"A" patients can be in the best of health physically - however, as the disease progresses, the part of the brain that tells the body to partake of nutrition offered stops. Then begins starvation. Another part of the brain stops telling the body to swallow. Thus, even saliva can aspirate into the lungs causing pneumonia. There are few things more hurtful than having your spouse or parent look at you and have no idea who you are. But you continue your caretaking because you remember who they are.
Yep. In the advancing stages of Alzheimers, those who have the disease cannot feed, drive, clothe, or bathe themselves, they become dependant upon others to do menial tasks such as brushing their teeth, coordinating their outfits, running errands, they even reach the point that they can get lost in their own home, or think the caretaker is someone who broke into their home and lash out at the caretaker. For a caretaker, they're doing the job of two people, the one they're caring for, and running their own personal life. Caretaking can become so stressful. It's been a two year "learning experience" for me as a caretaker to my grandmother.