When your memory suddenly disappears, it can be frightening — but transient global amnesia is typically temporary and harmless.
Transient global amnesia is an episode of confusion that comes on suddenly in a person who is otherwise alert. This confused state isn't caused by a more common neurological condition, such as epilepsy or stroke.
During an episode of transient global amnesia, a person is unable to create new memory, so the memory of recent events disappears. You can't remember where you are or how you got there. You may not remember anything about what's happening right now. You may keep repeating the same questions because you don't remember the answers you've just been given. You may also draw a blank when asked to remember things that happened a day, a month or even a year ago.
The condition most often affects people in middle or older age. With transient global amnesia, you do remember who you are, and you recognize the people you know well. Episodes of transient global amnesia always get better slowly over a few hours. During recovery, you may begin to remember events and circumstances. Transient global amnesia isn't serious, but it can still be frightening.
The main symptom of transient global amnesia is being unable to create new memories and remember the recent past. Once that symptom is confirmed, ruling out other possible causes of amnesia is important.
You must have these signs and symptoms to be diagnosed with transient global amnesia:
More symptoms and history that may help diagnose transient global amnesia:
Another common sign of transient global amnesia due to the inability to create new memories includes repetitive questioning, usually of the same question — for example, "What am I doing here?" or "How did we get here?"
Seek immediate medical attention for anyone who quickly goes from normal awareness of present reality to confusion about what just happened. If the person experiencing memory loss is too confused to call an ambulance, call one yourself.
Transient global amnesia isn't dangerous. But there's no easy way to tell the difference between transient global amnesia and the life-threatening illnesses that can also cause sudden memory loss.
The underlying cause of transient global amnesia is unknown. There may be a link between transient global amnesia and a history of migraines. But experts don't understand the factors that contribute to both conditions. Another possible cause is the overfilling of veins with blood due to some sort of blockage or other problem with the flow of blood (venous congestion).
While the likelihood of transient global amnesia after these events is very low, some commonly reported events that may trigger it include:
Interestingly, many studies have found that high blood pressure and high cholesterol — which are closely linked to strokes — are not risk factors for transient global amnesia. This is probably because transient global amnesia doesn't represent blood vessel diseases of aging. Your sex doesn't seem to affect your risk, either.
The clearest risk factors are:
Transient global amnesia has no direct complications. It's not a risk factor for stroke or epilepsy. It's possible to have a second episode of transient global amnesia, but it's extremely rare to have more than two.
But even temporary memory loss can cause emotional distress. If you need reassurance, ask your doctor to go over the results of your neurological exam and diagnostic tests with you.
Because the cause of transient global amnesia is unknown and the rate of recurrence is low, there's no real way to prevent the condition.
To diagnose transient global amnesia, your health care provider must first rule out more-serious conditions. This can include stroke, seizure or head injury, for example. These conditions can cause the same type of memory loss.
This begins with a neurological exam, checking reflexes, muscle tone, muscle strength, sensory function, gait, posture, coordination and balance. The doctor may also ask questions to test thinking, judgment and memory.
The next step is testing to look for abnormalities in the brain's electrical activity and blood flow. Your health care provider might order one or a combination of these tests:
No treatment is needed for transient global amnesia. It gets better without treatment and has no known lasting effects.
Anyone who experiences sudden loss of memory for all events leading up to the present needs emergency medical care. Call 911 or your local emergency number immediately.
If a friend or family member develops these symptoms in your presence, go with him or her to the hospital. Because he or she doesn't remember recent events, you'll need to provide important information to the doctor.
Write down questions to ask the doctor. Prepare a list of questions to ask the doctor on the person's behalf. Although people experiencing transient global amnesia can think and speak, it's likely that they will be feeling severe distress. For transient global amnesia, some basic questions include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions as they occur to you during the appointment.
The doctor is likely to ask both you and the person experiencing amnesia a number of questions about symptoms and about the period leading up to the memory loss.
The doctor may ask your loved one:
To determine the extent of memory loss, the doctor may check your loved one's knowledge of general information — such as the name of the current president — and assess his or her ability to recall a random list of words.
The doctor may ask you: