Here are some references;
https://www.guitartricks.com/forum/thread.php?p=287097
https://www.guitartricks.com/forum/thread.php?p=286756
https://www.guitartricks.com/forum/thread.php?p=292391
https://www.guitartricks.com/forum/thread.php?p=302008 specific to dementia
https://www.guitartricks.com/forum/thread.php?p=308465
There are probably others but my memory isn't so good anymore... 
"It takes a lot of devotion and work, or maybe I should say play, because if you love it, that's what it amounts to. I haven't found any shortcuts, and I've been looking for a long time."
-- Chet Atkins
-- Chet Atkins
