Chapter

Disorders associated with confabulation

Armin Schnider

in The Confabulating Mind

Published on behalf of Oxford University Press

Published in print February 2008 | ISBN: 9780199206759
Published online February 2013 | e-ISBN: 9780191754487 | DOI: http://dx.doi.org/10.1093/med/9780199206759.003.0005
Disorders associated with confabulation

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In this chapter, we have reviewed a number of disorders that have routinely been associated with confabulation: amnesia, disorientation, false recognition, paramnesic misidentification, and anosognosia. As it turns out, the relation between these disorders and the different forms of confabulation is quite inconsistent.

Provoked confabulations (intrusions) have no consistent association with amnesia, disorientation, or anosognosia. They can also be evoked in healthy subjects having no memory problem. A very powerful way of inducing specific provoked confabulations is the Deese-Roediger-McDermott (DRM) paradigm, in which subjects learn a series of semantically related words that together point to a target word – the ‘lure’ – which is not present in the list. Under this condition, healthy subjects very often produce the target word and also falsely recognize it. Other than that, there is no significant association between provoked confabulation and false recognition. In amnesic subjects, this effect tends to be weaker.

The more serious forms of confabulation have a more complex relationship. Amnesia, commonly considered a prerequisite for relevant confabulation, can be demonstrated in practically all patients with momentary, fantastic, or behaviourally spontaneous confabulation – provided amnesia is defined as impaired delayed free recall. By contrast, if amnesia is evaluated with a continuous recognition task, a conceptually very simple paradigm that only measures storage and recognition of information, then confabulation and amnesia dissociate. While severe confabulators, including behaviourally spontaneous confabulators, may have extremely severe amnesia with no appreciable explicit recognition capacity (Schnider et al. 2005a), occasional confabulators perform normally in such a task, indicating that they have no difficulty in storing information. In other words: severe confabulation does not require a gap in memory!

Disorientation, which has also routinely been associated with confabulation, is not necessary for momentary confabulation to occur, possibly not even for fantastic confabulation. Conversely, there is a very close association between behaviourally spontaneous confabulation and disorientation: behaviourally spontaneous confabulators probably always have a measurable deficit of orientation. As we will see in Chapter 8, in many patients, these two disorders may indeed have the same mechanism. But disorientation is also significantly associated with amnesia in that severe amnesia predicts disorientation. Conversely, even the combination of severe disorientation and amnesia does not reliably predict confabulation.

False recognition as emerging in ordinary memory tasks is not normally associated with any form of confabulation. However, under specific experimental conditions, which require the ability to sort out among a series of familiar items those that pertain to the current moment, patients with behaviourally spontaneous confabulation fail. Under such conditions, they have increased false recognition, although in other conditions, they have no such increased tendency. The experimental context leading up to this finding and its neurobiological foundation will be the main topic of chapter 8.

Paramnesic misidentification syndromes – déjà-vu, Capgras, Fregoli, intermetamorphosis, and reduplicative paramnesia for place – are mostly modality-specific. Even though they are accompanied by false statements that may be considered momentary confabulations, they have no consistent association with mnestic momentary confabulations reflecting falsification of memories. There is even less of an association with behaviourally spontaneous confabulation: paramnesic misidentification normally is not accompanied by acts emanating from currently inappropriate ideas. Conversely, however, behaviourally spontaneous confabulators typically present features of paramnesic misidentification: They confuse the hospital with their home and often misidentify people according to their falsely perceived reality. A plausible interpretation is that the mechanism causing behaviourally spontaneous confabulation is also one among different mechanisms of paramnesic misidentification. In contrast to these reduplicative phenomena for places and people, the other forms of paramnesic misidentification (déjà-vu, Capgras, Fregoli, intermetamorphosis) are not part of behaviourally spontaneous confabulation.

The link between mnestic confabulation and anosognosia is not consistent. Anosognosia – the unawareness of disease – is highly modular. It encompasses many disturbances that dissociate from each other both regarding the aspect of disease that patients are unaware of and their anatomical bases. Similar to paramnesic misidentification, anosognosic patients make objectively false statements – confabulations – about an incorrectly identified situation, in this case, their current health status. False statements about the past or future, which characterize mnestic confabulations, are not an essential part of anosognosic confabulation unless patients are in a confusional state where both disorders may coincide. Anosognosia does not predict mnestic confabulations. Inversely, mnestic confabulations do not require anosognosia. Momentary confabulations may also occur in patients who are fully aware of their memory impairment and suffer from it. The relation with behaviourally spontaneous confabulations is more subtle. At first sight, all of these patients show striking lack of insight into their memory impairment. They are consistently unaware of the falsehood of their inappropriate thoughts and plans. However, some patients may be aware of having a memory impairment, rarely even of having false memories. This insight does not protect them from acting according to their false ideas. The observation that anosognosia for impaired memory is particularly frequent after frontal and diencephalic damage – similar to many instances of significant confabulations – may be explained by anatomical proximity and partial overlap of the lesions causing the two disorders.

Chapter.  18865 words.  Illustrated.

Subjects: Psychiatry

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