The film is based on the memoir Brain On Fire: My Month of Madness by Susannah Cahalan, who was 24 years old when she began to suffer from a form of encephalitis. The onset of the disease caused her to have a sudden, violent seizures, and later manifested itself with disturbing emotional symptoms.
The disease signaled Cahalan's immune system to attack her brain, and the author became increasingly paranoid, delusional, violent and unstable. Doctors diagnosed her with anti-NMDA receptor encephalitis, a rare autoimmune disease, after she was committed to the hospital for a one-month stay.
Cahalan has no memory of her hospitalization, and wrote Brain On Fire based on hospital security footage and accounts from her doctors, family and friends. Fanning will star as the author in the movie adaptation.
Charlize Theron's production company, Denver and Delilah, has secured the rights to adapt the memoir. Theron will produce with Denver and Delilah's Beth Kono and AJ Dix.
Fanning will next star in U.K. film Effie Gray.