Well known as the leading prescription treatment to improve men’s sex lives, Viagra (sildenafil) may also keep Alzheimer’s at bay.
A new study led by the Cleveland Clinic showed the drug reduced the incidence of Alzheimer’s by a whopping 69 percent.
Some experts described the study as “clever” and “fantastic” and its use as “an exciting prospect”, but others weren’t so impressed.
The concept of drug repurposing – using an existing drug for new therapeutic purposes – offers a practical alternative to the costly and time-consuming traditional drug discovery process. What’s more, existing drugs have already gone through the FDA approval process.
With that in mind, researchers at the Cleveland Clinic started with the idea that since the interplay of toxic amyloid and tau proteins contributes to Alzheimer’s, they could use a gene-mapping network to identify genes and proteins that trigger these proteins to go rogue. Then, they would hunt for a drug to prevent this process.
Superior to Other Drug Candidates
Once the researchers identified the genes and proteins involved, they examined 1,608 commonly prescribed drugs. Out of this long list, sildenafil came out on top.
The result didn’t come entirely as a surprise. Sildenafil has already been identified as a potential dementia treatment by other research groups, and according to lead author Dr. Feixiong Cheng, it “has been shown to significantly improve cognition and memory in preclinical models.”
The drug has also been tested in a small number of patients.
The research team also showed that sildenafil was superior to two other drugs that are being tested in clinical trials to treat Alzheimer’s, and that it may be effective early in the disease process.
“Notably, we found that sildenafil use reduced the likelihood of Alzheimer’s in individuals with coronary artery disease, hypertension and type-2 diabetes, all of which are comorbidities significantly associated with risk of the disease, as well as in those without,” added Dr. Cheng.
The results were dramatic.
69 Percent Reduction in Alzheimer’s
The scientists analyzed medical records taken from insurance data for over seven million Americans to see if there’s a relationship between sildenafil and Alzheimer’s disease outcomes.
They found that sildenafil users were 69 percent less likely to develop Alzheimer’s disease than non-users after six years of follow-up.
Dr. Cheng and his team also carried out lab work showing sildenafil increased brain cell growth and decreased tau protein, the proteins believed to choke the life out of brain cells.
In their paper, published in the journal Nature Aging in December, the researchers admitted the study had quite a few limitations, and that their research can only show an association between the drug and a reduced risk of the disease. As a result, they’re planning a clinical trial to test causality; to see if sildenafil really will help prevent Alzheimer’s disease and help existing patients from getting worse.
Many brain health experts weighed in on the Cleveland Clinic study. Their responses were mostly positive, but not everyone was impressed.
What the Experts Say
Dr. Ivan Koychev at the University of Oxford described the sildenafil study as “a very comprehensive piece of research” and “an exciting development for Alzheimer’s disease research…”
Meanwhile, Dr. Catherine Hall at the University of Sussex thought the study was “clever” and the drug “is an exciting prospect for prevention of Alzheimer’s.”
At King’s College London researchers have been investigating another drug for dementia that’s chemically similar to sildenafil. Dr. Richard Killick, from King’s, found the Cleveland Clinic research “especially encouraging” and “bodes well” that one or both drugs “could prove to be truly effective treatments for Alzheimer’s.”
And Dr. Jack Auty at the University of Tasmania said it was “a fantastic paper…Very fascinating research” and “an excellent example of the future of medical research.”
Drs. Auty and Hall, while very positive about the research also picked up on the study’s limitations, most of which were admitted to by the researchers themselves.
Professor Tara Spires-Jones, a leading British neurologist, thought the study was scientifically interesting but “I would not rush out to start taking sildenafil as a prevention for Alzheimer’s.”
The only scientist that was completely unimpressed was Robert Howard, Professor of Old Age Psychiatry at University College London, who said the research “failed to excite me.” He felt there were too many factors the scientists couldn’t control for in the insurance data and these confounding effects “most probably explain these latest results.”
It looks like we’ll have to wait for the clinical trial to judge whether sildenafil is the real deal when it comes to protecting against Alzheimer’s disease.