The cognitive relevance of a structural endophenotype in psychosis

Background: Although structural cerebral endophenotypes in schizophrenia have been extensively documented, less is know about the degree to which such vulnerabilities translate to parameters of functional liability, for example altered cognitive performance. Methods: Magnetic resonance imaging and cognitive data on31 patients with psychosis, 32 non-psychotic first degree relatives of patients with psychosis, and 27 controls were acquired. Voxel-based analysis was used to determine associations between grey matter density and cognitive functioning. Results: In both patients and relatives, speed of information processing and grey matter density in areas of the fronto-thalamic cerebellar network were lower compared to controls. The Concept Shifting Test score was negatively correlated with grey matter density in the left cerebellar hemisphere (one significant cluster at pb0.001) in the patient group, indicating that lower speed of complex information processing was associated with cerebellar grey matter density deficits. In the relatives, two positive correlations (at pb0.001) were found, one in the left cerebellar hemisphere, and one in the cingulate gyrus, indicating that lower speed of complex information processing was associated with increased grey matter density in these areas. No significant correlations were found between regional grey matter density and the Stroop Task, the Word Learning Total Test and for the Digit Span backward test. Conclusions: The present data showed differential structure function relationships in patients with psychosis and their non psychotic first-degree relatives. The opposite findings in relatives may be suggestive of a compensatory mechanism.