I have a friend who has been diagnosed with Alzheimer's disease

Of late he has been spiralling downwards.
I rang just now to invite him out for coffee tomorrow.
He replied - "Do you know my address, do you know what number my place is"?
I replied "Yes, I know where you live"
He replied "How? I have never seen you here before"
I visit regularly; this is a marked deterioration of his condition. 🙁