APP and amyloidosis: To prove that functional decline of microglia is a general feature of AD pathology, and to exclude an impact of the PS1 transgene on microglia in APPPS1 mice unrelated to amyloid pathology, we assessed microglial phagocytic activity in APP23 mice, a transgenic mouse model of cerebral amyloidosis that is based on transgenic expression of APP with the Swedish mutation [22], but not of mutated PS1.