Betz, Linda Theresia 
ORCID: 0000-0003-1741-4069
(2022).
Towards Understanding the Role of Environmental Risk Factors in Psychosis and Beyond: A Data-Driven Network Approach.
PhD thesis, Universität zu Köln.
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Abstract
Psychotic disorders impose high burden on both the affected individual and society. Despite extensive research efforts in recent decades, their etiology remains poorly understood, hindering progress in prevention and treatment. Two distinct developments in the field may represent ways forward: First, there is a growing recognition of the importance of several potentially malleable environmental risk factors, such as childhood trauma, stressful life events, or cannabis use, in the onset, progression, and maintenance of psychotic disorders. Second, the ubiquitous common cause model of psychotic disorders is increasingly challenged by alternative conceptualizations of mental disorders, such as the network approach to psychopathology. In the common cause model, symptoms are viewed as mere effects of a common cause (the disorder itself, e.g., ‘schizophrenia’), i.e., symptoms covary because of their joint dependence on an assumed latent disorder entity. This traditional view also assumes that environmental factors influence symptoms via the disorder entity. In contrast, the network approach to psychopathology views mental disorders as networks of directly interacting symptoms and other components, such as environmental risk factors. Patterns of covariation between symptoms and other components are assumed to reflect meaningful relationships and become the focus of analysis. Building upon these developments, this thesis proposes a network approach to disentangle potential pathways by which environmental risk factors increase the risk for psychotic disorders. Specifically, the five presented papers focus on individual symptoms and their associations with common environmental risk factors of psychotic disorders. Network structures were generated from empirical data by estimating unique pairwise relationships, i.e., the associations between any two variables that remain after controlling for all other variables under consideration; primarily in the form of undirected pairwise Markov random fields. The first paper built upon evidence for an affective pathway from childhood trauma to psychosis and demonstrated that a similar pathway applied to exposure to recent stressful life events in at-risk and recent onset psychosis patients. Specifically, results showed that burden of recent life events did not link to positive and negative psychotic symptoms directly, but only indirectly, via symptoms of general psychopathology, such as depression, guilt, and anxiety. The second paper zoomed into the proposed affective pathway via increased stress reactivity through which childhood trauma is thought to contribute to the liability for psychopathology at large, including psychotic disorders. The findings provide a detailed characterization of putative psychological stress processes underlying distinct types of childhood trauma in the general population: childhood trauma reflecting deprivation (i.e., neglect) was exclusively associated with stressful experiences representing low perceived self-efficacy, whereas childhood trauma reflecting threat (i.e., abuse) was specifically associated with stressful experiences reflecting perceived helplessness. The third paper then addressed another important risk factor for psychotic disorders, cannabis use. The results suggest that characteristics of cannabis use in the general population may contribute differentially to the risk for certain psychotic experiences and affective symptoms: Network associations were particularly pronounced between increased frequency of cannabis use and certain delusional experiences, i.e., persecutory delusions and thought broadcasting, on the one hand, and earlier onset of cannabis use and visual hallucinatory experiences and irritability, on the other. The fourth paper investigated which environmental and demographic factors explained heterogeneity in symptom networks of psychosis to highlight potential etiological divergence in risk for psychosis in the general population. Results point to distinct sex-specific etiological mechanisms contributing to psychosis risk: In women, an affective pathway to psychosis may have distinct importance, especially after interpersonal trauma. In men, an ethnic minority background was associated with strong interconnections between individual psychotic experiences, which has been linked to poor outcomes in previous research. The fifth and final paper presented the protocol for an experience sampling study in the help-seeking population of the Early Recognition Center for Mental Disorders of the University Hospital Cologne. A central goal in this project will be to elucidate how personalized symptom networks derived from intensive longitudinal data differ as a function of environmental exposure. In sum, findings from this thesis illustrate that environmental risk factors increase psychosis risk through diverse, potentially sex-specific pathways that often involve affective psychopathology. This confirms the notion that the etiology of psychosis is complex and best understood from a broad, transdiagnostic perspective. The results presented are also relevant for clinical practice as they pave the way for a better selection of appropriate interventions and treatments. In particular, this thesis highlights affective disturbances and negative beliefs as potential intervention targets in the affective pathway to psychosis, especially following trauma and stressful life events. In perspective, the use of personalized network approaches may improve the ability to tailor therapeutic strategies based on the dynamics of a patient’s symptoms and environmental risk factors as captured in daily life. Recently proposed multilayered network approaches have potential to further advance our understanding of psychosis etiology by linking psychological and biological levels of analysis.
| Item Type: | Thesis (PhD thesis) | ||||||||
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| URN: | urn:nbn:de:hbz:38-627413 | ||||||||
| Date: | 2022 | ||||||||
| Language: | English | ||||||||
| Faculty: | Faculty of Medicine | ||||||||
| Divisions: | Faculty of Medicine > Psychiatrie und Psychotherapie | ||||||||
| Subjects: | Psychology Medical sciences Medicine |
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| Date of oral exam: | 9 June 2022 | ||||||||
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| Refereed: | Yes | ||||||||
| URI: | http://kups.ub.uni-koeln.de/id/eprint/62741 |
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