Viagra may be useful against Alzheimer's dementia The Cleveland team found: High doses of the drug (larger than a person would normally take) increased brain cell growth and reduced protein accumulation in lab studies of human tissue People on sildenafil were less likely to develop Alzheimer's than those not taking this medication, based on personal medical data spanning six years and involving more than 7.23m individuals Lead investigator Dr Feixiong Cheng said the findings were encouraging, but needed more exploring: "Because our findings only establish an association between sildenafil use and reduced incidence of Alzheimer's disease, we are now planning a mechanistic trial and a phase II randomized clinical trial to test causality and confirm sildenafil's clinical benefits for Alzheimer's patients."