 The neuropathology of AD is characterized by neuritic plaques, neurofibrillary tangles, and neuronal cell loss Braak and Braak, 1997. Amyloid plaques are believed to play an integral role in AD Selkoe, 1993. Plaques are neurotoxic Yankner, 1989. Elevated levels of Aβ in the brain are correlated with cognitive decline Naslund, 2000. Removal of plaques in animal models of AD results in behavioral improvements Arendash, 2001. 