In the passive avoidance test, compared to the APP/PS1 and WT control groups, the latency to enter the dark area was significantly shortened and the frequency of entries into the dark compartment was increased in the 27-OHC-treated group (Fig. 10a, b, P< 0.05), suggesting that 27-OHC treatment could induce learning and memory impairment. Here, APP is linked to memory impairment.