Transient global amnesia is a frightening and sudden loss of memory. The condition goes away almost as quickly as it appears: it lasts less than a day, causes no long-term damage and has a low recurrence rate. Though physicians say that those who have been diagnosed with one of these episodes have little cause for concern, it is the rare person who experiences an episode of transient global amnesia without being shaken by the event. (Mayo Clinic)
The Symptoms of Transient Global Amnesia
We’ve all seen fictional versions of amnesia — characters who suffer a bump on the head, then can’t remember who they are or recognize their family members — but that is not what happens in transient global amnesia. This condition specifically affects the ability to form new memories while leaving intact what is known as remote memory [reference link no longer working], which is the recollection of events that happened a long time ago. A person suffering from transient global amnesia will be able to remember their own name and will know the people who are meaningful to them, but will not have any recollection of how they got where they are. They will be able to remember how to perform basic and complex functions such as using a smart phone, but will not be able to retain any new information, leading them to ask the same questions over and over again. Perhaps most importantly, when brain scans and other tests are done on people experiencing transient global amnesia, there is no evidence of damage to the brain, and the symptoms entirely go away in a short period of time. The only long-term impact of transient global amnesia is that the patient doesn’t remember what happened during the episode. (Cedars-Sinai)
Experiencing Transient Global Amnesia
Many people who have experienced transient global amnesia have reported that their initial reaction to what is happening to them is that of terror: they have no sense of cause and effect. They don’t know what has led up to what is happening to them, and are unable to hold on to the facts as they are explained to them for any meaningful period of time – what is told to them is instantly forgotten. Still, when they reflect on the episode, many report that they felt a sense of freedom from being untethered to any of their normal stressors, fears or concerns. (New York Times [link removed]).
Who Is at Risk for Transient Global Amnesia
Though physicians have documented transient global amnesia for decades, it remains a poorly understood phenomenon. It is estimated that only one in every 10,000 people will ever experience an episode of TGA. No specific cause has been identified, though there are some theories about patterns and associations, particularly in terms of who is more likely to get them and what may precipitate their occurrence. Some studies have indicated that there is a link between people – and specifically females between the ages of 40 and 60 – who get migraines and the risk of transient global amnesia (Medscape), though epidemiologists say that the incidence of the disease is evenly split between males and females between the ages of 40 and 80 years old, with an average age of 60. (NCBI)
Possible Triggers for Transient Global Amnesia
One theory behind the association between people having migraine headaches and experiencing transient global amnesia is that the episodes are actually triggered by a physiological event involving increased blood flow to the superior vena cava, which is the large vein that carries blood from the head to the heart. (PLOS) The theory is that an insufficiency in this vein, which runs down the side of the neck, could allow blood to flow backwards into the brain. This hypothesis is supported by evidence that TGA is often preceded by emotional stress, exposure to extremely cold water, physical exertion, and sexual intercourse. (Medscape)
There are also some reports of people experiencing episodes of transient global amnesia after taking large doses of sedatives, drinking too much alcohol, or using a combination of illegal drugs. Though these incidents do result in difficulty concentrating and an inability to form and store memories, they are considered a different category of transient global amnesia. (Merck Manual)
Diagnosing Transient Global Amnesia
When a person is suffering from sudden onset memory problems, the most appropriate course of action is to take them to the nearest emergency room. Though the issue may be transient global amnesia, there are other differential diagnoses [reference link no longer functional] that need to be ruled out, including a stroke or seizure, a viral infection of the brain, or the aftermath of a concussion. Recovery from a TGA generally takes less than 8 hours and the patient has no after-effects other than the fact that they have little or no memory of the time period encompassing the episode itself. Emergency room doctors who patients of suffering transient global amnesia generally wait to see whether the symptoms resolve quickly, and if they don’t then the patient should be thoroughly tested. (Boston Globe)
