BDNF and Alzheimer disease: In summary, our data uncovered that the PDE8 inhibitor PF alleviated AD-like changes in behavior and pathology through various mechanisms, including attenuating microglia-mediated neuroinflammation, upregulating the expression of BDNF, restoring synaptic dysfunction and inhibiting Aβ generation, which seem to be involved by the PDE8/cAMP/CREB signaling pathway.