1. Neurogenesis (as defined by cell proliferation of progenitor cells) in the adult human brain is region specific.
2. Neurogenesis in the adult human brain is age dependant.
3. Altered neurogenesis might play an important but yet unexplored role in pathophysiology of neurodegenerative diseases.
1. To measure regional cell incorporation of a radiolabeled thymidine analogue within the brain in young, middle-age, and elderly normal subjects using PET imaging and brain mapping techniques, and to examine possible age-related decline.
2. To measure regional cell incorporation of a radiolabeled thymidine analogue in patients with early Alzheimer's disease using positron emission tomography (PET) imaging, and to compare with that of elderly normal subjects.
3. To explore the use of a new thymidine analogue coupled with a redox chemical delivery system as a potentially better radiotracer for imaging of neurogenesis.
Researchers will recruit through advertisements normal subjects, with no major medical history, in three different age groups (young 20-30 years old, middle age 40-50 years old, and elderly 60-70 years old). Each group will consist of 6 subjects. Also recruited for the study will be 6 patients with a very early stage of Alzheimer's disease. Researchers will use a new imaging technique to study and compare brain cell replication non-invasively in their subjects. The technique will use a small amount of radiolabeled compounds that can be injected safely in humans and will accumulate in replicating brain cells. PET will then be used to measure the amount and location of brain cell replication by detection of the emitted radioactivity from the compounds.