APA Dictionary of Psychology

a sudden global amnesia—a form of transient amnestic disorder—that typically resolves within 24 hours and occurs in the absence of any other neurological abnormalities. Individuals with TGA appear confused and disoriented and ask frequent repetitive questions to try and make sense of their experience. They are unable to acquire new memories (anterograde amnesia); they also exhibit amnesia for recently experienced events (retrograde amnesia). As the episode of TGA clears, new learning gradually returns to normal and retrograde amnesia shrinks; individuals are left with a dense memory gap for the period of TGA. Although TGA may be triggered by precipitating events (e.g., physical exertion), the mechanism responsible for its occurrence is poorly understood.