Clinical application of staging models in bipolar disorder

The studies in this thesis explored the rationale and utility of clinical staging models in bipolar disorder. There is a need for further improvement of diagnostics in psychiatry to organize the broad range of clinical expressions, to promote a longitudinal as opposed to cross-sectional perspective, that allows for efficient communication, and may guide a personalized treatment approach. Clinical staging models are a way to operationalize illness progression and may provide a solution in overcoming these issues. Staging models have been introduced and tested for several psychiatric illnesses such as depression, schizophrenia, personality disorders, anxiety disorders, alcohol use disorder as well as a model for all major mental health disorders This thesis described one of the first attempts to explore the validity and applicability of two staging models specifically designed for bipolar disorders (BD). In this thesis, we tested the two predominant staging models for BD by applying them to clinical data. Berk et al. proposed a staging model based on the recurrence of mood episodes, in some chapters referred to as Model A. A second staging model, in some chapters referred to as Model B, was proposed by Kapczinski et al. and is based on impaired inter-episodic functioning. We used five different approaches to apply these staging models to both longitudinal as well as cross-sectional clinical data, leading to five publications. Additionally, with the Staging Taskforce of the International Society for Bipolar Disorders, we defined a standardized nomenclature for the staging of BD. Lastly, we explored the similarities and differences between our current views on illness progression with those from the late 19th and early 20th century.