Changes in the frontotemporal cortex and cognitive correlates in first-episode psychosis

Abstract

Background: Loss of cortical volume in frontotemporal regions has been reported in patients with schizophrenia and their relatives. Cortical area and thickness are determined by different genetic processes, and measuring these parameters separately may clarify disturbances in corticogenesis relevant to schizophrenia. Our study also explored clinical and cognitive correlates of these parameters.

Methods: Thirty-seven patients with first-episode psychosis (34 schizophrenia, 3 schizoaffective disorder) and 38 healthy control subjects matched for age and sex took part in the study. Imaging was performed on an magnetic resonance imaging 1.5-T scanner. Area and thickness of the frontotemporal cortex were measured using a surface-based morphometry method (Freesurfer). All subjects underwent neuropsychologic testing that included measures of premorbid and current IQ, working and verbal memory, and executive function.

Results: Reductions in cortical area, more marked in the temporal cortex, were present in patients. Overall frontotemporal cortical thickness did not differ between groups, although regional thinning of the right superior temporal region was observed in patients. There was a significant association of both premorbid IQ and IQ at disease onset with area, but not thickness, of the frontotemporal cortex, and working memory span was associated with area of the frontal cortex. These associations remained significant when only patients with schizophrenia were considered.

Conclusions: Our results suggest an early disruption of corticogenesis in schizophrenia, although the effect of subsequent environmental factors cannot be excluded. In addition, cortical abnormalities are subject to regional variations and differ from those present in neurodegenerative diseases.

Figure 1

Lateral and midsagittal views of the frontal and temporal parcellations: 1, superior frontal; 2, rostral middle frontal; 3, caudal middle frontal; 4, pars opercularis; 5, rostral anterior cingulate; 6, caudal anterior cingulate; 7, superior temporal; 8, middle temporal; 9, inferior temporal; 10, transverse temporal; 11, temporal pole; 12, fusiform.

Figure 2

Scatter plot of the associations between premorbid IQ and current IQ with the average cortical area for the right and left hemispheres in patients and controls: superior frontal.

Figure 3

Scatter plot of the associations between premorbid IQ and current IQ with the average cortical area for the right and left hemispheres in patients and controls: rostral middle frontal.

Figure 4

Scatter plot of the associations between premorbid IQ and current IQ with the average cortical area for the right and left hemispheres in patients and controls: middle temporal.

Figure 5

Scatter plot of the associations between premorbid IQ and current IQ with the average cortical area for the right and left hemispheres in patients and controls: inferior temporal.

Figure 6

Scatter plot of the associations between premorbid IQ and current IQ with the average cortical area for the right and left hemispheres in patients and controls: fusiform parcellations.