How to handle someone with Dementia

This is how i was instructed to deal with my mom and dad. I learned early on not to argue with them about what they believe to be true. I had to have my mom and dad in separate nursing homes. My dad died in 2010. My sister 2011, my cousin who my mom was guardian over till dementia made it impossible in 2004 which then fell on me died in 2012 at 60 years old in diapers her whole life. All of these events my mom knew nothing of. Her doctors told me you never know what tragic event they would hold on to and that it was best not to tell her. She finally died in 2014 with never taking any meds aside from dementia medicines which didn’t work well. I can tell you from living thru this, there is not a worse way to die. My dad forgot how to swallow and had a feeding tube his last 2 years. Mom sat in a wheel chair fir the last 4 years of her life only because she forgot or refused to walk anymore. My dads mom suffered the same fate. Sometime when I was 17-18 my mom and dad both told me “ we never want to put you and your sister thru what we went thru with your grandmother”. But it happened. I could tell you the hell i went thru but enough to say is it is the worst most tragic event you will ever deal with. I don't envy anyone dealing with this.
I think your story would probably go for anyone dealing with this cruel disease. The only one that doesn't suffer is the patient themselves as they are in their own world.
Maybe this is the result or allowing these big companies from putting chemicals in our food to increase the shelf life and also polluting the air we breath all in the name of huge profits. But to be fair, dementia and Alzheimers isn't new, they've been around for many years.