My father has Alzheimer's/dementia. What symptoms have you all seen?

he is 88 He weights 100 w/ heart, lung & stomach probs &aspiration.He hasn't walked in 19 months, takes in minimal food & water. Doc recommended feeding tube after swallow tests - said he would die in weeks if we continue to let him have what he wants - that was 6 weeks ago. He still knows immediate family & talks.he sleeps 16-18 hours per day. What lies ahead for him? He is anxious.