CREB1 and Alzheimer disease: This signaling pathway is closely related to alcohol drinking behavior; activation of cAMP signaling inhibits alcohol drinking, and vice versa.23 Meanwhile, PDE4 plays an important role in the mediation of AD.18 Inhibition of PDE4 in the brain improves learning and memory ability by activating the cAMP-PKA-CREB signaling pathway and protecting against the decline of memory ability in AD.