Dissociative Disorders: Diagnostic Criteria and Treatment Dissociative Amnesia

Diagnostic Criteria and Treatment Dissociative Amnesia

This is the classical functional disorder of episodic memory. It does not involve procedural memory or problems in memory storage, as in Wernicke–Korsakoff syndrome. Furthermore, un-like dementing illnesses, dissociative amnesia is reversible for example, by using hypnosis or narcoanalysis. It has three pri-mary characteristics:

·   Type of memory lost: The memory loss is episodic. The first-person recollection of certain events, rather than knowledge of procedures, is lost.

·        Temporal structure: The memory loss is for one or more dis-crete time periods, ranging from minutes to years. It is not vagueness or inefficient retrieval of memories but rather a dense unavailability of memories that were encoded and stored. Unlike the situation in amnestic disorders, for example, resulting from damage to the medial temporal lobe in surgery (the case of H.M. [Milner, 1959]), in Wernicke–Korsakoff syn-drome, or in Alzheimer’s dementia, there is usually no diffi-culty in learning new episodic information. Thus, the amnesiaof dissociative disorders is typically retrograde rather than anterograde. However, a dissociative syndrome of continuous difficulty in incorporating new information that mimics or-ganic amnestic syndromes has been observed.

·   Type of events forgotten: The memory loss is usually for events of a traumatic or stressful nature. This fact has been noted in the language of the DSM-IV diagnostic criteria. In one study (Coons and Milstein, 1986), the majority of cases involved child abuse (60%) but disavowed behaviors such as marital problems, sexual activity, suicide attempts, criminal activity, and the death of a relative have also been reported as precipitants.

Dissociative amnesia most frequently occurs after an epi-sode of trauma, and its onset may be gradual or sudden.

Dissociative amnesia occurs most often in the third and fourth decades of life. It usually involves one episode, but multi-ple periods of lost memory are not uncommon. Comorbidity with conversion disorder, bulimia nervosa, alcohol abuse and depres-sion are common, and Axis II diagnoses of histrionic, dependent, or borderline personality disorders occur in a substantial minor-ity of such patients.

Such individuals typically demonstrate not vagueness or spotty memory but rather a loss of any episodic memory for a finite period. They may not initially be aware of the memory loss; that is, they do not remember that they do not remember. They often report being told that they have done or said things that they cannot remember.

Some individuals do suffer from episodes of selective amnesia, usually for specific traumatic incidents, which may be interwoven with periods of intact memory. In these cases, the amnesia is for a type of material remembered rather than for a discrete time period.