MAPT and Alzheimer disease: A study using sildenafil found improved memory taskperformance in a mouse model of AD.75 In a similar mouse model tadalafil improved water maze performance andreduced Tau phosphorylation after 12 weeks of treatment.76 Object recognition task performance was also improved by PDE5i in maleWistar rats.77 Acute stroke studies in rodents found improved outcome with PDE5i,apparently due to neurorepair.78, , –81