Our sense of smell can become less sharp with normal aging. In Alzheimer's disease and Parkinson's disease, it is often markedly diminished. With the hope of determining when olfactory deficits can be an indicator of a neurodegenerative disease, Mark Albers, MD, PhD is examining odor discrimination in mice, a species with a highly developed sense of smell. He proposes to determine odor discrimination thresholds in transgenic mouse models of Alzheimer's disease as they age. Once olfactory deficits are detected, a neuropathological examination of the mouse brain is performed, in which he quantifies markers of Alzheimer's disease such as plaque count, Aß levels, and synaptic density.