Rare form of amnesia involves inventing continuous stream of fictitious events

On the Neurophilosophy blog, a fascinating look at confabulatory hypermnesia, a rare disorder in which people with various kinds of amnesia (including amnesia resulting from alcoholism and Vitamin B1 deficiencies) invent a continuous stream of detailed, fictitious events to fill in the gaps in their memory. The write up comes from a paper published in the journal Cortex:

Most strikingly, LM confabulated plausible answers to questions about both his personal life and public events, which would normally elicit from most people an answer of "I don't know". When the researchers asked him "Who won the Palme d'Or at the Cannes Film Festival in 1980?" he replied "Fernandel"; when asked what he had for dinner on Tuesday two weeks ago, he answered "Steak with french fries"; and when asked "Do you remember what you did on March 13th, 1985?" he replied "We spent the day at the Senart Forest."

LM thus has a "pure" amnesic syndrome, in that his impairment is not associated with other cognitive deficits which might interfere with memory function. He scored normally on short-term memory tests, and the evaluation revealed mild, diffuse neurodegeneration, rather than damage in a specific part of the brain. False memories are not uncommon in patients with Korsakoff's syndrome - indeed the condition is also referred to as amnesic-confabulatory syndrome. However, the confabulations of such patients are sometimes extraordinary, bizarre and verging on being delusional. LM's confabulations, on the other hand, were always plausible, and therefore quite unlike those reported in other Korsakoff's patients.

Confabulatory hypermnesia, or severe false memory syndrome