I have watched a bunch of different videos on Youtube about different dementia. Here is one I just watched that I thought was interesting. 

https://www.youtube.com/watch?v=baQSf_9l-uk
 
Don't discount diet influence. Do some research on exogenous ketones.

https://www.youtube.com/results?search_query=exogenesis+ketones+and+dementia

I have no personal experience with dementia but at 70 years of age it is on my list of age related concerns.