Why Did Alzheimers Clinical Trials Peak In 2005?

from downloading all results of search term "alzheimers" at CT.gov, counting the "first received" field, and dividing by the total number of studies registered each year; code

What's up? The most highly cited paper from 2005 is a review by Tanzi and Bertram, "Twenty years of the Alzheimer's disease amyloid hypothesis: a genetic perspective". It discusses the history of the evidence for the amyloid hypothesis, mostly in the context of genetic mutations that have been associated with the disease. Perhaps 2005 represented the peak of the (insoluble) beta amyloid hypothesis, and now the field is retooling?