Introduction

Transient Global Amnesia (TGA) is a rare neurological condition which causes sudden short-term memory loss. Amnesia is a type of memory loss which affects your ability to form, store and retrieve memories. ‘Transient’ means temporary or short-lived. TGA episodes typically last for a brief period of a few hours, although in sporadic cases they last up to 24 hours.¹

While TGA episodes can be frightening, they are generally harmless and resolve on their own. This article aims to provide a clear understanding of the symptoms of TGA, how it differs from more serious neurological conditions and answers to commonly asked questions about TGA.

Overview of Transient Global Amnesia

TGA is characterised by a sudden, temporary loss of memory of events before, during and after the event that caused the amnesia. During an episode, people experience anterograde amnesia, meaning they are unable to create new memories, and temporary retrograde amnesia, meaning they lose memories of past events. 

People with TGA can remember who they are; however, they may not remember where they are or what happened during the episode. Memory loss usually resolves on its own within 24 hours. TGA mostly affects people between the ages of 50 and 70. It rarely occurs in those younger than 50.

The exact underlying causes of TGA are not yet fully known. Research suggests that it originates in the hippocampus, a part of the brain which plays a critical role in memory and learning. Several situations may trigger TGA episodes, including pain, hot or cold baths, physical exertion, psychological stress and excessive alcohol consumption ^{2, 5}

TGA is a harmless condition with no lasting effects. However, it is important to seek medical advice to rule out other causes of amnesia, which are more serious and can be life-threatening. If the underlying cause of TGA is identified, such as seizures, this will be treated.

Core symptoms of TGA include the inability to form new memories or recall memories from hours or days ago. Some people also experience confusion, disorientation and may repeatedly ask questions during a TGA episode. Other symptoms that can occur with TGA include headache, nausea, dizziness and anxiety.

It is important to understand the symptoms of TGA to gain a deeper understanding and differentiate it from other neurological disorders, such as stroke and seizure, which have more serious consequences.

Main symptoms of Transient Global Amnesia

Sudden memory loss

TGA is characterised by the sudden onset of memory loss, a condition known as retrograde amnesia. People living with TGA find it difficult to recall events which have happened a few hours or days before the TGA episode. Some people may not be able to remember even more distant events before the onset of amnesia. They may also be unable to recall events which happened during and after the TGA episode.

Despite their memory loss, during a TGA episode, people remain aware of who they are and can remember their family members. They keep their social skills and can still perform daily tasks, including cooking, driving or tasks at work. Speech, motor skills and consciousness also remain unaffected. 

However, they may forget recent events, where they are and what day and time it is. Memory loss is temporary, meaning that memories usually come back within a few hours of the TGA episode.

Confusion

One of the main symptoms of TGA is experiencing confusion. During and after a TGA episode, a person may feel confused about their surroundings and what is happening. This often includes repetitive questioning. They may ask the same thing multiple times, particularly about the date and time.

Confusion resulting from TGA usually resolves after the episode ends. It is recommended to seek medical advice to clear up any confusion about what has happened. This can help provide reassurance and address any concerns you may have.

Inability to form new memories

People experiencing a TGA episode are unable to create new memories.³ This means that they are temporarily unable to store recent events as memories, so the memory of recent events disappears.

This condition is known as anterograde amnesia, a type of memory loss which means a person cannot form new memories. Once the amnesia episode has passed, the ability to form new memories returns to normal.

Additional characteristics and observations 

Several other symptoms may occur as a result of TGA. For example, someone may appear disoriented, losing their sense of direction and ability to think clearly. Other important symptoms include having no sign of brain damage, being awake and alert during the episode and no epilepsy or seizure activity. If someone loses consciousness, this is an indication that there may be a serious medical condition causing the amnesia.

Living with TGA can often be emotionally distressing.² Episodes of amnesia can be scary and upsetting experiences, and many people experience anxiety due to memory loss. Therefore, it’s always helpful to speak with your healthcare provider about your TGA episode to alleviate any stress and worries.

Duration of symptoms 

TGA episodes typically last for 1 to 8 hours. In rare cases, symptoms may persist for up to 24 hours.¹ While it can be an unsettling experience, there are usually no long-term health or memory issues associated with transient global amnesia. Following a TGA episode, cognitive functions, such as thinking ability, remain normal.

However, some people may experience repeated TGA episodes, which, although rare, increase the risk of long-term memory issues. Recurrent TGA episodes are rare, with less than 20% of people who experience TGA having a second episode. Some research suggests that people who experience frequent migraines may have a higher risk of recurrent TGA.^4,5

Differential diagnosis 

While there are no diagnostic tests specifically for TGA, it is usually diagnosed by ruling out other memory-related conditions which may present similar symptoms. It is critical to differentiate TGA from neurological disorders with more serious consequences, such as stroke, seizures and dissociative amnesia.^6,7

TGA differs from a transient ischemic attack (TIA) or “mini stroke”. TIA is a very serious medical condition and requires emergency care.⁸ It means that there’s a temporary lack of blood flow to part of the brain, and brain cells start to malfunction. While both TGA and a TIA include symptoms of confusion and memory loss, a TIA presents more severe symptoms such as loss of muscle control, loss of speaking ability, blurred vision and one-sided paralysis.

Additionally, TGA shares some symptoms with seizures, including confusion. However, seizures often result in loss of consciousness, which is not usual during a TGA episode.⁹ Seizures are characterised by abnormal brain activity and only last for a few minutes, while TGA episodes often last several hours.

TGA is different from other types of amnesia, such as dissociative amnesia.¹⁰ Dissociative amnesia often results from psychological stress or trauma. While both conditions involve memory loss, TGA is typically triggered by physical or physiological triggers, such as strenuous physical activity or sudden immersion in hot or cold baths. Additionally, TGA episodes usually last a few hours, while dissociative amnesia may involve more prolonged memory issues.

To rule out other causes of amnesia, your healthcare provider will perform a physical exam and check your vital signs. They may also perform a neurological exam, imaging tests and blood tests.⁶

FAQs

Is transient global amnesia a mini stroke?

No, TGA is not a mini stroke. While TGA shares symptoms of confusion and memory loss with a mini stroke (also called a transient ischemic attack), they are very different conditions. It is essential to seek medical attention to differentiate between the two conditions.

Is there a treatment for transient global amnesia?

No, there is no specific treatment for TGA because it usually resolves on its own within a few hours. However, avoiding triggers such as stress, excessive alcohol consumption and physical exertion can help reduce the risk of further episodes.

What should I do if someone has a transient global amnesia episode?

It is important to go to the hospital immediately to rule out other causes of amnesia. Additionally, try to remain calm and provide a supportive environment to avoid any further emotional distress.

How long does a transient global amnesia episode last?

In the majority of cases, TGA episodes last between 1 to 8 hours. In very rare cases, they can last for up to 24 hours.

Are there any long-term effects of transient global amnesia?

No, TGA does not typically have any long-lasting effects. After the episode ends, cognitive functions return to normal.

Summary 

Transient global amnesia (TGA) is a rare neurological condition that causes sudden memory loss, primarily affecting people over 50. It affects short-term memory, leading to an inability to form new memories. Other symptoms of TGA include feeling disoriented and confused. 

TGA episodes are temporary, usually lasting for 1 to 8 hours, although in very rare cases, symptoms can persist for up to 24 hours. TGA does not require specific treatment since it typically resolves on its own within a few hours. The exact cause of TGA remains unknown, although several triggers have been linked to its onset, including stress, physical exertion and frequent migraines.

While TGA can be emotionally distressing, it is a harmless condition with no lasting effects or memory issues. However, TGA shares certain symptoms with more serious neurological disorders, such as stroke and seizures. It is important to seek medical evaluation immediately to rule out other causes of amnesia and address any concerns you may have.