The majority of driving instructors here teach on autos
If you do that here your driver's license gets a remark that you're only allowed to drive automatic, while doing driving school on a manual will allow you to drive both manual and automatic. For that reason almost all driving school cars are manual, and very few people do the automatic-only license to not limit themselves. If somebody had that license and wanted to upgrade it to allow them to drive manual as well they'd have to complete (and pay for, of course) additional 450 minutes of driving school on a manual, and finally do a 15mins practical driving test.
In Australia when you are diagnosed with dementia the specialist usually gives you the option of voluntarily giving up your license, and if you don't they will report that you should have your license withdrawn. The problem with dementia is that the person will often realise that something isn't right, but they also often have very poor insight into exactly how impaired they are, and particularly when it comes to driving. We had this with my Dad and feck me that was hard, nearly as hard as getting my folks into care.
And you can't really blame them. Unless you are wealthy most are homes are fairly dreadful and personally if I have dementia I'd rather be euthanised first. TBH if my mind has totally gone, as happens with mid/late stage Alzheimer's, I don't want to live as an empty shell of flesh anyway.
The situation for that here is pretty dumb. Basically, a doctor can prohibit you from driving, but it is not legally binding and if you do it anyway it will have no consequences. However if the doctor knows or suspects that you do not adhere to it they are then allowed to inform the license authorities of their diagnosis and those can then legally take your license away. Really wish they were just obligated to make a report. Not share your medical details, that should still be private, but that you're unfit to drive and for how long.
And of course that person would need to see a doctor about those issues first, and have them diagnosed. Plenty people don't. Hence why I want mandatory regular checkups and checkrides. In aviation that is already totally normal. If I want to keep my private pilot license, I have to have a minimum of flight hours as well as take-offs and landings in command of an aircraft logged in the past 24 months, and do a 1hr ride with a certified instructor. Alternatively I can do a proper checkride with an examiner which usually costs a lot more and is way stricter.
As for dementia... yeah, I feel you. My granduncle just came back from the hospital after we already thought he might finally lose the fight. Didn't recognize anyone anymore, lost the ability to speak and was just catatonic for large timespans. Surprisingly for everyone he actually got better. Still forgets a lot, but at least he recognizes his closest relatives again, he can talk, and he's mobile and even keeps himself busy by doing small household tasks like clearing the dishwasher. But just like you, if I ever developed a condition like that, I'd hope they just take me behind the metaphorical barn. I do not want to live out my days like that. I do have a patient's decree that states that I do not want lifesaving and lifeprolonging measures if it is unlikely that I will ever get my proper mental and physical faculties back. I can just hope it will be found and honored if that day comes.