A CONTROLLED POSITRON EMISSION TOMOGRAPHY STUDY OF OBSESSIVE AND NEUTRAL AUDITORY-STIMULATION IN OBSESSIVE-COMPULSIVE DISORDER WITH CHECKING RITUALS

Ten nondepressed patients with obsessive-compulsive disorder (OCD) who were characterized by predominant checking rituals were compared with 10 age- and sex-matched control subjects, Hemispheric and regional ce rebral blood flow levels (rCBF) were measured with positron emission t omography ((H2O)-O-15) across four conditions: rest, auditory stimulat ion with idiosyncratic normal or abnormal obsession, auditory stimulat ion with neutral verbal stimuli, and rest, Order of neutral and obsess ive stimulation was randomized, Higher subjective responses to obsessi ve than to neutral stimulation were found in both groups; subjective r esponse was higher in OCD patients when obsessive stimulation was pres ented first, A four-way analysis of variance (group x stimulation orde r x hemisphere x condition [neutral or obsessive stimulation]) was per formed on stimulation minus rest normalized rCBF values, Control subje cts had significantly higher rCBF in the thalamus and putamen, A trend toward higher rCBF in OCD patients was found in the superior temporal regions, When neutral stimulation was presented first, rCBF was signi ficantly higher in the caudate region of control subjects. Obsessive s timulation was associated with higher rCBF than neutral stimulation in orbitofrontal regions in both groups of subjects, Under obsessive sti mulation, superior temporal and orbitofrontal activities were correlat ed in OCD patients but not in control subjects. Our study suggests spe cific abnormalities of information processing in the basal ganglia and temporal structures of compulsive checkers.