Mr A is a 73-year-old resident of a nursing home, where the irate aides describe him as “a liar and a troublemaker.” Mr A had been a successful and well-liked businessman until 2 years ago, when he sustained a stroke secondary to a ruptured aneurysm of the anterior communicating artery. Prominent memory deficits ensued. Mr A also became irritable, verbally abusive, and “hard to manage.” Staff also complained that Mr A “made up stories about the staff, just to get us in trouble . . . like, that we were sleeping with him.” There was no evidence supporting any such claims, and Mr A’s “stories” were regarded by the staff as deliberate mischief on his part.
Confabulation was first described by Korsakoff in amnesic patients in 1889,1 yet its nature and etiology remain a source of some controversy. Indeed, in the literature since Korsakoff’s time, even the definition of “confabulation” has been inconsistent,2,3 reflecting the diverse theories concerning the origins of this syndrome. Thus, confabulation has been variously described as a falsification of memory in association with an organically derived amnesia,4,5 an extreme form of lying or deception,6 and “honest lying.”7(p133) In more recent texts, confabulation is usually defined as statements and/or actions that are “unintentionally incongruous to the patient’s history, background, and present situation,”8(p112) or as erroneous memories—either false in themselves or derived from true memories inappropriately retrieved or interpreted.2,9
Here we broadly define confabulation as the production of false or erroneous memories without the intent to deceive. As our opening vignette illustrates, the confabulating patient’s intentions may sometimes be misread as malicious, when in reality his confabulations may be better understood as products of one or more neuropsychological deficits. The false memories of confabulation may range from inaccurate or distorted recollections of past events, to incongruous intrusions during memory tasks, to fictitious and bizarre narratives.10
In this article, we place confabulation in a historical perspective, review current theories of confabulation, and discuss clinico-anatomical syndromes often seen by psychiatrists in which confabulation frequently occurs. Finally, we summarize the implications of recognizing and understanding confabulation in psychiatric practice.
TYPES OF CONFABULATIONS: HISTORICAL OVERVIEW
In 1901, Bonhoeffer distinguished the confabulation of embarrassment (later termed “momentary confabulation”) from spontaneous confabulation.4 Confabulation of embarrassment referred to fabricated memories that appeared to compensate for memory loss—in effect, the patient attempts to cover up an exposed “gap in memory.” In contrast, Bonhoeffer described spontaneous confabulation as exceeding the need to cover a memory deficit and often consisting of “fantastic” (grossly implausible) content.4
Berlyne,4 in 1972, also delineated 2 distinct forms of confabulation. Like Bonhoeffer, he referred to the first as “momentary” confabulation and the second as “fantastic” or “productive” confabulation. Momentary confabulations, for Berlyne, consisted of autobiographical content and were rooted in true memory. Furthermore, these confabulations occurred only in response to questioning. In contrast, fantastic (or productive) confabulations consisted of grandiose content and occurred without provocation.
Kopelman5 later revised this terminology, using the terms “provoked” (rather than “momentary”) and “spontaneous” (rather than “fantastic”) confabulation. Kopelman noted that provoked confabulations commonly occurred among amnesic patients given memory tests and resembled errors produced by healthy persons on tests of memory following prolonged retention intervals. Indeed, provoked confabulations have since been noted in various experimental studies to occur in healthy people. Accordingly, many authors consider provoked confabulations to be a normal strategy to compensate for memory deficits rather than a pathological process.5,11-13 Kopelman, for example, notes that provoked confabulations under experimental conditions—defined as intrusion errors or distortions made in response to a challenge to memory—reflect the “reconstructive” nature of normal memory retrieval. When a memory trace is particularly weak (for example, after long retention intervals), reconstruction becomes distorted or frankly erroneous.11
Provoked confabulations may reflect such normal compensatory mechanisms. However, several recent studies have shown that provoked confabulations may also reflect neuropathological conditions, such as Wernicke-Korsakoff encephalopathy14,15 and Alzheimer disease (AD).16,17
Many authors continue to use Kopelman’s “spontaneous” versus “provoked” dichotomy. Some argue, however, that these are not distinct types of confabulation. Rather, spontaneous confabulation may simply represent a more severe form of memory falsification.12,18,19
CLASSICAL CONFABULATION HYPOTHESES AND THEIR CRITICS
Confabulation and memory impairment
Confabulation is classically and historically associated with memory loss. As noted, one of the earliest hypotheses proposed that confabulations occurred as a compensatory mechanism for memory loss (ie, the patient produces confabulations to fill in memory gaps and avoid embarrassment).4 Yet numerous authors have challenged this view, noting that patients with memory deficits do not always demonstrate confabulations,4,20 that confabulation usually resolves during the chronic stage of Korsakoff syndrome despite ongoing memory deficits,3 and that the severity of amnesia does not correlate with the tendency to confabulate.21 Furthermore, confabulation has been observed in the complete absence of memory deficits.22-24
Frontal lobe lesions
Because confabulation was frequently seen in patients with frontal lobe damage it led to the belief that frontal lesions were the cause of confabulation.19,20,25,26 However, several experiments suggest that frontal lobe pathology may be neither necessary nor sufficient for confabulation. On the one hand, for example, there are reports of patients who confabulate but who show no signs of frontal executive dysfunction or frontal lobe structural pathology.18,24 On the other hand, controlled studies have found that common executive function deficits reflecting frontal lobe impairment do not distinguish spontaneously confabulating amnesiacs from nonconfabulating amnesiacs—suggesting that frontal dysfunction is not sufficient to produce confabulation.13,27,28 Moreover, in a study of patients with AD who had provoked confabulations, the tendency to confabulate did not correlate with performance on frontal/executive tasks.29
Partly as a consequence of these uncertainties, the essential role of frontal lobe pathology in confabulation has been challenged by several investigators.30-33 This skepticism, in turn, led to the “dual-lesion” hypothesis, which states that confabulations arise from the concomitant presence of frontal lobe pathology and an organic amnesia.19,25,34,35
MORE RECENT HYPOTHESES OF CONFABULATION
More recent views of confabulation focus on 3 central problems:
• Deficits in reality monitoring
• Dysfunction of strategic retrieval processes
• Temporal confusion
Reality monitoring (or source monitoring) refers to the neural mechanisms by which memories are “checked” to ensure that they correspond to actual (vs imagined) events.36 For example, one might think, “Did I really see Jim at the office party last year, or did I just dream that?” According to the reality- or source-monitoring deficit hypothesis, dysfunction or loss of these “fact-check” mechanisms results in confabulations. However, source-monitoring deficits may be seen in nonconfabulating patients, which suggests that such deficits may be necessary but not sufficient to produce confabulation.28,33,37 Even more troubling for the source-monitoring hypothesis was the demonstration by Dalla Barba and colleagues29 that the degree of source-monitoring deficits in a group of patients with AD who had provoked confabulations did not correlate with the tendency to confabulate.
1. Korsakoff SS. Disturbance of psychic function in alcoholic paralysis and its relation to the disturbance of the psychic sphere in multiple neuritis of non-alcoholic origin. Vestnik Psichiatrii. Vol 4, pt 2; 1889. Cited by: Victor M, Yakovlev PI. S. S. Korsakoff’s psychic disorhic disorder in conjunction with peripheral neuritis; a translation of Korsakoff’s original article with comments on the author and his contribution to clinical medicine. Neurology.1955;5:394-406.
2. Gündogar D, Demirci S. Confabulation: a symptom which is intriguing but not adequately known [in Turkish]. Turk Psikiyatri Derg.2007;18:172-178.
3. Talland GA. Confabulation in the Wernicke-Korsakoff syndrome. J Nerv Ment Dis. 1961;132:361-381.
4. Berlyne N. Confabulation. Br J Psychiatry. 1972; 120:31-39.
5. Kopelman MD. Two types of confabulation. J Neurol Neurosurg Psychiatry. 1987;50:1482-1487.
6. Joseph R. Confabulation and delusional denial: frontal lobe and lateralized influences. J Clin Psychol. 1986;42:507-520.
7. Moscovitch M. Confabulation and the frontal system: strategic versus associative retrieval in neuropsychological theories of memory. In: Roediger HL, Craik FI, eds. Varieties of Memory and Consciousness: Essays in Honour of Endel Tulving. Hillsdale, NY: Lawrence Erlbaum Associates; 1989:133-160.
8. Dalla Barba G, Rieu D. Differential effects of aging and age-related neurological diseases on memory systems and subsystems. In: Boller F, Cappa SF, eds. Handbook of Neuropsychology: Aging and Dementia. Vol 6. 2nd ed. Amsterdam: Elsevier Health Sciences; 2001: 97-118.
9. Dab S, Claes T, Morais J, Shallice T. Confabulation with a selective descriptor process impairment. Cogn Neuropsychol. 1999;16:215-242.
10. Mattioli F, Miozzo A, Vignolo LA. Confabulation and delusional misidentification: a four year follow-up study. Cortex. 1999;35:413-422.
11. Kopelman MD. Disorders of memory. Brain. 2002;125(pt 10):2152-2190
12. Burgess PW, Shallice T. Confabulation and the control of recollection. Memory. 1996;4:359-411.
13. Schnider A, von Däniken C, Gutbrod K. The mechanisms of spontaneous and provoked confabulations. Brain. 1996;119(pt 4):1365-1375.
14. Kessels RP, Kortrijk HE, Wester AJ, Nys GM. Confabulation behavior and false memories in Korsakoff’s syndrome: role of source memory and executive functioning. Psychiatry Clin Neurosci. 2008;62:220-225.
15. Borsutzky S, Fujiwara E, Brand M, Markowitsch HJ. Confabulations in alcoholic Korsakoff patients. Neuropsychologia. 2008;46:3133-3143.
16. Cooper JM, Shanks MF, Venneri A. Provoked confabulations in Alzheimer’s disease. Neuropsychologia. 2006;44:1697-1707.
17. Lee E, Akanuma K, Meguro M, et al. Confabulations in remembering past and planning future are associated with psychiatric symptoms in Alzheimer’s disease. Arch Clin Neuropsychol. 2007;22:949-956.
18. Dalla Barba G. Different patterns of confabulation. Cortex. 1993;29:567-581.
19. DeLuca J, Cicerone KD. Confabulation following aneurysm of the anterior communicating artery. Cortex. 1991;27:417-423.
20. Kapur N, Coughlan AK. Confabulation and frontal lobe dysfunction. J Neurol Neurosurg Psychiatry. 1980;43:461-463.
21. Mercer B, Wapner W, Gardner H, Benson DF. A study of confabulation. Arch Neurol. 1977;34:429-433.
22. Papagno C, Baddeley A. Confabulation in a dysexecutive patient: implication for models of retrieval. Cortex. 1997;33:743-752.
23. Delbecq-Derouesné J, Beauvois MF, Shallice T. Preserved recall versus impaired recognition. Brain. 1990;113(pt 4):1045-1074.
24. Nedjam Z, Dalla Barba G, Pillon B. Confabulation in a patient with fronto-temporal dementia and a patient with Alzheimer’s disease. Cortex. 2000;36:561-577.
25. Stuss DT, Alexander MP, Lieberman A, Levine H. An extraordinary form of confabulation. Neurology. 1978;28:1166-1172.
26. Baddeley A, Wilson B. Frontal amnesia and the dysexecutive syndrome. Brain Cogn. 1988;7:212-230.
27. Schnider A, Ptak R. Spontaneous confabulators fail to suppress currently irrelevant memory traces. Nat Neurosci. 1999;2:677-681.
28. Schnider A. Spontaneous confabulation and the adaptation of thought to ongoing reality. Nat Rev Neurosci. 2003;4:662-671.
29. Dalla Barba G, Nedjam Z, Dubois B. Confabulation, executive functions, and source memory in Alzheimer’s disease. Cogn Neuropsychol. 1999;16: 385-398.
30. Damasio AR, Graff-Radford NR, Eslinger PJ, et al. Amnesia following basal forebrain lesions. Arch Neurol. 1985;42:263-271.
31. DeLuca J. Predicting neurobehavioral patterns following anterior communicating artery aneurysm. Cortex. 1993;29:639-647.
32. Schacter DL. Memory, amnesia, and frontal lobe dysfunction. Psychobiology. 1987;15:21-36.
33. Johnson MK, O’Connor M, Cantor J. Confabulation, memory deficits, and frontal dysfunction. Brain Cogn. 1997;34:189-206.
34. Kopelman MD. Amnesia: organic and psychogenic. Br J Psychiatry.1987;150:428-442.
35. Fischer RS, Alexander MP, D’Esposito M, Otto R. Neuropsychological and neuroanatomical correlates of confabulation. J Clin Exp Neuropsychol. 1995;17: 20-28.
36. Johnson MK, Raye CL. False memories and confabulation. Trends Cogn Sci. 1998;2:137-145.
37. Janowsky JS, Shimamura AP, Squire LR. Source memory impairment in patients with frontal lobe lesions. Neuropsychologia. 1989;27:1043-1056.
38. Gilboa A, Alain C, Stuss DT, et al. Mechanisms of spontaneous confabulations: a strategic retrieval account. Brain. 2006;129(pt 6):1399-1414.
39. Moscovitch M, Melo B. Strategic retrieval and the frontal lobes: evidence from confabulation and amnesia. Neuropsychologia. 1997;35:1017-1034.
40. Schnider A, Gutbrod K, Hess CW, Schroth G. Memory without context: amnesia with confabulations after infarction of the right capsular genu. J Neurol Neurosurg Psychiatry. 1996;61:186-193.
41. Schnider A. Spontaneous confabulation, reality monitoring, and the limbic system—a review. Brain Res Brain Res Rev. 2001;36:150-160.
42. Turner MS, Cipolotti L, Yousry TA, Shallice T. Confabulation: damage to a specific inferior medial prefrontal system. Cortex. 2008;44:637-648.
43. Pearce JM. Wernicke-Korsakoff encephalopathy. Eur Neurol. 2008;59:101-104.
44. Kopelman MD. The Korsakoff syndrome. Br J Psychiatry. 1995;166:154-173.
45. Dalla Barba G, Wong C. Encoding specificity and intrusion in Alzheimer’s disease and amnesia. Brain Cogn. 1995;27:1-16.
46. De Anna F, Attali E, Freynet L, et al. Intrusions in story recall: when over-learned information interferes with episodic memory recall. Evidence from Alzheimer’s disease. Cortex. 2008;44:305-311.
47. Nathaniel-James DA, Frith CD. Confabulation in schizophrenia: evidence of a new form? Psychol Med. 1996; 26:391-399.
48. Kopelman MD, Guinan EM, Lewis PD. Delusional memory, confabulation and frontal lobe dysfunction. In: Campbell R, Conway MA, eds. Broken Memories: Case Studies in Memory Impairment. Oxford, UK: Blackwell; 1995:137-153.
49. Gilleen J, David AS. The cognitive neuropsychiatry of delusions: from psychopathology to neuropsychology and back again. Psychol Med. 2005;35:5-12.
50. Simpson J, Done DJ. Elasticity and confabulation in schizophrenic delusions. Psychol Med. 2002; 32: 451-458.
51. Eack SM, George MM, Prasad KM, Keshavan MS. Neuroanatomical substrates of foresight in schizophrenia. Schizophr Res. 2008;103:62-70.
52. Medalia A. Cognitive remediation for psychiatric patients. Psychiatr Times. 2009;26(3):23-25.
For more information
Schnider A. Spontaneous confabulation and the adaptation of thought to ongoing reality. Nat Rev Neurosci. 2003;4:62-671.