Pierced, tattooed, but manic?! - The influence of prototypicality on the diagnosis of borderline personality disorder and bipolar disorder

Kröber et al. (2023) have exploratively identified which diagnostically relevant and -irrelevant features characterize psychotherapists’ prototypes of selected mental disorders. This study builds on their work and examines the extent to which prototypicality affects the diagnosis of borderline personality disorder (BPD) and mania compared with the official diagnostic criteria. We aim to involve a total of 100 psychotherapists (in training) and psychiatrists. They will be recruited via our training center for psychotherapy and the Chamber of Psychotherapists (https://www.ptk-nrw.de/, 2025). We aim to employ a conjoint analysis to investigate the causal effects of several prototypical and peripheral criteria and features in a patient on the diagnosis of BPD and mania. We apply mixed regression models with a random intercept to calculate utilities. We test for differences in utilities by applying an ANOVA and subsequent planned pairwise comparisons. A Wald test is applied to test utility significance.