Twenty-year trajectories of negative symptoms following first hospitalization for schizophrenia: A Bayesian analysis

The aim of the study was to investigate whether three negative symptoms of schizophrenia - motor retardation, emotional withdrawal, and blunted affect - differ in their course over 20 years following first hospitalization.

Data from 80 patients in the Cracow Prospective Study of Schizophrenia, assessed at six time points over 20 years using the Brief Psychiatric Rating Scale, were reanalyzed with Bayesian cumulative ordinal multilevel models following the WAMBS (When to Worry and How to Avoid the Misuse of Bayesian Statistics) checklist.

All three symptoms displayed U-shaped trajectories characterized by early improvement and late-phase deterioration. Motor retardation was less severe at baseline than emotional withdrawal (β = -0.85; 95% CrI [-1.31; -0.39]) and blunted affect (β = -0.99; 95% CrI [-1.47; -0.52]). A preliminary indication, not reaching conventional evidential thresholds, was that motor retardation may be more persistent than emotional withdrawal (β = 0.25; 95% CrI [0.04; 0.45]). No differences were found in trajectory shape.

Negative symptoms show similar long-term U-shaped trajectories. The lower baseline severity but potentially higher persistence of motor retardation raises the possibility that motor symptoms, once present, may follow a more trait-like course, though this preliminary pattern requires replication. These results highlight the need for continuous monitoring of negative symptoms throughout the illness.