What disease did Sybil, the world's most famous multiple-personality patient, actually have?

Sybil, the book supposedly based on a real case study, made the concept of multiple personality disorder world-famous, and launched a pop culture phenomenon. The only trouble is, it's based on a woman who didn't actually have multiple personalities. What diagnosis did she actually have?

Sybil is arguably the most famous work about multiple personality disorder, despite being a near-complete work of fiction. Every biographical fact check on Shirley Mason, the woman Sybil was based on, showed that none of the abuse that she'd been "guided" to remember during drugged hypnotherapy sessions ever happened. No person in her life who wasn't directly connected with her therapy ever saw evidence of multiple personalities. A personal journal documenting her multiple personality "time lapses" before she came to therapy turned out to be a fake. And most damningly, Sybil herself wrote a letter confessing that she had been lying in therapy – only to have her therapist tell her that she was "fighting" the truth.

What disease did Sybil, the world's most famous multiple-personality patient, actually have?

But there was no question that Shirley was a troubled young woman. She was constantly exhausted. She felt estranged from herself. Sometimes she'd get up to walk out the door and instead find herself walking into a wall. At one point when she was young she became both exhausted and, when confined to her house for periods of time, manic.

And yet despite all of that, she was quite well adjusted. She had a tendency to drop in and out of college, as her energy level changed, but she had no trouble functioning, made friends, found jobs, and painted in her spare time. What condition did she have, that alternately let her do well or left her drained and mentally confused?

The author of the 2011 book Sybil Exposed, Debbie Nathan, makes a case for many of Shirley's troubles coming from congenital pernicious anemia. This condition stems from an inability to absorb vitamin B12, leading to a lifelong deficiency. There's evidence that Sybil's mother had it, since she had two characteristic symptoms: prematurely white hair and early-onset stomach cancer. Her mother was also nervous and often exhausted, just like Shirley was.

Other symptoms of this type of anemia fall more in line with the kind of symptoms that could be mistaken for multiple personality. Patients are often constantly tired. They experience confusion, disorientation, and estrangement from their own bodies. They also tend to be uncoordinated. Specifically, they tend to walk into walls because they either get dizzy and disoriented, or simply don't pay attention and think they're in another room – as people do when they're very tired in a hotel room and try to wander to the bathroom using the same route they take at home. This mental confusion can become permanent if treatment is delayed.

Shirley Mason was treated for anemia twice in her life, the first time as a child, when it was assumed to be a momentary dip in her vitamin B12 levels, and again with persistent anemia years after the book came out. There's no way to be sure, but it's interesting to think that a case that changed psychiatry, and had a massive impact on a woman's life, could have been solved with vitamin shots.

Via NCBI and Sybil Exposed.