We have first analyzed the Abeta content of soluble fractions prepared from the hippocampal formation (hippocampus proper, subiculum and entorhinal cortex), using Dounce homogenization and ultracentrifugation (see also [9], [10], [19], [22]), of AD (Braak stage V–VI) and non-demented control (Braak stages II to IV) age-matched autopsy samples. The gene discussed is APP; the disease is Alzheimer disease.