Tissue sections from each animal in the four treatment groups were stained for amyloid pathology by Hirano silver, Campbell-Switzer silver, thioflavin-S, and Aβ immunohistochemistry. As expected, the 6 mo untreated cohort displayed moderate amyloid pathology, and the 9 mo untreated cohort progressed to a severe amyloid burden. In contrast, the extent of amyloid pathology in mice from the 6 mo + 3 mo treated or 6 mo + 6 mo treated cohorts closely resembled that of the 6 mo untreated cohort, despite the significant age difference between the treated and untreated groups (Figures 4 and Figure S3). Well-formed plaques remained in the treated animals after 6 mo of transgene suppression, even though as much time was given to clear the lesions as they had taken to form. Moreover, both types of amyloid, diffuse and fibrillar, remained intact throughout treatment. Using the Campbell-Switzer silver stain to distinguish different forms of amyloid, we found diffuse plaques were as persistent as cored deposits (Figure S4). It was nevertheless clear that dox-induced suppression of transgenic APP had completely halted the progression of pathology.