New research suggests that usage of the medication Viagra is associated with a reduced incidence of Alzheimer's disease.
According to a study led by researchers at the Cleveland Clinic, taking the drug is associated with a 70 percent lower risk of developing Alzheimer's compared to non-users.
An analysis of health insurance claim data shows that people who took the medication were less likely to develop Alzheimer's over the next six years than people who didn't use it.
Even on a huge scale, observed associations like this are not proof of a causative effect. It's possible that the people who took the drug might have something to do with their improved chances of not developing Alzheimer's.
The researchers say the correlation shown here is enough to identify a promising candidate drug for Alzheimer's disease, which can be explored in future randomized clinical trials.
The senior author of the study says that the use of the drug reduced the likelihood of Alzheimer's in people with cardiovascular disease, hypertension, and type 2 diabetes.
It's not the first time that the drug has been linked with better health outcomes, with the drug previously showing promise in a range of different scientific contexts.
Cheng's team built over a dozen modules using computational techniques to map genetic factors that could be used to diagnose Alzheimer's disease.
The researchers looked at what kinds of FDA-approved drugs might hypothetically help against the identified phenotypes.
The FDA approved over 1,600 such medications, and out of them, sildenafil was one of the most promising.
The drug is only used for treating ED and pulmonary hypertension, so it's not clear if it has other health benefits.
Cheng says that recent studies show that the interplay between amyloid and tau is a greater contributor to Alzheimer's than either by itself.
The best drug candidate is Sildenafil, which has been shown to improve cognitive and memory in pre-clinical models.
The hypothesis appears to be correct, with the team finding that the risk of Alzheimer's disease was reduced by 69 percent for users of the drug, compared to non-users.
The researchers emphasize that there is no causality, but there may be other promising leads.
The researchers observed that the brain cells that were treated with the drug showed elevated growth and a decrease in the number of tangles.
It's early days, but the reduced chances of developing Alzheimer's in the insurance cohort could have something to do with those effects. The team says that it's important to follow the leads further.
Cheng says that they are planning a mechanistic trial and a phase II randomized clinical trial to confirm the benefits of sildenafil for Alzheimer's patients.
We expect our approach to be applied to other neurodegenerative diseases, including Parkinson's disease.
Nature Aging reports the findings.
