[I-123]beta-CIT SPECT demonstrates decreased brain dopamine and serotonin transporter levels in untreated parkinsonian patients

Striatal dopamine transporters (DATs) and serotonin transporters (SERTs) we re evaluated in untreated patients with Parkinson's disease (PD) and contro ls using single-photon emission computed tomography (SPECT) with 2 beta -ca rboxymerhoxy-3 beta-(4-iodophenyl)tropane ([I-123]beta -CIT). The striatal DAT specific to non-displaceable uptake ratios of 29, and the SERT uptake m easurements of 27, PD patients were compared with those of 21 and 16 contro ls, respectively. The results were correlated with Unified Parkinson's Dise ase Rating Scale (UPDRS) scores, the Hoehn & Yahr stage, age, duration of t he disease, and the major PD signs. The specific DAT binding in the caudate , the putamen and the caudate/putamen ratio were measured. In all of the PD patients the striatal uptake values were bilaterally reduced, being 36.9% (P < 0.001) lower than those of the controls. In the hemiparkinsonian patie nts the reduction was greater on the side contralateral to the initial symp toms (33.3% vs. 27.8%) and the uptake ratios indicated a more pronounced de ficit in the putamen (39.1%) than in the caudate (27.9%). The DAT uptake co rrelated with the UPDRS total score and activities of daily living (ADL) an d motor subscores, the Hoehn & Yahr stage, and rigidity score. PD patients had significantly higher caudate to putamen ratios than the controls. In th e PD patients the SERT values were lower in the thalamic and frontal region s. The SERT uptake ratio of the frontal area correlated with the UPDRS subs core I. [I-123]<beta>-CIT SPECT provides a useful method for confirming the clinical diagnosis of PD with correlation to disease severity. Additionall y, this technique allows the simultaneous measurement of SERT uptake and sh ows that PD patients, interestingly, seem to have decreased SERT availabili ty in the thalamic and frontal areas.