Sorry your family is not able to be there for you.
Alzheimer's is a terrible disease. My father had that, (he passed a few years ago.) My mother now has age related dementia which is a bit different, not quite as bad but she is not the person she was at all. Unfortunately I also am acquainted with addiction as well, having several family members who are in the throws of it. It is heartbreaking to watch your family seemingly 'vanishing' before your eyes. Even the ones who are still there, are really not.
Like you say, all we can do is "plod on" and keep hoping things will get better. .....One day at a time