Comparing the latent state-trait structure of the PANSS in cariprazine-medicated and placebo-controlled patients with acute schizophrenia

After over a hundred years of research, the question whether the symptoms of schizophrenia are rather trait-like (being a relatively stable quality of individuals) or state-like (being substance to change) is still unanswered. To assess the trait and the state component in patients with acute schizophrenia, one group receiving antipsychotic treatment, the other not. Data from four phase II/III, 6-week, randomized, double-blind, placebo-controlled trials of similar design that included patients with acute exacerbation of schizophrenia were pooled. In every trial, one treatment group received a third-generation antipsychotic, cariprazine, and the other group placebo. To assess symptoms of schizophrenia, the Positive and Negative Symptom Scale (PANSS) was applied. Further analyses were conducted using the five subscales as proposed by Wallwork and colleagues. A latent state-trait (LST) model was developed to estimate the trait and state components of the total variance of the observed scores. All symptom dimensions behaved more in a trait-like manner. The proportions of all sources of variability changed over the course of the observational period, with a bent around weeks 3 and 4. Visually inspected, no major differences were found between the two treatment groups regarding the LST structure of symptom dimensions. This high proportion of inter-individual stability may represent an inherent part of symptomatology that behaves independently from treatment status.