Dissociative phenomenon is specifically amnesic in that the patient is unable to recall an important memory, which is usually traumatic or stressful, but retains the capacity to learn new material. There is no medical explanation for the occurrence, nor is the condition caused by a drug.

The diagnostic criteria for dissociative amnesia emphasizes that the forgotten information is usually of traumatic or stressful nature. The forgotten memories are usually related to day-to-day information that is a routine part of conscious awareness (i.e., who a person is). Patients are capable of learning and remembering new information, and their general cognitive functioning and language capacity are usually intact. Onset of dissociative amnesia is often abrupt, and history usually shows a precipitating emotional trauma charged with painful emotions and psychological conflict. Patients are aware that they have lost their memories, and while some may be upset at the loss, others appear to be unconcerned or indifferent. Patients are usually alert before and after amnesia; however, some report a slight clouding of consciousness during the period immediately surrounding onset of amnesia. Depression and anxiety are common predisposing factors. Amnesia may provide a primary or a secondary gain (i.e., a woman who is amnestic about the birth of a dead infant). Dissociative amnesia may take one of several forms: localized amnesia (loss of memory for the events over a short time), generalized amnesia (loss of memory for a whole lifetime of experiences), and selective or systematized amnesia (inability to recall some but not all events over a short time). The amnesia is not the result of a general medical condition or the ingestion of a substance. See Table 17-1.

See Table 17-2.

The symptoms of dissociative amnesia terminate abruptly. Recovery is complete with few recurrences. The condition may last a long time in some patients, especially in cases involving secondary gain. Patient’s lost memories should be restored as soon as possible, or the repressed memory may form a nucleus in the unconscious mind where future amnestic episodes may develop. Recovery generally is spontaneous but is accelerated with treatment.

Dissociative fugue is characterized by sudden, unexpected travel away from home, with the inability to recall some or all of one’s past. This is accompanied by confusion about identity and, often, the assumption of an entirely new identity.

Memory loss is sudden and is associated with purposeful, unconfused travel, often for extended periods of time. Patients lose part or complete memory of their past life and are often unaware of the memory loss. They assume an apparently normal, nonbizarre new identity. However, perplexity and disorientation may occur. Once they suddenly return to their former selves, they recall the time antedating the fugue, but they are amnestic for the period of the fugue itself. See Table 17-3.