The descent
into dementia is horrific. It can creep up gradually, robbing people of
their personalities as well as their memories. Friends, family and
co-workers have a hard time dealing with the forgetfulness and cognitive
dysfunction. Family members often struggle to help their loved one stay
safely at home, but frequently that becomes an overwhelming task. For
those who have had to deal with dementia, the question we get most often
is, “How can I prevent Alzheimer’s disease myself?” A study in the Journal of Alzheimer’s Disease (March 19, 2024) was titled “Sildenafil as a Candidate Drug for Alzheimer’s Disease.”
In case you don’t recognize the drug sildenafil, it is the generic name for Viagra! That’s right, the medication that the FDA approved for erectile dysfunction in 1998.
The Pharmaceutical Industry Dropped the Ball:
With nearly 7 million people suffering from Alzheimer disease it
should come as no surprise to learn that drug companies have been trying
hard to come up with effective treatments. It would be a billion-dollar
bonanza for any drug company if it had a medication that actually
improved memory and/or helped keep people out of nursing homes. Families
would be ecstatic if there were ever such a breakthrough.
A nursing home can cost any where from $80,000 to $120,000 a year.
Many people would be willing to spend their life savings to stay out of
such a facility. If there were a medicine that could accomplish that, a
pharmaceutical manufacturer could charge $100,000 a year or more. Do the
math. That would equal $500,000,000,000. If you lost count of the
zeroes, that is $500 billion, which is a mind-boggling amount of money.
Drug companies are thrilled if a medication earns a billion dollars
in a single year. A $5 billion drug is a blockbuster. A $500 billion
dollar drug would bankrupt insurance companies and families. If it
worked, though, people would likely pay, just as they now are paying
over $100,000 a year for some cancer drugs.
The Anti-Amyloid Drug Disappointment
We have written a lot about the disappointing results from
anti-amyloid drugs. The FDA approved three medications in recent years.
One, Aduhelm, was discontinued. You can read about this hot mess at this link. The others include donanemab (Kisunla) and lecanemab (Leqembi). Estimating price is tricky, but we have seen numbers like $32,000 for Kisunla and $26,500. That is not the full story, though. CBS News did an in-depth report (Aug. 1, 2023) titled: “The real costs of the new Alzheimer’s drug, Leqembi — and why taxpayers will foot much of the bill:”
“In addition to the company’s $26,500 annual price tag
for the drug, treatment could cost U.S. taxpayers $82,500 per patient
per year, on average, for genetic tests and frequent brain scans, safety
monitoring, and other care, according to estimates from the Institute
for Clinical and Economic Review, or ICER.”
“To qualify for Leqembi, patients must undergo a PET scan that looks
for amyloid plaques, the protein clumps that clog the brains of many
Alzheimer’s patients. About 1 in 5 patients who took Leqembi in the
major clinical test of the drug developed brain hemorrhaging or
swelling, a risk that requires those taking the drug to undergo frequent
medical checkups and brain scans called MRIs.”
More about anti-amyloid drugs shortly.
What About Generic Sildenafil (Viagra) To Prevent Alzheimer’s Disease?
The pharmaceutical industry and a lot of neuroscientists don’t seem terribly excited about the paper in the Journal of Alzheimer’s Disease (JAD) (March 19, 2024) involving Viagra.
Maybe that’s because sildenafil is relatively inexpensive (anywhere
from $15 to $30 for 30 pills with a coupon). It does not fit the classic
anti-amyloid model of AD that has prevailed for so long.
The JAD study was ambitious. It suggests that the ED drug Viagra
might reduce the risk of developing Alzheimer disease. Researchers at
the Cleveland Clinic identified genes involved in the development of
amyloid plaques and tau tangles in the brain. These are distinctive
markers of dementia. Analysis showed that sildenafil (the generic name
for Viagra) had the potential to interact with these genes in a positive
way.
Then the investigators evaluated two large patient databases of
insurance claims. People taking sildenafil were substantially less
likely to be diagnosed with Alzheimer disease than those taking the
blood pressure pill spironolactone. Test tube research had previously
shown that the drug could improve neuron growth and reduce the
accumulation of toxic tau.
The authors describe their research in somewhat technical, but understandable language:
“Sildenafil is a selective PDE5 inhibitor and PDEs are
broadly expressed in human brain. Recent studies have shown that
sildenafil has beneficial effects in various preclinical models of AD by
modulating neuronal plasticity, reducing tau phosphorylation, improving
cognitive impairment, decreasing amyloid betaplaque accumulation, and
enhancing the level of BDNF [brain-derived neurotrophic factor]. Our
previous study found that sildenafil increased neurite growth and
decreased phospho-tau (pTau181) in AD patient iPSC-derived neurons,
mechanistically supporting its potential beneficial effect in AD.
“Furthermore, two pilot trials demonstrated beneficial effects of
sildenafil in treatment of AD, where a single dosage of 50 mg sildenafil
reduced spontaneous neural activity in the right hippocampus in 10
patients; and increased the cerebral metabolic rate of oxygen and
cerebral blood flow in 12 patients; and decreased cerebral vascular
reactivity in 8 patients.
“Recent observations involving data from over 30 million insured
members validates the association between sildenafil use and reduced
risk of AD. This study showed that sildenafil could reduce the risk of
AD by 60% which in consonant with our findings.”
We grant you that this is pretty technical. The authors sum up their research by suggesting that:
“…sildenafil can be a potential repurposable drug for the
treatment of AD and warrants further testing in more functional models
and randomized controlled clinical trials.”
Sadly, we do not expect any drug company to take them up on this
suggestion. Sidenafil is incredibly cheap compared to anti-amyloid
drugs. And drug companies cannot make money on medications that have
lost their patents. It remains to be seen whether other funding groups
will sponsor randomized controlled trials to demonstrate whether
sildenafil or other ED drugs that inhibit PDE5 could be truly effective
against Alzheimer’s disease.
A Recent Visitor to This Website Wanted a 2026 Update:
We received this question from a visitor to www.PeoplesPharmacy.com:
Q. A few years ago you wrote about a
Viagra study. It looked really promising, because it showed a 30 to 54
percent reduction in Alzheimer’s disease from a drug that isn’t even
taken daily! I really hope that researchers will follow up with a
clinical trial.
Meanwhile, men could try taking Viagra. But what about women?
A. Back in 2024 researchers reported preliminary
results suggesting that sildenafil (Viagra) might help protect against
Alzheimer’s disease (AD). One report noted that sildenafil reduced
phosphorylation of tau, one of the important risk factors neurologists
note for this dementia (Journal of Alzheimer’s Disease, 2024). In
addition, the investigators analyzed medical records in two large
databases and found, as you wrote, a significant reduction in AD.
Another study also relied on medical records and found that men
taking sildenafil or a similar drug were also less likely to develop AD
over five years (Neurology, Feb. 7, 2024).
The researchers concluded:
“…a randomized controlled trial including both sexes and
exploring various PDE5I [sildenafil-like drugs] doses would be
beneficial to confirm the association between PDE5I and AD.”
So far as we can tell, only one such study has been published (Journal of Prevention of Alzheimer’s Disease, Nov. 2025).
The study of mirodenafil was small and did not show benefit in people
who had already been diagnosed with AD. We are still waiting for a
large, well-controlled, long-term trial.
The Anti-Amyloid Bet: A Big Disappointment
The results of anti-amyloid drugs have been disappointing at best.
One experimental treatment that struck out was solanezumab. This
monoclonal antibody (“mab”) was designed to harness the brain’s immune
system to attack and remove amyloid.
Researchers know that beta-amyloid protein clumps together to form
plaques in the brains of people with Alzheimer disease. They made the
assumption that getting rid of these plaques would protect the brain
against dementia. Unfortunately, although solanezumab was quite good at
reducing brain levels of amyloid, it was no better than placebo at
slowing cognitive decline.
A Familiar Failure:
This is not the first time an anti-amyloid drug has produced
disappointing results. Since 2000, the pharmaceutical industry has
tested more than 200 compounds.
Some investigators are beginning to question the amyloid theory of
Alzheimer disease. There is even a suggestion that amyloid might play a
protective role when the brain is under attack by pathogens. That is
because it seems to have antimicrobial activity (Molecular Pharmaceutics, April 2012; Biological Chemistry, July 2012).
The Prevagen Promise:
Prevagen has been widely advertised on television as
a “breakthrough” that is “clinically shown to improve short term
memory.” The active ingredient, apoaequorin, was originally derived from
a protein in jellyfish.
The Federal Trade Commission and the New York Attorney General charged
the maker of this dietary supplement with “making false and
unsubstantiated claims that the product improves memory, provides
cognitive benefits, and is ‘clinically shown’ to work.”
The company, Quincy Bioscience,
“vehemently disagrees with these allegations…” and maintains that
“Prevagen improves memory and supports healthy brain function.”
ConsumerLab.com wrote an article titled: “Does Prevagen really improve memory?”
“According to the Prevagen website, ‘Prevagen is an
over-the-counter supplement for healthy brain function and memory
improvement.” A disclaimer indicates that these statements are “Based on
a clinical study of subgroups of individuals who were cognitively
normal or mildly impaired.’ Its package also claims that Prevagen
supports ‘healthy brain function, sharper mind, and clearer thinking.’
“However, as discussed below, there is little evidence that Prevagen
(from Quincy Bioscience) provides any meaningful benefit in terms of
memory improvement, and the extent of potential improvement appears to
be minimal. Due to actions by the FTC, the marketing claims for Prevagen
have been scaled back from earlier claims that it treats conditions
such as head injuries and Alzheimer’s disease.”
ConsumerLab.com goes on to discuss litigation:
“In March 2024, a jury verdict for another case brought against Prevagen by the state of New York (Federal Trade Commission et al v. Quincy Bioscience Holding Company, Inc. et al, Case #1:17-cv-00124) found that all eight statements challenged in the suit, including “Prevagen improves memory” and “Prevagen improves memory within 90 days,”
lacked support by “competent and reliable scientific evidence.”
Furthermore, the jury found two of the statements to be deceptive or
materially misleading: These were that “Prevagen reduces memory problems associated with aging” and “Prevagen is clinically shown to reduce memory problems associated with aging.”
You can read the full ConsumerLab.com report at this link.
These days, Prevagen commercials are very careful about the language that is used. What you will see and hear are the words:
Another 2026 commercial asks: “What do you do to take care of your brain?”
It recommends:
“Daily Brain Care” with Prevagen because “It’s made for your brain.”
The asterisk on the screen states: “not evaluated by the FDA. Not intended to treat/prevent disease.”
Can You Prevent Alzheimer’s Disease?
A Finnish study recruited older people with average or below-average
cognitive scores. It demonstrated through a randomized trial of
improvements in diet, exercise, cognitive training, blood pressure and
cholesterol control that these could lead to significant improvement in
cognitive scores (Lancet, June 6, 2015).
A Researcher Who Claims to Have Reversed Dementia:
Readers who would like to learn more about how a variety of
preventive strategies may wish to listen to our interview with Dale
Bredesen, MD. It can be found at PeoplesPharmacy.com. In it, he describes his multifactorial interventions to reverse dementia.
You may also find a more recent interview with Dr. Bredesen of interest as well:
Show 1412: Beyond Amyloid: The Science That Could Change the Course of Alzheimer Disease
A personalized approach considering multiple factors may be helpful for changing the course of Alzheimer disease.
You can listen to the podcast on Apple Podcasts at this link or on Spotify.
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