Abstract
BackgroundBiomarkers based on the underlying pathology of Alzheimer’s disease (AD) and Dementia with Lewy Bodies (DLB) have the potential to improve diagnosis and understanding of the substrate for cognitive impairment in these disorders. The objective of this study was to compare the patterns of amyloid and dopamine PET imaging in patients with AD, DLB and Parkinson’s disease (PD) using the amyloid imaging agent florbetapir F 18 and 18F-AV-133 (florbenazine), a marker for vesicular monamine type 2 transporters (VMAT2).MethodsPatients with DLB and AD, Parkinson’s disease (PD) and healthy controls (HC) were recruited for this study. On separate days, subjects received intravenous injections of florbetapir, and florbenazine. Amyloid burden and VMAT2 density were assessed quantitatively and by binary clinical interpretation. Imaging results for both tracers were compared across the four individual diagnostic groups and for combined groups based on underlying pathology (AD/DLB vs. PD/HC for amyloid burden and PD/DLB vs. AD/HC for VMAT binding) and correlated with measures of cognition and parkinsonism.Results11 DLB, 10 AD, 5 PD, and 5 controls participated in the study. Amyloid binding was significantly higher in the combined AD/DLB patient group (n = 21) compared to the PD/HC groups (n = 10, mean SUVr: 1.42 vs. 1.07; p = 0.0006). VMAT2 density was significantly lower in the PD/DLB group (n = 16) compared to the AD/ HC group (n = 15; 1.83 vs. 2.97; p < 0.0001). Within the DLB group, there was a significant correlation between cognitive performance and striatal florbenazine binding (r = 0.73; p = 0.011).ConclusionsThe results of this study show significant differences in both florbetapir and florbenazine imaging that are consistent with expected pathology. In addition, VMAT density correlated significantly with cognitive impairment in DLB patients (ClinicalTrials.gov identifier: NCT00857506, registered March 5, 2009).
Highlights
Biomarkers based on the underlying pathology of Alzheimer’s disease (AD) and Dementia with Lewy Bodies (DLB) have the potential to improve diagnosis and understanding of the substrate for cognitive impairment in these disorders
Demographic features The study included 11 subjects clinically diagnosed with DLB, 10 with AD, 5 with Parkinson’s disease (PD), and 5 healthy controls (HC) subjects (Table 1)
The gender distribution varied by group, with a higher proportion of men in the Lewy body disorders group (PD and DLB) compared to AD and HC (p = 0.0558)
Summary
Biomarkers based on the underlying pathology of Alzheimer’s disease (AD) and Dementia with Lewy Bodies (DLB) have the potential to improve diagnosis and understanding of the substrate for cognitive impairment in these disorders. The objective of this study was to compare the patterns of amyloid and dopamine PET imaging in patients with AD, DLB and Parkinson’s disease (PD) using the amyloid imaging agent florbetapir F 18 and 18F-AV-133 (florbenazine), a marker for vesicular monamine type 2 transporters (VMAT2). Biomarkers based on the underlying pathology of AD and DLB have the potential to improve diagnosis 11C-labeled Pittsburgh compound B (11C-PiB) was the first. Florbenazine (AV-133) is a fluorinated VMAT-2 ligand for PET that has been shown to identify dopaminergic deficits in patients with PD and DLB [14,15]
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