MAPT and Alzheimer disease: In contrast to tau, results regarding SV2A and Aβ have been mixed: while some PET studies reported a "paradoxical" positive correlation between SV2A and [11C]PiB in the hippocampus of AD patients [63], others reported a negative correlation between [18F]SynVesT-1 and [18F]florbetapir in the hippocampus and parahippocampus [64].