Alzheimer's disease is a degenerative disorder.

Alzheimer's disease is characterized by brain atrophy, loss of neurons, and major loss of synapses. It is primarily a degenerative disorder, even though some aberrant sprouting does occur. To the extent that the abnormal neurites in neuritic plaques might represent a combination of a degenerative and regenerative (1) process, it is more likely that any regenerative process is secondary to the trophic effects of the amyloid precursor protein than to NGF which would affect only neurons with appropriate receptors, namely the cholinergic neurons. Cholinergic terminals constitute only a small percentage of the neurites involved in neuritic plaque formation. In addition, studies in impaired aged rats support the hypothesis that NGF enhances rather than disrupts memory processes.