This is the context:
This happens in Alzheimer’s disease all the time, right? This is something everybody’s familiar with: an elderly person who’s slowly slipping down out of contact. If we had some way to bring them back so they could talk to their grandchildren for a year, this would be a very important thing. And while it may not save the person’s life and might not mean that they wouldn’t slip out of contact at some point in the future, it would be important.
source: The enigma of human consciousness.New York Academy of Sciences.
What is the meaning of "slip out of contact"? Does it mean that the person loses the ability to be aware of it's surrounding? or we can't communicate with him anymore?