Qualitative and quantitative changes in normal aging and Alzheimer's disease.

Qualitative changes in normal aging and Alzheimer's disease (AD) are as important as quantitative changes. Although qualitative changes do not c-vary with quantitative differences in every respect, quantitative changes, nevertheless, often accurately reflect qualitative changes. Moreover, the complementary use of each provides a more detailed characterization of brain changes with aging and AD. The quantitative and qualitative changes of choline acetyltransferase, as well as somatostatin-containing neurons and dendrites, in human cortex are described as examples of this.