I worked at an NIH-funded research institute that focused on ageing and age-related diseases. The reality is (a) ageing is complex and no single compound will do much to increase lifespan or healthspan, and (b) we already know how to increase lifespan and healthspan but hardly anyone wants to be bothered.
There is a huge mass of evidence that shows conclusively how to push back ageing and ill health: exercise strenuously at least 5 days per week and eat food that is good for you, not McSlop or the processed junk that comprises 80% of what’s in your typical supermarket. Plus, if you want to hold off neurodegeneration, learn new skills.
What people actually want is to sit on their sofas cramming McSlop down their throats and slurping Diabetes-Cola while gazing vacantly at Netflix. It’s unclear why we should go to the trouble of trying to find pharmacological solutions to what’s basically a very human problem of greed and indolence.