Dissociative Amnesia

Image courtesy of Super OfficeOpens in new window A person with dissociative amnesia is unable to recall important personal information, usually information about some traumatic experience. The holes in memory are too extensive to be ordinary forgetfulness and are not the effects of drugs or head injury.

The episode of amnesia may last as briefly as several hours or as long as several years. The amnesia usually disappears as suddenly as it began, with complete recovery of memory and only a small chance of recurrence.

The DSM-5 diagnostic criteria specify that the memory loss of amnesia typically involves information about a traumatic event or events, such as combat or childhood maltreatment, or events during a period of stress.

Despite the diagnostic criteria, not all amnesias immediately follow trauma (Hacking, 1998). In addition, dissociative amnesia is rare even among people who have experienced intense trauma, such as imprisonment in a concentration camp (Merckelbach, Dekkers, et al., 2003).

Procedural memoryOpens in new window remains intact—the person remembers how to answer the phone, ride a bike, and execute other complex actions, even though he or she is unable to remember specific events.

The defining symptoms of dissociative amnesia include:

• Inability to remember important autobiographical information, usually of a traumatic or stressful nature, that is too extensive to be ordinary forgetfulness.
• Specify fugue subtype if the amnesia is associated with bewildered or apparently purposeful wantering.

In the fugue subtypeOpens in new window of dissociative amnesia (from the Latin fugere, “to flee”), the memory loss is more extensive. The person typically disappears from home and work. Some people wander away from home in a bewildered manner. Others take on a new name, a new home, a new job, and even a new set of personality characteristics. The person may even succeed in establishing a fairly complex social life.

More often, however, the new life does not crystallize to this extent, and the fugue is more like the experience of Hannah UppOpens in new window—of relatively brief duration, consisting of limited but apparently purposeful travel during which social contacts are minimal or absent. As with other forms of amnesia, recovery is usually complete, although it takes varying amounts of time; after recovery, people are fully able to remember the details of their life and experiences, except for those events that took place during the fugue.

Dissociative amnesia raises fundamental questions about how memory works under stress. Psychodynamic theoryOpens in new window suggests that in dissociative amnesia traumatic events are repressed.

Repression, as initially defined by FreudOpens in new window, involved suppressing unacceptably painful memories from consciousness. Many cognitive scientists, though, have questioned how repression could happen (Patihis, Ho, et al., 2018) because study after study shows that stress usually enhances rather than impairs encoding of memories for the negative event (Shields, Sazma, et al., 2017).

Memory for traumatic events tends to be accurate and detailed even years later among survivors of plane crashes, natural disasters, and serious injuries (Goldfarb, Goodman, et al., 2019). Among a sample of veterans, those with the most severe war experiences were most likely to provide consistent descriptions of combat memories over time (Krinsley, Gallagher, et al., 2003). NorepinephrineOpens in new window, a neurotransmitter associated with heightened arousal, enhances memory consolidation and retrieval (Sara, 2009).

The nature of attention and memory, however, does change during periods of intense stress. People under stress tend to focus on the central features of the threatening situation and to stop paying attention to peripheral features (McNally, 2003).