Transient Global Amnesia Health Article

Definition

Transient global amnesia (TGA) is a temporary short-term memory loss that may result from the deactivation of the brain's temporal lobes and/or thalamus (the part of the brain that serves as a center for the relay of sensory information). Usually occurring in otherwise healthy persons, TGA triggers memory loss from external stresses such as strenuous exertion, high levels of anxiety, sexual intercourse, immersion in water, and other similar conditions. The event may also be triggered by a condition called the Valsalva maneuver. During this maneuver, a person performs the "breathe-in-bear-down" movement that is automatically performed during strenuous exercise. It is thought that this maneuver temporarily siphons blood from the temporal lobes of the brain. The temporal lobes are where the memories are stored. This loss of blood may induce the loss of memory by persons experiencing TGA. While this hypothesis is still under review, it has been accepted as a logical explanation for a condition that currently has no generally accepted causal explanation.

Description

Transient global amnesia was first identified and described around 1960. Since that time, there have been extensive writings and studies about the condition, but its etiology (causation) is still not clearly known or understood.

TGA affects memory function. People experiencing TGA can register information and there is no loss of social skills and sense of identity, but their ability to retain information is severely impaired. One of the puzzling associations with TGA is that many people who experience this disorder are also migraine headache sufferers. However, there is no report of a migraine prior to onset, nor is there any reported nausea, sensitivity to light or sound, or headache.

Demographics

There are no race or inherited conditions associated with TGA. Men experience the condition more often than women. In addition, the occurrence of this type of amnesia rarely happens before middle age, with about 12 out of 100,000 people ever experiencing the condition before age 50. The most likely ages in which to experience TGA are the 50s and 60s. About 3% of people who experience one episode of TGA will experience another episode sometime during their lifetime, but it is very rare for a person to experience more than three episodes of TGA.

The reason people in their 50s and 60s are more likely to experience TGA is not understood. No definitive links to any particular pathology or reaction to medication have been discovered. It is an elusive medical experience. For example, the connection of TGA with exposure to cold water cannot be explained in any convincing way. However, the condition has, as one of its major triggers, the exposure to cold water as in swimming, or prolonged exposure to cold rain or snow.