Researchers who analysed medical insurance claims from 7.23 million Americans have found Viagra (sildenafil) prescriptions were associated with a 69% reduced risk of Alzheimer’s in claimants over the following 6 years.
The scientists at the Cleveland Clinic, whose study was published in Nature Aging, set out to predict which existing drugs could potentially provide new treatments for Alzheimer’s, using a computational model incorporating data about the disease’s genetics and the involved networks of metabolic pathways – particularly between proteins in networks that play a part in creating plaques of beta- amyloid and fibrous tangles of tau.
They generated ‘network proximity measures’ for over 1,600 approved drugs – according to how closely they interact with the Alzheimer’s-related networks – which allowed them to narrow the candidates initially to 66 drugs which could potentially treat the disease, from which (taking into account other factors, such as promising results from experiments in animal models) sildenafil emerged as the most promising candidate. The association remained statistically significant after accounting for other factors that influence Alzheimer’s risk.
In addition, the researchers reported laboratory tests on nerve cells from people with Alzheimer’s supported the notion that sildenafil may treat the disease. They found sildenafil promoted the growth of new nerve projections and decreased tau accumulation in the cells.
Senior author Dr Feixiong Cheng said: ‘Taken together, the association between sildenafil and decreased incidence of Alzheimer’s disease does not establish causality or its direction, and our results therefore warrant rigorous clinical trial testing of the treatment efficacy of sildenafil in patients with Alzheimer’s, inclusive of both sexes and controlled by placebo.
‘We are planning a mechanistic trial and biomarker-guided phase 2 trial in the next step to further verify the clinical benefit of sildenafil in early Alzheimer’s patients.”
