HIGH-ENERGY PHOSPHATES IN THE FRONTAL-LOBE CORRELATE WITH WISCONSIN-CARD-SORT-TEST PERFORMANCE IN CONTROLS, NOT IN SCHIZOPHRENICS - A (31)PHOSPHORUS MAGNETIC-RESONANCE SPECTROSCOPIC AND NEUROPSYCHOLOGICAL INVESTIGATION

In recent years, a number of (31)phosphorus magnetic resonance spectro scopy (P-MRS) studies on the frontal lobe of schizophrenics have been performed, reporting alterations of phospholipids and high-energy phos phates. Deicken et al. (1994b) recently found positive correlations be tween left frontal phosphomonoester% (PME%) levels and the performance of a specific frontal lobe task, the Wisconsin Card Sorting Test (WCS T), in schizophrenics. In the present paper, the correlations between phospholipids and high-energy phosphates in the frontal lobe of 26 sch izophrenics and 23 controls measured with a volume-selective P-MRS met hod were investigated. Overall, we could not find any correlations bet ween WCST results and phospholipid levels, but in controls phosphocrea tine% (PCr%) and PCr/adenenosine triphosphate (ATP) ratios were negati vely correlated with test performance. Since PCr behaves as a buffer o f ATP, in the sense that when ATP is consumed by neuronal activity PCr is catalysed rapidly to ATP, increased PCr% values and, moreover, inc reased PCr/ATP ratios point to a decreased ATP consumption. Thus, the correlations found between PCr% and PCr/ATP and test performance in co ntrols point to an association between reduced performance in a specif ic frontal lobe task and decreased energy demanding processes at rest. This association was not found in schizophrenics, possibly due to the influence of neuroleptic medication or the disease process per se. (C ) 1998 Elsevier Science B.V. All rights reserved.