Over the past decade, an increased clinical awareness, together with advanc
es in biochemical, cellular, and molecular analyses, have catapulted the st
udy of Alzheimer disease to the forefront of biomedical research. During th
is time, a great number of theories, regarding disease pathogenesis, have c
ome and gone but several have persisted. Here, we critically evaluate these
theories in an attempt to delineate the facts from the artifacts. (C) 1998
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