Thank you, and the Alzheimer's question deserves a careful answer rather than a quick comfort, because millions are carrying it and most never hear it addressed from Scripture. Here is where I would put your hope, and I think it rests on solid ground. A believer's standing before God was never held in his memory. It was held in Christ. "Your life is hidden with Christ in God" Colossians 3:3. Hidden. Not stored in the brain. The disease can take a man's recognition of his own children, and it cannot reach the place where God keeps His people, "no one will snatch them out of My hand" John 10:28. If salvation depended on our continuing to remember, then every sleeping believer would lose it nightly and every dying one in the last hour, and it does not. And the covenant was always built on God's remembering rather than ours. That is why He says, "I will remember My covenant" Genesis 9:15, and why the psalmist could pray, "when my father and my mother forsake me, the Lord will take me up" Psalm 27:10. Your relative may no longer know you. God knows your relative, "the Lord knows those who are His" 2 Timothy 2:19, and His knowing does not decay. On communication at the level of the soul, I will not claim more than Scripture gives, but it does give this. The Holy Spirit indwells the believer permanently, "that He may be with you forever" John 14:16, and He intercedes for us "with groanings too deep for words" Romans 8:26, which is to say at a level beneath what the mind can form. And we have a Lord who was Himself a helpless infant, held and fed by others, knowing His Father before He could speak a word of it. Personhood before God has never required a functioning cortex. So keep praying. Not to secure something uncertain, but as a son talking to a Father about someone the Father is already holding closer than you can see. The disease is real and the grief is real, and the One who keeps your relative is not confused about who that is. To Him be the glory.