Objective: To assess the prevalence of radiological magnetic resonance imaging (MRI) findings in individuals at high risk of schizophrenia. Methods: MRI scans from individuals at high risk of schizophrenia (HR; n = 37) were assessed by a radiologist blind to group status and compared with scans from patients with first episode psychosis (FE; n = 30), depressive controls (DC; n = 17), and healthy controls (HC; n = 26).Results: There was a significantly higher proportion of radiological findings in individuals at high risk of schizophrenia (35%) and patients with first-episode psychosis (40%) than in patients with depression (18%) or healthy controls (12%). These differences were specific to findings regarded as potentially clinically significant as opposed to normal variants; however, there was no indication for medical treatment. Conclusions:The results suggest that a large proportion of those at high risk of psychosis have radiological findings on MRI scanning, and that the prevalence of radiological findings in this group is similar to that in patients with first episode psychosis. While there is an extensive literature on magnetic resonance imaging (MRI) abnormalities in psychotic disorders, most of the findings are of relatively small reductions in global and regional grey matter volume that are evident at a group level but are not detectable in an individual patient in a radiological examination. 1Nevertheless there are some abnormalities that can be detected by visual inspection, such as enlarged fluid spaces, ventricular enlargement, and cerebral atrophy.2-8 Radiological findings in first episode patients have focused mainly on cavum septi pellucidi, which is more common in this group than in controls. 9-12It is not clear as yet at what stage of the disorder these brain abnormalities occur. Neurodevelopmental models of schizophrenia propose that brain abnormalities are present before the onset of psychosis, but there is also evidence that at least some of MRI abnormalities progress over the course of the disorder. 13MRI studies of non-psychotic subjects who are at high risk of psychosis indicate that regional volumetric abnormalities comparable to those seen in schizophrenia are evident in those who are vulnerable to psychosis. Thus Lawrie et al 14 found that the relatives of patients with schizophrenia had reduced left medial temporal volume, while decreased global white and grey matter volumes were found in the nonpsychotic co-twins of patients with schizophrenia, 15 and decreased left amygdala and hippocampal volume has been described in the offspring of schizophrenic patients. 16 More recently, Pantelis et al 13 showed that individuals at high risk of psychosis who had ''prodromal'' symptoms had reduced grey matter in the right medial temporal, inferior frontal cortex, and cingulated cortex.The only radiological study in individuals at high risk of psychosis concentrated on cavum septi pellucidi and found no differences between first episode patients, relatives at high risk, and healthy volunteers.11 ...

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