Amnesia

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Amnesia

Amnesia is a dissociative psychological disorder manifested by total or partial loss of memory and usually caused by a trauma. Unlike ordinary forgetfulness (the inability to remember a friend’s telephone number), amnesia is a serious threat to a person’s professional and social life. Amnesia, which depending on its cause can be either organic and psychogenic, has several types.

How amnesia is manifested

Global or generalized amnesia indicates the total loss of a person’s identity: the individual has forgotten who she or he is. What makes this type of amnesia baffling is the fact that only personal memory is affected. The amnesiac does not remember who he or she is but displays no loss of general knowledge. A person suffering from retrograde amnesia cannot remember events that happened immediately before the trauma. In anterograde amnesia, all events following the trauma are forgotten. Finally, amnesia can also be selective, or categorical, manifested by a person’s inability to remember events related to a specific incident.

Causes of amnesia

The causes of amnesia can be physiological and/or psychological. Amnesia caused by physical trauma is called organic amnesia, while the term psychogenic amnesia is used in reference to amnesia caused by psychological trauma.

Organic amnesia

Examples of organic amnesia include cases of memory loss following head injuries, brain lesions, stroke, substance abuse, carbon monoxide poisoning, malnutrition, electro-convulsive therapy, surgery, and infections. Persons suffering from any kind of organic amnesia display a number of typical characteristics. Their memory loss is anterograde: events after the trauma are forgotten. In addition, they can remember the distant past well, but their grasp of the immediate past is tenuous. If treatment is unsuccessful, the amnesiac’s condition can worsen, leading to progressive memory loss. In such cases, memory loss is irreversible. If therapy is successful, the patient may partially regain memories blocked by retrograde amnesia, while anterograde amnesia usually remains.

Psychogenic amnesia

The causes of psychogenic amnesia are psychological, and they include career-related stress, economic hardship, and emotional distress. Experts have maintained that psychogenic amnesia has no physiological causes, although recent research has established that emotional trauma may alter the brain physiology, thus setting the stage for the interplay of psychological and physiological factors in the etiology of amnesia. In other words, psychogenic amnesia may have secondary causes that could be defined as organic. The most enigmatic psychogenic amnesia is identity loss; the person affected by this type of amnesia loses all personal memories, while retaining his or her general (impersonal) knowledge. For example, the amnesiac may not know his or her name, but can still be able to speak an acquired second language. Furthermore, in psychogenic amnesia, there is no anterograde memory loss. Finally, although psychogenic amnesia is reversible and can end within hours or days, it is a serious condition that can be difficult to treat.

Diagnosis

In diagnosing amnesia, doctors look at several factors. During a physical examination, the doctor inquires about recent traumas or illnesses, drug and medication history, and checks the patient’s general health. Psychological exams may be ordered to determine the extent of amnesia and the memory system affected. The doctor may also order imaging tests such as magnetic resonance imaging (MRI) to reveal whether the brain has been damaged, and blood work to exclude treatable metabolic causes or chemical imbalances.

Treatment depends on the root cause of amnesia and is handled on an individual basis. Regardless of cause, cognitive rehabilitation may be helpful in learning strategies to cope with memory impairment.

Some types of amnesia, such as transient global amnesia, are completely resolved and there is no permanent loss of memory. Others, such as Korsakoff syndrome, associated with prolonged alcohol abuse or amnesias caused by severe brain injury, may be permanent. Depending on the degree of amnesia and its cause, victims may be able to lead relatively normal lives. Amnesiacs can learn through therapy to rely on other memory systems to compensate for what is lost.

Amnesia is only preventable in so far as brain injury can be prevented or minimized. Common sense approaches include wearing a helmet when bicycling or participating in potentially dangerous sports, using automobile seat belts, and avoiding excessive alcohol or drug use. Brain infections should be treated swiftly and aggressively to minimize the damage due to swelling. Victims of strokes, brain aneurysms, and transient ischemic attacks should seek immediate medical treatment.

KEY TERMS

Dissociative disorder— Referring to psychological conditions, such as psychogenic amnesia and multiple personality disorder, in which an area of personal memory is dissociated from a person’s consciousness.

Etiology— The cause or origin of a disease or condition.

Resources

BOOKS

Baddeley, Alan D., Michael D. Kopelman, and Barbara A. Wilson, eds. The Essential Handbook of Memory Disorders for Clinicians. Chichester, UK, and Hoboken, NJ: John Wiley, 2004.

Bowers, Jeffrey S., and Chad J. Marsolek. Rethinking Implicit Memory. Oxford, UK, and New York: Oxford University Press, 2003.

Carr, Alan. Abnormal Psychology. Hove, UK, and Philadelphia, PA: Psychology Press, 2001.

Papanicolaou, Andrew C. The Amnesias: A Clinical Textbook of Memory Disorders. Oxford, UK, and New York: Oxford University Press, 2006.

Schacter, Daniel L. The Seven Sins of Memory: How the Mind Forgets and Remembers. Boston, MA: Houghton Mifflin, 2002.

Squire, Larry R. and Daniel L. Schacter, eds. Neuropsychology of Memory. New York: Guilford, 2002.