No, they shouldn’t. Makes no sense to plan for living with a mental disability if you’re not close to needing it.
I am absolutely not going to plan on a care facility right now. That sounds absolutely bogus.
Notarizing any wishes against some medical procedures in case a sudden accident ruins your ability to dissent prevents doctors from being forced to keep your body alive as long as possible.
I was more referring to an advance directive / living will sort of thing
My genetics are such I'm more likely to drop dead of a heart attack too young.
If I were likely to develop alzheimer's, I'd make more and more expensive accommodation for power of attorney and trusts to shield assets while I was competent to do so.