Striatal dopamine transporter function in dementia with Lewy bodies and Parkinson's disease

The aim of this study was to compare parkinsonian features and loss of stri atal dopamine transporter (DAT) function in patients with dementia with Lew y bodies (DLB) and Parkinson's disease (PD), matched for age and disease du ration. Twenty patients with DLB. 24 PD patients and 10 matched controls we re examined with SPET using a dual-head camera and the dopamine-transporter ligand I-123-beta -CIT (148 MBq). Moreover, in a subgroup of patients (16 DLB and 20 PD patients), subscores of the Unified Parkinson's Disease Ratin g Scale (UPDRS) - motor examination (ME) subscale were obtained during "pra ctical off", i.e. 12 h following withdrawal of antiparkinsonian therapy. Co mpared with controls, striatal/cerebellar (S/C) ratios of DAT binding were significantly reduced in both DLB and PD, deficits being more marked in DLB patients (controls 7.2 +/-1.2. DLB 3.3 +/-1, PD 4.2 +/-1.4;, means +/- SD) . The side-to-side differences in the S/C ratios were lower in the DLB grou p and the controls than in PD patients (0.4 +/-0.4, 0.2 +/-0.2 and 0.6 +/-0 .3., respectively, P <0.05). The total UPDRS-ME scores during practical-off were significantly higher in the DLB than in the PD group (41.2 +/- 12.7 v s 26.6 +/- 15.3, P <0.01). The side-to-side differences of the summed UPDRS extremity subscores were smaller in the DLB than in the PD group (2.2 +/-2 .3 vs 7.4 +/-3.9, P <0.0001). Our findings suggest that parkinsonism evolve s largely symmetrically and progresses more rapidly with more severe loss o f striatal dopamine transporter function in DLB compared to PD. Whether the se findings are helpful in the differential diagnosis of DLB and PD needs t o be examined in further studies.