Ha ha, my poor old Dad had dementia for the last couple of years of his life. Before he eventually went into a nursing home he admitted to me that he'd driven up the full length of our main street on the wrong side of the road, and told me not to tell mum. I told mum right away.
We had a talk to him about it, and he said to my mum, "Bloody hell woman, I've been driving for 30 years!" And I said, "No Dad, I've been driving for 30 years", so he said, "Sh1t, well how long have I been driving?" When I explained that he'd probably been driving for close to 60 years, he sort of accepted that it was about time he handed in his keys.
My mum still drives at 89, but she's still got all her marbles, she's just finished another semester of an online university course, still lives at home, and will probably outlive me.