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Confabulations without
memory deficits in
Behavioural Variant
FrontoTemporal
Dementia and other
conditions: A case report and
review
Sid Williams 2018
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Confabulation
“To fabricate imaginary experiences as compensation for loss of memory” OED
“a memory error defined as the production of fabricated, distorted, or misinterpreted memories about oneself or the world, without the conscious intention to deceive”.
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Wernicke-Korsakoff syndrome
Memory impairment
+ Executive function impairment
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R.P.C. Kessels, H.E.Kortrijk, A.J.Wester and G.M.S.Nys, Confabulation behavior and false
memories in Korsakoff ’s syndrome: role of source memory and executive functioning.
Psychiatry and Clinical Neurosciences 62 (2008), 220-225
Confabulation without
memory impairment
Confabulations without memory impairment
impaired executive function alone
FrontoTemporal Dementia
Case report: old anterior right hemisphere old infarct
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M.F. Mendez, I.A. Fras, S.A. Kremen and P-H Tsai, False reports from patients with
fronto-temporal dementia: Delusions or confabulations? Behavioural Neurology 24 (2011),
237-244
Confabulation without memory
impairment: ‘Mr Mitty’
Large anterior right hemisphere infarct 4 yrs before
Residential age care facility. Age 74
Left hemiparesis, just able to walk with walking stick
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Confabulation without memory
impairment: ‘Mr Mitty’
Unrestrained rambling narrative - false reports, boastful,sexual and racist themes:
Senior male nurse homosexual, planning to leave his wife for his lover
Young female nurse to leave husband and marry him
Fellow resident (shared room) quadriplegic deliberately snoring etc.
His athletic defense of a nurse, surgical restoration of enucleated eye
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Confabulation without memory
impairment: ‘Mr Mitty’
Behaviour completely out of character
Previous response to firm consistent feedback
Admission to subacute psychogeriatric unit
Explanations ++ to care staff
Antipsychotic or other psychoactive not given
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Non-memory mechanisms
of confabulation
Source monitoring deficits
Impaired ability to distinguish real memories/events from internally-generated thoughts
Abnormal level of certainty for the false report
Attenuation of the ‘doubt tag’
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Non-memory Mechanisms
of confabulation
Ventromedial prefrontal cortex esp. R (VMPFC) involved in both:
Source monitoring
The preconscious doubt tag
VMPFC lesions are sufficient for confabulation
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Non-memory mechanisms
of confabulation
Posterior medial orbitofrontal cortex (OFC) may contribute via:
Inability to suppress interference of thoughts
Inability to extinguish previous anticipations
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Confabulation or
delusion?
Common clinical approach:
Confabulation:
• ‘organic’ condition
•probably not Rx antipsychotic
Delusion:
• ‘non-organic’ condition
•Probably Rx antipsychotic 11
Confabulations and
delusions in bvFTD
Mendez et al.:
46 patients with behavioural variant FrontoTemporal Lobar Degeneration (bvFTD)
4/46 (8.3%) false reports:
• 2 spontaneous confabulations
• 2 delusions (delusional jealousy)
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M.F. Mendez, I.A. Fras, S.A. Kremen and P-H Tsai, False reports from patients with
fronto-temporal dementia: Delusions or confabulations? Behavioural Neurology 24 (2011),
237-244
Confabulations and
delusions in bvFTD
Other reports:
Delusion of pregnancy
De Clarembault syndrome
Paranoid
Religiose
Somatic and infestation delusions
Visual and tactile hallucinations
May precede clear-cut FTD 13
Confabulations and
delusions in bvFTD
Associations:
Early onset
Motor Neuron Disease (FTD-MND)
TDP-43 or FUS pathologies
Possibly presenilin mutations
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confabulations and delusions:
Common features
Distinction not always clear
Mechanisms common to both
‘Final Common Pathway*’ one phenomenon, several causes
But still worth distinguishing between these phenomena – just not too rigidly
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*Apologies to Sherrington
Pathological lying?
“What he lacked in facts, he made up for with an understated
conviction; and what he lacked in conviction he made up for with
facts, albeit mostly invented, and rendered all the more plausible
because they were so lightly thrown up from an unexpected
angle”
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