Susannah Cahalan talks about her experience of having a rare autoimmune form of encephalitis that meant her body attacked her brain.
Aged 24, Susannah, now 28, woke up in hospital with no memory of how she got there.
Within weeks her health deteriorated and she was undergoing acute psychosis, rages, convulsions, hallucinations and muscle paralysis. Over one month she descended into madness and baffled doctors.
After a desperate hunt for a diagnosis, eventually one doctor gave her a pen and paper test and diagnosed her with a rare autoimmune form of encephalitis. Her body was attacking her brain. She has pieced together what happened to her to write a memoir Brain On Fire - My Month of Madness.