It is mostly adult children of a parent with dementia who are asking this question. Of course the answer depends on the stage of the dementia, and specifically if the person has Alzheimer's disease, a more specific strain of dementia. Why? Because most dementia patients have long-term memory still available. Most dementia patients lose short term memory but their personalities don't change. The rage and anger responses are quite often limited to persons who are diagnosed with Lewy Body dementia, which often comes with Parkinson's disease, or Alzheimer's disease which messes with the person's ability to separate truth from fiction, today from a long time ago. Alzheimer's disease robs its victims of rational thought processes, so telling them anything requiring logic to understand, doesn't get through the diseased part of the brain!
There is another reason for withholding this information from persons in the Moderate Stage of Alzheimer's disease, other than the fact that they cannot process the information and cannot hold onto the information if indeed they understand it. In many social and economic and regions of our country there is still shame in the diagnosis. For example, one woman was sharing her journey caring for her grandmother. All of a sudden, her voice lowered to a whisper. "You know," she confided, "Grandma became nasty," as she wrinkled her nose.
A man who lives in the same assisted living home as my husband asked me this week, "What is wrong with him?" This man is confined to a wheelchair and my spouse walks. The man speaks and is lucid. He shares,"I talk with him. We have conversations, but I really don't understand what he is saying."
I answered, "He has Alzheimer's disease." The man lowered his voice and said, "Don't worry, I won't tell anyone."