'Monsters Inside' Filmmaker Says Dissociative Disorder Is Mostly An American Phenomenon 

Whether or not a person can have multiple personalities is a controversial subject. 

"This is something abstract,” “Monsters Inside: The 24 Faces of Billy Milligan” docuseries director Olivier Megaton told Oxygen.com. “We are not talking about muscles or cancer. It’s not something we can see on the MRI or whatever. Therefore today it’s still something controversial.”

“Monsters Inside” explores the case of Billy Milligan, a serial rapist who assaulted three Ohio State University students in 1977 before psychiatrists diagnosed him with multiple personality disorder — now known as dissociative identity disorder. Experts ultimately decided that as many as 24 distinct “multiples” existed within Milligan’s mind.

"We don’t have multiple personalities in Europe and especially in France," Megaton, who is French, said. "Americans say that it exists in the rest of the world but [...] we don’t have the same way of thinking and living. We don’t have the same way of viewing that specific diagnosis.”

Milligan became the first person in American history to successfully use multiple-personality disorder as a defense for violence at trial. A jury believed the story enough to find him not guilty by insanity. Later, his psychiatrist, Dr. Dorothy Lewis, testified as an expert witness for several murderers, including serial killer Arthur Shawcross in 1990. Her work has since been widely criticized and renowned forensic psychiatrist Dr. Park Dietz, who consulted for both the FBI and CIA, claimed under oath during Shawcross' trial that he felt Lewis was inviting Shawcross to play various roles.

Because there is no way to know for sure, as no test can completely prove the existence of multiple personalities or not, many are still undecided on the diagnosis. A few years before Milligan's trial, the 1973 book “Sybil” became a subject of fascination. The story claimed to be based upon the true life story of Shirley Mason, a woman with 16 personalities. Following the book’s publication report of multiple personality disorder skyrocketed from fewer than 100 to thousands, National Public Radio reported in 2011, describing it as a “psychiatric phenomenon."

Later Mason admitted to dramatizing certain elements of her story, leading many to believe that the disorder, in general, is a hoax. 

A 2004 Psychiatric Times story states that the disorder is “largely confined to North America (one of the few culture-bound syndromes in the region), and that it is rare or nonexistent in Great Britain, Sweden, Russia, India and Southeast Asia.” 

The Psychiatric Times calls it “endemic to North America” and that the main issue in proving dissociative disorder's existence “is the reliance on individual accounts that are largely retrospective and not verifiable with more objective sources.”

A 2016 study by the Harvard Review of Psychiatry claims that the disorder is indeed real and not a “fad.” Still, the disorder remains relatively rare. It is diagnosed in only about 1.5% of the global population.

“It’s sexy and exciting to believe that there are people inside you telling you what to do but it’s much more complex,” Megaton told Oxygen.com.