Dementia and Prison Visits - From Sister of a Prisoner

Please do not publish my name thanks. My brother is in prison for a long time. Our Mum has dementia and I noticed a few other posts on your blog about the illness and a prison connection.
Our Mum's illness is getting worse and she will shortly be going on an EMI Unit which is a closed unit. She keeps asking about my brother and when I tell her he is in prison, she doesn't understand.
I would like to ask if some of your readers have ever taken their parent with dementia to a prison visit? I would really like a bit of help and advice from anyone who is or has been in the same situation. Thanks all.