The paper mentions neuroprotective effects, but it has been known for a while that nearly all types of PDE inhibitor can boost cognitive function, which has led to some interest in them as nootropics: https://pubmed.ncbi.nlm.nih.gov/25464010/
There has been some interest in PDE5 inhibitors, specifically, as treatments for Alzheimer's: https://www.sciencedirect.com/science/article/abs/pii/S03619...
And, in a 20 year old paper, a PDE5 inhibitor appears to have direct effects on memory consolidation in an animal model: https://pubmed.ncbi.nlm.nih.gov/15312986/
So, yeah, if I fancied myself at risk for dementia, I don't think it would be unwise to take viagra or sildenafil as a precautionary neuroprotective measure.
[1] https://www.reddit.com/r/Nootropics/search?q=Phosphodiestera...
Edit based on comment below: possibly I am too cynical :-D
There's two mindsets:
1) An emotional one. "Words impact emotions"
2) A logical one. "Study has issues 1, 2, and 3"
Both have places, but science must be in #2 to work at all. That is the point of science.
One of the critical parts of this mindset is separating criticism of work, quality of work, and the individual. Indeed, the more significant the science, the more it needs criticism. There is little (and probably even a negative) correlation between the quality of science and the quantity of criticism.
If I list out the limitations of your work in a blog post, that is not, should not, and cannot be read as a condemnation of your work, and especially not of you as an individual.
Indeed, generally, what that means is I took an interest in your work, found it compelling enough to do a deep dive, and I wrote a blog post because I'm trying to figure out next steps.
There is a pipeline from speculation to hypothesis to theory to fact, and it RELIES on people doing their best to invalidate a piece of work, understand methodological limitations, find alternative explanations, and otherwise poke holes. Once those holes are filled, and there are no more criticisms, you have trustworthy knowledge.
PLEASE attack my work (so long as you do it honestly and correctly; not unhinged emotional attacks). It makes my work better.
Of course, they cannot take everything into account.
Short of having a thousand identical twins locked up in a room from birth you're swimming against a very strong tide. Long gone are the days when science was as simple as castrating a rooster and grafting his balls back: https://en.wikipedia.org/wiki/Arnold_Adolph_Berthold
They acknowledge that they are just looking at the number of prescriptions and that the research doesn't show that the drugs themselves were reducing people's risk.
It could equally be the amount of sex that is reducing the risk.
(more seriously, anything that improves your circulation will probably help with alzheimers, plus good sleep)
Especially in older men, these groups can look nothing like each other.
So it's conceivable that it could clear a wider exit pathway for amyloid plaques and other garbage that accumulates in the brain.
It's also why a significant fraction of men who take it develop headaches so painful that sex is the last thing on their mind. Welcome to vasodilators.
Oh and if you already take nitroglycerin for cardiac angina, you can't take viagra because you get twice the headache -- right before you pass out because your blood pressure crashed.
that this ffect is rue for taladafil/sindemafil based pills?
There is so much low hanging fruit and we're all thinking of several I suspect. My initial thought was in the lane of 'drug is affecting one more head than intended', but it's missing some refinement I'll admit