Dissociative Amnesia

Dissociative amnesia occurs when someone loses memories and personal information. It is not a normal type of forgetfulness or a result of a brain condition like Alzheimer’s disease or dementia. Amnesia is one of a few types of mental illnesses known as dissociative disorders. They are characterized by a dissociation or disconnection between memories, identity, perceptions, and sense of reality. With amnesia, the characteristic disconnection is of one’s personal memories and identifying information.

When someone suffers from dissociative amnesia it is an involuntary response to a traumatic experience, a strategy the brain uses to try to cope with the trauma and resulting negative emotions. Amnesia may last for only a few minutes, but in rare cases it can persist for years. Memory loss may be total, related to one period of time or one event, or it may be selective. Treatment with therapy can help recall lost memories and information, but it can take a long time and patient persistence.

The degree of memory loss caused by dissociative amnesia, as well as the types of memories that have disappeared can vary greatly by individual. There are four main types of amnesia based on the pattern of memory loss, as well as another type characterized by a unique behavior the amnesia causes:

• Localized amnesia. This type of amnesia causes memory loss related to a specific event or period of time. Usually the localized memory loss is related to a traumatic event, with intact memories from before and after the occurrence. Some people may have more than one period of memory loss.
• Selective amnesia. Selective amnesia may or may not occur with localized amnesia. It occurs when someone loses specific memories related to an event or a period of time. For instance, the memories related to one specific person or to certain aspects of one event may be lost while others remain intact.
• Continuous amnesia. This occurs when someone forgets new memories. As new events occur, the memories of them are lost.
• Generalized amnesia. Generalized amnesia is rare and is characterized by total loss of memories related to one’s past and identity. A person may not remember anything about his or her life before a certain point, including where they have been, what they have done or said, or who they were with. A person may even lose information about the world, history, or previously-held skills.
• Dissociative fugue. Fugue is another unusual and rare type of amnesia. It occurs when someone wanders away from their life, often traveling far and assuming a new identity. Why this happens is not well understood but it is usually a sudden change accompanied by generalized amnesia. People suffering from fugue are often reported missing by family and may be found later living a new life, with no memories of their original life and identity.

Dissociative amnesia is not very common, but it occurs more often than many people realize and is more common in men than women.

• Dissociative amnesia is more common than other dissociative disorders, including dissociative identity disorder and depersonalization/derealization
• Amnesia commonly occurs with personality disorders
• The rates of dissociative amnesia in the U.S. population are one percent for men and just over 2.5 percent for women
• Regional rates of amnesia generally go up after large-scale traumatic events, like war or a natural disaster
• Amnesia may last for minutes, weeks, months, or even years, although this is rare.
• Dissociative amnesia can occur in someone of any age and many people suffer multiple episodes throughout their lives
• Someone suffering from amnesia may or may not be aware that they have lost memories

Amnesia is not generally difficult to diagnose, as the symptoms are clearly defined. However, depending on the extent of memories lost and the individual’s own awareness or lack of awareness of lost memories, it may take time to realize someone has suffered from amnesia. It is not uncommon for someone who has lost memories from a specific event or period of time to downplay the loss, which makes it difficult for others to recognize the symptoms.

The most recent version of The Diagnostic and Statistical Manual of Mental Disorders, which is used by mental health professionals to diagnose patients, lists the diagnostic symptoms and characteristics of dissociative amnesia:

• The most important and defining symptom is the inability to remember important autobiographical information. The forgetting is not normal and is associated with stress or trauma.
• The memory loss causes significant distress and impairment in multiple areas of one’s life
• The loss of memories cannot be better explained by drug or alcohol use or a medication, by a neurological condition, or by another mental illness
• There is also a specifier for amnesia, dissociative fugue, which is characterized by confused wandering and traveling after having lost autobiographical information and memories

Diagnosis for dissociative amnesia usually involves a psychiatric evaluation, observations, and interviews with family. There may also be medical screenings, such as imaging scans or blood tests to determine if there is a physiological cause for the memory loss.

The cause of any type or degree of dissociative amnesia is trauma. What constitutes trauma depends on the individual, but any highly stressful or frightening situation can potentially be traumatic. Not everyone who experiences trauma will dissociate or lose memories, but for those who do, it is not voluntary. It is the brain’s involuntary response to the trauma as a way to cope.

Risk factors for dissociative amnesia include any experience of trauma. Some types of trauma most strongly associated with amnesia and dissociation include physical, sexual, and emotional abuse, natural disasters, and combat service. Trauma over an extended period of time puts a person at a greater risk of developing amnesia, and children who have been abused are particularly susceptible. Anyone who has had an episode of amnesia is at risk for having it occur again in the future.

Trauma and amnesia go hand-in-hand, and other trauma-related disorders may co-occur with amnesia. These may include acute stress disorder or posttraumatic stress disorder. Amnesia and other dissociative disorders are also strongly correlated with personality disorders. Dissociative amnesia may also cause an individual to turn to substance abuse in an attempt to cope, so substance use disorders may co-occur with it. Other possible co-occurrences include depression, anxiety disorder, eating disorders, and suicidal behaviors.

The main type of treatment used to help someone restore memories and cope more healthfully with trauma is therapy. There are no medications approved for treating amnesia. Therapies may vary depending on the needs of the patient, but the general goals are to restore memories, to process and manage emotions related to trauma, to develop healthy coping skills, and to improve overall life functioning. Some types of therapy and treatment strategies used to meet these goals are:

• Cognitive behavioral therapy (CBT). CBT is the backbone of modern therapy and can be adapted for patients who need to process trauma. The focus is on recognizing and shifting negative thoughts, reactions, behaviors, and emotions. It helps patients face negative memories and work through them.
• Dialectical behavior therapy (DBT). DBT is a modified form of CBT that was originally developed to treat personality disorders but that is also often used for trauma-focused therapy. It includes the practice of mindfulness, accepting events and emotions, learning to tolerate distress, regulating emotions, and learning to better communicate with and relate to other people.
• Eye movement desensitization and reprocessing (EMDR). EMDR was developed to help people cope with trauma. A therapist guides a patient through eye movements while recalling traumatic memories. Something about the brain stimulation triggered by eye movements helps to lessen the emotional impact of the memories.
• Creative therapies. Supplemental therapies using art, music, drama, animals, and other creative elements help patients to open up and explore their troubling emotions and memories.
• Mindfulness and meditation. Also typically supplemental, mindfulness practices, meditation, and relaxation techniques can help patients learn better and more healthful coping mechanisms for stress and painful memories.
• Hypnosis. Some patients may try clinical hypnosis, which uses focused concentration and relaxation to delve into subconscious memories in an attempt to recall them and process them.

The prognosis for dissociative amnesia is generally positive with treatment. Most people who seek out treatment will recover their memories. They may come back suddenly or gradually over a long period of time. In rare cases a person will never have their memories restored, but treatment can help improve function and address any other mental health issues.