Grey matter volume differences in non-affective psychosis and the effects of age of onset on grey matter volumes: A voxelwise study

Previous evidence indicates that structural brain alterations are already present in the early phases of psychosis. In this study we aim to investigate the relationships among the different diagnoses in the spectrum of non-affective psychosis. A hundred-and-one first-episode psychosis patients (FEP) and 69 healthy volunteers, matched for age, gender, handedness and educational level were analyzed by structural MRI and high-dimensional voxel-based morphometry as implemented in SPM8 software. We obtained three main results: (1) FEP patients showed reduction of grey matter volume (GMV) in the frontal, temporal and occipital lobes, left insula and cerebellum. (2) Age of disease onset was an important factor revealing a gradual decrease of GMV (healthy controls > late onset > intermediate onset > early onset) in the frontal, temporal and occipital lobes, insula and cerebellum. (3) A gradual reduction of GMV related to diagnosis spectrum in the frontal, temporal, parietal and occipital lobes of schizophrenia patients being the most affected. These results suggest that an earlier onset of psychosis is linked to an earlier disease-related disruption of structural brain development, which may be most pronounced in schizophrenia compared to other psychoses.