A Trial of 18F-AV-133 and 18F-AV-45 Positron Emission Tomography (PET)

Inclusion Criteria DLB: * Male or female \> 50 years of age * Meet the diagnostic criteria for probable DLB as established by the DLB Consortium (McKeith et al., 2005) Inclusion Criteria AD: * Male or female \> 50 years of age * Meet the NINCDS criteria for probable AD and have a Mini Mental State Examination (MMSE) score at screening between 10 and 24 inclusive Inclusion Criteria PD: * Male or female \> 50 years of age * Have probable PD according to the following criteria (Gelb et al., 1999): * Presence of 2 of the following 3 features: rest tremor, rigidity, bradykinesia; * Documented history of a sustained (\>6 months) improvement to Levodopa (L-DOPA) or a dopamine agonist * Absence of atypical clinical features or other possible signs or symptoms suggesting another cause of parkinsonism such as a history of frequent falls as a prominent early feature, localized brain lesion(s) or neuroleptic use * Asymmetric onset * A diagnosis of PD made within the 4 years prior to enrollment Normal subjects: * Are males or females \> 50 years of age * Have a MMSE score \> 29, and are cognitively normal on the psychometric test battery at screening * Have no signs or symptoms of clinically meaningful parkinsonism Exclusion Criteria: * Have a history or current diagnosis of other neurologic disease * Have evidence of clinically significant cerebrovascular disease * Have evidence from MRI or other biomarker studies that suggests the presence of a CNS pathology other than that associated with the study diseases