Transient Global Amnesia

What is transient global amnesia (TGA)?

Transient global amnesia (TGA) is a rare medical condition in which you experience a sudden episode of memory loss.

During a TGA episode, you can’t form new memories (a condition called anterograde amnesia), and you have difficulty recalling recent memories (a condition called retrograde amnesia). “Transient” means passing. Transient global amnesia episodes usually last no more than several hours. In rare cases, they last 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.

Even though researchers have been studying transient global amnesia for over 50 years, they’re still not sure what causes it or why it happens.

Who does transient global amnesia affect?

Transient global amnesia mainly affects people between the ages of 50 and 80 (75% of cases). It rarely affects people younger than 40.

Some studies suggest that people who have a history of the following health conditions may be more at risk for developing transient global amnesia:

• Heart disease.
• Migraine.
• Hyperlipidemia (high cholesterol).

How common is transient global amnesia?

Transient global amnesia is rare. It affects about 5 to 10 people per 100,000 per year in the general U.S. population.

For people aged 50 and older, it affects 23 to 32 people per 100,000 a year.

What are the symptoms of transient global amnesia?

The main sign of transient global amnesia is a sudden inability to form new memories. Some people also can’t recall memories from hours or days ago or longer in the past.

People experiencing a TGA episode may:

• Appear disoriented and confused.
• Repeatedly ask the same questions, especially about the date, time and their location.

People experiencing TGA do not:

• Lose consciousness.
• Have other neurological or cognitive symptoms, such as loss of language or issues moving.
• Wake up with TGA. It happens later in the day.

Other symptoms that can occur with TGA include:

• Headache.
• Nausea and vomiting.
• Dizziness.
• Anxiety.

In most cases, TGA episodes last one to 10 hours (six 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 aren’t part of TGA and are likely related to other causes.

What causes transient global amnesia?

Researchers don’t know the exact cause of transient global amnesia (TGA). But they believe it’s due to a temporary issue in your hippocampus — the part of your brain that plays a significant role in learning and memory.

Some research suggests that TGA results from a lack of sufficient blood flow (ischemia) or oxygen flow (hypoxia) to your brain. Other research suggests that TGA may be related to seizure activity in your brain.

Certain situations may trigger TGA, including:

• Physical exertion.
• Emotional or psychological stress.
• Sudden immersion in cold or hot water.
• Pain.
• Sexual intercourse.
• Performing the Valsalva maneuver. This is a breathing technique you purposely perform as part of a medical test or to slow a rapid heart rate. It involves closing your mouth and pinching your nose and bearing down as if you’re having a bowel movement.

One type of TGA — benign transient amnesia after substance ingestion — results from any of the following:

• Excessive alcohol consumption.
• Using large doses of barbiturates (sedative and sleep-inducing drugs).
• Using several recreational drugs.
• Using small doses of benzodiazepines (drugs that treat anxiety, insomnia and seizures).

If you or a loved one has symptoms of sudden memory loss, you should go to the hospital as soon as possible to be sure there’s not a potentially life-threatening condition causing it.

How is transient global amnesia diagnosed?

There’s no diagnostic test for transient global amnesia. Instead, healthcare providers rule out all other possible causes of amnesia before diagnosing TGA.

To rule out other causes, a provider will perform a physical exam and check your vital signs. They may also perform a neurological exam.

They may order imaging tests and certain blood tests, such as:

• Comprehensive metabolic panel.
• Drug test (toxicology screen).

How is transient global amnesia treated?

There’s no treatment for transient global amnesia. The condition resolves on its own within 24 hours — your memory function will return to its normal state.

Your healthcare team will likely recommend staying in the hospital until the amnesia goes away to be sure there isn’t an underlying medical cause and you don’t develop additional symptoms.

What are the long-term effects of transient global amnesia?

There are usually no long-term issues related to transient global amnesia. In most cases, people experiencing TGA recover completely. When the episode is over, they can form new memories, but they won’t remember what happened during the episode. Any other recent memories generally return within 24 hours.

In rare cases, transient global results in longer-lasting memory issues. This issue generally occurs only for people who have repeated episodes. Recurring transient global amnesia episodes are rare — less than 10% of people who experience TGA have another episode.

Is TGA a mini stroke?

Transient global amnesia (TGA) isn’t a mini stroke (transient ischemic attack). Even though the conditions share a word in their name and both have symptoms that come on suddenly, they’re different conditions.

Sudden memory loss is the main — and generally only — sign of TGA. Mini strokes have the same symptoms as strokes, such as:

• Difficulty seeing from one or both eyes.
• Numbness or weakness in your face, arms or legs, especially on one side.
• Severe headache.

If stroke symptoms appear, it’s very important to go to the emergency room to get immediate medical help.

Does TGA lead to dementia?

In the majority of cases, transient global amnesia doesn’t cause long-term memory problems, like those seen in dementia. However, you could develop dementia for other reasons.

A note from Cleveland Clinic

It’s important to take your loved one to the hospital as soon as possible if they’re suddenly unable to form new memories and are asking repeated questions about where they are and what time it is. While it can be frightening, the good news is that transient global amnesia (TGA) is harmless and resolves within 24 hours. However, sudden memory issues could be a sign of a more serious medical condition, so it’s essential to get evaluated by medical professionals.