CEREBRAL GLUCOSE-UTILIZATION IS REDUCED IN 2ND TEST SESSION

Cerebral glucose utilization was higher during the first positron emis sion tomography (PET) session than during the second session, as assay ed using the PET [F-18]-fluorodeoxyglucose method in male human volunt eers. This difference was due largely to data from subjects with low t rait anxiety, since subjects with high anxiety showed similar metaboli sm in both PET sessions. High-anxiety subjects showed greater right/le ft ratios of cerebral metabolism than low-anxiety subjects, particular ly during the second PET session. These findings suggest that the leve l of anxiety may be an important variable to consider in PET studies u sing multiple sessions.