He sometime uses his walker but it has become very difficult to walk at times due to the disease. His memory is progressively getting worse and some days he can not remember his own age. He still has some strength in his hands and feet but still needs assistance with bathing and dressing. I’ve read that an elderly parent with dementia usually loses the desire to eat first, but isn’t it possible that the person can lose the ability to walk?
It didn't take long for my mom to lose her leg strength once she used wheelchair (for only a week) after a minor fall. She was a hard worker too, always struggling to get back to her walker but to no avail. It makes me sad to tell that story, cuz it was the beginning of the end for her. Aging is awful.
Best of luck with your dad, I know how tough it is to witness the decline of our once strong parents.