I think I already have a good sense of what lifestyle changes can slow down aging and the progression of dementia and to what extent, but I don't know how to implement these changes. There is lots of advice here on how to change your life, which I appreciate, but not that much on how to change another person's life (please do correct me if I'm wrong), particularly if they are older and set in their ways or even suffering from dementia and find it difficult to learn new things while not quite comprehending the urgency of change. In this case, I couldn't even convince the primary caregiver (which is not, or at least should not be me) of the importance of diet and exercise.
How did/would you deal with these problems or any other problems in elder care in general? (Since my model of average rationalist told me that someone would bring up cryonics, I asked and they don't want that.)
As a side note, I feel like this topic does not receive enough attention on LessWrong, for instance it does not have a tag, unlike e.g. parenting.
Ah yes it's a separate question when we have someone who does not yet suffer from dementia but is at risk and who can plausibly take some actions to reduce the risk / delay the onset of dementia. I am definitely no expert on this but I would assume promoting better physical and psychological health reduces dementia risk alongside other bad side-effects of aging. The psychological part is key. I think if you know someone at risk of dementia, making sure they have a supportive family and/or friends and they don't feel lonely goes a long way to promoting better psychological health and reducing dementia risk, even if, for example, their diet and exercise regime is not optimal.