Understanding multiple personality disorder

July 2, 2012, King's College London
Understanding multiple personality disorder
Permission to use the artwork was kindly given by the Ackworth School in England, United Kingdom.

(Medical Xpress) -- New research from King’s College London’s Institute of Psychiatry brings us closer to understanding the mechanisms behind multiple personality disorder.  The study is the first of its kind and finds evidence suggesting that the condition is not linked to fantasy, thereby strengthening the idea that it is related to trauma.

It is estimated that multiple personality disorder, more recently known as dissociative identity disorder (DID), may affect approximately one percent of the general population, similar to levels reported for schizophrenia. People who are eventually diagnosed with DID have often had several earlier misdiagnoses, including schizophrenia or bipolar disorder. DID is characterized by the presence of two or more distinct `identities' or `personality states' - each with their own perception of the environment and themselves. 

Despite being recognised in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) controversy remains around the diagnosis. Some experts argue that DID is linked to trauma such as chronic emotional neglect and/or emotional, physical, or sexual abuse from early childhood. Others hold a non-trauma related view of DID, whereby the condition is believed to be related to fantasy proneness, suggestibility, simulation or enactment. 

Dr. A.A.T. Simone Reinders from the Department of Psychosis Studies at the Institute of Psychiatry at King’s and lead author of the study published in PLoS ONE says: ‘Whether dissociative identity disorder is considered a genuine mental disorder is subject to passionate debate amongst scientists, clinicians and psychiatrists.'

‘We aimed to test the validity of the non-trauma related view. By comparing people with dissociative identity disorder to both high and low fantasy prone participants enacting the condition, we found stark differences in their psychological and biological responses to recalling trauma, suggesting that the condition is not related to enactment or fantasy. The study is an interesting and important step forward in the debate surrounding the condition.’

The trauma-related view implies that DID is a coping strategy where different types of identities can develop. For example neutral identity states (NIS) where DID patients concentrate on functioning in daily life and deactivate access to any traumatic memories; and trauma-related identity states (TIS) where DID patients have conscious access to the traumatic memories.

The researchers studied 29 people: 11 patients diagnosed with DID, 10 high fantasy prone and 8 low fantasy prone healthy controls simulating DID. The level of fantasy proneness is an indication for how easily an individual can engage in fantasy, imagery and/or day dreaming.  The researchers measured participants' reactions, cardiovascular responses and brain activity with positron emission tomography (PET) scans, when genuine and simulated NIS and TIS were exposed to autobiographical trauma-related or neutral information.

They found that there were strong differences in regional cerebral blood flow and psychophysiological responses between the DID patients and both high and low fantasy prone controls, suggesting that the different identity states in DID were not convincingly enacted by DID simulating controls. 

The study was  supported by the Netherlands Organization for Scientific Research and in collaboration with the University Medical Centre Groningen at the University of Groningen in The Netherlands. 

Explore further: Fragmented sleep, fragmented mind: A new theory of sleep disruption and dissociation

More information: Reinders, A.A.T. S. et al. ‘Fact or factitious: a psychobiological study of authentic and simulated dissociative identity states’ PLoS ONE (29 June 2012) doi: 10.1371/journal.pone.0039279

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