Could Viagra Help Prevent and Treat Alzheimer’s Disease?

“I think it’s interesting in terms of exploring new options and potential treatments for Alzheimer’s disease,” says Ronald Petersen, M.D., director of the Mayo Clinic Alzheimer’s Disease Research Center, who was not involved in the study. “It’s a scholarly study with a very elegant analytical model — and an example of how people are thinking more expansively about potential treatments for Alzheimer’s disease,” he added, referring to the study’s drug repurposing strategy.

The concept — finding new therapeutic uses for already licensed drugs — is one that’s gaining ground in Alzheimer’s research after decades of drug-discovery disappointment. The reason? It offers a faster and more cost-effective approach, which is especially important as the number of Americans living with Alzheimer’s is expected to spike from over 6 million to nearly 14 million by 2050, barring any breakthroughs in treatment.

So far, the FDA has approved a few medicines that help manage symptoms of Alzheimer’s disease but do not stop it from advancing. One treatment has received a green light from the agency for its potential to slow the progression of the disease, although it has yet to prove that it can alter the course of cognitive decline in a clinical setting, the National Institute on Aging says.  

A matrix of possible mechanisms 

How is it that Viagra may be able to stave off a neurodegenerative disease?

As part of the study, the researchers developed a brain cell model using stem cells from actual Alzheimer’s patients to explore how sildenafil might confer protection against Alzheimer’s-associated cognitive decline. They found that sildenafil increased neuron growth and reduced the accumulation of tau proteins, which form disruptive tangles in the brains of people with Alzheimer’s. The researchers noted that other studies have shown that drugs that are phosphodiesterase inhibitors, like sildenafil, have additional therapeutic effects in preclinical models of Alzheimer’s disease, such as decreasing the accumulation of amyloid plaques (another hallmark of Alzheimer’s), improving cognitive impairment and enhancing the level of brain-derived neurotrophic factor, a key molecule in memory function.  

The current study found that the effects of sildenafil on reducing the risk of Alzheimer’s disease were particularly strong for men, which isn’t surprising given that the drug is prescribed primarily to men with erectile dysfunction. But Cheng told AARP he thinks Viagra has the potential to reduce the risk of Alzheimer’s disease in women as well, which would be especially beneficial given that approximately two-thirds of people who are diagnosed with Alzheimer’s are women.

“If the mechanisms are increased blood flow, which could enhance cognitive function, and other biochemical effects on amyloid and tau, [the drug] could be effective in women as well as men,” Petersen adds. “The mechanisms they’re suggesting are probably not sex-specific.”

Looking to the future

In addition to further studying sildenafil’s impact on Alzheimer’s, Cheng says his team is researching other drug combination therapies that could interrupt the disease through a variety of pathways, including reducing inflammation. He also foresees the approach “being applied to other neurodegenerative diseases, including Parkinson’s disease and amyotrophic lateral sclerosis, to accelerate the drug discovery process,” Cheng said in a statement.

If the results of these studies prove to be positive, the arsenal of potential preventive therapies and treatments for Alzheimer’s may expand in ways that have important clinical implications.  

“Alzheimer’s is a complex disease,” Cheng says — one that likely requires a personalized approach “and drug combination therapy strategies” to prevent and treat it in the future.

Stacey Colino is an award-winning writer, specializing in health, psychology, and science. Her work has appeared in The Washington Post, U.S. News & World Report, Prevention, Newsweek, Parade, and many other national magazines.