Transient Global Amnesia (TGA): Causes & Symptoms

ByAgkidzone Staff

Updated: Oct 14, 2024

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Transient global amnesia (TGA) is a rare condition that affects about five out of every 100,000 people per year. The sudden onset of memory loss can be scary for both the individual and those around them. While the exact cause of TGA is still unclear, certain triggers seem to be more common in those who have experienced it. Thankfully, this condition resolves itself within 24 hours and does not leave behind any lasting effects.

What is Transient Global Amnesia?

Transient global amnesia is a sudden, temporary loss of short-term memory that isn't caused by a more serious event, like a stroke or epilepsy. During an episode, a person may become confused about where they are or what they’re doing. They often ask the same questions repeatedly because they can’t remember the answers they just heard. Despite this, the individual remains alert and can think clearly about everything else.

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TGA vs Dementia

While both TGA and dementia involve memory issues, they are not the same. People with dementia often forget who they are or fail to recognize loved ones. However, in a TGA episode, individuals still know who they are and recognize family and friends. They may not be able to remember what just happened, but they retain important personal information. Also, people with TGA do not form new memories during the episode and will not recall the event after it ends.

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Diagnosis

The hallmark of transient global amnesia is its sudden onset of memory loss. To diagnose TGA, a witness must confirm that the memory problems began suddenly. The person experiencing TGA will still know who they are, can follow simple instructions, and recognize familiar things around them. Importantly, there should be no signs of other neurological issues, like facial drooping or limb paralysis, which might indicate a stroke or other serious condition.

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Memory Loss

Short-term memory loss, or what is called "anterograde amnesia," is the primary symptom of TGA. Individuals often ask the same questions again and again because they are confused and unable to recall the answers they were just given. People experiencing TGA are often described as sounding “like a broken record” due to the repetition. The length of lost memories can vary, covering hours, days, or even weeks.

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Additional Signs and Symptoms

Several other factors can help doctors diagnose TGA. Memory loss usually lasts between one and eight hours, with the average episode lasting about six hours. The episode never lasts longer than 24 hours. Once the memory returns, it comes back gradually. For a diagnosis of TGA, there should be no head injury or seizures involved, and the person should not have active epilepsy. Reflexes, balance, and coordination remain normal during and after the episode.

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Causes

The exact cause of transient global amnesia remains unknown. However, experts believe several factors may contribute. Abnormal blood flow or oxygen deprivation (hypoxia) to the brain could be one reason. There is also a potential link between migraines and TGA. Still, these factors do not apply to everyone who experiences TGA, which suggests that the condition may have multiple causes.

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Triggers

Certain activities are thought to trigger TGA, although the chances of an episode occurring are low. These triggers may include intense physical exercise, sudden immersion in hot or cold water, mild head trauma, sexual activity, or even emotional distress. Additionally, medical procedures like endoscopy or angiography, as well as excessive alcohol or drug use, have also been linked to TGA episodes.

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Risk Factors

Surprisingly, risk factors like high blood pressure and high cholesterol, which increase the risk of stroke, do not seem to affect the likelihood of TGA. Gender doesn’t play a role either. However, two known risk factors do stand out: being over 50 years old and having a history of migraines significantly increase the risk of experiencing transient global amnesia.

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Prognosis

TGA generally resolves itself within 24 hours, and most people experience no long-term damage. There is no increased risk of future strokes or seizures. Cognitive function typically returns to normal within a few days. While TGA is usually a one-time occurrence, there is up to a 26% chance that someone could experience another episode in the future.

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Diagnostic Testing

There is no specific test to diagnose transient global amnesia. Instead, doctors run tests to rule out other possible causes. These might include MRI or CT scans to check for brain damage, an EEG to monitor brain activity, and blood tests. Doctors may also perform neurological exams and psychological evaluations to ensure there are no underlying conditions that could have caused the memory loss.

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