Dissociation is a common defense and coping mechanism people use when confronted with trauma or overwhelming stress. Dissociation can be utilized as a healthy coping strategy, however when overused, it can create a fissure in one’s identity. There are several dissociative disorders recognized by the American Psychiatric Association including dissociative amnesia, dissociative fugue, depersonalization disorder, dissociative identity disorder, and dissociative disorders not otherwise specified (Spiegel, 2011). The Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) defines dissociation as “a disruption of and/or discontinuity in the normal, subjective integration of one or more aspects of psychological functioning, including- but not limited to- memory, identity, consciousness, perception, and motor control” (Spiegel, 2011, p. 826). An individual with a dissociative disorder has usually experienced trauma or prolonged stress and uses dissociation to separate their conscious thoughts from the memories of the traumatic events in an effort to preserve their ego.
Dissociative Identity Disorder (DID), previously referred to as Multiple Personality Disorder (MPD), is the most well-known of the dissociative disorders, but also one of the most misunderstood and controversial mental illnesses. DID is believed to be caused by an extreme traumatic experience or several overwhelmingly stressful events throughout childhood (Steinberg, 2000). Dissociative identity disorder is characterized by the presence of two or more unique personalities that may take control of an individual’s behavior (Spiegel, 2011).
Changes within the limbic system of the brain are thought to be involved in the development of DID. The limbic system is comprised of the amygdala, hippocampus, hypothalamus, thalamus, and prefrontal cortex and regulates emotions and memory (Stangor, 2010). The amygdala is responsible for sensing and responding to fear and aggression, as well as remembering the details of dangerous experiences (Stangor, 2010). These details are then stored by the hippocampus, which is responsible for long-term memory. The hypothalamus serves as a communication center between the nervous system and the endocrine system. The hypothalamus receives nervous impulses and conducts them to the spinal cord in addition to producing hormones that are released by the anterior pituitary gland (Thibodeau & Patton, 2008).
The Broca’s area, located in the left hemisphere of the prefrontal cortex, is responsible for language development and transferring experiences into semantic memory. Neuroimaging has shown decreased activity in the Broca’s area of patients with dissociative identity disorder. Conversely, increased activity has been found in the right hemisphere, suggesting that traumatic memories are stored on a somatic level that cannot be understood or communicated verbally. Further imaging studies using Magnetic Resonance Imaging (MRI) have found decreased volume of the amygdala and hippocampus, suggesting a decreased tolerance to fear and aggression and explaining the amnesia experienced by most DID patients (Vermetten, 2011).
There are numerous neurotransmitter and hormonal abnormalities that could affect the DID patient. Neurotransmitters that respond to and regulate the experience of stress are the most commonly affected chemicals in dissociative identity disorder. Excess cortisol, epinephrine, norepinephrine and endogenous opioids can eventually desensitize the limbic system, causing extreme reactions in response to minor events.
Neuroimaging allows us to map the brain and see what regions are activated by different stimuli and thought processes. Neuroimaging is helpful in understanding what is happening in the patient’s brain, but it does not give any insight into how the patient feels about, and responds to, stressful situations. Surveys and questionnaires like the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D) and the Dissociative Experience Scale help counselors understand what is happening to the patient cognitively and emotionally and how their condition has impacted their life (Steinberg, 2000).
Dissociative identity disorder is an extreme reaction to overwhelming trauma and stress that result in the compartmentalization of each trauma in a different area of the brain. When triggered, these separated experiences can cause the individual to retrogress to the emotional and cognitive state they were in when they first experienced the trauma. The emotional, cognitive, and even physiological state of the individual changes in response to the stimulus, creating alter personalities. These “alters” are what gave dissociative identity disorder its first and most recognized name, Multiple Personality Disorder.
Spiegel, D. Loewenstein, R., et al. (2011). Dissociative Disorders in DSM-5. Retrieved from http://www.dsm5.org/Documents/Anxiety,%20OC%20Spectrum,%20PTSD,%20and%20DD%20Group/PTSD%20and%20DD/Spiegel%20et%20al_Dissociative%20Disorders.pdf
Stangor, C. (2010). Introduction to psychology. Irvington, NY: Flat World. Knowledge, Inc.
Steinberg, M. (2000). In-Depth: Understanding Dissociative Disorders. Retrieved from http://psychcentral.com/lib/2008/in-depth-understanding-dissociative-disorders/all/1/
Thibodeau GA, Patton KT. (2008). Structure and function of the body (13th Ed). St. Louis, MO: Mosby-Elsevier Inc.
Vermetten, E., Schmahl, C., et al. (2011). Hippocampal and Amygdalar Volumes in Dissociative Identity Disorder. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3233754/