Cingulate gyrus volume and metabolism in the schizophrenia spectrum

The cingulate gyrus, which is involved in affect, attention, memory and higher executive functions, has been implicated as a dysfunctional region in schizophrenia. Postmortem studies report cytoarchitectural changes in the anterior cingulate gyrus (ACG) and functioning imaging studies show correlations between the degree of hypometabolism of the anterior cingulate and clinical symptoms in schizophrenia.

Unmedicated patients with schizophrenia (n=27) and schizotypal personality disorder (SPD) (n=13), as well as sex- and age-matched control subjects (n=32), were studied with (18)F-fluorodeoxyglucose positron emission tomography (PET) scans and magnetic resonance imaging (MRI). As a control over mental activity, all subjects performed a verbal working memory task during the PET protocol. The cingulate gyrus was first outlined on the MRI scans and, after coregistration, the coordinates were applied to the PET scans to yield a three-dimensional metabolic map of the cingulate gyrus for each subject. A statistical resampling method was used to analyze the metabolic differences between groups.

Compared with controls, patients with schizophrenia had lower relative glucose metabolic rates in the left anterior cingulate and the right posterior cingulate gyrus (PCG) assessed by 3-D significance probability mapping. SPD patients had higher glucose metabolic rates (GMRs) in the left posterior cingulate than did controls. Furthermore, volumetric measurement with MRI showed the left anterior cingulate and Brodmann area 24' to be smaller in schizophrenic patients than controls.

Compared with controls, patients with schizophrenia have metabolic and volumetric reductions in a cingulate gyrus area that is related to higher executive functions. Schizotypal patients rely more on sensory association areas to perform a cognitive task than do controls and seem to be a group that is partially distinct in its physiological and functional characteristics.