APOE and major depressive disorder: At 12 months old, no significant difference was observed between the control and CUMS groups in the elevated plus maze test (the time percentage and the frequency percentage of entering the open arm), open field test (the horizontal movement, the vertical movement and total movement), and tail suspension test (resting time percentage) (p > 0.05) (Fig. 3a-b, Fig. 3c-e, Fig. 3f, respectively), suggesting that ApoE-TR mice recover from depression after CUMS intervention is terminated.