ACHE and Alzheimer disease: The PET tracer [11C] donepezil has been successfully utilized to measure AChE density in the brain of patients with Alzheimer’s disease or PD.62, 63 We recently implemented this tracer for quantification of AChE density in peripheral organs of healthy individuals and showed that the distribution of [11C] donepezil approximates vagal innervation of the internal organs.64 Two [11C] donepezil PET studies of 12 early-to-moderate stage PD patients and 19 newly diagnosed patients have been performed.