The official descriptions that the end is near are based on a collection of averages. Most discussed are how the average person with Alzheimer's will wind down. But each one is unique. Doctors often don't document what caused the actual death very often. They just put down what is expected. Usually things like low sodium, low potassium, congestive heart failure, kidney failure, systemic organ failure etc and add Alzheimer related to the report. So gathering reliable information is almost impossible. It depends on what type of care the person is getting. It depends on what areas of the brain are effected. The human body has an uncanny ability to fight death. I wish there was an easy answer I could give you. There isn't one.
Doctors know a lot less than they want you to know. Very few spend more that a few minutes with an Alzheimer's patient. All they see are little snapshots of the disease. They base their knowledge on poorly sourced information. Hearsay from other doctors and most have little time or dedicate little time to keep up with cutting edge research. Most seldom or never read medical journal publications to keep up on the latest findings. Often when they tell you something new they heard it from another patient telling them what they discovered. Doctors are also protective of what they know and often don't share amongst themselves. This is true of other diseases also.
As the disease progresses most or all memory related abilities degrade and they become totally reliable on someone to do everything for them. They may constantly stare. This may not indicate anything. They sort of trance out. Almost like a day dream state but deeper. They may not respond to talking or normal noises. You can look right in their eyes and be a foot or two in front of their face. You can talk to them and they seem not to respond. They often drift in and out of this trance like state. They may also come out of it if there is an unusual sound. I found that my mother, would at times, not respond if I talked to her. But if I snapped my fingers she would come out of it. As if she was somewhere else or was sleeping with her eyes open. At times it seemed like a young child when they sit in front of a television and get so involved with what they are watching they enter a trance like state. My friends father didn't respond to sound like the finger snapping. But wave your hand quickly about a foot in front of his face and he would snap out of it. I would often wonder if they were having an out of body experience.
Eating and drinking will most likely become a problem. Being able to take any kind of pill may be impossible. My mother could eat but she had false teeth and it was a daily game to get her to let me take them out to clean them. When it came time to replace them it usually took several attempts. She just didn't understand. so I would try for a second and if I didn't get them in I would just try again 10 or 15 minute later. No arguing or fussing just accept the fact and try later. No big deal.
Occasionally she would forget how or just not want to chew. That's when I would use a juicer and organic fruits and vegetables. Sometimes she liked it but I couldn't get her to drink from a glass. So I got some of those large plastic eyedropper like things they use to give kids a dose of medicine and I would give her fresh juice.
As long as the person is getting sufficient liquids and nutrition the need for feeding tubes and IV's can be put off. They may sound like a good solution but they come with there own set of problems. Like trading one evil for another. Many times a feeding or drinking problem, like the disease itself occurs in cycles. It is easy to say put the tubes in but if you do there is a much greater chance that regular drinking or eating will not resume.
If or I should say as the parts of the brain that control the proper function of the body are effected things can start to decline. Sight may be effected to the degree of blindness. Any or all of the bodily functions or organs may not work well. Urine may concentrate and become strongly colored and have a strong smell. As these things stop working as well as they should energy levels usually decline. The person may hallucinate and see things that you can not see. They may become unconscious. Breathing may be shallow or a struggle. The lungs may start to sound like there is fluid starting to collect in them. Blood pressure often starts to lower and as it does the heart may try to pump harder. Or heart rate may decline too. Even if they are put on a breathing machine they may be gasping for air. Some people are lucky and just drift away while others seem to struggle to hang on.
If a natural death is taking place the brain sends out chemical messengers that tell the organs to shut down. If the heart stops and electric shock is used to try and restart the heart it is thought these chemicals are neutralized. If this occurs the body can be often kept alive. The automatic functions like the heart beating and breathing may resume. Often a breathing machine will be hooked up and the person may be breathing above the rate the machine is set at.
That does not indicate life. It is most likely the person is not there. Families often keep the body alive for days or even weeks refusing to accept the person has died. Continuing to return to the hospital everyday and stretch out the ordeal. As the person is actually dead with the machines giving the appearance of life. Even when you are prepared for a death it can be hard to accept. Turning the machines off isn't easy. Everyone needs to deal with it in their own way and do what they feel is right. Whoever has to make the decision will remember it for life. I know I've had to do it for a few family members.