Of course you are exactly correct. There are forces – namely entrepreneurs who seek to enrich themselves by catering to the undemanding life-extension crowd (which judging by the shelves in the local Walmart are many). These people want to do the same with education – substituting private or at least ‘charter’ schools for the public school system (at least here in Utah – the home of anti-aging supplements in the US). Unfortunately, they don’t seem to add anything to the efforts except hype and red herrings both in supplements and in education.
Since what I believe about aging comes mainly from rodent studies – I take your caution about them seriously, but I believe in the case of what I have seen that mice represent us well enough to believe that what occurs in mouse or rat aging is in broad outline what all mammals experience.
Your emphasis on brain shrinkage makes total sense – and I will include brain MRIs as a means for deciding the effectiveness of aging interventions. Sure we all want to live longer (well all of us in any case), so we discount results we don’t like and emphasize those we do – and that is not science. Any real life-extension should be shown conclusively – and the reversal (or at least stoppage) of brain shrinking should be an important piece of data. So thanks.