There are a lot of things that can already be done - for me I have ADHD related dopamine dysregulation resulting in brain fog so I take slow acting dopamine reuptake inhibitors in the form of low dose modafinil. I also take strict care of my diet, sleep and other medications and I feel as sharp as ever. And since I'm already on top of it I do hope that I can maintain this into old age. I have a friend and former work colleague in his early 50s that is clearly suffering from a similar worsening ADHD brain fog but I've been unable to convince him to do anything about it. Every time I try he acts as if it's the first time I'm mentioning it. He knows he has memory issues but considers it more of a problem for other people since he is still able to cope within his daily routines. He is very anti-medication and thinks there is nothing really wrong with him. I think some medications and lifestyle changes could clear up his brain fog and bring him back to full mental capacity. I don't think he is past the point of no-return physically but there is no way for me to convince him to try meds, so in effect he's past the point of no-return mentally. It's like watching a slow motion train wreck that is still preventable but all my attempts at preventing it have thus far been ineffectual and likely always will be.