ABO and Alzheimer disease: Aβ*56 (12-mer, ~56 kDa) and AβO (15-mer, ~80 kDa) are highly neurotoxic without causing the formation of neuritic plaques or neurofibrillary tangles,31 and their high deposition have been found in the initial early stages of AD.36 By immunohistochemistry, we found that a toxic Aβ*56 was significantly increased in the OE of 6-month-old Tg2576 mice compared with WT, and was saturated in the OE of 14-month-old mice (Figure 6g).