standard Model particles and neutrino free-streaming affect the expansion history of the universe and thus leave characteristic signatures on the amplitude of the gravitational wave spectrum. Adding extra light or heavy particles damps the spectrum at frequencies before the particle decouples. Including an extra neutrino species amplifies the spectrum at larger wave numbers, but damps it at shorter wave numbers. Measuring these primordial gravitational waves reveals the thermal history of the universe. One possible non-standard thermal history is early matter domination due to the inflaton. It is shown that, in this cosmology, the end of early matter domination and beginning of the radiation era depend linearly on the reheating temperature.Show less
Earlier research suggests that some exercise intensities are more beneficial to enhance creativity than others. However, if and why specific exercise intensities are related to better creativity is...Show moreEarlier research suggests that some exercise intensities are more beneficial to enhance creativity than others. However, if and why specific exercise intensities are related to better creativity is not exactly clear yet. This study aimed to gain insight into which exercise intensity is best for improving creativity and to explore the possible role of physical fitness in the relationship between exercise intensity and creativity. This is the first study in which participants were given a more objective individually-tailored instruction with regard to exercise intensity and in which four conditions (low intensity exercise, moderate-intensity exercise, high-intensity exercise and a control condition) were compared with respect to the enhancement of divergent creativity (including fluency and originality). First, it was expected that moderate-intensity is best to enhance creativity compared to low intensity exercise, highintensity exercise and no exercise. Second, it was expected that creativity is enhanced more after someone exercises at an intensity level that matches his/her level of physical fitness compared to someone exercising at an intensity level that does not match his/her physical fitness. A total of N = 73 students were studied. A between-subjects design was used in which participants were randomly assigned to one of the four conditions. The participants had to visit the lab of Leiden University twice. First they had to perform a physical fitness test and then they were randomly assigned to one of the four conditions and they had to do a task that measured divergent creativity. For the first hypothesis, the Two-Way ANOVA indicated that neither the fluency (η² = .009, p = .88) nor the originality scores (η² = .006, p = .94) differed between conditions. For the second hypothesis, the Two-Way ANOVA indicated that neither the fluency (η² = .024, p = .19) nor the originality scores (η² = .008, p = .45) differed between participants who had a match or non-match between their physical fitness level and the assigned exercise intensity. The results suggest that changing exercise intensity and matching exercise intensity to physical fitness level do not make a difference in the improvement of creativity.Show less
Aggressive behaviour is one of the most common behavioural issues in children and adolescents. Given its negative effects on social, emotional and academic development, early intervention is deemed...Show moreAggressive behaviour is one of the most common behavioural issues in children and adolescents. Given its negative effects on social, emotional and academic development, early intervention is deemed necessary. This study investigated the predictive role of emotion regulation and executive functioning, along with the mediating role of emotion regulation in the relationship between executive functioning and aggression problems. This current correlational study is part of the TRIXY project. The sample consisted of 47 children between the ages of three and seven year old. Aggression was measured using the Child Behaviour Checklist, emotion regulation was measured using the Child Behaviour Questionnaire – Very short form and the executive functions inhibition, planning ability, working memory and cognitive flexibility were measured using the Behavior Rating Inventory of Executive Functions (BRIEF) and the BRIEF-P. The findings indicated that children who experienced more difficulties in executive functioning exhibited heightened levels of aggressive behaviour. Additionally, research showed that emotion regulation is a mediating factor in the relation between executive functioning and aggression. However, the relation between these three constructs differ when splitting the sample in a group consisting of children aged three to four years of age and a group consisting of children who are five to seven years of age, indicating that the relation between these three constructs changes during development. Furthermore, research showed that inhibition, working memory, and cognitive flexibility were predictors of emotion regulation problems and aggression, with inhibition being the most significant predictor of aggression in all ages. Results showed no relation between planning ability, emotion regulation and aggression. This research contributes to the development of effective interventions and the understanding of the development of aggression.Show less
Job Burnout (JB) is a demanding syndrome that leaves employees exhausted and dealing with cognitive and emotional problems, with symptoms lasting up to 10 years. To understand why JB symptoms...Show moreJob Burnout (JB) is a demanding syndrome that leaves employees exhausted and dealing with cognitive and emotional problems, with symptoms lasting up to 10 years. To understand why JB symptoms pertain for so long, different resource theories were integrated to investigate the impact of JB on an individual gain process between job resources, personal resources, and recovery gained through physical exercise. It was predicted that skill discretion (SD), a common job resource, increases the personal resource self-efficacy (SE) which, in turn, enhances the recovery gained from physical exercise. This gain process was proposed to be dampened by JB, leaving employees with higher JB symptoms in a less advantageous position for resource gain as compared to those with lower symptoms. Using longitudinal data across three workweeks, self-report questionnaires were administered among full-time employees (N = 163). Although correlations revealed that the proposed relationships were found at specific weeks, hierarchical regression analyses revealed no across-time relationships, meaning no weekly gain process could be identified between SD, SE, and recovery gained through exercise. In addition, against expectations, no negative impact of JB on the gain process was found. Thus, the exact relationships between job resources, personal resources, recovery gained through exercise, and JB remain unclear. Future research is needed to further investigate these relationships preferably by using a different time lag than one week and by applying different roles of personal resources within the Job Demands-Resources framework.Show less
