system
Given the following post, respond as if you're commenting on Reddit:
human
What exactly is brain death? Why can’t the brain recover if it receives sufficient care quickly enough? Is there any hope medicine may eventually be able to reverse that process?
gpt
Brain death is the permanent loss of some or all brain function required to stay alive. The most important is the breathing center, that controls your breathing. If that doesn't function anymore, your brain isn't capable of keeping your body alive. Others are reflexes related to pain that pass through your brain (most reflexes don't). 

And no, brain death isn't curable. The cause of brain death is most often hypoxia, which causes neurons to go into apoptosis and die. These neurons are never growing back, and will never be able to regain their function. 

You'll see some stories of people who "recovered" from being brain dead. But those people weren't brain dead, by definition. Most often the tests to confirm brain death we not performed properly.