I am somewhat familiar with low or no communication. My sister who is schizoaffective can talk when she wants to and then she has forced speech where she starts a sentence and literally never ends and what she is talking about is what I call an “info loop” where she may be rehashing an incident at her apartment or something about her hair or fingernails (2 things that worry her to death for no reason) she won’t hear anyone talking to her or even seem like she is aware of her surroundings that much. I don’t understand it other than I know she is not properly medicated by choice. She is on Wellbutrin only and she smokes marijuana even though at the age of 57 she acts like a sneaky teenager and lies about it but it is so obvious and in other instances she has admitted to it. I don’t know what to do for her.
Today she refuses to call me or to answer the door when I knock, or the phone when I call her, it has been 2 years so far and prior to this there was not really any significant “falling out” that would explain why she shut me out again…she does this and has done it off and on all through the years. I have had the best luck with letter writing and sending cards, they usually don’t get answered but very rarely I will get a letter back from her-- all in hen scratch and hard to make out but with hearts and smiley faces all over it which seems to be our “thing” from years ago…she told me once that made us the same because we put hearts and smileys on our letters. I am sending cards and letters now in hopes of getting one back…she lives about a 15 minute drive away and I have tried so many times to get her to answer her door and the best I get is screaming: "Go away!!! I am fine and I love you in the name of Jesus!!! sigh
As for my sz son he did not speak very well if at all before his diagnosis and it was part of his diagnosis Disorganized Schizophrenia is characterized by a “poverty of speech” and when he spoke his words were all jumbled up and his doctor referred to it as a “word salad” he said perhaps another reason he didn’t wish to try to talk --that and as we found out later after he was diagnosed the 1000’s of voices he described were so loud and noisy in his head he said he could never even hear his own thoughts to know what to say anyway. Thankfully today on the right medicine my son can talk fine and seems to think well also. He is still not a chatterbox by any means but he will converse on some things and can be interactive pretty regularly.
So I do have some experience but not sure what to advise. If your sister could be professionally re-evaluated then maybe that would shed more light on her behaviors.
Maybe keeping a journal on your visits would at least document what is happening in case the time comes she can get a re-evaluation and then you could share your notes with a professional and it would likely help a great deal in an assessment in light of her limited communication. In some states and counties mental health organizations have home visitation assessments especially for the severely housebound patients. Maybe you could see if there is any availability for that in your sister’s area? Your sister is fortunate that she has you to visit with her and that you are trying to bridge the gap in whatever way you can. I hope you find a way.