Neurodegeneration and neurogenesis: focus on Alzheimer's disease.

Neurogenesis, or the production of new neurons from neuronal precursor cells, is a normal phenomenon in the adult brain, and is accentuated by brain injury. Forms of injury associated with increased neurogenesis include both acute (e.g., stroke) and chronic neurodegenerations. Studies on human postmortem material and transgenic mice overexpressing amyloid precursor protein mutations found in familial Alzheimer's disease (AD) suggest that AD is associated with enhanced neurogenesis. However, the mechanism responsible for this effect is unknown, as is what influence it may have on the clinical course of murine or human AD. If AD leads to the production of fully functional, mature neurons that can restore brain function, strategies aimed at further increasing endogenous neurogenesis may have therapeutic value.