Jul 22 2013
A recent article in The Guardian has the provocative title, “American man wakes up with amnesia speaking Swedish.” The article itself contains some significant misconceptions about amnesia, and so is a good opportunity to discuss this interesting topic.
In brief, amnesia is a pathological loss of memories (not just normal forgetting). The most common type of amnesia is traumatic – caused by trauma to the brain. Trauma can cause retrograde amnesia, which is loss of memories prior to the injury, and anterograde amnesia, which is loss of memories following the trauma. Contrary to the common movie cliche, these lost memories cannot be recovered by subsequent head trauma (or by any other means).
Another cause of amnesia, especially anterograde amnesia, is drugs. Alcohol and benzodiazepines in particular can prevent the formation of memories while intoxicated.
In The Guardian article they discuss the case of a man who was apparently found unconscious in a hotel room. When he awoke he was speaking only Swedish and believed his name was Johan Ek. Identification on his person, however, identified him as Michael Boatwright, an American. The man does not remember the name Boatwright and reports not to remember any of the photographs of family that were with him.
The Guardian reports that Boatwright was diagnosed with “transient global amnesia” (a claim they derive from an original report in the Desert Sun). This, however, is almost certainly an incorrect diagnosis. I don’t know if the journalists made this mistake, or the treating doctors who reported it to the media.
Transient global amnesia (TGA) has a very specific presentation, which does not fit the story of Boatwright. In TGA a person is suddenly confused as to their location and situation. They know who they are and will typically recognize people who are familiar to them, but will be completely disoriented to current events and be unable to recall recent events. They won’t know where they are or what they are doing. They appear confused to those around them, who typically bring them to medical attention.
The duration of TGA is typically about a day. After they recover from the TGA episode they will have no memories for the time period in which they had TGA. Therefore, during the TGA episode they are not forming any new memories.
The cause of TGA is not completely known. It is sudden event, which raises the possibility of either a migraine-like process, a seizure, or a transient ischemic attack (TIA or brief stroke that does not cause permanent damage), possibly affecting the hippocampus, which is necessary for the formation of new memories. They can sometimes be triggered by emotional or physiological stress. They are typically isolated incidents, rarely recurring in the same person.
At no point during or after a TGA, however, does the sufferer lose their memory for who they are. In fact, there is no neurological condition in which a person has amnesia for their own identity. This makes sense because your personal identity is so connected to your memories that if you have enough brain power to generate consciousness, you will also be able to know who you are.
A profound form of amnesia is Wernicke-Korsakoff syndrome. The most common cause of this syndrome is thiamine deficiency, often resulting from chronic alcoholism, which results in damage to parts of the brain necessary for memory formation. Patients with severe cases cannot form any new memories. They are living in a three-minute window of short term memory. They also typically have some degree of retrograde amnesia, and so are typically living in the past. (This condition was depicted in the movie Memento.)
What, then, is Mr. Boatwright suffering from if not from any form of amnesia? His clinical presentation, the complete loss of personal identifying memory or memory of one’s previous life, is called a fugue state. This diagnosis exactly fits Boatwright.
A fugue state is characterized by a loss of personal identifying memories, and typically lasts for several days but can last much longer, even months. People in a fugue state will typically have unplanned travel or will wander, and commonly adopt a new persona. Further, the episode is not triggered by drugs, physical trauma, or any neurological event. Fugue episodes typically occur only once, but can recur in the same individual.
Fugue states are purely psychological in nature. This does not mean, however, that the person is “faking” or that they have any insight into what is happening.
Stories of people who suffer from amnesia are fascinating, and scary, which is probably why it is a common theme in movies and fiction. Not surprisingly, the common fictional depiction of amnesia is often inaccurate. I outlined the few basic types of amnesia above. Ironically, what is most commonly depicted as amnesia in fiction is not amnesia, but is a fugue state – the loss of personal biographical memories.
I hope Mr. Boatwright recovers. Most people with a fugue state do, and recovery, once it starts, can be very rapid. I do wonder what effect the media attention is having, if any, on the course of Boatwright’s fugue.
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