What is transient global amnesia (TGA)?

Transient global amnesia (TGA) is a rare medical condition in which a person experiences a sudden episode of memory loss. During a TGA episode, a person cannot form new memories (a condition called anterograde amnesia) and has difficulty recalling recent memories (a condition called retrograde amnesia). Transient means “passing,” and TGA episodes usually last no more than several hours. In rare cases, TGA lasts up to 24 hours.

People with TGA remember who they are and can remember their friends and family members. They can still perform complex daily tasks, such as cooking or driving. They also retain their language and social interaction skills. However, during a TGA episode, they may not know where they are or the day or time.

Who is likely to have transient global amnesia (TGA)?

This condition usually occurs in people between the ages of 50 and 70.

How common is transient global amnesia (TGA)?

Transient global amnesia (TGA) occurs in approximately 3 to 10 people out of every 100,000.

What causes transient global amnesia (TGA)?

The exact cause of transient global amnesia (TGA) is unknown. However, some research suggests that TGA results from lack of sufficient blood flow (a condition called ischemia) or oxygen flow (a condition called hypoxia) to the brain. In some cases, TGA may be related to seizure activity in the brain.

Migraine headache appears to be a risk factor for developing TGA. Psychological factors, such as anxiety, may also make TGA more likely.

For some people, TGA may occur as a result of certain triggers or events, including:

  • Physical exertion
  • Emotional or psychological stress
  • Sudden immersion in cold or hot water
  • Head trauma
  • Pain
  • Sexual intercourse
  • Performing the valsalva maneuver. This is a breathing technique purposely performed by a person as part of a medical test or to slow a rapid heart rate and other uses. It is performed by closing your mouth and pinching your nose and bearing down as if having a bowel movement.

One type of TGA results from excessive alcohol consumption, large doses of barbiturates, illicit “street” drugs or small doses of benzodiazepines.

What are the symptoms of transient global amnesia (TGA)?

Transient global amnesia (TGA) involves a sudden inability to form new memories. Some people also cannot recall memories from hours, days, or longer in the past.

People experiencing a TGA episode may appear disoriented and confused. They know who they are and know their friends and family members, but may repeat questions about the time or date. Other complex mental tasks, such as the ability to drive a car or cook, are not affected.

Other symptoms that can occur with TGA include:

  • Headache
  • Dizziness
  • Nausea and vomiting
  • Anxiety
  • Confusion
  • Tingling in the feet, legs, hands, or arms

In most cases, TGA episodes last 1 to 10 hours (6 hours is average). In rare cases, symptoms may persist for up to 24 hours.

Memory problems that develop gradually or last for more than a day are not part of TGA and are likely related to other causes.

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