The Main Symptoms of Amnesia

Although there are many different causes of organic amnesia Opens in new window, there are some general symptoms which seem to be common to most cases, regardless of their aetology. This suggests the possibility that there may be a general pattern of memory impairment which is common to all organic amnesics, and this is referred to as the organic amnesic syndrome.

The main characteristic of the organic amnesic syndrome is known as anterograde amnesia Opens in new window, which means an inability to remember events occurring since the onset of the disorder.

There may also be retrograde amnesia Opens in new window, which is an inability to remember events from the period before the onset of amnesia. However, any retrograde amnesia is usually less severe than the anterograde amnesia, and in fact its severity varies considerably from patient to patient.

A third characteristic of the amnesic syndrome is that sufferers usually retain an intact short-term memory Opens in new window, despite the severe impairment of long-term memory Opens in new window. More recently it has been discovered that certain other memory functions may remain relatively unimpaired in organic amnesia, notably procedural memory Opens in new window and implicit memory Opens in new window.

Recent studies have revealed that there is actually considerable variation between amnesic patients. Although most organic amnesics suffer from the symptoms listed above, the relative severity of each of the symptoms can vary dramatically from one patient to another, so it may be more accurate to regard the main symptoms of amnesia as separate and independent types of impairment.

Perhaps the most interesting feature of organic amnesia is that it does not involve a universal impairment of memory function. There are many aspects of memory which seem to remain largely unimpaired in a typical case of organic amnesia, and these islands of intact functioning are of great interest because they not only tell us a great deal about the nature of the underlying memory dysfunction, they also shed light on the mechanisms underlying normal memory function.