Medial temporal structural changes are not seen until after the onset of a psychotic illness, and the pattern of structural change differs according to the type of psychosis. These findings have important implications for future neurobiological studies of psychotic disorders and emphasize the importance of longitudinal studies examining patients before and after the onset of a psychotic illness.

Spatial working memory abilities are impaired in those at high-risk for psychosis. The relationship between working memory and negative symptoms may be useful as a predictive tool.

The first episode of a psychosis is associated with a larger pituitary volume, which we suggest is due to activation of the HPA axis. The smaller pituitary volume in the group with established schizophrenia could be the consequence of repeated episodes of HPA axis hyperactivity.