Amnesia: Lack of memory. Amnesia after trauma can be antegrade or retrograde, depending upon whether the lack of memory relates to events occurring after or before the trauma. Amnesia is as compared to hypermnesia and hypomnesia. From a- + the Greek mneme, memory. (MedicineNet, Inc., 2005)
Definition and History
Amnesia is a psychiatric disorder characterized by a sudden loss of memory covering a variable period of time, an absence of underlying brain disease and awareness by the patient that a memory disturbance is present. (Kaplan, Sadock, 1985) Except in its generalized form, this disorder is nearly always characterized by anterograde amnesia (i.e., loss of memory for a period following a profoundly distressing event). (Kiersch, 1962; Kaplan, Sadock, 1985)
Psychogenic amnesia was first classified with conversion disorder as a hysterical neurosis in the late 1800s. (Kiersch, 1962; Kaplan, Sadock, 1985)
In the first edition of the Diagnostic and Statistical Manual of Mental Disorders amnesia was recognized as an independent process, separated from conversion disorder and reclassified with dissociative disorders involving alteration of consciousness or identity. (American Psychiatric Association, 1952) Dissociative disorders, including psychogenic amnesia, remain in a separate classification from conversion disorder in the revised third edition of the American Psychiatric Association's manual (1987). In psychogenic amnesia, a suspected internal conflict is manifested by memory loss and subsequent dissociative state, while in conversion disorder, internal conflict is manifested by sensorimotor symptoms. (American Psychiatric Association, 1987)
Causes & symptoms
Amnesia has several root causes. Most are traceable to brain injury related to physical trauma, disease, infection, drug and alcohol abuse, or reduced blood flow to the brain (vascular insufficiency). In Wernicke- Korsakoff syndrome, for example, damage to the memory centers of the brain results from the use of alcohol or malnutrition. Infections that damage brain tissue, including encephalitis and herpes, can also cause amnesia. If the amnesia is thought to be of psychological origin, it is termed psychogenic.............
