AMNESIA

From Big Medical Encyclopedia

AMNESIA (Greek. amnesia — forgetfulness, loss of memory) — disturbance of memory with loss of ability to keep and reproduce the acquired knowledge. In clinical medicine the term «amnesia» is used usually as a combined concept and of cases of generalized dysmnesias, and of narrower sense for designation of a limited gap of memoirs, lack of memory on a certain interval of time.

Within generalized dysmnesias speak about And. hl. obr. in two cases. At organic diseases of a brain ability to remember, fix new data — fixating amnesia quite often is early broken. At this disturbance there is no memory on the current, recent events at its safety on knowledge acquired in the past. Disorders of storing of type fixating And. happen especially expressed at a korsakovsky syndrome (see) and korsakovsky psychosis (see. Alcoholic encephalopathies ), at some intoxications (e.g., carbon monoxide), craniocereberal injuries, atherosclerotic and other pathopsyhosis. The impossibility to keep fresh experience in memory, to remember the new facts and circumstances just happened, inability «to learn» or «study» (according to many foreign authors) lead, despite some safety of ability to «note» of what occurs to an anamnestic disorientation in a situation and surrounding persons, in time and the sequence of events.

At senile dementia, other atrophic damages of a brain, a general paralysis and other roughly organic processes there are deeper forms of generalized disturbance of memory, there is gradual and far-reaching devastation of its stocks, i.e. the acquired data and knowledge — the progressing amnesia.

Destruction and loss of stocks of memory develop at progressing And. in a certain sequence: from more private to more general, from later acquired, less strongly fixed and less automated to what is acquired earlier, is stronger fixed, more organized and automated, from less emotionally rich to more emotionally significant. The most fixed automated motor traces (movement skills, gait, gestures, etc.) remain therefore most longer. Patterns of gradual, consecutive devastation of memory at progressing And. were formulated by the French psychologist Ribot (T. Ribot) — Ribot's law; they submit to the main patterns of disintegration of mental activity in general.

Phenomena And. in narrower understanding, i.e. development full (total) or partial (partial, lacunary) gaps of memory for a certain span, are observed during the obscuring or change of consciousness (a coma, a sopor, twilight, delirious and amental conditions, conditions of pathological affect, pathological intoxication, etc.). Such forms A. uraemias, poisonings, electroconvulsive attacks, epileptic frustration meet often after craniocereberal injuries. At the changes of consciousness accompanying, as a rule, all these morbid conditions the attention, perception, ability to concentrate that results in impossibility of storing and more or less full loss of memoirs on a certain interval of time is broken. Loss (as a rule, full) memoirs is limited often not only the period of disturbance of consciousness — kongradny amnesia, but can extend also to events which preceded a condition of the changed consciousness or development of an acute psychotic syndrome. Such And. carries the name of retrograde amnesia; it can extend to various intervals of time — of several o'clock and days up to several months and even years. If memories of experiences and events which were upon termination of disorder of consciousness or a disease mental state are lost, speak about an ecmnesia. Sometimes both forms are combined, i.e. memoirs both about preceding disease state, and about the subsequent to it events — anteroretrogradny amnesia drop out. Duration and expressiveness posttraumatic retro and anterograde And. correlates usually with weight of a craniocereberal injury and happens the most expressed at first after an injury.

After the corresponding suggestion also limited gaps of memory for events are observed during hypnosis — posthypnotic amnesia. Ship's boys (Page G. Jung) distinguished as well autogipnotichesky And., caused by auto-suggestion and hysterical replacement of certain events. Katatimny amnesia call the gaps of memory arising psikhogenno concerning unpleasant, affektivno saturated impressions and events. Under the name of periodic amnesia of Ribot described cases of «alternating consciousness» at which in one condition of consciousness there are no memoirs about endured in other state. During the escaping of all these states And. the patient remembers nothing or only vaguely remembers the separate facts and images.

See also Memory , frustration.


Bibliography: Gilyarovsky V. A. Psychiatry, page 59, M., 1954; R. Ya. O Golant dysmnesias, L. — M, 1935, bibliogr.; Kerbikov O. V., etc. Textbook of psychiatry, M., 1968; Perelman A. A. Functions of memory and its pathology, Baku, 1927; Wieck H. H. u. Stäcker K. Zur Dynamik des «amnestischen» Durchgangs — Syndroms, Arch. Psyeniat. Nervenkr., Bd 205, S. 479, 1964, Bibliogr.

E. Ya. Shternberg.

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