Types of amnesia

There are two major types of amnesia:

Post-traumatic amnesia (PTA) or anterograde amnesia is characterized by a reduced ability to form new memories after a brain injury, which may lead to decreased attention and inaccurate perception. Anterograde memory is frequently the last function to return after the recovery from a loss of consciousness (LOC). Following the recovery of consciousness patients may be unable to recall little or anything that occurred for days, weeks, or even months after their injury.

Retrograde amnesia (RGA) is characterized by the partial or total loss of the ability to recall events that have occurred during the period immediately preceding brain injury. RGA may extend backwards for seconds, minutes, hours, days, months or even years depending on the severity of the injury. The duration of retrograde amnesia usually progressively decreases.

Testing for RGA

When checking for orientation and RGA, the Sport Concussion Assessment Tool (SCAT) issued in conjunction with the Summary and Agreement Statement of the 2nd International Conference on Concussion in Sport held in Prague in 2004 calls for the team physician or ATC, to ask the following questions:

1. At what venue are we?
2. Which half is it?
3. Who scored last?
4. What team did we play last?
5. Did we win the last game?

Testing for PTA

When checking for PTA or anterograde amnesia deficits, the Prague consensus statement recommends that the team physician or ATC conduct three cognitive assessment tests:

1. A five-word recall test using random, unrelated words, reading each word at a rate of one word per second, and asking the athlete to recall the words both immediately and after a delay (not informing the athlete of the delayed testing until after tests 2 and 3 below, and choosing a different set of words each time the test is performed at follow-up exams);


2. A months-of-the-year test in which the athlete is asked to recite the months of the year in reverse order starting with a random month (not December or January) or


3. A backwards digit test in which the athlete is asked to recite backwards two sets of increasingly long strings of digits.

PTA: Just One Factor in Determining Severity

Until the early 2000's, the most widely followed concussion management guidelines focused on loss of consciousness (LOC) and PTA in determining the severity, or grade, of a concussion and return-to-play protocol. Many considered the duration of PTA the best indicator of traumatic brain injury severity and the most dependable factor in predicting outcome, even in mild cases.

Beginning in 2001 with the Vienna international consensus statement on concussion in sport and revisions to Dr. Cantu's guidelines and continuing with the consensus statement of the 2nd international conference on concussion in sport in Prague in 2004 the recent trend has been away from using PTA as a surrogate measure of injury severity:

• Studies suggest that the nature, severity, and duration of clinical post-concussive symptoms such as headache, dizziness, confusion, disorientation, and blurred vision are more common than amnesia (A 2000 study of 1003 concussions sustained by high school and college football players reported that amnesia was present in only 27% of all cases), and may be more important than the presence or duration of amnesia alone.


• Studies have also shown that, because RGA varies with the time of measurement after injury, it is a poor measure of injury severity.

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Article Updated: December 26, 2007

	Reprint Policy Return to Head Injury Home Page

 Concussion Grading Systems And Return-To-Play Guidelines: A Comparison
 Determining Loss Of Consciousness In Athletes
 Post-Concussion Signs & Symptoms: A Checklist
 Standardized Assessment of Concussion (SAC)
 Balanced Error Scoring System (BESS)

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