Personality, Psychopathology, and Psychotherapy: A Pre-specified Analysis Protocol for Confirmatory Research on Personality–Psychopathology Associations in Psychotherapy Outpatients

Abstract

The role of personality trait variation in psychopathology and its influence on the outcome of psychotherapy is a burgeoning field. However, thus far most findings were based on controlled clinical trials that may only poorly represent real-world clinical settings due to highly selective samples mostly restricted to patients with major depression undergoing antidepressive medication. Focusing on personality and psychopathology in a representative naturalistic sample of psychotherapy patients is therefore worthwhile. Moreover, up to date hardly any confirmatory research has been conducted in this field. Strictly confirmatory research implies two major requirements: firstly, specific hypotheses, including expected effect sizes and statistical approaches to data analysis, must be detailed prior to inspection of the data, and secondly, corresponding protocols have to be published online and freely available. Here, we introduce a longitudinal naturalistic study aimed at examining, firstly, the prospective impact of baseline personality traits on the outcome of psychotherapy over a 6-month observation period; secondly, the stability and change in personality traits over time; thirdly, the association between longitudinal change in psychopathology and personality; fourthly, the agreement between self-reports and informant rating of personality; and fifthly, the predictive validity of personality self-reports compared to corresponding informant ratings. For it, we comprehensively state a priori hypotheses, predict the expected effect sizes and detail the statistical analyses that we intend to conduct to test these predictions. Such a stringent confirmatory design increases the transparency and objectivity of psychopathological research, which is necessary to reduce the rate of false-positive findings and to increase the yield of scientific research.

Personality Traits and Psychopathology Over the Course of Six Months of Outpatient Psychotherapy: A Prospective Observational Study

“…All analyses were conducted with SPSS version 24 for Windows according to the analytic plan pre-specified in the study protocol (Hengartner and Yamanaka-Altenstein, 2017). Mean-level stability was analyzed with paired-samples T-tests and differential stability with Pearson correlations between baseline and follow-up scores.…”

“…These regression models can account for the intra-individual dependency of repeated outcome measures. As detailed in the study protocol (Hengartner and Yamanaka-Altenstein, 2017), the influence of baseline personality on both GAF and BSI-GSI over time was modeled as an interaction term between the personality trait score and the time slope, while adjusting for the main effect of the personality trait and either GAF or BSI-GSI. Because GAF was left-skewed, scores were inverted to transform the scale into a right-skewed distribution.…”

“…These are important issues that are insufficiently addressed in the literature. All hypotheses detailed below were outlined in the pre-registered study protocol (Hengartner and Yamanaka-Altenstein, 2017).…”

“…This study was pre-registered online using the open science framework 1 and the study protocol was pre-specified and published online (Hengartner and Yamanaka-Altenstein, 2017). All participants gave their informed consent and the study was approved by the Cantonal Ethics Committee of Zurich (reference number 2015-0601).…”

“…However, most findings published thus far are based on exploratory post hoc analyses of data that were collected for other principal research questions, which is prone to false-positive findings (Wagenmakers et al, 2012). Research that included more than a one-time personality assessment in order to study dynamic personality-psychopathology covariation over time in naturalistic samples is scarce and longitudinal studies that included patients with other mental disorders than major depression are almost completely lacking (Hengartner and Yamanaka-Altenstein, 2017). This confirmatory longitudinal study in a representative sample of private psychotherapy outpatients was designed to address these gaps in the literature.…”