My Dad died from the complications of good old fashioned Senile Dementia - essentially a hardening of the blood vessels in his brain and a subsequent shrinkage of brain tissue.
It was not easy.
He knew he was losing his faculties, but not which ones or how badly. He was extremely intelligent, which meant that he was able to hide his problems for far too long. It basically resulted in my sister and I having to whisk him out of his home and put him in a closed ward in an assisted living facility. We tried to recreate his home in a single room with his own furniture and favorite things, but he still knew he was essentially a prisoner.
He HATED for anyone to do anything for him, and he ended up having to have someone all the time because he would forget that he couldn’t walk well unassisted.
His life ended when the dementia had progressed to he point he couldn’t swallow well enough to avoid choking and pneumonia.
It. Was. Awful.
My husband suffered a terrible head injury several years ago and his biggest fear is that it has increased his chances of Alzheimer’s. It’s my fear too.