The majority of people experience lapses of memory from time to time as, at worst, an irritating feature of daily life. The most common experience of memory loss involves forgetting a single word, alleviated by a pertinent cue. These lapses are generally brief. Amnesia is a profound and sometimes permanent memory loss.
There are two forms of amnesia:
- Retrograde Amnesia
Refers to the inability to recall memories prior to the onset of the amnesia
- Anterograde Amnesia
Refers to the inability to recall memories subsequent to the onset of the amnesia
Amnesia is usually caused by damage to the limbic system which includes the hippocampus and the amygdala. Not all people with amnesia experience a permanent loss of memory. Some people experience amnesia which has a sudden onset but is time limited. This is the syndrome of transient amnesia.