Almost any time when you watch a Hollywood action movie, or play an action video game, you will most likely meet a character suffering from memory loss. This phenomena of memory loss, also known as amnesia, is a complicated neurological mechanism, hiding behind a seemingly simple facade. Amnesia is extremely widespread worldwide, because, unlike popular belief, it can be triggered not only by a head trauma, but also by a number of other factors.
So, what exactly is amnesia? Doctors usually use this term to define a group of mental conditions characterized by a temporary (most often) disturbance or complete loss of the ability to recall stored memories, or memorize something (The Human Memory). The causes of amnesia will be analyzed below; so far, it is important to point out that there exist at least four major types of this mental condition: retrograde amnesia, anterograde amnesia, transient global amnesia, and infantile amnesia.
Retrograde amnesia is probably what the majority of people have in their minds when talking about this mental condition; retrograde amnesia implies a person’s inability (or impaired ability) to recall events that occurred in the past. Although it might be a result of a trauma, there can be other factors causing this condition, including various mental disorders. Anterograde amnesia prevents a person from forming new memories. The memories stored in the brain before the case leading to amnesia can be perfectly preserved, but at some point, it stops memorizing objects, events, etc. around it, leading to the inability to recall the most recent events (those that occurred after the amnesia-causing case). For example, a person who overused alcohol and experienced a blackout will most likely be unable to remember everything that followed the episode of getting drunk, although other memories (such as a person’s name or living place will remain untouched). Another type of amnesia—transient global amnesia—can appear and vanish within a couple of hours. TGA is not studied well enough, but scientists believe it has something to do with a seizure-like contraction of the blood vessels supplying the brain; as a result, a person may “fall out” of the memorization process, losing memories immediately preceding the “seizure,” and those that would be obtained within its course. Yet another type—infantile amnesia—is something that all of us have experienced: it is a natural condition when a person cannot remember (clearly, or entirely) their first 3-5 years of life (Health Line).
As for symptoms, there are two major signs of amnesia: a degraded ability to memorize something new (anterograde amnesia), or a disability to recall events from the past (retrograde amnesia). It can take different forms—for example, a person might not be able to recall what they have been doing five minutes ago (problems with short-term memory), but would perfectly restore the details of some presidential election that occurred 20 years ago; or, vice versa, a person could live with a memory span of a couple of minutes, completely forgetting everything that goes beyond this time limit. Unlike some people tend to think, amnesia is not the same as dementia: amnesiac memory loss does not affect one’s intelligence or personality. Rather often, people with amnesia understand there is a problem with their memorizing capabilities, and do not lose the adequacy of perception and actions. There are also some other symptoms typical for amnesia: confabulation (a condition when a person unintentionally makes up their memories in order to fill the gap in perception; these memories may be made up completely from scratch, or combined from fragments of real ones) and disorientation (Mayo Clinic).
There are several major causes of amnesia: seizures and strokes (which tend to do a lot of brain damage, so it is unsurprising that they often cause memory loss); brain inflammations such as encephalitis, as well as viruses such as herpes; oxygen deprivation; organic changes in the brain structure (for example, in cases of schizophrenia or brain tumors) or head injuries. There are also causes of psychogenic origins; for example, victims of rape or molestation often subconsciously develop a form of amnesia to protect themselves from painful memories. Soldiers who have gone through extremely stressful combat situations, victims of natural disasters, terrorist acts and other forms of violence can also develop certain forms of amnesia as a response to traumatizing experiences.
As we can see, amnesia is not the same as dementia or other cognitive-behavioral disorders. It does not affect one’s personality, judgment, or perceptive-cognitive capabilities, but only affects a person’s ability to memorize and/or recall events. There are several types of amnesia, such as retrograde/anterograde amnesia, transient global amnesia, and infantile amnesia. The main signs of any form of amnesia are either an impaired ability to recall the events that occurred in the past, or to memorize/learn new information. The factors causing amnesia can have different origins, starting from head injuries or mental disorders, and ending up with traumatizing experiences or viruses.
- “Amnesia: Symptoms.” Mayo Clinic. N.p., n.d. Web. 23 Oct. 2016.
- Nordqvist, Christian. “Amnesia: Causes, Symptoms and Treatments.” Medical News Today. MediLexicon International, 27 July 2015. Web. 23 Oct. 2016.
- “What is Amnesia?” Healthline. N.p., n.d. Web. 23 Oct. 2016.
- “Amnesia.” The Human Memory. N.p., n.d. Web. 23 Oct. 2016.