PER2 and Alzheimer disease: Aggression-related genes repressive to circadian rhythm genes Cry1, Cry2, Per1, Per2 were downturned in AD species, except for Nr1d1, but the key circadian genes (Arntl, Clock, Npas2) had not yet recovered their expression, implying an acute transition state in the AD group, featuring specifically high expression of the antagonistic Nr1d1 DEG in the AD group (Figure 6).