system
Given the following post, respond as if you're commenting on Reddit:
human
Are Brain Damaged people cognizant of how much smarter/functional they used to be?

There are several ads about "Not texting while driving" currently going around online and tv. One features a young guy who shows he sent a text saying "yea" before flipping his car over and causing permanent brain damage to himself. He goes on to speak about how much harder everything is now.

And I wonder. Just how cognizant can he, or other people like him, be about their difference in brain function. I realize that trauma to the brain can be so many different levels.  But for someone like this young man who is functional, if not just slow and needs assistance. How much does he really grasp of how he used to function?  Is it kinda of like being trapped in your own body? You remember the past perfectly and now you just know your brain isn't the same? Or would it be more like his past self is a story that he read once, and he can't remember or connect to it anymore.  I understand its not a great question and kinda tricky to phrase. Hopefully someone out there can understand what I'm trying to ask.
gpt
I am doctor of physical therapy who is a certified brain injury specialist and works in a brain injury rehabilitation facility.  

The answer to your question is that some brain damaged people are very cognizant of how much more functional they used to be (I avoid using the word "smart" in most contexts, as it is too subjective), others are entirely unaware of how much function they've lost and will swear up and down there is nothing wrong with them, while they can't remember where they are, or what they did 30 seconds ago, or perhaps have no ability to walk due to a spinal cord injury received at the same time as the head injury, yet will swear they're choosing not to walk because they prefer sitting in the wheelchair.  There is no "one person is one way, and another is the other way," as brain injured individuals come on a continuum of function ranging from no function whatsoever to so functional nobody can tell they're injured except themselves, because they know things are not as easy for them as they once were.

The ones who are aware do know enough to compare how well they can remember things post-injury compared to how little effort was required to remember things or perform physically pre-injury.