A Message to Medical Professionals on Mental Illness Diagnosis

From #1 New York Times Bestselling Author, Susannah Cahalan

In 2009, New York Post reporter Susannah Cahalan began to feel ill. Although she was just 24 years old, she started experiencing flu-like symptoms and one-sided numbness. Doctors did an MRI which showed enlarged lymph nodes in her spine. At the time, they concluded that she had some type of flu or virus.


Later she experienced depression for a week or two before emerging from it very manic. Susannah describes it as “extreme energy followed by insomnia. And rapid cycling. Almost the classic case of bipolar disorder.” 


She would go from one moment being very manic, and the next, crying hysterically under her desk. This lasted for just short of a week.


From here, Susannah had her first seizure. This was really the dividing line in her illness. Afterward, she started having hallucinations and delusions, and became violent.

Brain on Fire

Throughout these medical challenges, Cahalan struggled to get an accurate diagnosis.  Instead, she spent a month in the hospital where doctors ran $1 million worth of blood tests and brain scans—all of which came up inconclusive. 


Her doctors grew frustrated. They were getting ready to commit her to the psychiatric ward, agreeing that it was perhaps all in her head. 


At the time—at her mother’s wishes—Susannah was already hospitalised on the epilepsy unit of NYU Medical Center. She had spent the last month there.

"In retrospect, I realise that context and environment influence psychosis.

Susannah says, “I was placed in an AMU—advanced monitoring unit—with three other patients. It was a high energy room with lots of activity which wasn’t good for my state of mind at the time. I started to create these kind of delusions around what was going on, just because there was so much stimulus.


“My psychosis heightened, then regressed very fast. I became catatonic and I wasn’t really speaking, I couldn’t read or write, I wasn’t really reacting. My neurological exams showed that my eyes weren’t properly constricting, and my reflexes were off.” 

A diagnosis, finally

Around three weeks into the case, neurologist Souhel Najjar became involved and diagnosed Susannah with autoimmune encephalitis. A rare disease, autoimmune encephalitis occurs when the body’s immune system starts attacking healthy brain cells, causing brain inflammation.


Dr Najjar diagnosed Susannah using a test that involved her drawing a clock, a test normally given to people suspected of having dementia or Alzheimer’s disease. 


Rather than drawing the clock face normally, the disease caused Susannah to draw all the numbers 1 through 12 on the right face of the clock, because the right side of her brain, which regulates the left side of the body, was inflamed. 


Susannah explains, “He ordered up a brain biopsy and a lumbar puncture. While he was waiting for the results of the lumbar puncture, he looked at my brain and found evidence of inflammation.


“As he was waiting for more results, he put me on IV steroids. Once he diagnosed me with autoimmune encephalitis—I was actually the 217th person to be diagnosed with the disease in 2009—he started me on IV, IVIG, plasma exchange. That began the road to recovery.”


Because of the disease’s rarity—alongside its perplexing neurologic and psychiatric symptoms—autoimmune encephalitis often remains misdiagnosed. This was especially true a decade ago. 

“Dr Najjar estimates that in 2009, only 10% of autoimmune encephalitis cases were diagnosed correctly. Happily, Susannah was among that 10%.”


To learn more about Susannah’s experiences firsthand—as well as to uncover her key takeaways for those in the medical profession—I spoke to her recently. 

The big lesson from Brain on Fire

When I asked Susannah what she thought the big lesson from her experience was, she says, “I think it’s that doctors need to really listen to patients and take the time to hear the stories of their caregivers. That was something that Dr Najjar did more than any other doctor—which makes him a great doctor.”

Susannah recalls going to a psychiatric hospital to talk about Brain on Fire. “When I was there, one of the doctors came up to me and the physician I was speaking with, and said, ‘We have someone here who I think sounds like Susannah’.


“Later, I found out they tested her spinal fluid, and she tested positive for the same illness that I had—but she was misdiagnosed for two years, and I was misdiagnosed for only several months. So, she would never recover fully, and according to him, she would remain a ‘permanent child’… those were his words.

“That really upset me. It’s like, ‘do we know what these diagnoses mean?’ She was diagnosed with schizophrenia, what does schizophrenia mean if we can get it so wrong?

“These questions led me to this study on being sane and insane, which kind of asked a similar question.”  

A second book, The Great Pretender

This led to Susannah’s second and most recent book, The Great Pretender: The Undercover Mission That Changed Our Understanding of Madness.


The book follows a 1970s study involving Stanford psychologist David Rosenhan and seven other people—sane, healthy, well-adjusted members of society. 

They went undercover into asylums across America to test the legitimacy of psychiatric labels. Forced to remain inside until they’d ‘proven’ themselves sane, all eight emerged with alarming diagnoses and even more troubling stories of their treatment. 

Rosenhan’s watershed study broke open the field of psychiatry, closing down institutions and changing mental health diagnosis forever.

“They were diagnosed with schizophrenia most of the time,” Susannah explains. “And once they were diagnosed, everything they did in the context of the psychiatric hospital became further proof of their mental illness.”

Two books, one lesson

“I think an important takeaway is to acknowledge how much context plays a role in the way that we diagnose and see people,” Susannah says. 


“And I think it’s important as much as possible to try to take a step back as a physician, or as a nurse or a nurse’s assistant. Take a step back and remind yourselves that you’re dealing with someone who is a person, with a family, with a whole history. And not just a diagnosis. And I think that’s easier said than done.


“I mean, we’re dealing with a lot of people who are overworked and see a lot of patients, and deal with a lot of illness. These are not easy jobs. But I think as much as they can, healthcare workers need to humanise the people that they’re working with.


“They also need to remember that this is just one aspect of their existence—being a patient is just one aspect of the person. I think that it’s really important for medical professionals to remind themselves of that daily.”

Read more about Susannah Cahalan

If you’re interested in learning more about Susannah Cahalan, you can visit her website here. And, if you want to read either of her books, both Brain on Fire and The Great Pretender, are available for purchase.

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