Knockout of the BACE1 gene, but not CatB, in AβPPSwe/Lon mice results in improved memory acquisition, memory deficits, and memory retention. Control AβPPSwe/Lon mice, AβPPSwe/Lon × CatB knockout (CatB KO), and AβPPSwe/Lon × BACE1 KO (BACE1 KO) mice were evaluated in the Morris water maze test during each day of the training sessions by measuring the latency period (A). After the training sessions had concluded, memory deficits were determined by measuring the latency period (B) and the distance traveled to the platform (C). Memory retention was assessed by measuring the percent time in the quadrant from which the platform had been removed (Northeast (NE) quadrant) (D) and the percent time in the annulus of the pool (E). Values are expressed as x ± s.e.m., n = 10 per group. ***Statistically significant (p < 0.05).