Is there any way to find out a prognosis for someone with Alzheimer's? It would be helpful for planning finances, living arrangements, etc. Our Neurologist seems to be reluctant or unable to give us much information. He just says "it's not good." I realize that every case is unique and somewhat different.
Even if the person has "only" Alzheimer's and is following the identified stages closely, there is no way to predict how long each stage will last.
My experience is with a different kind of dementia, LBD, and the literature says the typical life expectancy with the disease is 5 to 7 years. In the caregiver's support group I attend, one loved one died in less than 2 years. Another one is in year 12 with very little functionality. My husband is in his 9th year, still at home, and surprisingly functional. I suspect that Alzheimer's is similar in that individual experiences are all over the map.
Your Neurologist really is not able to give you information that would be helpful for planning purposes. You'll know what happens next when it happens. I know this uncertainty is extremely stressful to live with. Welcome to the world of caregiving.
You will recognize as further losses occur, and adjust and adapt to the new situation. FLexibility is a huge asset in dealing with dementia.