Volumetric abnormalities predating the onset of schizophrenia and affective psychoses: An MRI study in subjects at ultrahigh risk of psychosis

It remains unclear whether brain structural abnormalities observed before the onset of psychosis are specific to schizophrenia or are common to all psychotic disorders. This study aimed to measure regional gray matter volume prior to the onset of schizophreniform and of affective psychoses. We investigated 102 subjects at ultrahigh risk (UHR) of developing psychosis recruited from the Personal Assessment and Crisis Evaluation Clinic in Melbourne, Australia. Twenty-eight of these subjects developed psychosis subsequent to scanning: 19 schizophrenia, 7 affective psychoses, and 2 other psychoses. We examined regional gray matter volume using 1.5 mm thick, coronal, 1.5 Tesla magnetic resonance imaging and voxel-based morphometry methods of image analysis. Subjects were scanned at presentation and were followed up clinically for a minimum of 12 months, to detect later transition to psychosis. We found that both groups of subjects who subsequently developed psychosis (schizophrenia and affective psychosis) showed reductions in the frontal cortex relative to UHR subjects who did not develop psychosis. The subgroup that subsequently developed schizophrenia also showed smaller volumes in the parietal cortex and, at trend level, in the temporal cortex, whereas those who developed an affective psychosis had significantly smaller subgenual cingulate volumes. These preliminary findings suggest that volumetric abnormalities in UHR individuals developing schizophrenia vs affective psychoses comprise a combination of features that predate both disorders and others that may be specific to the nature of the subsequent disorder. © 2012 The Author

Altered depth of the olfactory sulcus in ultra high-risk individuals and patients with psychotic disorders

A shallow olfactory sulcus has been reported in schizophrenia, possibly reflecting abnormal forebrain development during early gestation. However, it remains unclear whether this anomaly exists prior to the onset of psychosis and/or differs according to illness stage. In the current study, magnetic resonance imaging was used to investigate the length and depth of the olfactory sulcus in 135 ultra high-risk (UHR) individuals [of whom 52 later developed psychosis (UHR-P) and 83 did not (UHR-NP)], 162 patients with first-episode psychosis (FEP), 89 patients with chronic schizophrenia, and 87 healthy controls. While there was no group difference in the length of the sulcus, UHR-P subjects had significantly shallower olfactory sulcus at baseline as compared with UHR-NP and control subjects. The depth of this sulcus became increasingly more superficial as one moved from UHR-P subjects to FEP patients to chronic schizophrenia patients. Finally, the depth of the olfactory sulcus in the UHR-P subjects was negatively correlated with the severity of negative symptoms. These findings suggest that the altered depth of the olfactory sulcus, which exists before psychosis onset, could be predictive of transition to psychosis, but also suggest ongoing changes of the sulcus morphology during the course of the illness. © 2014 Elsevier B.V

Reduced parahippocampal cortical thickness in subjects at ultra-high risk for psychosis

Background Grey matter volume and cortical thickness represent two complementary aspects of brain structure. Several studies have described reductions in grey matter volume in people at ultra-high risk (UHR) of psychosis; however, little is known about cortical thickness in this group. The aim of the present study was to investigate cortical thickness alterations in UHR subjects and compare individuals who subsequently did and did not develop psychosis. Method We examined magnetic resonance imaging data collected at four different scanning sites. The UHR subjects were followed up for at least 2 years. Subsequent to scanning, 50 UHR subjects developed psychosis and 117 did not. Cortical thickness was examined in regions previously identified as sites of neuroanatomical alterations in UHR subjects, using voxel-based cortical thickness. Results At baseline UHR subjects, compared with controls, showed reduced cortical thickness in the right parahippocampal gyrus (p<0.05, familywise error corrected). There were no significant differences in cortical thickness between the UHR subjects who later developed psychosis and those who did not. Conclusions These data suggest that UHR symptomatology is characterized by alterations in the thickness of the medial temporal cortex. We did not find evidence that the later progression to psychosis was linked to additional alterations in cortical thickness, although we cannot exclude the possibility that the study lacked sufficient power to detect such differences. © 2013 Cambridge University Press