Dissociative identity disorder

Dissociative identity disorder (DID) is a psychiatric diagnosis and describes a condition in which a person displays multiple distinct identities (known as alters or parts), each with its own pattern of perceiving and interacting with the environment.

In the International Statistical Classification of Diseases and Related Health Problems the name for this diagnosis is multiple personality disorder. In both systems of terminology, the diagnosis requires that at least two personalities (one may be the host) routinely take control of the individual's behavior with an associated memory loss that goes beyond normal forgetfulness; in addition, symptoms cannot be the temporary effects of drug use or a general medical condition. DID is less common than other dissociative disorders, occurring in approximately 1% of dissociative cases, and is often comorbid with other disorders.

There is a great deal of controversy surrounding the topic of DID. The validity of DID as a medical diagnosis has been questioned, and some researchers have suggested that DID may exist primarily as an iatrogenic adverse effect of therapy. DID is diagnosed significantly more frequently in North America than in the rest of the world.

Signs and symptoms

Individuals diagnosed with DID demonstrate a variety of symptoms with wide fluctuations across time; functioning can vary from severe impairment in daily functioning to normal or high abilities. Symptoms can include:

• Disruption of identity characterized by two or more distinct personality states
• Multiple mannerisms, attitudes and beliefs
• Pseudoseizures or other conversion symptoms
• Somatic symptoms that vary across identities
• Distortion or loss of subjective time (a long time)
• Current memory loss of everyday events
• Depersonalization
• Derealization
• Depression
• Flashbacks of abuse/trauma
• Sudden anger without a justified cause
• Frequent panic/anxiety attacks
• Unexplainable phobias

Patients may experience a broad array of other symptoms that may appear to resemble epilepsy, schizophrenia, anxiety disorders, mood disorders, post traumatic stress disorder, personality disorders, and eating disorders.

Physiological findings

Reviews of the literature have discussed the findings of various psychophysiologic investigations of DID. Many of the investigations include testing and observation in a single person with different alters. Different alter states have shown distinct physiological markers and some EEG studies have shown distinct differences between alters in some subjects, while other subjects' patterns were consistent across alters.

Neuroimaging studies of individuals with dissociative disorders have found higher than normal levels of memory encoding and a smaller than normal parietal lobe.

Another study concluded that the differences involved intensity of concentration, mood changes, degree of muscle tension, and duration of recording, rather than some inherent difference between the brains of people diagnosed with DID. Brain imaging studies have corroborated the transitions of identity in some DID sufferers. A link between epilepsy and DID has been postulated but this is disputed. Some brain imaging studies have shown differing cerebral blood flow with different alters, and distinct differences overall between subjects with DID and a healthy control group.

A different imaging study showed that findings of smaller hippocampal volumes in patients with a history of exposure to traumatic stress and an accompanying stress-related psychiatric disorder were also demonstrated in DID. This study also found smaller amygdala volumes. Studies have demonstrated various changes in visual parameters between alters. One twin study showed heritable factors were present in DID.

Causes

This disorder is theoretically linked with the interaction of overwhelming stress, traumatic antecedents, insufficient childhood nurturing, and an innate ability to dissociate memories or experiences from consciousness. A high percentage of patients report child abuse. People diagnosed with DID often report that they have experienced severe physical and sexual abuse, especially during early to mid childhood. Several psychiatric rating scales of DID sufferers suggested that DID is strongly related to childhood trauma rather than to an underlying electrophysiological dysfunction.

Others believe that the symptoms of DID are created iatrogenically by therapists using certain treatment techniques with suggestible patients, but this idea is not universally accepted. Skeptics have suggested that a small subset of doctors are responsible for the majority of diagnoses that a small number of therapists were responsible for diagnosing the majority of individuals with DID. Psychologist Nicholas Spanos and others skeptical of the condition have suggested that in addition to iatrogenesis, DID may be the result of role-playing rather than separate personalities, though others disagree, pointing to a lack of incentive to manufacture or maintain separate personalities and point to the claimed histories of abuse of these patients.

Development theory

Severe sexual, physical, or psychological trauma in childhood by a primary caregiver has been proposed as an explanation for the development of DID. In this theory, awareness, memories and feelings of a harmful action or event caused by the caregiver is pushed into the subconscious and dissociation becomes a coping mechanism for the individual during times of stress. These memories and feelings are later experienced as a separate entity, and if this happens multiple times, multiple alters are created.