Morphological abnormalities of the superior temporal gyrus have been consistently reported in schizophrenia, but the timing of their occurrence remains unclear.

To determine whether individuals exhibit superior temporal gyral changes before the onset of psychosis.

We used magnetic resonance imaging to examine grey matter volumes of the superior temporal gyrus and its subregions (planum polare, Heschl's gyrus, planum temporale, and rostral and caudal regions) in 97 antipsychotic-naive individuals at ultra-high risk of psychosis, of whom 31 subsequently developed psychosis and 66 did not, and 42 controls.

Those at risk of psychosis had significantly smaller superior temporal gyri at baseline compared with controls bilaterally, without any prominent subregional effect; however, there was no difference between those who did and did not subsequently develop psychosis.

Our findings indicate that grey matter reductions of the superior temporal gyrus are present before psychosis onset, and are not due to medication, but these baseline changes are not predictive of transition to psychosis.

Grey matter changes have been described in individuals who are pre- and peri-psychotic, but it is unclear if these changes are accompanied by changes in white matter structures.

To determine whether changes in white matter occur prior to and with the transition to psychosis in individuals who are pre-psychotic who had previously demonstrated grey matter reductions in frontotemporal regions.

We used magnetic resonance imaging (MRI) to examine regional white matter volume in 75 people with prodromal symptoms. A subset of the original group (n=21) were rescanned at 12–18 months to determine white matter volume changes. Participants were retrospectively categorised according to whether they had or had not developed psychosis at follow-up.

Comparison of the baseline MRI data from these two subgroups revealed that individuals who later developed psychosis had larger volumes of white matter in the frontal lobe, particularly in the left hemisphere. Longitudinal comparison of data in individuals who developed psychosis revealed a reduction in white matter volume in the region of the left fronto-occipital fasciculus. Participants who had not developed psychosis showed no reductions in white matter volume but increases in a region subjacent to the right inferior parietal lobule.

The reduction in volume of white matter near the left fronto-occipital fasciculus may reflect a change in this tract in association with the onset of frank psychosis.

Patients with psychosis have activation of the hypothalamic-pituitary-adrenal (HPA) axis during the acute phase of the psychosis. Whether this has any morphological consequences for the pituitary gland is currently unknown.

To examine pituitary volume variation in people at different stages of psychotic disorder.

Pituitary volume was measured using 1.5 mm, coronal magnetic resonance images in 24 people with first-episode psychosis, 51 with established schizophrenia and 59 healthy controls.

Compared with the control group, the people with first-episode psychosis had pituitary volumes that were 10% larger, whereas those with established schizophrenia had pituitary volumes that were 17% smaller. In both of the groups with psychosis, there was no difference in pituitary volume between those receiving typical antipsychotic drugs and those receiving atypical antipsychotics.

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.