A very interesting article and I can believe that the main points are true.
The father of my wife's best friend died last year from something unrelated to his dementia but he was at an advanced stage having had it for a decade.
His first proper sign was that he got lost in his lifetime home town on a simple errand. After the diagnosis all minor signs made sense.
Also I was ill last year with Covid and it has affected my brain power considerably, I still have problems with memory some 16 months later and its affected my driving. My first trip out after being ill was shocking, it was as if I had to re-learn how to use my limbs.
My main point is that we spend many decades learning to drive, constantly adjusting our technique to the specific car, traffic conditions and our bodies and growing new neurons to replace those that have been lost.
If the brain can't keep up with the change, because it is disappearing, then the mental programme that is driving will loose little subroutines and subtleties that allow safe and smooth driving, corrections will become more gross and that common accident – pressing the accelerator instead of the brake becomes more likely. The gizmo was recording how smoothly the subjects drove as well as their speed, so it is just like the boxes they use for young drivers.
Watch out, big brother is coming to your boot some time soon.