Alzheimer's and loss of appetite. Any suggestions?

My father is almost 90-years-old and was diagnosed at moderate-to-severe Alzheimer's almost two years ago. He also has Afib, Macular degeneration, HBP, stage 3 kidney failure and hearing loss.While I can handle the repetition of questions, events in his life - sometimes, 8 times in 15 minutes - it is the loss of appetite now that worries me. He has seen the specialists for everything and say for his age, he's doing well, despite the litany of decline and medications. Out of the blue, he just says he's not hungry. He won't snack on anything, he won't finish a meal. I calculate he's at about 900 calories a day.

We've talked about him needing to eat more. He just feels full at meal time and doesn't want to eat more. He will literally take 5 bites, put his fork down and then not touch his plate again. I've switched up the variety, the finger foods-to-utensil eating, and it doesn't matter. He has lost 10 lbs in one month.

He has an appointment with his neurologist this next week, but this one scares me. The possible domino effect of his other conditions frightens me if he's not getting the nutrition he needs. It's not a deliberate or conscious act, he just hasn't the appetite. Is this common? I've heard about Alzheimer's victims not being able to eat because they forget, but this is something different.

Any suggestions would be appreciated.