Regional cerebral blood flow in schizophrenia while in attention task.

ABSTRACT:

Introduction: Blood perfusion patterns may be useful in identifying specific deficits in persons with schizophrenia. This exploratory study uses data from high-resolution single-photon emission computed tomography (SPECT) analysis of regional cerebral blood flow (rCBF) in brain regions of interest (ROI) to seek relationships between rCBF and a clinical diagnosis of schizophrenia while participants are engaged in a selective and sustained attention task. The amygdala, hippocampus, and temporal lobe were chosen as focal points of this study based on prior research.

Methods: Clinical participants were adults presenting for psychiatric care at 8 clinics on both U.S. coasts (n=74; age 18-84, M=40.8; 59% male, 65% White, 42% West Coast) who consented to participation; historical diagnosis was confirmed clinically prior to study. Healthy participants (defined as persons having no mental health disorder, neither historically nor upon clinical assessment) were solicited from a West Coast university (n=46; age 18-84, M=40.8; 46% male, 46% White, 100% West Coast). SPECT scans were made of the left- and right-sided ROIs of the amygdala, hippocampus, and temporal lobe, in a resting state, for baseline values of rCBF. Second, SPECT was conducted in the same areas under a concentration task in which the participant engaged in the Conners’ CPT. Z-scores were computed in each lobe of each ROI (z-scores were used rather than raw scores, due to each ROI having unique statistical descriptors), representing rCBF as an index above or below the mean rCBF for the entire sample. The difference of the concentration z-score and the baseline z score was computed, representing net magnitude and direction of change in blood flow. Positive differences represent increases in flow of blood or rCBF, while negative values are decreases in flow. The full procedure is described elsewhere (Amen, Hanks, & Prunella, 2008).

Results: Six t-tests were performed (3 ROIs in each hemisphere) comparing rCBF in concentration condition minus rCBF at baseline, of participants with schizophrenia to healthy participants; all calculations used a significance criterion of p=.01. The t-tests were significant for: the left amygdala with schizophrenia (M=.053, SE=.072) versus healthy (M=-.54, SE=.20), t(56.921)=-2.8; the right amygdala (M=.082, SE=.077) versus healthy (M=-.62, SE=.19), t(60.011)=-3.4; the left hippocampus with schizophrenia (M=.032, SE=.071) versus healthy (M=-.57, SE=.20), t(56.659)=-2.9; the right hippocampus (M=.082, SE=.065) versus healthy (M=-.65, SE=.19), t(55.583)=-3.6; the right temporal lobe (M=-.098, SE=.064) versus healthy (M=.74, SE=.064), t(59.049)=4.8.

Discussion(s): This exploratory analysis found that the ROIs of the amygdala and hippocampus experienced a decrease in rCBF in moving from baseline to a concentration task, in persons with schizophrenia. In the healthy participants, the flow rate instead increased very slightly. The opposite effects were observed in the temporal lobes, with the schizophrenia group showing small decreases in flow rate, and healthy participants showing increases of up to three-quarters of an SD unit in blood flow. In all cases, the right-side flow increased or decreased from 20% to 900% more than the left side; lateral rate differences were greater in the diagnosed group than the healthy group, and in the temporal lobes more so than the amygdala and hippocampus.