Memory Loss & the Brain

Amnesia is a severe disruption of memory without deficits in intelligence, attention, perception or judgment. It may occur following damage to any of several brain structures which are critical for memory.

There are three major classes of amnesia: anterograde amnesia, which is an impairment in storing new memories, retrograde amnesia, which is a loss of old memories, and psychogenic amnesia (or fugue state), which involves temporary loss of identity. Anterograde and retrograde amnesia usually result from brain injury or disease, while psychogenic amnesia is a psychological condition that occurs in the absence of brain injury. When the term "amnesia" is used alone, it usually connotes a syndrome of anterograde amnesia (possibly including some degree of retrograde amnesia).

Temporary amnesia can also follow use of certain drugs. In these cases, the individual may experience anterograde amnesia for events that occurred while under the influence of the drug; events occurring after the drug has worn off are remembered normally. Drugs which can cause temporary amnesia include benzodiazepines (e.g. Valium and Mogadon) and anticholinergics (e.g. scopolamine). Electroconvulsive therapy can also cause amnesia for the period of treatment.