Maintenance of neuronal plasticity in the reticular core and changes in trophic activity in Alzheimer's disease.

1. Neuronal loss in Alzheimer's disease (AD) is accompanied by a proliferative response of the remaining neurons. 2. Different cell types are differently involved in the process of degeneration and proliferation in AD. 3. The extent of dendritic growth in AD is related to the formation of amyloid, not preamyloid. 4. Proliferative changes similar to those observed in AD can be induced in an animal model as a response to neuronal death. 5. The processes of degeneration and proliferation in AD are probably associated with an increase in trophic activity.