I'm sure it varies from person to person and disease to disease.

About three years ago my brother died of brain cancer and I was there helping him through the whole process of decline and death. He was definitely aware he was dying earlier on, of course, when the tumor's effects were mild. But in his final days he just kind of shut down bit by bit. He seemed to be unaware of some of the degradation that was happening to his mind - he would lose specific words, for example, substituting random words in their place, but he was unaware this was happening even when we told him about it. One of the surgeries ended up taking out a quarter of his visual field but we only knew that because they explicitly checked - he didn't seem to be aware that he couldn't see stuff in that quadrant any more. So I suppose in his case the progression was fairly "merciful."

If you're dealing with a specific situation here, I'd recommend asking one of the doctors involved. I'm sure they'll have some knowledge more specific to it.

It's hard to say because by the time you're in what would generally be considered late stage, you really aren't able to communicate effectively.

What I can say is that what communication I have had with people that far gone did not entail anything about death. They weren't doing their screaming or babbling or general word salad about death in any perceptible way. Overall, I'd say half of the patients I took care of were patients because of some kind of dementia, and I was very often there at the very end of their process.

I never had any patient close to the end that had a form of dementia as their primary diagnosis bring up death at all. Meaning, no Alzheimer's type out dementia. Now, patients that exhibited dementia-like symptoms as a result of some other condition (usually brain tumors) did, in a small handful of instances say and do things that made it seem like death was on their mind.

Out of those, there's only two where I feel confident that what they were saying was about their perception that they were dying, rather than it being more likely that it was a product of the same kind of random things that weren't a sure sign that they were aware of their dying, if that makes sense.

Someone just saying disjointed strings of things that happen to include the words death or dying, it's impossible to be sure what they were thinking or feeling. Because it could be jumbled in with completely unrelated things.

But yeah, those two in specific, I'm fairly sure that they were at least partially aware of the fact that they were near death. Both of them said that they wanted to die, at some point in the process, though they didn't always say that. One of them said they weren't ready, or that they didn't want to go yet.

I don't know, and there's no way to know for sure, what they were thinking, if it was conscious thought, or even if it was actually them rather than just misfiring brains parroting things they'd heard in the past. But I "felt" like it was them, whatever kernel of their mind was left.

Dementia isn't stupidity.

Dementia is (among other symptoms) a loss of memory. The loss starts with the latest, newest memories, and proceeds to the older memories.

Analyses of focus-group discussions at four nursing homes showed that dying was silent and silenced, emotions were put into the background and death was talked about after a person’s death. The staff did not talk about death neither with each other nor with the residents (100). This seems unfortunate as several residents have revealed that they were aware of the fact that they soon would die. One person emphasized that she was waiting to go to her real heavenly home. Another resident said that she was only living at the ward temporarily until she would meet her deceased spouse again and another one said that she wanted to listen to gospels while dying. Some did not speak about death and dying but reasoned about their funeral (60). At the last stages of life persons with advanced dementia often experience eating difficulties, especially swallowing problems (84–85). Several qualitative studies have reported that persons with advanced dementia at the end of life often exhibit aversive refuse-like eating behavior (101). There have been discussions about whether tube-feeding or comfort feeding should be used (102–103). The American Geriatrics Society (96) has recommended comfort feeding.

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So apparently yes, even in the later stages there's still awareness and in the latest stage the refusal to eat may be tied to an awareness of its relationship to death and the choice shouldn't be taken away from them.

(Though really, starving to death sounds pretty terrible and like there might be better options for a more evolved society.)

I think yes, but how they experience it may be different from how they would have if they didn't have dementia. It also varies person to person, and time to time.

This elderly lady I know, she would talk about experiences from decades ago as if it was recent. But from time to time she'd also talk about missing the people in those stories knowing that they passed away.

It must be hard for them too trying to work through it all

When a person is truly late stage dementia they're barely more than a vegetable.

Depending on the damage done to the brain, it could be a full-on recognition of impending death or just a primal, lizard brain fear that something is wrong and getting worse. I think Robin Williams was in the first category, and he was so fearful of the future that he took his own life and prevented himself from reaching stage two.

Late stage dementia can't even feed themselves, so no.

I suspect you don't aware.