CONFABULATION, EXECUTIVE FUNCTIONS, AND SOURCE MEMORY IN ALZHEIMER'S DISEASE

Source recognition discriminability impairment in Huntington's versus Alzheimer's disease: Evidence from the CVLT-3

Research suggests that individuals with Huntington's disease (HD) perform better than individuals with Alzheimer's disease (AD) on the California Verbal Learning Test (CVLT) Yes/No Recognition trial. However, those with HD have been shown to have deficits comparable to those with AD on the Source Recognition Discriminability (RD) index (which assesses the ability to distinguish between List A targets and List B distractors), suggesting that HD may involve selective impairment in aspects of yes/no recognition that rely on source memory. However, whether individuals with HD and AD show comparable deficits on Source RD across stages of dementia severity has not been adequately investigated. We examined performance on the CVLT-3 List A vs. List B RD index in individuals with HD or AD and mild or moderate dementia. Among individuals with mild dementia, scores were higher in the HD versus AD group, whereas among individuals with moderate dementia, scores were comparable between the HD and AD groups; this corresponded to differential performance across dementia stages among individuals with HD, but not AD. The present findings suggest that, relative to AD, HD may be associated with disproportionate decline in aspects of yes/no recognition that rely on source memory.

Clinical Heterogeneity in Alzheimer's Disease: A Possible New Amnesic Phenotype

We rediscovered a phenotype of AD known in the early 1900s as presbyophrenia, but then forgotten, and renamed as confabulation-misidentification phenotype. The phenotype includes diencephalic amnesia whose prototype is Korsakoff syndrome. The main features are anterograde and retrograde amnesia with marked disorientation and confabulation, executive impairments, reduced insight and attention deficits, misidentification, minor hallucination and other delusions, behavioral disturbances, and early anxiety. In this article, we summarize what we have discovered about the new phenotype and what is still missing to confirm this diencephalic variant of AD.

Somatostatin and the pathophysiology of Alzheimer's disease

Among the central features of Alzheimer's disease (AD) progression are altered levels of the neuropeptide somatostatin (SST), and the colocalisation of SST-positive interneurons (SST-INs) with amyloid-β plaques, leading to cell death. In this theoretical review, I propose a molecular model for the pathogenesis of AD based on SST-IN hypofunction and hyperactivity. Namely, hypofunctional and hyperactive SST-INs struggle to control hyperactivity in medial regions in early stages, leading to axonal Aβ production through excessive presynaptic GABAB inhibition, GABAB1a/APP complex downregulation and internalisation. Concomitantly, excessive SST-14 release accumulates near SST-INs in the form of amyloids, which bind to Aβ to form toxic mixed oligomers. This leads to differential SST-IN death through excitotoxicity, further disinhibition, SST deficits, and increased Aβ release, fibrillation and plaque formation. Aβ plaques, hyperactive networks and SST-IN distributions thereby tightly overlap in the brain. Conversely, chronic stimulation of postsynaptic SST2/4 on gulutamatergic neurons by hyperactive SST-INs promotes intense Mitogen-Activated Protein Kinase (MAPK) p38 activity, leading to somatodendritic p-tau staining and apoptosis/neurodegeneration - in agreement with a near complete overlap between p38 and neurofibrillary tangles. This model is suitable to explain some of the principal risk factors and markers of AD progression, including mitochondrial dysfunction, APOE4 genotype, sex-dependent vulnerability, overactive glial cells, dystrophic neurites, synaptic/spine losses, inter alia. Finally, the model can also shed light on qualitative aspects of AD neuropsychology, especially within the domains of spatial and declarative (episodic, semantic) memory, under an overlying pattern of contextual indiscrimination, ensemble instability, interference and generalisation.

Performance on the Latin American version of the Face-Name Associative Memory Exam (LAS-FNAME) distinguishes individuals with Mild Cognitive Impairment from age-matched controls in a sample from Argentina

INTRODUCTION

The Latin American Spanish version of the Face-Name Associative Memory Exam (LAS-FNAME) has shown promise in identifying cognitive changes in those at risk for Alzheimer's disease (AD). However, its applicability for Mild Cognitive Impairment (MCI) detection in the Latin American population remains unexplored. This study aims to analyze the psychometric properties in terms of validity and reliability and diagnostic performance of the LAS-FNAME for the detection of memory disorders in patients with amnestic MCI (aMCI).

MATERIALS AND METHODS

The study included 31 participants with aMCI, diagnosed by a neurologist according to Petersen's criteria, and 19 healthy controls. Inclusion criteria for the aMCI group were to be 60 years of age or older, report cognitive complaints, have a memory test score (Craft Story 21) below a -1.5 z-score and have preserved functioning in activities of daily living. Participants completed LAS-FNAME and a comprehensive neuropsychological assessment.

RESULTS

LAS-FNAME showed the ability to discriminate against healthy controls from patients with aMCI (AUC= 75) in comparison with a gold-standard memory test (AUC = 69.1). LAS-FNAME also showed evidence of concurrent and divergent validity with a standard memory test (RAVLT) (r = 0.58, p < .001) and with an attention task (Digit Span) (r = -0.37, p = .06). Finally, the reliability index was very high (α = 0.88).

DISCUSSION

LAS-FNAME effectively distinguished aMCI patients from healthy controls, suggesting its potential for detecting early cognitive changes in Alzheimer's prodromal stages among Spanish speakers.

Diencephalic versus Hippocampal Amnesia in Alzheimer's Disease: The Possible Confabulation-Misidentification Phenotype

BACKGROUND

Alzheimer's disease (AD) is clinically heterogeneous, including the classical-amnesic (CA-) phenotype and some variants.

OBJECTIVE

We aim to describe a further presentation we (re)named confabulation-misidentification (CM-) phenotype.

METHODS

We performed a retrospective longitudinal case-series study of 17 AD outpatients with the possible CM-phenotype (CM-ADs). Then, in a cross-sectional study, we compared the CM-ADs to a sample of 30 AD patients with the CA-phenotype (CA-ADs). The primary outcome was the frequency of cognitive and behavioral features. Data were analyzed as differences in percentage by non-parametric Chi Square and mean differences by parametric T-test.

RESULTS

Anterograde amnesia (100%) with early confabulation (88.2%), disorientation (88.2%) and non-infrequently retrograde amnesia (64.7%) associated with reduced insight (88.2%), moderate prefrontal executive impairment (94.1%) and attention deficits (82.3%) dominated the CM-phenotype. Neuropsychiatric features with striking misidentification (52.9%), other less-structured delusions (70.6%), and brief hallucinations (64.7%) were present. Marked behavioral disturbances were present early in some patients and very common at later stages. At the baseline, the CM-ADs showed more confabulation (p < 0.001), temporal disorientation (p < 0.02), misidentification (p = 0.013), other delusions (p = 0.002), and logorrhea (p = 0.004) than the CA-ADs. In addition, more social disinhibition (p = 0.018), reduction of insight (p = 0.029), and hallucination (p = 0.03) persisted at 12 months from baseline. Both the CA- and CM-ADs showed anterior and medial temporal atrophy. Compared to HCs, the CM-ADs showed more right fronto-insular atrophy, while the CA-ADs showed more dorsal parietal, precuneus, and right parietal atrophy.

CONCLUSION

We described an AD phenotype resembling diencephalic rather than hippocampal amnesia and overlapping the past-century description of presbyophrenia.

Fetal alcohol spectrum disorder and confabulation in psycholegal settings: A beginner's guide for criminal justice, forensic mental health, and legal interviewers

Fetal alcohol spectrum disorders (FASD) are neurodevelopmental/neurobehavioral conditions caused by prenatal alcohol exposure (PAE). Impairments caused by PAE contribute to the over-representation of individuals with FASD in the United States juvenile and adult criminal justice systems. These same impairments can equally impact on individuals with FASD who are witnesses to or victims of crime who also have to navigate the complexities of the criminal justice system. Difficulties include increased susceptibility to confabulation throughout the legal process that, in turn, can contribute to increased rates of poor outcomes including false confessions and wrongful convictions. Individuals with FASD are particularity at risk of confabulation when they are subjected to tactics, such as stressful and anxiety-provoking situations, threats, and leading, suggestive, or coercive questioning. Many professionals in the forensic context are unfamiliar with FASD or related confabulation risk and may unintentionally utilize tactics that intensify impacts of pre-existing impairment. This article serves as a beginner's guide for professionals working in criminal justice settings by (a) providing research-based overviews of FASD and confabulation, (b) describing how FASD may lead to confabulation, and (c) suggesting ways that professionals can modify protocols when interacting with individuals with FASD. Suggestions in this article hold the potential to decrease the risk of confabulation in the criminal justice system and decrease problematic outcomes, such as false confessions and wrongful convictions among individuals with FASD.

Episodic memory false recognition for familiar information in Alzheimer's disease

Patients with Alzheimer's disease (AD) suffer from various types of memory distortions. We showed that confabulations are plausible memories, mainly reflecting the recall of repeated personal events mistakenly considered by confabulating patients as specific and unique events. The aim of this study is to see whether the notion that over-learned information interferes in episodic memory recall, as it does in confabulation, can be extended to another type of memory distortion, namely false recognition (i.e., a claim to recognize something that was not encountered previously). If this is the case, it should be expected that in an episodic recognition memory task AD patients produce more false recognition for well known non-studied, non to-be-remembered material than for unknown non-studied, non to-be-remembered material. In order to verify this prediction, AD patients and normal controls (NC) were administered two experiments. In Experiment 1, we presented pictures, of which half were supposed to be well known and the other half unknown monuments. For each picture, participants were asked to say whether or not the monument was known or not to them. Immediately following this semantic encoding task, participants were administered an episodic recognition memory task in which, in the same way as in the previous phase, among the non-studied items, half were supposed to be well known and the other half unknown. In Experiment 2 the same procedure was used employing well known and unknown symbols. It was predicted that AD patients make more false recognitions for non-studied well-known items than for non-studied unknown items. The results show that this is actually the case, suggesting that confusion between "uniqueness," i.e., specific unique events, and "multiplicity," i.e., repeated events, is also involved in false recognition.

Repeated recall on source misattribution in Alzheimer's disease

We assessed the effect of repeated recall on item memory and source monitoring in Alzheimer's disease (AD). AD patients and controls were instructed to either look at or imagine items. They then had to either retrieve the items without indicating their source in three consecutive free recall tests, or to remember the source of the retrieved items in three consecutive source tests. Results showed a significant increase in item memory across all three free recall tests and all three source monitoring tests in control participants, but not in AD patients. More source misattributions were observed in AD patients and controls in the third source test than in the first and second tests. The absence of beneficial effect of repeated recall on item memory in AD patients may be attributed to compromise in memory consolidation processes, while the increase in source misattributions due to repetitions may be attributed to the inflation effect.

Personality and social memory: High source and destination memory in extroverts

We evaluated relationship between personality and memory for social interactions. More specifically, we investigated the relationship between extraversion and the ability to remember who told us some information (i.e., source memory) and the ability to remember to whom we told that information (i.e., destination memory). On a source memory task, participants received information from pictures of celebrities; a subsequent recognition test required them to identify the celebrities from whom they had received that information. On a destination memory task, participants were invited to tell information to celebrities; a later recognition task instructed them to identify the celebrity to whom they had previously told that information. Besides the assessment of source and destination memory, participants answered a questionnaire regarding extraversion. Results demonstrated significant positive correlation between extraversion and source memory, as well as significant positive correlation between extraversion and destination memory. In other words, the more participants described themselves as extraverts, the higher their source and destination memory. During social communications (e.g., in a conversation), extraverts may demonstrate high source and destination memory as these individuals typically value social communication, public sharing, and processing of social information.

Prevalence and Associated Factors of Visual Hallucinations in Patients with Vascular Cognitive Impairment

Visual hallucinations (VHs) are striking features for dementia, especially dementia with Lewy bodies (DLB). We aimed to study the frequency and associated factors of VH in vascular cognitive impairment (VCI) and investigate the feasibility of clinically diagnosing the mixed pathology of VCI with DLB. This is a multicentre registration study. A consecutive series of VCI patients with and without dementia were enrolled. Frequency of VH and associated factors, including age, gender, education, disease severity, DLB clinical features, vascular risk factors, cognitive function, and neuropsychiatric symptoms, were compared between VCI with VH (VH+) and without VH (VH-). Among the 1281 patients analysed, 155 (12.1%) had VH. The VH+ group was older (t = 5.07; p < 0.001), was more likely to be female (χ ² = 13.46; p < 0.001), and has a higher clinical dementia rating (χ ² = 70.51; p < 0.001). After adjusting for age, gender, and disease severity, the VH+ group had poorer cognition and more severe neuropsychiatric symptoms. The VH+ group was more associated with DLB features in fluctuating cognition (OR = 2.48; p < 0.001), parkinsonism (OR = 1.85; p = 0.001), rapid eye movement (REM) behavioral disorder (OR = 4.56; p < 0.001), and ≧2 DLB core features (OR = 26.01; p < 0.001). VCI patients with VH tend to have more severe dementia, neuropsychiatric symptoms, and poorer cognitive function. Additionally, highly associated with clinical DLB features in VCI with VH raised the possibility of mixed pathology with DLB in this group. More than two core features in VCI might help in diagnosing a mixed pathology with DLB.

The picture of the past: Pictures to cue autobiographical memory in Alzheimer's disease

INTRODUCTION

This study investigated the effect of pictorial cues on autobiographical memory in Alzheimer's disease (AD). We assessed autobiographical memory of patients with AD and cognitively normal older adults in two conditions.

METHODS

In one condition, the participants were provided with verbal instructions to retrieve three autobiographical memories. In the second condition, the same verbal instructions were provided; however, the participants were simultaneously presented with three pictures. We analyzed autobiographical memory regarding specificity, that is, the ability to remember unique events situated in time and space.

RESULTS

Analysis demonstrated higher autobiographical memory after verbal-and-visual cuing than after the no cue condition in both patients with AD and cognitively normal older adults.

DISCUSSION

Pictorial cues seem to be an effective method to alleviate autobiographical compromise in AD.

Confabulation affecting Temporal Consciousness significantly more than Knowing Consciousness

Confabulation, defined as the production of statements and actions that are unintentionally incongruous to the patient's history, background, present and future situation, is a rather infrequent memory disorder, which usually affects patients with significant memory impairment, but may be also observed in patients with normal memory and learning abilities. Confabulation may be selective affecting some cognitive, memory domains while relatively sparing others. In particular, it may affect more Temporal Consciousness, i.e. a specific form of consciousness that allows individuals to remember their personal past, to be oriented in their present world and to predict their personal future, than Knowing Consciousness, i.e. a specific form of consciousness allowing individuals to be aware of past, present and future impersonal knowledge and information. In this study we evaluated confabulations in TC and KC in a group of confabulatory amnesics of various aetiologies. Based on previous studies, it was predicted that confabulations affect significantly more TC than KC. It was also predicted that "Habits Confabulations", i.e. habits and repeated personal events mistaken as specific, unique past and future personal episodes, is the more frequently observed type of confabulation. The results confirmed these predictions and are discussed within the framework of the Memory, Consciousness and Temporality Theory.

Neuroimaging correlates of false memory in 'Alzheimer's disease: A preliminary systematic review

Alzheimer's disease (AD) is characterised by episodic memory impairment, but people also experience memory distortions, including false memories, which can impact on safety and reduce functioning. Understanding the neural networks that underpin false memories could help to predict the need for intervention and guide development of cognitive strategies to reduce memory errors. However, there is a relative absence of research into how the neuropathology of AD contributes to false memory generation. This paper systematically reviews the methodology and outcomes of studies investigating the neuroimaging correlates of false memory in AD. Four studies using structural imaging and three studies using functional imaging were identified. Studies were heterogenous in methodology and received mostly 'weak' quality assessment ratings. Combined, and consistent with neuroimaging findings in non-AD populations, results from identified studies provide preliminary support for the hypothesis that medial temporal lobe and prefrontal cortex dysfunction may lead to generation of false memories in AD. However, the small number of studies and significant heterogeneity within them means further study is necessary to assess replicability of results.

False Memory in Alzheimer's Disease

Patients with Alzheimer's Disease (AD) not only are suffering from amnesia but also are prone to memory distortions, such as experiencing detailed and vivid recollections of episodic events that have never been encountered (i.e., false memories). To describe and explain these distortions, we offer a review to synthesize current knowledge on false memory in AD into a framework allowing for better understanding of the taxonomy and phenomenology of false memories and of the cognitive mechanisms that may underlie false memory formation in AD. According to this review, certain phenomenological characteristics of memories (e.g., high emotional load, high vividness, or high familiarity) result in misattributions in AD. More specifically, this review proposes that generalized decline in cognitive control and inhibition in AD may result in difficulties in suppressing irrelevant information during memory monitoring, especially when irrelevant (i.e., false) information is characterized by high emotion, vividness, or familiarity. This review also proposes that binding deficits in AD decrease the ability to retrieve relevant contextual details, leading to source monitoring errors and false memories. In short, this review depicts how phenomenological characteristics of memories and failures of monitoring during retrieval contribute to the occurrence of false memory in AD.

Confabulations on Time: Relationship between Confabulations and Timing Deviations in Alzheimer’s Disease

Objectives

We investigated the relationship between confabulations and the ability to process chronological characteristics of memories in Alzheimer’s Disease (AD).

Methods

We evaluated provoked confabulations, spontaneous confabulations, and time perception in 31 AD patients. We evaluated provoked confabulations with questions probing general and personal knowledge. We evaluated spontaneous confabulations with a scale rated by nursing and medical staff. Regarding time perception, we invited the participants to perform a simple ongoing activity (i.e., deciding whether words were abstract or concrete), in order to provide a verbal estimation of the elapsed time intervals.

Results

We observed significant positive correlations between provoked/spontaneous confabulations and deviations in time estimation on the time perception task.

Conclusions

These findings demonstrate a relationship between confabulations in AD and difficulties in processing the chronological characteristics of elapsed events.

Reduplicative paramnesia for places: A comprehensive review of the literature and a new case report

Reduplicative paramnesia for places (i.e., the delusional belief that a place has been duplicated or exists in two different locations) is a rare disorder observed in neurological patients. We review the existing literature on the topic, highlighting commonalities and differences among the 51 cases published since the first report in 1903. Our results highlight the combination of multiple factors in the pathogenesis of this monothematic spatial delusion. From a neurological perspective, a crucial role is played by damage to the right frontal and temporal lobe. Deficits of non-verbal memory and executive functions, along with topographical disorientation, appear to be the most common (but, not systematic) cognitive impairments. The clinical picture of the disorder is further complicated by often overlooked psychological and motivational factors. Consequently, the precise neuro-cognitive substrate of this disorder is yet to be described in detail. We stress the need for a more detailed and systematic approach exploiting neurological, neuroimaging, neuropsychological and psychopathological methods. To guide future investigations, we provide clinical- and research-oriented recommendations. Finally, we illustrate the interplay of all above-mentioned factors with a new case report.

Context Memory in Alzheimer's Disease: The "Who, Where, and When"

Objective

Context memory, a component of episodic system, refers to the ability to retrieve conditions under which an event has occurred, such as who was present during that event and where and when it occurred. Context memory has been found to be compromised in older adults, an issue that we investigated in Alzheimer's disease (AD).

Methods

Thirty-one participants with AD and 35 older adults were asked to generate three autobiographical events. Afterward, they were asked to remember the names of all people who were evoked during the events, and the names for any location that was mentioned during the events. Participants were also asked to remember the year, season, month and day of the week when the events occurred.

Results

Compared to older adults, participants with AD showed lower memory for "who" (p < .001), "where" (p < .05), and "when" (p < .01). Compared to "who" and "where", both participants with AD and older adults showed pronounced difficulties in remembering the "when".

Conclusion

these findings highlight difficulties in remembering temporal information as an indication of context memory decline in AD. The difficulties in retrieving temporal information are discussed in terms of timing failures and hippocampal degenerations in AD.

Everyday Memory in Patients with Alzheimer's Disease: Fragmentary and Distorted

BACKGROUND

Errors of omission are an established hallmark of memory impairment in Alzheimer's disease (AD). Much less is known about other memory errors in AD such as false memories.

OBJECTIVE

We investigated false memories in healthy elderly controls (HC; n = 23) and patients with AD (n = 20) using real-life tasks of watching news and commercials.

METHODS

Participants received a comprehensive neuropsychological assessment and were shown original news and commercials with a subsequent recognition task to assess veridical and false memories.

RESULTS

Subjective estimate of the number of errors were alike in HC and patients with AD. However, memory performance in both the news and the commercials task was significantly worse in patients with AD. Trail-Making Test and Symbol-Span Test were significant predictors of false memories on viewing news and commercials. In patients with AD, levels of Aβ1 - 42, but not levels of tau-protein were correlated with false memories in both tasks.

CONCLUSIONS

Everyday life in patients with AD is impeded not due to the incompleteness of memory but also due to its distortions. Furthermore, it is hindered by the lack of awareness towards these deficits. False memory content in patients with AD is associated with Aβ42 levels in the CSF as a surrogate of the overall extent to which the brain has been affected by AD pathology. Future studies will need to address the impact of this duality of memory failure on everyday life of patients with AD and their proxies in greater detail.

Factors influencing confabulation in Japanese patients with Alzheimer's disease

BACKGROUND

Confabulations are often observed in patients with Alzheimer's disease (AD) and can increase family caregivers' burdens. Previous studies have focused on the relationship between confabulation and cognitive ability. However, few studies have investigated the association between confabulation and familial factors. Here, we aimed to examine whether confabulation relates to familial factors, such as the level of family caregivers' expressed emotion or the level of functioning of the family.

METHODS

Twenty-seven outpatients with AD and their family caregivers participated in this study. We examined confabulations about episodic memory, semantic memory, and future planning using the Modified Confabulation Battery (MCB). We investigated correlations between scores on the MCB and scores on the Mini-Mental State Examination (MMSE), Geriatric Depression Scale (GDS), Family Attitude Scale (FAS), and the Family Adaptability and Cohesion Evaluation Scale. Multiple regression analyses were performed using the total scores on the MCB and domain-specific scores on the MCB as dependent variables, and the scores on the MMSE, GDS, and FAS as independent variables.

RESULTS

MCB scores were positively related to FAS scores (P < 0.01) and negatively to GDS scores (P < 0.05), but not to MMSE scores. Regarding the three domains the MCB measured, confabulation about episodic memory and future planning showed a positive relationship with FAS scores.

CONCLUSIONS

Family attitude was the factor most related to confabulation in our study. Patients with AD may attempt to avoid confronting family caregivers' high emotional expression through confabulation, or confabulation itself might result in high emotional expression among family caregivers. Psychoeducational or therapeutic approaches for family caregivers might reduce confabulation in patients with AD.

Delusions in Patients with Dementia with Lewy Bodies and the Associated Factors

Objective

Delusions are common neuropsychiatric symptoms in patients with dementia with Lewy bodies (DLB). The aim of this study was to investigate the associated factors of delusions in patients with DLB.

Method

A retrospective study of outpatients with DLB registered in a regional hospital's database was performed. The associated factors including cognitive performance, clinical features, vascular risk factors, and neuropsychiatric symptoms between delusional and nondelusional patients with DLB were compared.

Results

Among 207 patients with DLB, 106 (51.2%) were delusional and 101 (48.8%) were not. Delusion of other persons are stealing was the most common symptom (35.3%). The delusional group had a significantly higher diagnostic rate of probable than possible DLB, higher disease severity, poorer cognitive performance, more severe neuropsychiatric symptoms, and higher caregiver burden (all p < 0.05). In addition, the delusional group had a significantly lower frequency of diabetes compared to the nondelusional group (odds ratio = 0.28, p < 0.001).

Conclusion

Delusion of other persons are stealing was the most common delusional symptom. The patients with DLB who presented with delusions had poorer cognitive function and more severe neuropsychiatric symptoms. A novel finding is that the DLB patients with diabetes had a lower frequency of delusions.

Screening for confabulations with the confabulation screen

The objective of this work is to devise and validate a sensitive and specific test for confabulatory impairment. We conceived a screening test for confabulation, the Confabulation Screen (CS), a brief test using 10 questions of episodic memory (EM), where confabulators most frequently confabulate. It was postulated that the CS would predict confabulations not only in EM, but also in the other subordinate structures of personal temporality, namely the present and the future. Thirty confabulating amnesic patients of various aetiologies and 97 normal controls entered the study. Participants were administered the CS and the Confabulation Battery (Dalla Barba, G., & Decaix, C. (2009). "Do you remeber what you did on March 13 1985?" A case study of confabulatory hypermnesia. Cortex, 45(5), 566-574). Confabulations in the CS positively and significantly correlated with confabulations in personal temporality domains of the CB, namely EM, orientation in time and place and episodic plans. Conversely, as expected, they did not correlate with confabulations in impersonal temporality domains of the CB. Consistent with results of previous studies, the most frequently observed type of confabulation in the CS was Habits Confabulation. The CS had high construct validity and good discriminative validity in terms of sensitivity and specificity. Cut-off scores for clinical and research purposes are proposed. The CS provides efficient and valid screening for confabulatory impairment.

The role of encoding in reality monitoring: A running memory test with Alzheimer's type dementia

Reality monitoring refers to the discrimination between memories of internal and external events (e.g., Johnson & Raye, 1981). A total of 28 healthy older adults and 28 older adults with Alzheimer's type dementia (DAT) were asked to perform or to imagine performing simple action statements in a running memory test. This task required participants to tell whether the action statement had been carried out or imagined, or whether it was new at unpredictable intervals. The results indicated that older adults with DAT had greater difficulty in reality monitoring than did the healthy control group. The finding is discussed in terms of the role of working memory functions in reality monitoring.

The cart before the horse: When cognitive neuroscience precedes cognitive neuropsychology

Cognitive neuropsychology (CN) has had an immense impact on the understanding of the normal cognitive processes underlying reading, spelling, spoken language comprehension and production, spatial attention, memory, visual perception, and orchestration of actions, through detailed analysis of behavioural performance by neurologically impaired individuals. However, there are other domains of cognition and communication that have rarely been investigated with this approach. Many cognitive neuropsychologists have extended their work in language, perception, or attention by turning to functional neuroimaging or lesion-symptom mapping to identify the neural mechanisms underlying the cognitive mechanisms they have identified. Another approach to extending one's research in CN is to apply the methodology to other cognitive functions. We briefly review the domains evaluated using methods of CN to develop cognitive architectures and computational models and the domains that have used functional neuroimaging and other brain mapping approaches in healthy controls to identify the neural substrates involved in cognitive tasks over the past 20 years. We argue that in some domains, neuroimaging studies have preceded the careful analysis of the cognitive processes underlying tasks that are studied, with the consequence that results are difficult to interpret. We use this analysis as the basis for discussing opportunities for expanding the field.

Effectiveness of a neuropsychological treatment for confabulations after brain injury: A clinical trial with theoretical implications

Confabulators consistently generate false memories without intention to deceive and with great feelings of rightness. However, to our knowledge, there is currently no known effective treatment for them. In order to fill this gap, our aim was to design a neuropsychological treatment based on current theoretical models and test it experimentally in 20 confabulators sequentially allocated to two groups: an experimental and a control group. The experimental group received nine sessions of treatment for three weeks (three sessions per week). The sessions consisted of some brief material that participants had to learn and recall at both immediate and delayed time points. After this, patients were given feedback about their performance (errors and correct responses). Pre- and post-treatment measurements were recorded. Confabulators in the control group were included in a waiting list for three weeks, performed the pre- and post- measurements without treatment, and only then received the treatment, after which a post-treatment measurement was recorded. This applied to only half of the participants; the other half quit the study prematurely. Results showed a significant decrease in confabulations and a significant increase in correct responses in the experimental group; by contrast, patients in the control group did not improve during the waiting list period. Only control group patients who subsequently received the treatment after serving as controls improved. The effects of the treatment were generalized to patients' everyday lives, as reported by relatives, and persisted over time. This treatment seems to be effective and easy to implement and consequently of clinical interest. Moreover, it also has theoretical implications regarding the processes related to the genesis and/or maintenance of confabulations. In particular, results point to a deficit in early stages of memory retrieval with the preservation of later strategic monitoring processes. Specifically, some of the processes involved may include selective attention or early conflict detection deficits. Future research should test these hypotheses.

The use of metacognitive strategies to decrease false memories in source monitoring in patients with mild cognitive impairment

Patients with amnestic mild cognitive impairment (MCI) and Alzheimer's disease (AD) often demonstrate high rates of false memories, leading to stressful and frustrating situations for both patients and caregivers in everyday life. Sometimes these false memories are due to failures in monitoring the source of the information. In the current study, we examined interventions aimed to enhance the use of the metacognitive "recall-to-reject" memory strategy. Such interventions could improve source memory and decrease false memory in patients with MCI. Because the picture superiority effect (better memory for pictures compared to words) has been shown to be present in both patients with MCI and healthy older controls, we investigated whether pictures could help patients with MCI use a recall-to-reject strategy in a simulation of real-world source memory task. In this experiment, patients with MCI and healthy older adults were asked to simulate preparing for and then taking a trip to the market. Subjects first studied 30 pictures of items in their "cupboard," followed by a list of 30 words of items on their "shopping list." At test, participants saw 90 pictures (30 cupboard, 30 list, 30 new) organized as they would be if walking down the market aisles, and are provided with either standard or metacognitive instructions. With standard instructions, they were asked if they needed to buy the item. With the metacognitive instructions, they were asked a series of questions to help guide them through a recall-to-reject strategy to highlight the different sources of memories. Results showed that the metacognitive instructions did significantly reduce the false memory rates for patients with MCI. Further studies need to investigate how to best implement these practical strategies into the everyday lives of patients.

Provoked and spontaneous confabulations in Alzheimer's disease: An examination of their prevalence and relation with general cognitive and executive functioning

AIM

A dissociation can be made between confabulations that are produced when the subject is directly questioned (i.e., provoked confabulations) and context-free, unprovoked confabulations (i.e., spontaneous confabulations). Unlike provoked confabulations, there is a paucity of research on spontaneous confabulations in Alzheimer's disease (AD). Our paper assessed this issue by assessing both types of confabulation in participants with mild to moderate AD and controls.

METHODS

Provoked confabulations were evaluated with questions probing personal and general knowledge, whereas spontaneous confabulations were rated by nursing and medical staff.

RESULTS

Findings showed more provoked confabulations in AD participants than in controls. Only occasional appearance of spontaneous confabulations was observed in the AD participants. Further, spontaneous confabulations in AD participants were significantly correlated with general cognitive functioning, but not with executive functioning.

CONCLUSION

Our findings suggest that spontaneous confabulations in AD are relatively rare, at least in the mild to moderate stage of the disease.

Spontaneous confabulations in amnestic-mild cognitive impairment due to Alzheimer's disease: a new (yet old) atypical variant?

Confabulation may be present in Alzheimer's disease (AD), but usually it is not a primary feature of either its typical or atypical variants. In this report, we describe the case of an AD patient who showed an unusual and enduring neuropsychiatric phenotype characterized by early and prominent spontaneous confabulation. Surprisingly, such atypical AD presentation bears a striking resemblance to presbyophrenia, a subtype of dementia which was described at the beginning of the twentieth century and then sank into oblivion. In discussion, we speculate on the "return" of presbyophrenia as an unrecognized neuropsychiatric variant of AD and its possible neuroanatomical substrates.

Intrusions and provoked and spontaneous confabulations on memory tests in Korsakoff's syndrome

INTRODUCTION

Intrusions on verbal memory tests have been used as an index for clinical confabulation. Severe memory impairments in combination with executive dysfunction have been suggested to be the underlying mechanism of confabulation, but to date, this relation is unclear. The aim of this study was (a) to examine the relation between (different types of) intrusions and confabulations in a large sample of confabulating patients with Korsakoff's syndrome (KS) and (b) to investigate whether different measures of executive functioning and memory performance are related to provoked and spontaneous confabulation.

METHOD

The Dutch version of the California Verbal Learning Test (CVLT) and various executive function and memory tests were administered to a group of 51 confabulating patients with KS. Professional caregivers rated the severity of provoked and spontaneous confabulation behavior of the patients using the Nijmegen-Venray Confabulation List-20 (NVCL-20).

RESULTS

The total number of intrusions on the CVLT was not related to either provoked or spontaneous confabulation scores. None of the CVLT intrusion scores correlated significantly with any of the confabulation scores, but we did find small-to-medium, positive correlations between unrelated intrusions and both provoked confabulations and spontaneous confabulation. Provoked confabulation behavior was associated with executive dysfunction and poorer memory performances. Spontaneous confabulation was not related to performance on measures of executive function and memory.

CONCLUSIONS

The total number of intrusions on verbal memory tests and clinical confabulations appear to be different phenomena. Only unrelated intrusions produced on the CVLT might possibly be related to confabulations. The production of provoked, but not spontaneous, confabulation is associated with executive dysfunction and memory deficits.

Self-representation in delusional misidentification and confabulated "others"

In some instances the ostensibly false narratives produced by patients with delusional misidentification syndromes (DMS) or confabulation may - unbeknownst to the patient - contain some authentic self-referential information. In this review, extracted from a video library or verbatim transcripts of approximately 50 clinical cases with either delusional misidentification or some variety of confabulation, we identified four cases (Feinberg, 2001, 2009, 2010; Feinberg & Shapiro, 1989) with either DMS for persons or confabulations about "phantom" persons, who showed prominent "self-referential" (SR) narratives. The presence of self-referential narratives was judged by: 1) the misidentification or confabulation was generally consistent and repeatable, e.g., the narrative was repeated on more than one occasion and not variably "provoked," 2) the content of the delusional misidentifications or confabulations were facts, feelings, or motivations that were true of the patients themselves either by history obtained from collateral sources (medical records, family, friends, etc.) or by admission by the patients themselves, but were attributed to a "double" of confabulated person, 3) these facts or feelings attributed to the "double" or confabulated "other" were either denied by the patients or admitted but also attributed to the "other." For purposes of comparison we also selected from the original group of 50 patients four "comparison" cases with delusional misidentification for persons and/or confabulation who based on these same criteria for self-referential material, were judged not to show self-referential (SR) aspects (Comparison cases 1-4). The neuroanatomy and neurocognitive features of these cases are reviewed and compared, the possible role of psychological defense in the self-referential cases is considered, and a model that integrates the neuroanatomical, neuropsychological and dynamic psychological aspects of these self-related disorders is offered. We propose that an appreciation of these self-related productions could have significant clinical and therapeutic implications.

Different patterns of recollection impairment in confabulation reveal different disorders of consciousness: A multiple case study

Recollection is used to refer to the active process of setting up retrieval cues, evaluating the outcome, and systematically working toward a representation of a past experience that we find acceptable. In this study we report on three patients showing different patterns of confabulation affecting recollection and consciousness differentially. All patients confabulated in the episodic past domain. However, whereas in one patient confabulation affected only recollection of events concerning his personal past, present and future, in another patient confabulation also affected recollection of impersonal knowledge. The third patient showed an intermediate pattern of confabulation, which affected selectively the retrieval of past information, both personal and impersonal. We suggest that our results are in favor of a fractionation of processes involved in recollection underling different disorders of consciousness.

Apolipoprotein E (APOE) ε4 and episodic memory decline in Alzheimer's disease: A review

A growing body of research has examined the relationship between episodic memory decline, the cognitive hallmark of Alzheimer's disease (AD), and the presence of Apolipoprotein E ε4 (APOE ε4) allele, a major genetic risk factor for the disease. Our review attempts to summarize and critically evaluate this literature. We performed a systematic search for studies assessing episodic memory in AD patients who were genotyped for APOE ε4 and identified fourteen papers. Although most of these papers reported significant relationships between APOE ε4 and episodic memory decline in AD, some papers did not confirm this relationship. Our review links this controversy to the conflicting literature about the effects of APOE ε4 on general cognitive functioning in AD. We identify several shortcoming and limitations of the research on the relationship between APOE ε4 and episodic memory in AD, such as small sample sizes, non-representative populations, lack of comparison of early-onset vs. late-onset disease, and lack of comparison among different genotypes that include APOE ε4 (i.e., zero, one, or two ε4 alleles). Another major shortcoming of the reviewed literature was the lack of comprehensive evaluation of episodic memory decline, since episodic memory was solely evaluated with regard to encoding and retrieval, omitting evaluation of core episodic features that decline in AD, such as context recall (e.g., how, where, and when an episodic event has occurred) and subjective experience of remembering (e.g., reliving, emotion and feeling during episodic recollection). Future research taking these limitations into consideration could illuminate the nature of the relationship between APOE ε4 and episodic memory decline in AD.

Inhibitory deterioration may contribute to hallucinations in Alzheimer's disease

INTRODUCTION

Although delusions and hallucinations are relatively common symptoms in individuals with Alzheimer's disease (AD), very little is known regarding underlying mechanisms. We examined whether these manifestations could be underpinned by psychological distress and executive impairments.

METHODS

Thirty-one participants with probable mild AD and 33 healthy older adults were administered a neuropsychological and clinical battery assessing delusions, hallucinations, anxiety, depression, episodic memory and executive functions (shifting, updating and inhibition).

RESULTS

Prevalence of delusions and hallucinations were significantly higher in AD participants compared to control participants. Further, hallucinations in AD participants were significantly correlated with poor inhibition, with the latter uniquely predicting the former, as compared to other variables. In addition, hallucinations in AD participants were associated with depression, a relationship that was further mediated by inhibition.

CONCLUSION

Hallucinations in individuals with AD seem to be related to difficulties suppressing irrelevant thoughts, resulting in these irrelevant thoughts becoming confused with ongoing reality.

Episodic memory in normal aging and Alzheimer disease: Insights from imaging and behavioral studies

Age-related cognitive changes often include difficulties in retrieving memories, particularly those that rely on personal experiences within their temporal and spatial contexts (i.e., episodic memories). This decline may vary depending on the studied phase (i.e., encoding, storage or retrieval), according to inter-individual differences, and whether we are talking about normal or pathological (e.g., Alzheimer disease; AD) aging. Such cognitive changes are associated with different structural and functional alterations in the human neural network that underpins episodic memory. The prefrontal cortex is the first structure to be affected by age, followed by the medial temporal lobe (MTL), the parietal cortex and the cerebellum. In AD, however, the modifications occur mainly in the MTL (hippocampus and adjacent structures) before spreading to the neocortex. In this review, we will present results that attempt to characterize normal and pathological cognitive aging at multiple levels by integrating structural, behavioral, inter-individual and neuroimaging measures of episodic memory.

Assessment of Confabulation in Patients with Alcohol-Related Cognitive Disorders: The Nijmegen-Venray Confabulation List (NVCL-20)

OBJECTIVE

Even though the first awareness of confabulations is often based on observations, only questionnaires and structured interviews quantifying provoked confabulations are available. So far, no tools have been developed to measure spontaneous confabulation. This study describes and validates an observation scale for quantifying confabulation behavior, including spontaneous confabulations, in clinical practice.

METHOD

An observation scale consisting of 20 items was developed, the Nijmegen-Venray Confabulation List-20 (NVCL-20). This scale covers spontaneous confabulation, provoked confabulation, and memory and orientation. Professional caregivers completed the NVCL-20 for 28 Korsakoff (KS) patients and 24 cognitively impaired chronic alcoholics (ALC). Their ratings were related to the Dalla Barba Confabulation Battery (DBCB), Provoked Confabulation Test (PCT), and standard neuropsychological tests.

RESULTS

The categories of the NVCL-20 have "good" to "excellent" internal consistency and inter-rater agreement. The KS patients confabulated more (both spontaneously and provoked), and more memory and orientation problems were observed. Correlations with neuropsychological test scores showed that confabulations were associated with memory deficits, but not with intrusions or tests of executive dysfunction.

CONCLUSIONS

The NVCL-20 is the first instrument that includes items addressing spontaneous confabulation. Administration is reliable, valid and feasible in clinical practice, making it a useful addition to existing confabulating measures.

A neurophenomenological model for the role of the hippocampus in temporal consciousness. Evidence from confabulation

Confabulation, the production of statements or actions that are unintentionally incongruous to the subject's history, background, present and future situation, is a rather infrequent disorder with different aetiologies and anatomical lesions. Although they may differ in many ways, confabulations show major similarities. Their content, with some minor exceptions, is plausible and therefore indistinguishable from true memories, unless one is familiar with the patient's history, background, present and future situation. They extend through the whole individuals' temporality, including their past, present and future. Accordingly, we have proposed that rather than a mere memory disorder; confabulation reflects a distortion of Temporal Consciousness (TC), i.e., a specific form of consciousness that allows individuals to locate objects and events according to their subjective temporality. Another feature that confabulators share is that, regardless of their lesion's location, they all have a relatively preserved hippocampus (Hip), at least unilaterally. In this article, we review data showing differences and similarities among forms of confabulation. We then describe a model showing that the hippocampus is crucial both for the normal functioning of TC and as the generator of confabulations, and that different types of confabulation can be traced back to a distortion of TC resulting from damage or disconnection of brain areas directly or indirectly connected to the hippocampus. We conclude by comparing our model with other models of memory and confabulation.

Directed forgetting of source memory in normal aging and Alzheimer's disease

BACKGROUND AND AIMS

Using the source directed forgetting method, the present paper investigated whether older adults and Alzheimer's disease (AD) patients were able to inhibit source information.

METHODS

Younger adults, older adults and AD participants were presented with two sets of six items each: Set1 and Set2. Each item was presented by one of two sources: an experimenter black- or white-gloved hand. After the presentation of the Set1 items, participants were instructed either to forget or to continue remembering the source of the items. Afterward, all participants were presented with the Set2 items, and were asked to remember their source. Finally, subjects were exposed to the Set1 and Set2 items, and were asked to recall, for each item, its original source presentation (i.e., the experimenter black- or white-gloved hand).

RESULTS

In comparison with younger adults, older adults and AD participants showed no differences in remembering the source of the Set1 and Set2 items. In other words, they failed to inhibit the source information.

DISCUSSION AND CONCLUSION

Our outcomes are discussed in terms of retrieval inhibition deficits and changes in adaptive nature of memory in normal aging and AD.

Associative memory and its cerebral correlates in Alzheimer׳s disease: evidence for distinct deficits of relational and conjunctive memory

This study investigated the impact of Alzheimer׳s disease (AD) on conjunctive and relational binding in episodic memory. Mild AD patients and controls had to remember item-color associations by imagining color either as a contextual association (relational memory) or as a feature of the item to be encoded (conjunctive memory). Patients׳ performance in each condition was correlated with cerebral metabolism measured by FDG-PET. The results showed that AD patients had an impaired capacity to remember item-color associations, with deficits in both relational and conjunctive memory. However, performance in the two kinds of associative memory varied independently across patients. Partial Least Square analyses revealed that poor conjunctive memory was related to hypometabolism in an anterior temporal-posterior fusiform brain network, whereas relational memory correlated with metabolism in regions of the default mode network. These findings support the hypothesis of distinct neural systems specialized in different types of associative memory and point to heterogeneous profiles of memory alteration in Alzheimer׳s disease as a function of damage to the respective neural networks.

Implausible future events in a confabulating patient with an anterior communicating artery aneurysm

Patient MW, a known confabulator, and healthy age-matched controls produced past and future events. Events were judged on emotional valence and plausibility characteristics. No differences in valence were found between MW and controls, although a positive emotional bias toward the future was observed. Strikingly, MW produced confabulations about future events that were significantly more implausible than those produced by healthy controls whereas MW and healthy controls produced past events comparable in plausibility. A neurocognitive explanation is offered based on differences between remembering and imagining. Possible implications of this single case in relation to confabulation and mental time travel are discussed.

Context memory in Alzheimer's disease

Background

Alzheimer's disease (AD) is a neurodegenerative disease characterized by a gradual loss of memory. Specifically, context aspects of memory are impaired in AD. Our review sheds light on the neurocognitive mechanisms of this memory component that forms the core of episodic memory function.

Summary

Context recall, an element of episodic memory, refers to remembering the context in which an event has occurred, such as from whom or to whom information has been transmitted.

Key Messages

Our review raises crucial questions. For example, (1) which context element is more prone to being forgotten in the disease? (2) How do AD patients fail to bind context features together? (3) May distinctiveness heuristic or decisions based on metacognitive expectations improve context retrieval in these patients? (4) How does cueing at retrieval enhance reinstating of encoding context in AD? By addressing these questions, our work contributes to the understanding of the memory deficits in AD.

Searching for an integrated self-representation

Recent inquiries into the nature of self-representation have put forward a new and interesting conceptualization of the self, as a "center of gravity" of one's private and social behavior. We review recent neuroimaging work that has suggested interactions among brain regions comprising the default state network, including medial and temporo-parietal cortical regions and the mirror neuron system including lateral fronto-parietal regions as two interacting neural systems that work in concert to produce a cohesive self-representation through simulation. Simulation processes-broadly construed here as using existing representations as templates for understanding novel information-are instantiated by these brain systems across a wide range of domains including time, space, physical and social, giving rise to the multifaceted Self that we all are. Accumulating evidence also suggests, that these simulation processes are used in a multitude of cognitions that constitute the self, including autobiographical memory and prospection, perspective taking, understanding other's actions and mental states and embodied self-representation.