PDE5A and Alzheimer disease: PDE5 is among the moststudied families in the brain,12,13 but very recent reportsare also supporting the role of PDE1 andPDE7 inhibitors in Alzheimer’s disease (AD) and neurodegeneration.14,15 More in general, brain bioavailable PDE inhibitors activating cGMPsignaling are being investigated as potential therapeutic strategiesagainst AD.11,16