In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
Q: Alzheimer 's Disease ( AD ) is a brain disease that slowly destroys brain cells .
A: 
Alzheimer 's disease ( AD ) , also referred to simply as Alzheimer 's , is a chronic neurodegenerative disease that usually starts slowly and gradually worsens over time .