Was one of the world's most famous medical cases a mistake? Or, worse yet, a hoax?

Author Debbie Nathan's book "Sybil Exposed" explores the history of the Minnesota woman who became a cause célèbre in the 1970s after it was reported that she had 16 different personalities. Following the best-selling book "Sybil" and a movie adaptation starring Sally Field, multiple personality disorder (MPD) was officially classified as a psychiatric disorder.

The medical records for Sybil -- who really was Shirley Mason, a native of Dodge Center, Minn. -- were sealed until she died in 1998. After combing through those records, which included tape recordings of therapy sessions involving hypnosis while under the influence of "mind-bending drugs," Nathan is convinced that the treatment caused rather than cured her condition.

"I don't think she had MPD," said Nathan, a journalist who rose to prominence in the 1980s for her investigation of so-called "therapeutic interrogation" techniques. "I'm not a doctor, but in retrospect, I think she had a physical illness, pernicious anemia, which is known to cause hallucinations."

If so, the condition would have been exacerbated by Mason's psychiatrist, Dr. Cornelia Wilbur, who prescribed liberal doses of drugs, many of which are now known to be hallucinogenic. When Mason was depressed, she would double, triple and sometimes even quadruple the dosages, Nathan alleges in her book.

Wilbur believed that Mason had repressed memories from a traumatic childhood. She would hypnotize Mason and suggest things that might have happened. Mason incorporated many of the suggestions into her stories about growing up.

"She was very susceptible to hypnosis and to suggestion," Nathan said of Mason. Even her real memories are suspect, she added, because they "got all mixed up with her hallucinations."

A case in point: "Sybil" describes an incident when she was 7 in which a gun went off and killed a friend right in front of her. Wilbur theorized that she escaped the emotional trauma by turning her body over to an alternative personality. But Nathan's check of newspaper archives revealed that while the story about the friend's death was true, it happened 10 years later and Mason wasn't there.

Hoax or sloppiness?

While it's easy to disprove Mason's "memories," how those stories came to be taken as fact is harder to pin down.

"Some people in the media who have skimmed my book or just read parts of it are saying that I'm arguing that it was a hoax" conceived by Wilbur and Flora Schreiber, the author of "Sybil," Nathan said. "I'm not willing to go that far. I don't know if it was a lie or a hoax or simply an inability to deal with the truth."

If it was a hoax, they did a really bad job of it. For starters, they saved things that refuted their claims.

"One of 'Sybil's well-known stories was that when she was 9, she was taken over by an alternative personality for two years," Nathan said. "During that time, she learned the multiplication tables. The story is that she was good at math, but when her real personality returned, she flunked math because she couldn't remember anything that the alternative personality had been taught.

"Within the first hour of opening the first box [of documents], I found all of her report cards. She was never good at math. And as I'm looking at those grades, I'm asking myself, 'Why did they save this stuff?'"

She wonders if Wilbur and Schreiber got caught up in the ego rush of breaking new medical ground and were afraid to explore any avenues that might burst that bubble. The latter included diaries that contradicted many of Mason's trance-induced stories about her childhood.

"I don't know if they ignored what was in the journals or simply never bothered to read them," Nathan said.

A lucky break

The real story about Mason surfaced thanks to two French medical researchers who stumbled on a letter that listed Sybil's real name and address, information that enabled them to determine that she died in 1998 at age 75. Arguing that patient privacy rules no longer applied, they petitioned for her medical records to be unsealed. Late in 2001, they were granted access to the files.

They wrote a book challenging the concept of MPD but devoted only one chapter of it to Mason. Plus, the book has never been translated into English. Nathan felt there was a need for a bigger story, and not just for its sensationalism.

While others might be focusing on the deception behind the Sybil myth, she sees her book as more of a cautionary tale. With "Sybil" and the movie both becoming hugely successful, MPD became the trendy diagnosis of the 1970s.

"It just made everything worse," she said. "Sybil supposedly had 16 personalities, which was unprecedented at the time. Within a couple of years, there were people claiming to have hundreds of personalities. There were even a few who were said to have more than a thousand."

The moral of the story, she said, is that even science is subject to fads.

"Science is not just test tubes," she said. "It comes from humans. What we need to take from this is that when science makes new claims that sound really, really impressive, we need to situate those claims in the culture."

Jeff Strickler • 612-673-7392