The possibility that stem cells might be able of value in treating AD has gained considerable attention. Yet most investigators believe this is not a practical strategy for the treatment of AD. However, developing small molecules that could stimulate the proliferation of naturally occurring neuronal stem cells in the brain is thought to be an exciting approach. Year 1 of this preclinical project demonstrated that allopregnanolone (AP), a small blood-brain-barrier permeable neurosteroid, promoted generation of new neurons in transgenic animal models of Alzheimer's disease. The investigators also demonstrated the efficacy of AP in increasing the number of human neuronal stem cells in animals (neurogenesis). Results of these analyses provide preclinical evidence of the efficacy of AP? as a regenerative neural stem cell factor in AD. In this second year of funding, the investigators will investigate the ability of AP to induce neurogenesis in an animal model of AD.