Dissociative Amnesia

Amnesia refers to the partial or total forgetting of some experience or event. An individual with dissociative amnesia is unable to recall important personal information, usually following an extremely stressful or traumatic experience such as combat, natural disasters, or being the victim of violence. The memory impairments are not caused by ordinary forgetting. One study of residents in communities in upstate New York reported that about 1.8% experienced dissociative amnesia in the previous year (Johnson, Cohen, Kasen, & Brook, 2006). Some individuals with dissociative amnesia will also experience dissociative fugue (from the word “to flee” in French), whereby they suddenly wander away from their home, experience confusion about their identity, and sometimes even adopt a new identity (Cardeña & Gleaves, 2006). Most fugue episodes last only a few hours or days, but some can last longer. 

Figure 2. People with dissociative fugue temporarily lose their sense of personal identity and impulsively wander away from their homes or places of work.

People with dissociative fugue may travel far distances during the fugue, as far as several thousand miles, and could remain in the fugue state for a couple of days, several weeks or even months. Once they have returned to their pre-dissociative states, they do not remember any events that occurred during the fugue. Dissociative fugue is a rare disorder and data available indicate a prevalence of 0.2% in the general population. The onset is often in adolescence or early adulthood and onset is usually sudden, and often related to traumatic or stressful life events. Dissociative fugue has also been noted to be associated with a previous history of child abuse. Other factors that could predispose someone to dissociative reactions include neuropsychological cognitive dysfunctions and genetic factors. Recovery is usually sudden and often complete, although the fugue state may end gradually in some individuals.

Some have questioned the validity of dissociative amnesia (Pope, Hudson, Bodkin, & Oliva, 1998); it has even been characterized as a “piece of psychiatric folklore devoid of convincing empirical support” (McNally, 2003, p. 275). Notably, scientific publications regarding dissociative amnesia rose during the 1980s and reached a peak in the mid-1990s, followed by an equally sharp decline by 2003; in fact, only 13 cases of individuals with dissociative amnesia worldwide could be found in the literature that same year (Pope, Barry, Bodkin, & Hudson, 2006). Further, no description of individuals showing dissociative amnesia following a trauma exists in any fictional or nonfictional work prior to 1800 (Pope, Poliakoff, Parker, Boynes, & Hudson, 2006). However, a study of 82 individuals who enrolled for treatment at a psychiatric outpatient hospital found that nearly 10% met the criteria for dissociative amnesia, perhaps suggesting that the condition is underdiagnosed, especially in psychiatric populations (Foote, Smolin, Kaplan, Legatt, & Lipschitz, 2006).

Depersonalization/Derealization Disorder

Depersonalization/derealization disorder is characterized by recurring episodes of depersonalization, derealization, or both. Depersonalization is defined as feelings of “unreality or detachment from, or unfamiliarity with, one’s whole self or from aspects of the self” (APA, 2013, p. 302). Individuals who experience depersonalization might believe their thoughts and feelings are not their own; they may feel robotic as though they lack control over their movements and speech; they may experience a distorted sense of time and, in extreme cases, they may sense an “out-of-body” experience in which they see themselves from the vantage point of another person. Derealization is conceptualized as a sense of “unreality or detachment from, or unfamiliarity with, the world, be it individuals, inanimate objects, or all surroundings” (APA, 2013, p. 303). A person who experiences derealization might feel as though he is in a fog or a dream, or that the surrounding world is somehow artificial and unreal. Individuals with depersonalization/derealization disorder often have difficulty describing their symptoms and may think they are going crazy (APA, 2013).

Etiology

Figure 3. Pierre Janet was one of the first people to allege a connection between events in a subject’s past life and their present-day trauma, and coined the words “dissociation” and “subconscious.”

One prominent interpretation of the origins of dissociative disorders is that they are the direct result of exposure to traumatic experiences. The exposure is known as the post-traumatic model or PTM. According to the post-traumatic model (PTM), dissociative symptoms can best be understood as mental strategies to cope with or avoid the impact of highly aversive experiences. Within post-traumatic model (PTM), individuals rely on dissociation to escape from painful memories. Once individuals have learned to use this defensive coping mechanism, it can become automatic and habitual, even emerging in response to minor stressors. The idea that dissociation can serve a defensive function can be traced back to Pierre Janet (1899–1973), one of the first scholars to link dissociation to psychological trauma.

The empirical evidence that trauma leads to dissociative symptoms is the subject of intense debate. Most important, however, is that the PTM does not tell us how trauma produces dissociative symptoms. Therefore, workers in the field have searched for other explanations. Clinicians and researchers proposed that due to their dreamlike character, dissociative symptoms such as derealization, depersonalization, and absorption are associated with sleep-related experiences. Clinicians and researchers further noted that sleep-related experiences can explain the relationship between highly aversive events and dissociative symptoms.