The mystery of transient global amnesia: Sudden, temporary memory loss

Imagine suddenly finding yourself unable to form new memories or remember how you arrived at your current location. Yet, you still know exactly who you are, recognize your loved ones, and can perform complex everyday tasks.

This alarming scenario describes a rare neurological condition known as transient global amnesia (TGA).

To demystify this sudden and often scary event, William Ares, MD, a fellowship-trained neurosurgeon at Endeavor Health, explores what TGA is, what triggers it, and why it is crucial to seek immediate medical attention if you or a loved one experiences it.

What is transient global amnesia?

Transient global amnesia is a temporary, sudden episode of memory loss. It is not a stroke or a seizure, though those conditions can also cause memory loss.

"TGA is an unusual and rare condition where there is - suddenly and temporarily - a disruption of the brain's ability to form memories," Dr. Ares said. "It's almost as if the brain's record function has temporarily stopped working."

What are the symptoms of TGA?

"One of the key hallmarks of TGA is sudden memory loss. Some people can even forget things that happened in the previous couple of hours," said Dr. Ares.

An episode of TGA may look like this:

• Difficulty making new memories: The individual temporarily loses the ability to form new memories (called anterograde amnesia). Because their brain isn't saving what just happened, they might ask the same question over and over again, completely forgetting the answer you just gave them.
• Mild gaps in recent memories: They might have trouble remembering things that happened right before the episode started, such as what they ate for breakfast or what they did the day before (called retrograde amnesia).
• Core functions stay normal: Even though their short-term memory is temporarily paused, the person still knows exactly who they are, recognizes family and friends, speaks normally, and can still perform everyday tasks like driving or drawing.

Someone experiencing TGA may also have nausea, vomiting, dizziness and anxiety. However, they usually don't lose consciousness or experience other neurological symptoms, such as loss of language and issues with movement.

What are common triggers of TGA?

A TGA episode can come out of nowhere, or start right after:

1. Strenuous physical exertion
2. Acute emotional or psychological stress (e.g., receiving distressing news or experiencing an intensely anxious event)
3. Sudden immersion in cold or hot water
4. Sexual intercourse
5. Mild head trauma (distinct from classic concussive amnesia)

Does TGA cause permanent damage?

While experts don't actually know exactly why it happens, the condition almost always resolves on its own within 24 hours and causes no permanent neurological damage.

"Patients typically recover completely, usually within 24 hours," Dr. Ares explained. "But they actually won't regain the memories that were made during that time - that record function was off. So, it is common that they have a permanent blank spot in their memory during those several hours," said Dr. Ares.

When memory fails, why call 911?

The symptoms of TGA can be frightening for both the individual and their family members. Because the sudden onset of severe memory loss closely mimics more critical, life-threatening conditions, Dr. Ares stresses that any sudden onset of amnesia must be treated as a medical emergency.

Doctors will want to immediately rule out other conditions, such as:

• Stroke or transient ischemic attack (TIA): A blockage or bleed in the brain requiring immediate intervention
• Seizures: Uncontrolled electrical activity in the brain that can impair awareness and memory
• Encephalitis: An inflammation or infection of the brain tissue

A proper emergency evaluation, which usually includes neurological examinations and imaging like an MRI or CT scan, ensures that dangerous underlying vascular or neurological issues are not the cause.

What is recovery like?

"This is a temporary condition," said Dr. Ares. "You should most certainly be seen by a medical professional to make sure there there's not something more severe going on, but TGA tends to have a good prognosis without associated with long-term health risks," said Dr. Ares.

The brain's memory-making functions return gradually, usually over the course of a few hours up to a single day. Once the episode ends, the individual can fully return to their normal daily activities without a high risk of recurrence; TGA rarely happens to the same person twice.