CM-414 is a dual inhibitor of HDACs and PDE5 for the Treatment of Alzheimer’s Disease (IC50 values of 60 nM, 310 nM, 490 nM, 322 nM, and 91 nM against PDE5, HDAC1, HDAC2, HDAC3, and HDAC6, respectively). Chronic treatment of Tg2576 mice with CM-414 diminished brain Aβ and tau phosphorylation (pTau) levels, increased the inactive form of GSK3β, reverted the decrease in dendritic spine density on hippocampal neurons, and reversed their cognitive deficits, at least in part by inducing the expression of genes related to synaptic transmission.