Transient global amnesia (TGA) causes sudden short-term memory loss that resolves on its own within 24 hours. Even though the condition is harmless, it’s important to seek immediate medical care if you or a loved one experience sudden memory loss to be sure there’s not a more serious underlying cause.
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.
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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:
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.
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:
People experiencing TGA do not:
Other symptoms that can occur with TGA include:
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.
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:
One type of TGA — benign transient amnesia after substance ingestion — results from any of the following:
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.
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:
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.
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.
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:
If stroke symptoms appear, it’s very important to go to the emergency room to get immediate medical help.
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.
Last reviewed by a Cleveland Clinic medical professional on 01/25/2023.
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