One close relative with a sharp mind is an alcoholic. She moved further away to keep some behaviors secret. Her heavy drinking increased after caregiving for her spouse until his death from COPD. Out of kindness people look the other way and/or pick up the pieces. I wish family and friends would have intervened years ago as it is painful to watch the inevitable decline. Even her doctors look the other way. With dementia the mood swings can come out of nowhere. I imagine you are dealing with a double whammy.