It doesn't matter what you take in gear amount, if you do not take enough insulation for the expected temps to make him comfortable. That involves the person taking him into the wilderness.
I would be very concerned about taking an Alzheimers patient alone (just the two of you) in the wilderness and would only do that with his physicians permission. If just you two, make sure you can handle the situation of him becoming disoriented, confused, not knowing you and walking away on his own.
Here is my generic gearlist in pdf file.