Susannah Cahalan (born January 30, 1985) is an American writer and author, known for writing the memoir Brain on Fire: My Month of Madness, about her hospitalization with a rare autoimmune disease, anti-NMDA receptor encephalitis.

Cahalan's work has raised awareness for her brain disease, making it more well-known and decreasing the likelihood of misdiagnoses.

[citation needed] Cahalan was a journalist for the New York Post before she became ill and her editor suggested that she write about her disease and its effect on her.

As she recovered from her brain illness, she decided to bring the same journalistic approach to writing her memoir, using fact and research as the foundation for her story.

Concerned by the numbness, Cahalan sought out a neurologist who ran multiple inconclusive tests, including two normal MRIs.

Because high white blood cells count signify brain swelling, the case was officially passed to neuro-pathologist and epileptologist Dr. Souhel Najjar at NYU medical center.

After a brain biopsy, it was concluded that Cahalan's issue was not psychiatric, but the result of anti-NMDA encephalitis, a brain-inflammation disease with an unknown cause.

In the work she accuses psychologist David Rosenhan of fabricating the results of seminal research published in the journal Science.