Caudate nucleus volume in individuals at ultra-high risk of psychosis: a cross-sectional magnetic resonance imaging study.

The aim of the present study was to investigate whether volumetric abnormalities of the caudate nuclei predate the onset of psychotic illness. Caudate nuclei volume (CNVs), excluding the tail, were measured using region-of-interest (ROI) tracing of magnetic resonance imaging (MRI) scans acquired on a 1.5T scanner. Subjects included 39 individuals deemed at ultra-high risk of psychosis who converted to psychosis (UHR-P) after initial MRI scanning; 39 matched individuals at ultra-high risk who did not convert to psychosis (UHR-NP); and 39 matched healthy controls. All subjects were neuroleptic-naïve. After adjusting CNVs for intracranial volume (ICV), univariate analyses of variance and repeated measures analyses of variance were undertaken to examine the relationship of CNVs to psychosis transition and to family history of psychosis. Pearson's correlations were used to investigate the relationship of psychopathological scores to CNVs. CNVs did not differ significantly between UHR individuals and healthy controls, and there was no significant difference between converters and non-converters to psychosis. In the UHR group, presence of family history of psychosis was not related to CNVs. There was no correlation between CNVs and either positive or negative symptoms of schizophrenia. Significant associations were found between larger CNV and increased errors on a spatial working memory task but better verbal fluency performance. These data suggest that the caudate is macroscopically normal prior to illness onset, while the relationship to tasks of executive function may implicate the caudate together with its connections to prefrontal regions. Future research should examine changes longitudinally together with analysis of shape to assess subregions of the caudate that connect with prefrontal cortex.