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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