Dementia is absolutely brutal and I wouldn't wish it on my worst enemy.
I don't want to sound callous, but an 85 year old with dementia absolutely shouldn't be driving. Even if the skills are currently still there, they are going to go at some point and the majority of families learn they have gone after an incident. The odds that you and your family will recognize the tipping point based on something other than a crash are pretty slim.
As a prosecutor, one of the worst experiences of my career was a careless driving causing death case where the defendant had dementia. There are no winners in any careless driving causing death case, but even less so when the main issue is whether the defendant has the cognitive function to recognize what is going on around them. You have a defense attorney fairly asserting that we shouldn't prosecute and incarcerate a person with limited mental capacity and a victim's family fairly asserting that these limited capacities are exactly what caused the death of a loved one so someone needs to be held accountable for such a person being behind the wheel. Dementia is a nightmare and tacking on a tragic death, a criminal case and a civil case is a near-guarantee that two families get devastated. If anyone holds power of attorney or provides regular care for a driver with dementia, then that person is very likely to get sued for damages caused by that driver. The criminal case likely means that the state winds up dictating the end of life care for the person with dementia after a finding of incompetency to stand trial or a not guilty by reason of insanity verdict. Or that the state is ordering the person to remain incarcerated pending proceedings to protect the community. Or that the dementia isn't quite bad enough to eliminate legal culpability and the person is convicted and gets to end life in prison.
This is all worst case scenario of course, but it is not a crazy unlikely scenario. I saw too many crashes involving elderly people with diminished mental capacity. I only saw the one resulting in the death of another, but I saw plenty of frail people in handcuffs or hospitals because they hurt themselves or left the scene in confusion and an officer suspected drugs.
Take his f***ing keys away before the driving skills are gone, not after you learn the hard way that they are gone. It's going to be a brutally hard conversation whenever it happens. I watched my grandmother descend into an unrecognizable shell of herself. We put off the nursing home too long out of guilt and it was a horrible mistake. The decision to take his keys is going to be a painful one, but it is less painful to do it before a crash than after.
