Identity and Illness Theme Analysis

Brain on Fire tells the story of 24-year-old Susannah Cahalan, a journalist at the New York Post who suddenly contracts the disease anti-NMDA receptor autoimmune encephalitis. The disease temporarily changes Susannah from a driven, strong-willed, and passionate person into someone who is paranoid, angry, and mean. Most difficult for Susannah, who describes herself as a proudly independent person, is that the disease also makes her entirely dependent on her caregivers in the hospital, her family, and her boyfriend. As Susannah changes over the course of the memoir, she and her family continually question who she is and whether she'll ever be the same as she once was, and Susannah in particular chafes when she senses that her friends and family aren't able to see who she is due to the way her illness affects her body and brain. In this way, the memoir explores different modes of expressing and experiencing one's own identity or the identity of another person, as well as the ways in which questions of identity are entangled with health and the body.

When Susannah first becomes ill, her symptoms are primarily psychotic ones. She becomes paranoid about bedbugs and thinks that her boyfriend, Stephen, might be cheating on her. She becomes delusional and experiences intense mood swings, all of which are worsened by aural and visual hallucinations. These symptoms turn Susannah into a completely different person than the woman she was before she became ill. This leads her parents and Stephen to question who, exactly, this new person is—and whether this new person is still Susannah. When her family doesn't recognize Susannah's personality as her own at various points in her illness, they're actually perceiving that their memories of Susannah don't match up with the person in front of them. By explaining her personality and mood changes in terms of how well her brain is functioning at any given time, Susannah makes the very concept of personality into a matter of body chemistry. This approach makes Susannah's aggression in particular easier for her family to tolerate, as it shows them that she's not actually trying to be difficult or mean—she's simply at the mercy of her medical condition and her malfunctioning brain.

Susannah describes how her family, friends, and doctors came to think of her personality as being split into distinct identities: one before she became ill and one during her illness. This split is further complicated as she recovers, as doctors ask her at every appointment to rate how much she feels like her “old self” on a scale of 1-100. In the throes of her illness, her family talks often about "getting her back," implying that while she's ill, Susannah herself is gone. Susannah echoes this sentiment when she describes watching the EEG monitoring videos for the first time—she says that she doesn't recognize the crazed, fearful, and skinny girl who spoke into the TV remote and insisted that her coworkers were talking about her on the news. Because Susannah knows that that girl is definitely her but doesn't remember being her, this suggests that one's public or social identity—who others see a person as—isn't even always known to the person themselves. It's something that exists whether a person is aware of it or not, and it doesn't always necessarily match a person's intimate, personal identity that exists within their own mind. This becomes particularly apparent when Susannah begins to recover and notes that other people speak to her in slow, measured tones. They have no way of knowing that Susannah's mind is fully functional, unlike her body--and it's her poorly functioning body that keeps her from being able to properly perform for others her identity that exists in her recovering mind.

In the end, Susannah makes a full recovery and returns to a version that closely resembles her former driven self—though with some notable changes. She doesn't regain the full independence she enjoyed before her illness, and moves in with Stephen earlier than they'd planned due to her need for monitoring (though she shares that she did eventually regain full independence). Most distressing for Susannah, because she didn't have a teratoma (a type of tumor that's often responsible for instigating the onset of the disease), she's also at an increased risk for becoming ill again without warning. This leaves her with an underlying feeling of paranoia and heightened awareness about the tenuousness of her recovered identity, since she could easily return to being that girl from the EEG footage at any point.

Ultimately, the book suggests that identity as a whole isn't something fixed or static, or something separate from a person's body. There is the social aspect of identity—who others see as Susannah, based on their memories and judgments of her “self”—and then there is the personal aspect, which is most intimately explored over the course of Susannah’s disease. She doesn’t address questions of the soul or spirit apart from the body, perhaps because it is abundantly clear to her that one’s “self” is a very physical thing, which can be fundamentally changed by physical changes to the brain. Instead of holding up a “self” apart from the body, Susannah suggests that identity is formed chemically in the brain, and the brain can be a dangerously unreliable host.