I have an elderly family member with severe , getting progressively worse dementia who cannot even distinguish common items , places , people ,common concepts they always knew shown to them anymore , and who is very slow to speak and difficult to understand , has started doing something that is completely incredible to me . When she is asleep she will speak entire conversations , in perfect clarity , flow , relevance about very specific things as she did 20 years ago . It makes wish I could wake her and continue the conversation . Have you ever heard of this ? How common is it ? Does it indicate anything about her overall condition ?