Hey, just doing some googling you can find a lot of information on brain injury.
Anoxia happens when your body or brain completely loses its oxygen supply. Anoxia is usually a result of hypoxia. Here's what you need to know.
www.healthline.com
Anoxia is when bloodflow to the brain is conpletely cut off. That's probably what would happen in a full suspension hanging. Brain damage will occur after a few minutes. The longer the brain is deprived of oxygen, the more damage will occur. It's difficult to predict what the consequences will be. It depends on how long oxygen has been cut off. How old you are etc. You could be left in a vegetative state if you fail.
This youtube video shows some examples of the consequences of brain injury. All of these people are conscious and responsive. You may end up worse.
You can live out your life with these injuries, you might never regain some skills.
Added; This is not meant to scare people. It's just to make clear that you have prepare. Make sure the rope won't fail. Test things thoroughly. Don't use a necktie folks. Even if somewhere someone succeeded using a necktie or some crappy rope. For yourself, make sure you do it right.