To investigate possible links between the severities of memory impairment and amyloid deposition, we examined amyloid plaque load and the protein levels of Aβ and CT in the brains of 15-month-old WT_sh-CTL, WT_sh-S100a9, Tg_sh-CTL and Tg_sh-S100a9 mice (i.e., after behavioral tests) using 6E10 antibody, which specifically recognizes amino acids 1–17 of the Aβ region. The gene discussed is S100A9; the disease is memory impairment.