Despite the fact that dissociative identity disorder has been listed in psychiatry bible Diagnostic and Statistical Manual of Mental Disorders (currently DSM-IV) for years, the origins of the condition are not well-understood. Despite – or perhaps because of – the agony that the condition can cause, the illness has captured the public’s imagination, being documented in literature, film and song.

Dissociative identity disorder (DID) – or multiple personality disorder, as it is commonly known – affects one percent of the population, roughly the same amount as schizophrenia. Often sufferers from the condition have been misdiagnosed with schizophrenia and bipolar disorder before receiving their DID diagnosis. DID is usually characterized as a person who has with two or more personalities with completely different viewpoints on their environments and themselves.

Some believe that those afflicted use DID as a means of coping with extreme trauma, while others think that those affected simply have overactive imaginations. Of those who believe in the overactive imagination theory, scientists do not believe that DID is a genuine mental disorder.

Researchers at King’s College London sought to find a clearer picture of the answer to that question. They studied 29 people, 11 had dissociative identity disorder, 10 were people who were highly prone to fantasy and 8 people were not very prone to fantasy, as a control. Of those without DID, they were made to simulate the symptoms of dissociative identity disorder. The researchers measured subjects’ brain activity, cardiovascular system, and their reactions.

They found that there were strong differences, both in regional blood flow and in reactions, between the DID sufferers and the control subjects. Researchers believe that indicates that DID sufferers do not merely have overactive imaginations, and that the origins of their ailment stem more likely from trauma.

Finding the root of dissociative identity disorder is important particularly because it suggests different methods of treatment. If the illness was not classified as a mental illness, it could mean that those affected would never be able to seek treatment. If the root is trauma, that can inform psychologists and psychiatrists, and may cause them to model various, more effective modes of treatment.

The study was published in PLoS One.