You bring up some interesting ideas, and I am well aware of the current research on dementia (first hand exposure for prolonged periods will either turn you into an expert on the etiology of dementia, or make you run for the hills). If you're like me, you also notice the utter lack of progress we've made in this area. Pharma has hit or miss symptom management approaches that many cannot afford; once symptoms are noticed, intervention is unlikely to have much of an impact, except to further degrade the quality of life of the patient. We should be aggressive when it comes to new approaches, and I have been closely following studies and the experiences of those who self-experiment. I did trials of vinpocetine, among other nootropics, follow the community, and if a promising compound is released, procure a sample prior to someone patenting it. When my Grandmother was showing signs, I took a course of memantine to help stall with growing ineffectiveness of medication that I relied upn, and also to let the family know about what to expect if they decided to go that route. That was several years ago; they chose not to use meds, and it was too late at that point anyway, as I came to realize upon arrival.

BTW, after a week of acclimating, I was pleasantly surprised at the effects offered by that compound. I'm currently obsessed with certain types of inflammation, and am using a dietary approach, augmented by certain supplements, yoga (oxygen!), socializing, challenging myself (SICP, why not), and meditation (more oxygen! and meta-cognitive benefits to boot - observing changes in cognition is not easy without it, and observations regarding mental status decline from others is hard to accept). I'm not young enough anymore to believe hype on longecity, e.g., but I'm not going to discount personal experiences either.

One thing to remember about the O2 hypothesis you propose,is that dementia sufferers often do not get sufficient nutrients. The forget how cooking works, what food is, that water should be consumed on a regular basis, develop phobias around food, security, paranoia, and in my case as a temporary (but almost full time) caregiver is showing me the limits of care. In the morning, I systematically walk through the house, open all windows, blinds, remove barricades, turn on all fans, and prepare meals (was a chef in a past life, luckily), ensure the food is labeled, with a note to enjoy, and we cook a meal (I cook, and give out busy-work assignments while the meal is prepared. It is important to do an evening meal and do what you can to make it "fun"; oftentimes that is the best part of the day for someone experiencing cognitive decline. Food is intimately tied to memory, and I notice the effects, especially when incorporating ingredients from her childhood. Ah, I don't know... If you are young (I'm early thirties), now is the time to become an expert. Doctors are not equipped or understandably risk-averse when it comes to dealing with our new era of elongated morbidity. I'm getting a tattoo that reads "DNR" somewhere on my torso whe I hit 60. The devastation to family in the case of unclear wishes regarding such matters cannot be overstated. I have been doing this for just under a year, almost burned out twice, and have radically changed my own life to decrease stress, engage in primary prevention, and live as well as I can.