I have read that the metaphysical cause of alzheimer's is it is a means of escape for the person. Gradually the person is less and less cognitive of life till they finally have total escape. No people don't ask for the disease but perhaps deep inside they don't want to deal with something any more.
Disease split down is dis-ease.
"Death where is thy sting". There is only a physical death and the spirit/consciousness/soul lives on.
I also don't believe in a punishing God. Why would God give us free will then send us to hell for using it? Sorry but I don't think God would do that. These are my thoughts about it after realizing God is total unconditional love.