Evaluation of [18F] FMH3 and PET as a Marker of Histamine-3 Receptor Activity in Subjects With AD Compared w/ HC

Approximately 10 subjects with Alzheimer disease (AD) and 8 healthy control (HC)subjects will be recruited to participate in this study. All subjects will undergo written informed consent and a screening evaluation including baseline clinical laboratory testing, a baseline physical and neurological evaluation and baseline cognitive evaluations. Subjects will be asked to undergo a bolus injection of \[18F\]-FMH3. Subjects will undergo serial PET imaging scans and plasma sampling for measurement of \[18F\]-FMH3 in plasma (both protein bound and free) over a period of up to 8 hours. The primary imaging outcome measure will be the brain regional distribution volumes expressed as a brain tissue to plasma ratio of the radioligand, \[18F\]-FMH3. At least 2 weeks following the initial imaging visit, subjects may be asked to return for a second injection and scanning procedure to evaluate the reproducibility of the imaging measure using this procedure. Subjects may decline to participate in the second scan.