Fig. 1

Impaired social memory in 3-month old APP/PS1 mice. A Schematic of the three-chamber social recognition memory test consisting of stage 1 (habituation), stage 2 (social interaction) and stage 3 (social recognition memory). B Normal social interaction during stage 2 in APP/PS1 mice (WT n = 10, p < 0.001; APP/PS1: n = 10, p < 0.001; two-tailed paired t-test). C Impaired preference for S2 over S1 during stage 3 in APP/PS1 mice (WT n = 10, p = 0.002; APP/PS1: n = 10, p = 0.386; two-tailed paired t-test). D Discrimination scores during stage 3 showing impaired social memory in APP/PS1 mice (p = 0.009, two-tailed t test). E Schematic of the five-trial social memory test. F Both WT and APP/PS1 mice showed memory acquisition during trials 1–5 (WT n = 10, APP/PS1 n = 17; genotype group: F_(1,9) = 0.002, p = 0.965; trial: F_(4,36) = 17.572, p < 0.001; repeated two-way ANOVA for trial 1 versus trial 5). On trial 6, APP/PS1 mice showed significantly decreased interaction time compared to WT mice during the presentation of a novel stranger mouse (p < 0.001, two-tailed t test). G Open field test showing travel distance in WT and APP/PS1 mice (WT n = 10, APP/PS1 n = 17, p = 0.864, two-tailed t-test). H Average travel speed of WT and APP/PS1 mice in open field test (WT n = 10, APP/PS1 n = 17, p = 0.851, two-tailed t-test). I Time spent in center arena in open field test (WT n = 10, APP/PS1 n = 17, p = 0.242, two-tailed t-test). J Time spent in peripheral area in open field test (WT n = 10, APP/PS1 n = 17, p = 0.235, two-tailed t-test). K Travel distance in elevated plus maze test (WT n = 10, APP/PS1 n = 17, p = 0.899, two-tailed t-test). L Time spent in closed arms in elevated plus maze test (WT n = 10, APP/PS1 n = 17, p = 0.092, two-tailed t-test). M Time spent in open arms in elevated plus maze test (WT n = 10, APP/PS1 n = 17, p = 0.455, two-tailed t-test). Data are presented as mean ± s.e.m. n = number of mic. **p < 0.01, ***p < 0.001, ns = not significant