Yves Rosseel

On the definition of signal-to-noise ratio and contrast-to-noise ratio for FMRI data.

Signal-to-noise ratio, the ratio between signal and noise, is a quantity that has been well established for MRI data but is still subject of ongoing debate and confusion when it comes to fMRI data. fMRI data are characterised by small activation fluctuations in a background of noise. Depending on how the signal of interest and the noise are identified, signal-to-noise ratio for fMRI data is reported by using many different definitions. Since each definition comes with a different scale, interpreting and comparing signal-to-noise ratio values for fMRI data can be a very challenging job. In this paper, we provide an overview of existing definitions. Further, the relationship with activation detection power is investigated. Reference tables and conversion formulae are provided to facilitate comparability between fMRI studies.

The relationship between the perception of distributed leadership in secondary schools and teachers' and teacher leaders' job satisfaction and organizational commitment

This study investigates the relation between distributed leadership, the cohesion of the leadership team, participative decision-making, context variables, and the organizational commitment and job satisfaction of teachers and teacher leaders. A questionnaire was administered to teachers and teacher leaders (n = 1770) from 46 large secondary schools. Multiple regression analyses and path analyses revealed that the study variables explained significant variance in organizational commitment. The degree of explained variance for job satisfaction was considerably lower compared to organizational commitment. Most striking was that the cohesion of the leadership team and the amount of leadership support was strongly related to organizational commitment, and indirectly to job satisfaction. Decentralization of leadership functions was weakly related to organizational commitment and job satisfaction.

JEM Spotlight: Fungi, mycotoxins and microbial volatile organic compounds in mouldy interiors from water-damaged buildings

Concerns have been raised about exposure to mycotoxin producing fungi and the microbial volatile organic compounds (MVOCs) they produce in indoor environments. Therefore, the presence of fungi and mycotoxins was investigated in 99 samples (air, dust, wallpaper, mycelium or silicone) collected in the mouldy interiors of seven water-damaged buildings. In addition, volatile organic compounds (VOCs) were sampled. The mycotoxins were analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) (20 target mycotoxins) and quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). Morphological and molecular identifications of fungi were performed. Of the 99 samples analysed, the presence of one or more mycotoxins was shown in 62 samples by means of LC-MS/MS analysis. The mycotoxins found were mainly roquefortine C, chaetoglobosin A and sterigmatocystin but also roridin E, ochratoxin A, aflatoxin B(1) and aflatoxin B(2) were detected. Q-TOF-MS analysis elucidated the possible occurrence of another 42 different fungal metabolites. In general, the fungi identified matched well with the mycotoxins detected. The most common fungal species found were Penicillium chrysogenum, Aspergillus versicolor (group), Chaetomium spp. and Cladosporium spp. In addition, one hundred and seventeen (M)VOCs were identified, especially linear alkanes (C(9)-C(17)), aldehydes, aromatic compounds and monoterpenes.

Psychometric Properties of the Dutch Rosenberg Self-Esteem Scale

Interest in self-esteem has been fuelled by the suggestion that level of self-esteem is associated with psychological well-being. In the present study, we translated the Rosenberg Self-Esteem Scale (RSES) into the Dutch language and evaluated its psychometric properties in a sample of 442 adults. The results of both exploratory and confirmatory factor analyses confirmed that a single-factor solution provides the best fit. In addition, the Dutch RSES showed high internal consistency as well as high congruent validity. Overall, these findings support the usefulness of the Dutch RSES as a measure for global self-esteem.

The psychological impact of forced displacement and related risk factors on Eastern Congolese adolescents affected by war

BACKGROUND While the current knowledge base on the mental health effects of displacement is mainly limited to refugees residing in industrialised countries, this paper examines the impact of war-induced displacement and related risk factors on the mental health of Eastern Congolese adolescents, and compares currently internally displaced adolescents to returnees and non-displaced peers. METHODS Data were collected from a community sample of 819 adolescents aged 13 to 21 years, attending one of 10 selected schools across the Ituri district in the Democratic Republic of Congo. Respondents completed culturally adapted self-report measures of posttraumatic stress symptoms (using the Impact of Event Scale - Revised) and internalising and externalising behaviour problems (by means of the Hopkins Symptoms Checklist - 37 for Adolescents). Associated factors studied were age, sex, parental death, exposure to war-related violence and daily stressors. RESULTS Internally displaced persons (IDPs) reported highest mean scores for the IES-R and the HSCL-37A internalising scale, followed by returnees, while non-displaced adolescents scored significantly lower. However, ANCOVA tests showed that posttraumatic stress and internalising symptoms were mainly associated with traumatic exposure and daily stressors and not with displacement status. Externalising problem scores were associated with traumatic exposure, daily stressors and displacement. Remarkably, death of father was associated with fewer externalising problems. Sex was differently associated with internalising and externalising problems through traumatic and daily stressors. CONCLUSIONS As IDPs are highly exposed to violence and daily stressors, they report most psychological distress, when compared to returnees and non-displaced peers. The distinct mental health outcomes for returned youngsters illustrate how enhancing current socio-economic living conditions of war-affected adolescents could stimulate resilient outcomes, despite former trauma or displacement.

Unfavourable family characteristics and their associations with childhood obesity: a cross-sectional study

OBJECTIVE This cross-sectional study explores the influence of multiple familial factors on childrens weight status and the interaction between parenting stress and unfavourable family characteristics. METHODS A total of 197 families with children between 6 and 14 years participated in this study. Of this group, 97 families had a child with normal weight and 100 families had a child with overweight. Parents reported on seven family factors (maternal BMI, number of children, family structure, socioeconomic position, life events, parental psychopathology and parenting stress). RESULTS Families with overweight children experience more parenting stress. A regression analysis revealed that familial factors explain 27% in the variance in childs weight status. The hypothesis that a combination of familial factors will be more able to explain childs adiposity could not be confirmed. CONCLUSIONS Familial factors have moderate ability to predict childrens weight status. There is a need to identify other familial mechanisms taking into account developmental and temporal evolutions over the past decade.

Development and Validation of Scores on the Distributed Leadership Inventory

Systematic quantitative research on measuring distributed leadership is scarce. In this study, the Distributed Leadership Inventory (DLI) was developed and evaluated to investigate leadership team characteristics and distribution of leadership functions between formally designed leadership positions in large secondary schools. The DLI was presented to a sample of 2,198 respondents in 46 secondary schools. The input from a first subsample was used to perform exploratory factor analyses; the second subsample was used to verify the factor structure via confirmatory factor analysis. A one-factor structure for the leadership team characteristics (coherent leadership team) and a two-factor structure for the leadership functions (support and supervision) were confirmed. The results of the DLI underpin that leading schools involve multiple individuals, which differs by the type of function.

Maladaptive schemas and psychopathology in adolescence: on the utility of Young’s schema theory in youth

The present article reports on two studies that investigated the utility of Young’s cognitive theory Young et al. (Schema therapy: A practitioner’s guide, Guilford Publications, New York, 2003) in adolescents. Study 1 focused on the factorial validity of the Young Schema Questionnaire (YSQ) in youth. In Study 2, the dimensionality of Young’s schemas and their (content-specific) association with psychopathology were investigated. In Study 1, 635 adolescents were asked to complete the YSQ. In Study 2, participants were 112 non-referred and 104 referred adolescents. They were interviewed with the Structured Clinical Interview for DSM-IV–Child edition and completed the YSQ and the Youth Self Report. Their parents were asked to fill out the Child Behavior Checklist. It was demonstrated that Young’s theoretically proposed taxonomy of schemas and domains can be retrieved in adolescents. Referred youth displayed a higher severity of maladaptive schemas as compared with non-referred adolescents. A content-specific association of schemas and psychopathology was established. Young’s schema theory might constitute a valuable framework to understand psychopathology in youth.

Can the Children's Communication Checklist differentiate autism spectrum subtypes?

The study explored whether children with high functioning autism (HFA), Asperger syndrome (AS), and pervasive developmental disorder not otherwise specified (PDD-NOS) can be differentiated on the Childrens Communication Checklist (CCC). The study also investigated whether empirically derived autistic subgroups can be identified with a cluster analytic method based on the Autism Diagnostic Interview–Revised. Fifty-seven children with HFA, 47 with AS, 31 with PDD-NOS, and a normal control group of 47 children between 6 and 13 years participated. Children with HFA,AS, and PDDNOS showed pragmatic communication deficits in comparison to the controls. Little difference was found between the three subtypes with respect to their CCC profile.A three-cluster solution explained the data best.The HFA cluster showed most autism characteristics, followed by the combined HFA + AS cluster, and then the PDD-NOS cluster. The findings support the autism spectrum concept based on severity of symptom impairment rather than distinct categories.

White matter hyperintensities and imaging patterns of brain ageing in the general population

White matter hyperintensities are associated with increased risk of dementia and cognitive decline. The current study investigates the relationship between white matter hyperintensities burden and patterns of brain atrophy associated with brain ageing and Alzheimers disease in a large populatison-based sample (n = 2367) encompassing a wide age range (20-90 years), from the Study of Health in Pomerania. We quantified white matter hyperintensities using automated segmentation and summarized atrophy patterns using machine learning methods resulting in two indices: the SPARE-BA index (capturing age-related brain atrophy), and the SPARE-AD index (previously developed to capture patterns of atrophy found in patients with Alzheimers disease). A characteristic pattern of age-related accumulation of white matter hyperintensities in both periventricular and deep white matter areas was found. Individuals with high white matter hyperintensities burden showed significantly (P < 0.0001) lower SPARE-BA and higher SPARE-AD values compared to those with low white matter hyperintensities burden, indicating that the former had more patterns of atrophy in brain regions typically affected by ageing and Alzheimers disease dementia. To investigate a possibly causal role of white matter hyperintensities, structural equation modelling was used to quantify the effect of Framingham cardiovascular disease risk score and white matter hyperintensities burden on SPARE-BA, revealing a statistically significant (P < 0.0001) causal relationship between them. Structural equation modelling showed that the age effect on SPARE-BA was mediated by white matter hyperintensities and cardiovascular risk score each explaining 10.4% and 21.6% of the variance, respectively. The direct age effect explained 70.2% of the SPARE-BA variance. Only white matter hyperintensities significantly mediated the age effect on SPARE-AD explaining 32.8% of the variance. The direct age effect explained 66.0% of the SPARE-AD variance. Multivariable regression showed significant relationship between white matter hyperintensities volume and hypertension (P = 0.001), diabetes mellitus (P = 0.023), smoking (P = 0.002) and education level (P = 0.003). The only significant association with cognitive tests was with the immediate recall of the California verbal and learning memory test. No significant association was present with the APOE genotype. These results support the hypothesis that white matter hyperintensities contribute to patterns of brain atrophy found in beyond-normal brain ageing in the general population. White matter hyperintensities also contribute to brain atrophy patterns in regions related to Alzheimers disease dementia, in agreement with their known additive role to the likelihood of dementia. Preventive strategies reducing the odds to develop cardiovascular disease and white matter hyperintensities could decrease the incidence or delay the onset of dementia.