Research into the relation between psychopathology and etiological factors has not yet resulted in clear findings. One of the probable causes is that most researchers use the categorical DSM-IV... Show moreResearch into the relation between psychopathology and etiological factors has not yet resulted in clear findings. One of the probable causes is that most researchers use the categorical DSM-IV Classification of mental disorders. A dimensional system has several advantages compared to categorical systems: comorbidity, lack of diagnostic agreement and arbitrary nature of used boundaries are no longer a problem. Our aim was to develop a model with dimensions that can adequately describe patients with mood- and anxiety disorders. This project used data collected through Routine Outcome Monitoring (ROM), a monitoring system for patient care. First, we validated a Dutch adaptation of an instrument based on the tripartite model. Next, we formulated an extension of this model with 5 dimensions. Consequently we presented a second model with 6 dimensions: feelings of worthlessness, fatigue, somatic arousal, anxious apprehension, phobic fear and tension. We used several analysis techniques to create a valid and reliable dimensional model. Each individual factor and the total of factors can be regarded as unidimensional measurement scales. This model can describe the clinical state of patients more specifically than the tripartite model, and can be used in subsequent research into etiological factors of psychopathology (e.g. endophenotype, genotype, trauma's, personality). Show less
There is a growing awareness that research of the etiology of depressive and anxiety disorders has been hampered by their strictly categorical definition in the Diagnostic and Statistical Manual ... Show moreThere is a growing awareness that research of the etiology of depressive and anxiety disorders has been hampered by their strictly categorical definition in the Diagnostic and Statistical Manual (DSM). The DSM uses a syndrome approach, which __ although beneficial for standardization - has inherent problems that make it suboptimal for research: high rates of (artificial) comorbidity, diagnostic heterogeneity and the unrealistic assumption of discontinuity between ill and healthy. A dimensional approach that focusses on the relative severity of continuous symptom domains could be more optimal but measurement and the added value of such dimensions has been debated. Therefore, this dissertation was aimed to investigate (1) the internal validity and possibility to measure dimensions and (2) their added value in etiological and clinical research. The results showed that measurement of dimensions can be optimized using self-report questionnaires. In addition, dimensions were shown to have added value in etiological and clinical research. Because of their specific and continuous nature, dimensions could be used to uncover symptom-specific and/or non-linear association. Together, the results suggest that dimensions of depression and anxiety have internal and external validity and have the potential to improve the psychiatric research. Show less
Hollander-Gijsman, M.E. den; Wardenaar, K.J.; Beurs, E. de; Wee, N.J.A. van der; Mooijaart, A.; Buuren, S. van; Zitman, F.G. 2012
