Spatial working memory among middle-aged and older patients with schizophrenia and volunteers using fMRI.

OBJECTIVE: Goldman-Rakic and Selemon (Schizophr. Bull. 23 (1997)) hypothesized that many of the symptoms of schizophrenia can be explained by deficits of working memory (WM) that are, in turn, caused by dysfunction of dorsolateral prefrontal cortex (DLPFC). We examined whether older patients with schizophrenia would show an aberrant neural response in the DLPFC or other brain sites when performing a spatial working memory (WM) task adapted from McCarthy et al. (Proc. Natl. Acad. Sci. U. S. A. 91 (1994)).

METHOD: Middle-aged and older patients with schizophrenia or schizoaffective disorder and healthy volunteers performed a spatial WM task contrasted with two baselines, passive and active viewing (PV and AV, respectively), while blood oxygen level dependent (BOLD) images were acquired in a functional magnetic resonance study.

RESULTS: Patients did not perform significantly less well on the spatial tasks compared to the volunteers. Although we found no significant group effects in spatial WM activation of DLPFC, we did observe areas in medial frontal cortex including the left anterior cingulate gyrus, parietal areas of the both hemispheres, multiple sites within the basal ganglia of the left hemisphere, and the left superior temporal gyrus where healthy volunteers showed greater BOLD response to WM. In a second pattern, patients showed a greater BOLD response to WM in left fusiform gyrus [Brodmann's Area (BA) 19], peri-rolandic areas, medial frontal area; right anterior cerebellum (culmen), middle occipital lobe, and postcentral/supramarginal gyri (BA 2/40).

CONCLUSIONS: Middle-aged and older patients with schizophrenia display normal or near-normal spatial WM activation of DLPFC when the processing demands of the WM task are within their performance capacity. Nonetheless, even when patients perform nearly normally, they demonstrate an aberrant pattern of brain response.