Amnestic disorders Health Article

Definition

The amnestic disorders are a group of disorders that involve loss of memories previously established, loss of the ability to create new memories, or loss of the ability to learn new information. As defined by the mental health professional's handbook, the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (2000), also known as DSM-IV-TR, the amnestic disorders result from two basic causes: general medical conditions that produce memory disturbances; and exposure to a chemical (drug of abuse, medication, or environmental toxin). An amnestic disorder whose cause cannot be definitely established may be given the diagnosis of amnestic disorder not otherwise specified.

Description

The amnestic disorders are characterized by problems with memory function. There is a range of symptoms associated with the amnestic disorders, as well as differences in the severity of symptoms. Some people experience difficulty recalling events that happened or facts that they learned before the onset of the amnestic disorder. This type of

amnesia is called retrograde amnesia. Other people experience the inability to learn new facts or retain new memories, which is called anterograde amnesia. People with amnestic disorders do not usually forget all of their personal history and their identity, although memory loss of this degree of severity occurs in rare instances in patients with dissociative disorders.

Causes

In general, amnestic disorders are caused by structural or chemical damage to parts of the brain. Problems remembering previously learned information vary widely according to the location and the severity of brain damage. The ability to learn and remember new information, however, is always affected in an amnestic disorder.

Amnestic disorder due to a general medical condition can be caused by head trauma, tumors, stroke, or cerebrovascular disease (disease affecting the blood vessels in the brain). Substance-induced amnestic disorder can be caused by alcoholism, long-term heavy drug use, or exposure to such toxins as lead, mercury, carbon monoxide, and certain insecticides. In cases of amnestic disorder caused by alcoholism, it is thought that the root of the disorder is a vitamin deficiency that is commonly associated with alcoholism, known as Korsakoff's syndrome. The causes of transient global amnesia, or TGA, are unclear.