Korsakoff’s syndrome, or Wernicke-Korsakoff syndrome, is a brain disorder caused by extensive thiamine deficiency, a form of malnutrition which can be precipitated by over-consumption of alcohol and alcoholic beverages compared to other foods. Its main symptoms are anterograde amnesia (inability to form new memories and to learn new information or tasks) and retrograde amnesia (severe loss of existing memories), confabulation (invented memories, which are then taken as true due to gaps in memory), meagre content in conversation, lack of insight and apathy.
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|Confabulation is the spontaneous reporting of events that never actually happened, usually as a result of neurological or psychological dysfunction.|
Such false memories, perceptions or beliefs may take the form of either the confusion of imagination with memory or the confused application of true memories.
Individual Korsakoff’s sufferers may exhibit wildly differing symptoms. In some cases, a patient may just continue “living in the past”, convinced that their life and the world around them is unchanged since the onset of the condition (which may have been twenty or thirty years before). Others may adopt a constant, almost frenzied, fever of confabulation (see box at right), constantly inventing a series of new identities, often with detailed and convincing back-stories, in order to replace the reality which has been forgotten and lost.
Much about the disorder has been gleaned from a sufferer known as “Patient X”, who wrote an autobiography in 1979 and then developed the disease a short time later. Thus, his post-Korsakoff memories could be directly compared with the details in his written autobiography.
Korsakoff’s syndrome is caused by a deficiency of thiamine (vitamin B1), which is thought to cause damage to the thalamus and to the mammillary bodies of the hypothalamus (which receives many neural connections from the hippocampus), as well as generalized cerebral atrophy, neuronal loss and damage to neurons.
Typically, the retrograde amnesia of Korsakoff’s syndrome follows a distinct temporal curve: the more remote the event in the past, the better it is preserved and the sharper the recollection of it. This suggests that the more recent memories are not fully consolidated and therefore more vulnerable to loss, indicating that the process of consolidation may continue for much longer than initially thought, perhaps for many years.