Déjà vécu with recollective confabulation: an unusual presentation of Alzheimer’s disease

Abstract

A man in his 80s presented with gradual onset of a persistent and delusion-like perception that novel encounters are repetitions of previous experiences. Within 2 years of symptom onset, he had impaired verbal memory and executive dysfunction on neuropsychological assessment. Cerebrospinal fluid core Alzheimer’s disease (AD) biomarkers analysis supported probable AD. Generalised and left temporal atrophy was seen on MRI of the brain. Neurological fludeoxyglucose-positron emission tomography (PET)/CT showed left temporal and bilateral frontal lobe hypometabolism. His presenting symptom is known as déjà vécu with recollective confabulation, a rare phenomenon associated with AD and other neurodegenerative disorders. While several potential mechanisms have been previously proposed, the fludeoxyglucose-PET/CT hypometabolism in the temporal and frontal lobes in this case suggests dual deficits in recognition memory and metacognition may be culprit mechanisms. Although uncommon, déjà vécu with recollective confabulation is a fascinating phenomenon that can provide a unique insight into memory and delusional processes in dementia.

Background

Déjà vécu with recollective confabulation can be an unusual manifestation of common primary neurodegenerative disorders such as Alzheimer’s disease (AD).¹ This phenomenon has properties that intersect the related domains of paramnesias, confabulations and delusions.² Unlike the commonly reported déjà vu, where there is a fleeting sensation of false familiarity, déjà vécu describes a persistent, false perception that novel encounters are repetitions of previous experiences. Those with déjà vécu often lack insight and develop disabling, delusion-like false beliefs and behaviours to justify their abnormal perception, which is altogether referred to as recollective confabulation. Recollective confabulation can be regarded as a form of confabulation where false beliefs and abnormal behaviours are limited to the novel encounters affected by déjà vécu, with autobiographical memory relatively spared. Déjà vécu with recollective confabulation has been characterised in a handful of patients mainly with neurodegeneration including AD.¹ Déjà vécu without clear documentation of recollective confabulation has also been documented in other neurological diseases including temporal lobe epilepsy and traumatic brain injury, psychiatric disorders such as schizophrenia and in association with pharmacological agents.^2–5

Previous studies have shown that compared with patients with typical AD, patients with recollective confabulation have impaired recognition memory but are also overconfident in their self-assessment of recognition memory. Proposed mechanisms for this phenomenon include focal hippocampal dysfunction, giving rise to a false sense of recollection, or more global processes as seen in delusional misidentification syndromes.¹ Given the prevalence of AD, the reason for the rarity of recollective confabulation is unclear and implores further investigation. We present a case of recollective confabulation in AD with functional neuroimaging, cerebrospinal fluid (CSF) AD biomarker and longitudinal follow-up results, and discuss how the study of this rare phenomenon could further our understanding of memory, behaviour and neurodegeneration.

Case presentation

A right hand-dominant retiree in his 80s presented with gradual onset of recollective confabulation. On one occasion, he believed his eBook was malfunctioning as it appeared to display the same material he previously encountered. He contacted the manufacturer only to learn that it was functioning normally. Similarly, he asked a technician to repair his television because he falsely perceived that it was playing the same news repeatedly. These misperceptions progressed to involve all aspects of his recognition memory including that of people, places and events. In his own words: “Every day is a repeat of the day before… Every (television) session is identical. Wherever I go, the same people are on the side of the road, the same cars behind me with the same people in them… the same person gets out of the cars wearing the same clothes, carrying the same bags, saying the same things… nothing is new.” He cannot be convinced by family members that these symptoms are misperceptions. No other delusion-like features or hallucinations were reported. While he had little insight into his memory deficits, neuropsychological assessment within 2 years of symptom onset revealed a reduction in verbal memory of the rapid forgetting type. His delayed recall of stories was notable for conflating two stories into a single one. His recall of autobiographical information was relatively preserved. The neuropsychological assessment also found executive dysfunction, impulsive behaviour, and milder changes in language and visual memory. His Addenbrooke’s Cognitive Examination (ACE) III score was 78/100 (cut-off 88 for cognitive impairment). His other medical history consists of depression, prostate carcinoma and lung nodule treated 1 year prior with radiation and resection, respectively. There is no history of alcohol excess. He lives at home and is independent with self-care.

Investigations

Investigations were completed within 2 years of symptom onset. The MRI of the brain showed mild generalised atrophy and small vessel disease (figure 1A). Neurological fludeoxyglucose-positron emission tomography/CT (FDG-PET/CT) found hypometabolism in the left temporal lobe and bilateral frontal lobes, right more pronounced than left (figure 1B). The CSF was acellular with a normal protein level of 0.29 g/L, positive for oligoclonal bands (matched to serum) and negative for classic paraneoplastic neuronal antibodies (anti-Hu, Yo, Ri, Ma1, Ma2, PCA1, PCA2, Amph, Sox, CV2, Tr) and neuronal plasma membrane receptor antibodies (anti-NMDAR, LGi1, CASPR2, AMPAR, DPPX, IgLON5 and GABA_b). The CSF 14-3-3 protein level was not elevated. The CSF amyloid beta 1–42 level was reduced at 262 pg/mL, while total-tau and phosphorylated-tau were borderline elevated at 340 pg/mL and 66 pg/mL, respectively. Serum syphilis, HIV and antinuclear antibody serology were negative.

Figure 1.

MRI of the brain and fludeoxyglucose-positron emission tomography (PET)/CT. (A) MRI of the brain fluid-attenuated inversion recovery sequence axial and coronal images show mild generalised atrophy and left temporal atrophy (arrows). (B) Neurological fludeoxyglucose-PET/CT axial and coronal images show hypometabolism at the left temporal and to a lesser extent the bifrontal lobes (arrows).

Differential diagnosis

The presence of rapid forgetting and executive dysfunction on neuropsychological assessment is consistent with the focal FDG-PET/CT abnormalities found at the bilateral frontal and left temporal lobes. The pattern of rapid forgetting and CSF amyloid beta 1–42 and tau findings are most consistent with probable AD, rather than another neurodegenerative condition. Aside from the malignancy history and presence of matched CSF oligoclonal bands, there is no convincing evidence for a paraneoplastic or non-paraneoplastic autoimmune process.

Treatment

In the context of positive CSF oligoclonal bands, the patient was treated with a trial of immunotherapy including intravenous methylprednisone, intravenous immunoglobulin and rituximab (two doses of 2 g). Immunotherapy was ceased following a lack of clinical improvement. There was no improvement in cognitive symptoms with a trial of a cholinesterase inhibitor.

Outcome and follow-up

The patient had a repeat neuropsychological assessment 2 years after the first neuropsychological assessment, corresponding to 4 years from symptom onset. His recollective confabulation symptoms remain pervasive and bothersome. He continued to live at home and remained independent with self-care. On formal testing, the ACEIII score has declined to 71, with an interval decline in verbal memory and executive function. The cognitive profile remained consistent with AD.

Discussion

Although uncommon, the phenomenon of déjà vécu with recollective confabulation described in this case report has been repeatedly described in the literature under various guises. One of the first case reports from 1896 described the phenomenon as a ‘pathological form of déjà vu’.⁶ More recent reports have used déjà vécu for the experience of the phenomenon and recollective confabulation to describe the observed behavioural response.^7–9 The largest published case series of déjà vécu with recollective confabulation summarised 13 patients; of which, 9 of 13 had probable AD, 3 of 13 had mild cognitive impairment, and 1 of 13 had frontotemporal dementia.¹ Similar to the case presented here, these cases had symptoms limited to novel encounters; impaired recognition memory compared with healthy controls; overconfidence in self-assessment of recognition memory compared with typical patients with AD; lack of other delusional beliefs; relatively unaffected autobiographical memory; and no alleviation in recollective confabulation symptoms with cholinesterase inhibitors.¹ Neuroimaging results were available in 8 of 13 patients. Focal neuroimaging findings were noted in four of eight patients with neuroimaging data; two patients had atrophy of the temporal lobes on CT or MRI; one had single-photon emission computed tomography (SPECT) hypoperfusion in the right frontal and lateral temporal lobes, and one had SPECT hypoperfusion in the bilateral medial temporal lobes and visual cortex. Our case report adds to the existing literature as the first report of déjà vécu with recollective confabulation with (a) functional neuroimaging using FDG-PET/CT, (b) CSF AD biomarker results demonstrating AD pathology and (c) repeat formal neuropsychology assessment demonstrating persistence of symptoms at 4 years. The commonality between the case reports suggests that although infrequently reported, déjà vécu with recollective confabulation is a distinctive phenomenon, commonly but not exclusively seen in AD. When it appears in AD, it can be a presenting, as well as a persistent and bothersome symptom. Further cases with CSF and neuroimaging profiling are required to corroborate our findings. It is unclear why déjà vécu with recollective confabulation appears to co-occur with neurodegeneration, while isolated cases of déjà vécu not necessarily associated with recollective confabulation have been reported in non-neurodegenerative neurological disorders, psychiatric disorders and medication-related experiences.^2–5 It is possible that the pattern of insight loss in recollective confabulation is specifically facilitated by neurodegeneration. However, it may also be possible that recollective confabulation is under-recognised in the wider literature. Detailed documentation of future cases in non-neurodegenerative neurological disorders will help clarify whether déjà vécu with recollective confabulation occurs mainly in primary neurodegeneration.

While the pattern of rapid forgetting and CSF results seen in this case is convincing for probable AD, there are notable atypical features. Specifically, the pattern of FDG-PET/CT hypometabolism in the left temporal and bifrontal lobes (right more than left) within 2 years of symptom onset is atypical for AD, where a posterior pattern of hypometabolism is more commonly seen. Although FDG-PET hypometabolism patterns can be non-specific in neurodegeneration, this unusual pattern of hypometabolism could support an emerging theory that recollective confabulation is contributed by dual deficits in both memory and metacognition from damage to the temporal and right frontal regions.¹ It may also explain the rarity of recollective confabulation in AD, that dual deficits and/or a specific network disruption are required for the phenomenon to manifest. The persistence of the patient’s symptoms after 4 years suggests that the associated pattern of network disruption may be robust. As an unusual presentation of AD, recollective confabulation could be useful for the study of network dysfunction in AD.

Although recollective confabulation is uncommon in AD, general confabulatory symptoms are common in dementia. The metacognition deficit theory could be extended to confabulatory symptoms in general. In literature, it has been shown that the severity of confabulation can correlate with memory impairment (especially autobiographical) and executive impairment (especially in making cognitive estimates).¹⁰ The metacognition deficit theory might also explain the delusion-like quality of déjà vécu with recollective confabulation and relate to the wider occurrence of delusions in neurodegeneration. Lack of insight and inappropriate familiarity are not unique to déjà vécu with recollective confabulation but are also seen in more well-known delusional misidentification syndromes such as the Fregoli syndrome, where an unfamiliar person or a place is perceived to be familiar. Delusional misidentification syndromes can occur in neurodegeneration. Such patients are known to have bifrontal lobe pathology on functional and structural neuroimaging (often right more than left), a pattern similar to that found in our case report.¹¹ Delusional symptoms in general can be commonplace in dementia. For example, studies have shown that 16%–76% of patients with AD have delusions of various types, including delusions of theft, persecutory, infidelity and misidentification.¹² Delusions in dementia may often be under-reported in favour of other cognitive and behavioural symptoms, as they are often not part of core diagnostic criteria. As seen in our case, these symptoms can cause significant distress to patients and families. Better characterisation of delusions in dementia will not only further our understanding of underlying pathophysiology but could also improve patient care.

Learning points.

• Déjà vécu is a persistent, false perception that novel encounters are repetitions of previous experiences. Recollective confabulation describes the delusion-like belief and behavioural response associated with déjà vécu.

• Déjà vécu with recollective confabulation can be an unusual and early manifestation of Alzheimer’s disease.

• Déjà vécu with recollective confabulation may be due to dual deficits in recognition memory and metacognition.

• Symptoms with delusional qualities and metacognitive errors can have profound impacts on the quality of life of patients with dementia.

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