My mother has Alzheimer's Disease, and she also stopped urinating. We took her to the emergency room, they sent her home with a catheter, and got her in to see a specialist. He prescribed a medicine (Urecholine) and she has not had the problem since. We do have to encourage her to drink. She is 68, was diagnosed several years ago, and, like your mother, can no longer communicate verbally. She still walks very well, but has some of the same problems as your mother......bathroom, eating, dressing, etc. She has been through periods when she eats very little, and will lose weight, then regains her appetite and some of her weight. When Mother quit urinating last fall, I was so afraid that her kidneys had quit functioning, but thankfully, I was wrong. She is doing quite well right now. Sorry this is so lengthy, but hope it helps. I couldn't find much info on this problem, even on this healthboard, which is a great source of information and encouragement.