Presence of spike-wave discharges correlates with impairments in spatial memory in APP/PS1 and 3xTg-AD mice. Both strains of transgenic mice underwent Morris water maze testing immediately after continuous in vivo electroencephalography recording. (A) and (C) The presence of more than one spike-wave discharge (SWD) worsened the performance of 8- to 10-month-old APP/PS1 mice in the acquisition phase of the Morris water maze (A), and the same was true of 3xTg-AD mice (C) (*P = 0.039 and **P = 0.002 by repeated-measures analysis of variance with post hoc analysis). (B) and (D) A 48-hour probe trial showed an inverse relationship between frequency of SWDs and entries into the target area, defined as the platform area, during a 1-minute trial in APP/PS1 mice (B), but not in 3xTg-AD mice (D) (P = 0.005 and 0.39, respectively; Pearson correlation coefficient). WT: n = 8; APP/PS1 with SWDs: n = 8; APP/PS1 without SWDs: n = 9. 3xTg-AD mice included six females and four males. v1 through v4 indicate visible platform swim trials.