As a full-time carer to my Mother Who has Alzheimer's for over 2 1/2 years, I asked Mom this question while She's still capable of thinking for Herself. Suppose you had to go into a hospital or a care home at the latter stage of life, and you needed to be fed by tube or needed resuscitation, would you want this?
The answer Mom made Me was absolutely positive, with NO hesitation.
NO..NO WAY, let me go quietyly into the night...when life is gone from me, why bring me back, back to what? More suffering?
I needed to hear this from Mom, as I will see that Her wishes are carried out to the LETTER.
Yes I will get a Solicitor to prepare an Advance Medical Directive, and a Medical Power of Attorney, Naming Myself as the POA. Mother had My Name included in all of Her affairs years ago, in case She might die suddenly, eg Bank Account, + Prize Bonds etc. Mom does not own property any more, since Mom left Her business and property to Her first born Son, Wife and seven Children, when She retired. Mom came to live with Me then.
It's very good to have the conversation and know what your mother wants, but also have her put in in writing if she's competent enough to do that.
Sounds like your Mother is still thinking clearly about situations such as that, so make an appointment with an Elder Law attorney to prepare an "Advance Medical Directive" and a medical "Power of Attorney" naming you as the POA and a "Living Will" and/or any other legal documents required by your State. Do this immediately because with Alzheimer's you never know when that clear thinking might fade quickly.