A Longitudinal Approach to Biological Psychiatric Research: The PsyCourse Study

Abstract

In current diagnostic systems, schizophrenia and bipolar disorder are still conceptualized as distinct categorical entities. Recently, both clinical and genetic evidence have challenged this Kraepelinian dichotomy. There are only few longitudinal studies addressing the potential overlaps between these conditions. Here, we present design and first results of the PsyCourse study, an ongoing transdiagnostic study of the affective-to-psychotic continuum that combines longitudinal deep phenotyping and dimensional assessment of psychopathology with an extensive collection of biomaterial. Within the DSM-IV framework, we compare two broad diagnostic groups: one consisting of predominantly affective and one of predominantly psychotic disorders. Depressive, manic, and psychotic symptoms as well as global functioning over time were analyzed. Furthermore, we explore the effects of polygenic risk scores for schizophrenia on diagnostic group membership and address their effects on non-participation in follow-up visits. While phenotypic results show differences in both current psychotic and manic symptoms, depressive symptoms did not vary between both groups. Polygenic risk scores for schizophrenia significantly explained part of the variability of the diagnostic group. Furthermore, there was a trend that a higher polygenic loading for schizophrenia was associated with attrition. Because of its unique properties, the PsyCourse study presents a prime resource for the interrogation of complex genotype-phenotype relationships.

Investigating polygenic burden in age at disease onset in bipolar disorder: Findings from an international multicentric study

“…PsyCourse is an ongoing, multicenter study conducted at a network of clinical sites across Germany and Austria (http://psycourse.de). The phenotypic characteristics of the patients recruited at the individual sites and the respective sample sizes are presented in Supporting Information Table S1. The reported sample sizes represent those available after quality control (exclusion of patients with no information on age [N = 59], gender [N = 2], or AAO, or having improbable AAO data [N = 162]).…”

Polygenic Risk for Schizophrenia and Global Assessment of Functioning—A Comparison with In-Silico Data

“…We obtained imputed genotypes based on original genotyping with the Illumina Infinium PsychArray as well as the top ten principal components (PCs) of ancestry for n = 771 patients from the PsyCourse study [14]. We considered baseline information on symptom severity in these patients [14].…”

“…We obtained imputed genotypes based on original genotyping with the Illumina Infinium PsychArray as well as the top ten principal components (PCs) of ancestry for n = 771 patients from the PsyCourse study [14]. We considered baseline information on symptom severity in these patients [14]. PsyCourse is an ongoing multicenter study in Germany and Austria that aims to understand the genetic-molecular underpinnings of the longitudinal course of the affective-to-psychotic continuum (for details see [14]).…”

“…We considered baseline information on symptom severity in these patients [14]. PsyCourse is an ongoing multicenter study in Germany and Austria that aims to understand the genetic-molecular underpinnings of the longitudinal course of the affective-to-psychotic continuum (for details see [14]). All patients in the study were classified into two broad diagnostic groups, psychotic and affective.…”

“…We examined the properties of PRS for correlated quantitative phenotypes with complete overlap of causal genetic markers with a focus on the distribution of explained variance (R 2 ) and optimal p-value threshold (p 0 ) in the replications. Our second goal was to interpret our simulation results in view of the SZ-PRS applied to phenotypes in the PsyCourse dataset (version 2.0.1) [14] including 653 psychotic and affective individuals and to compare our findings with previous studies [8,9]. We analyzed the symptoms and severity in terms of the association between GAF and SZ-PRS.…”