Frontal lobe brain damage can affect ability to form new memories and also our inbuilt inhibitions against being aggressive, inappropriate and/or shouting, for example. Car accidents (e.g. shunts from behind or in front) will cause varying amounts of frontal lobe brain damage because the brain will bounce within the skull (which has sharp parts around the frontal lobes) and even one small pinprick of damage can have noticeable effects.
The Man Who Slept for 19 Years - YouTube
Worryingly, hubby and I had a shunt a while back and hubby had another the other day.