BRAIN 6-[F-18]FLUORODOPA METABOLISM IN EARLY AND LATE-ONSET OF PARKINSONS-DISEASE STUDIED BY POSITRON EMISSION TOMOGRAPHY

We measured 6-[F-18]fluorodopa (FDOPA) uptake in the caudate nucleus a nd the putamen of 20 patients with early and late onset of Parkinson's disease (EOPD and LOPD) and 20 normal control subjects using positron emission tomography. The mean influx rate constant values (K-i) were significantly reduced in the caudate nucleus and the putamen of the pa tients with EOPD and LOPD compared with age-matched control groups (p < 0.01), respectively. There were significant negative correlations be tween K-i values in the caudate nucleus (r = -0.67, p = 0.0024) and th e putamen (r = -0.67, p = 0.0014), and duration of disease in the LOPD group compared with the EOPD group. Similar negative relationships be tween K-i values and clinical stages by Hoehn and Yahr and degrees of main clinical symptoms (bradykinesia, tremor and rigidity) were more m arkedly seen in the LOPD group than in the EOPD group, The present res ults suggest that the function of presynaptic dopaminergic terminals c orrelates well with clinical disease severity and degrees of main symp toms in the LOPD group, but not in the EOPD group. We speculate that c ompensatory up-regulatory function in the postsynaptic dopaminergic re ceptors may modify disease severity and the degrees of main clinical s ymptoms of EOPD.