DRUG-NAIVE PATIENTS WITH PARKINSONS-DISEASE IN HOEHN AND YAHR STAGE-IAND STAGE-II SHOW A BILATERAL DECREASE IN STRIATAL DOPAMINE TRANSPORTERS AS REVEALED BY [I-123] BETA-CIT SPECT

Ten healthy subjects and 16 patients with early Parkinson's disease (P D) were examined with single photon emission computed tomography (SPEC T) and [I-123]beta-CIT, a ligand for the dopamine (DA) transporter. On ly drug-naive patients were examined since the expression of and bindi ng to DA transporters may be influenced by dopaminergic medication. Th e main finding was a significant reduction in [I-123]beta-CIT binding in the ipsi- and contralateral striatal regions, especially in the put amen, which showed a mean reduction of 65% of the control mean. Discri minant function analysis of the putaminal [I-123]beta-CIT binding meas ures classified 100% of the eases in the correct group. Disease severi ty correlated negatively and highly significantly with the binding mea sures. Tremor ratings did not correlate with the SPECT measures, where as rigidity, and to a lesser extent bradykinesia, did. Patients with u nilateral PD showed a bilateral loss of striatal DA transporters. Our findings indicate that with [I-123]beta-CIT SPECT it is possible to di agnose PD in subjects with very mild symptoms and signs. Moreover, fin ding a bilateral loss of striatal DA transporters in patients with uni lateral PD also suggests that it may be possible to identify subjects in the preclinical phase of the disease.