Amnesia can be classified as retrograde (for events before the cause), anterograde (inability to store new memories after the cause), global (for information related to all senses and past times), and sense-specific (for events processed by one sense—eg, an agnosia). Amnesia may be transient (as occurs after brain trauma), fixed (as occurs after a serious event such as encephalitis, global ischemia, or cardiac arrest), or progressive (as occurs with degenerative dementias, such as Alzheimer's disease).

Dissociative amnesia is classified by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision, also known as the DSM-IV-TR as one of the dissociative disorders, which are mental disorders in which the normally well-integrated functions of memory, identity, perception, or consciousness are separated (dissociated).

In Dissociative Amnesia, the person is unable to remember personal information. They are aware that they have forgotten information, but do not know what they have forgotten. While they are able to perform simple tasks, they usually are unable to perform more complex ones such as shopping and cooking, instead wandering aimlessly. This type of amnesia usually lasts for a period of hours to days follows a severe stressor, and may be selective for a traumatic event.

Causes

Dissociative amnesia has been linked to overwhelming stress, which might be the result of traumatic events—such as war, abuse, accidents or disasters—that the person has experienced or witnessed. There also might be a genetic link to the development of dissociative disorders, including dissociative amnesia, since people with these disorders usually have close relatives who have had similar conditions.

Dissociative Fugue:

Causes are similar to those of dissociative amnesia with some additional factors. Fugue is often thought to be malingering, because the fugue may remove the person from accountability for his actions, may absolve him of certain responsibilities, or may reduce his exposure to a hazard (such as a dangerous job assignment). Many fugues appear to represent disguised wish fulfillment. The fugue may remove the patient from an embarrassing situation or intolerable stress or may be related to issues of rejection or separation and some fugues appear to protect the person from suicidal or homicidal impulses.

Symptoms

Amnesia manifests in different ways. Typically, patients forget details of past events that occurred in their lives, are unable to recall information they learned in the past, or are unable to learn and recall new information. The extent of memory loss depends on the nature and severity of the injury or trauma that triggered the amnesia. In some cases, amnesia may also impair the patient’s ability to learn new information. Some patients may be aware of their memory loss and try to account for it or lie about periods of time they cannot recall.

Treatment for Dissociative Amnesia

Psychotherapy-This kind of therapy for mental and emotional disorders uses psychological techniques designed to encourage communication of conflicts and increase insight into problems.

Cognitive therapy - This type of therapy focuses on changing dysfunctional thinking patterns and the resulting feelings and behaviors.

Family therapy helps to teach the family about the disorder and its causes, as well as to help family members recognize symptoms of a recurrence.