> But he died due to Alzheimer's disease, which must have been terrifying.

I wonder. Having had a parent go through this, one of the small mercies, at least for them, was that they themselves were not aware of what was happening. Their world felt normal to them. Instead, they thought everything and everyone else around them was becoming confused, crazy and hostile.

But then, this is just one data point. As they say, when you have seen one case of dementia, you have seen one case of dementia.