It is the child, the caregiver, who will speak.
They said that about my mom. She seemed to be in the moderate-severe phase. It was a happy dementia, because she was smiling. She didn't cause any problems. She was not a burden for the nursing home health care team. Every time I visited her, however, she asked me to find a way to end her life.
Different regions of the brain die during the course of Alzheimer's disease. It evolves differently from one individual to the next. It follows a general pattern, but the disease progresses differently from one individual to the next. The biochemical changes may resemble changes that bring on alterations in the biology of the brain, which go hand in hand. For example, the dopamine receptors play a role in pleasure and drug use. These regions of the brain die in the same way in the case of Alzheimer's disease. Chemical imbalances occur.
Are these people happy? No. My mom would not have repeatedly asked me to die. There are biological changes over which we have no control, as I explained earlier. Underestimating psychological pain is often the problem in our fine health care system. We look for physical problems and tend to see psychological problems less. I think that is where the problem lies. In research, we have tools to document it.
I'm sorry, but in my opinion, happy dementia is a strange myth.