My sister was diagnosed with Parkinson's in her early 60's, and not too long after, with Lewy Body Dementia. From what I have read since that time, it seems Lewy Body is its own disease and comes with Parkinson-like symptoms. In any event, it was a horrible 6 years until she passed away at 68. Hallucinations, paranoia, calling the police on family members with imagined threats.
She did get regular medical care but absolutely refused to take any medications. Well, medical visits, she refused any care. She lived in a small suburban area and the local police became used to her calls. When she said her family told her she had to "get out of the house" they took that opportunity to have EMS take her to the hospital "so she would not be homeless in the cold."
She went from the hospital to a nursing home. Even though she had scheduled visitors all day long (we worked out a schedule that some family member or a friend was there from 8 am till 7 pm) she deteriorated rapidly. Became combative at times, took on a persona that was not her at all. Became seductive with male nurses, again very out of character for her.
We had no choice but to place her with Hospice 2 months later and she passed away peacefully 2 months after that.
Since she refused just about everything, even physical therapy, we really could not find out exactly what was going on. I have a strong feeling that she was misdiagnosed. She progressed so quickly.
Her son bought her what is known as an Alzheimer's clock when she was still at home. Everyone must know what it is. A large digital clock with day, date, time with Morning, Afternoon, Evening designation. She would say, "He paid a lot of money for this clock, and it is always wrong." She insisted that she was always right and the rest of the world was wrong.