Mild cognitive impairment and feeling-of-knowing in episodic memory

Subjective cognitive decline: Memory complaints, cognitive awareness, and metacognition

Cognitive complaints are common in elderly subjects and are a frequent reason for referral to memory clinics. If the complaints are not associated with objective cognitive impairment, the condition is labelled subjective cognitive decline (SCD). SCD is often considered as a stage antedating objective impairment, and an at-risk condition for subsequent dementia. Recent large-scale studies indicate that a significantly increased risk of clinical progression in subjects with SCD is associated with positivity for Alzheimer's disease (AD) biomarkers, a finding supporting the notion that SCD can be due to different mechanisms not associated with neurodegeneration, including functional cognitive disorders. In this paper we present a selective review of research on the relations among SCD, cognitive awareness, and metacognitive abilities. We propose that longitudinal studies of metacognitive efficiency in SCD may provide useful cues about the risk of progression to dementia and the possible presence of a functional cognitive disorder, with different implications for the management of this prevalent aging-related condition. HIGHLIGHTS: Subjective cognitive decline (SCD), a common cause of referral to memory clinics, can be due to multiple conditions. The predictive value of SCD for progression to Alzheimer's disease (AD) dementia is high in association with AD biomarker positivity. The awareness of cognitive decline is the mechanism responsible for the emergence of SCD and metacognition is the underlying neuropsychological function. The awareness of cognitive decline in clinical patients is usually assessed comparing an informant rating to the patient self-assessment, a method that can be affected by informant bias. While there is strong evidence that awareness starts to decline with the onset of objective cognitive impairment, progressively leading to the anosognosia of AD, the status of metacognitive efficiency in SCD needs to be further investigated. Quantitative, performance-based indexes of metacognitive efficiency may contribute both to the assessment of progression risk and to the management of subjects with functional cognitive disorders.

Lack of effects of online HD-tDCS over the left or right DLPFC in an associative memory and metamemory monitoring task

Neuroimaging studies have shown that activity in the prefrontal cortex correlates with two critical aspects of normal memory functioning: retrieval of episodic memories and subjective "feelings-of-knowing" about our memory. Brain stimulation can be used to test the causal role of the prefrontal cortex in these processes, and whether the role differs for the left versus right prefrontal cortex. We compared the effects of online High-Definition transcranial Direct Current Stimulation (HD-tDCS) over the left or right dorsolateral prefrontal cortex (DLPFC) compared to sham during a proverb-name associative memory and feeling-of-knowing task. There were no significant effects of HD-tDCS on either associative recognition or feeling-of-knowing performance, with Bayesian analyses showing moderate support for the null hypotheses. Despite past work showing effects of HD-tDCS on other memory and feeling-of-knowing tasks, and neuroimaging showing effects with similar tasks, these findings add to the literature of non-significant effects with tDCS. This work highlights the need to better understand factors that determine the effectiveness of tDCS, especially if tDCS is to have a successful future as a clinical intervention.

The Efficacy of a Metacognitive Training Program in Amnestic Mild Cognitive Impairment: A 6-Month Follow-Up Clinical Study

This study was conducted in response to the increasing prevalence of Alzheimer's disease (AD) dementia and the significant risk faced by individuals with amnestic mild cognitive impairment with multiple-domain deficits (aMCI-md). Given the promising effects of MTPs, the primary aim of this study was to further explore their impact by assessing the maintenance of their benefits. Thus, 45 participants were randomly allocated in two groups: the Experimental group (n = 22), which received the metacognitive training program (MTP), and the Control group (n = 23) that received the cognitive exercises program (CEP). The training programs-the MTP and the CEP-included 10 individual sessions of a one-hour duration and took place once per week. To test the efficacy of the MTP, cognitive and metacognitive outcomes were compared between two groups-Experimental (EG) and Control (CG)-at four distinct time points: before-after-3 months-6 months after intervention. Based on this study's findings, the positive effects of the MTP were evident over a six-month period. Specifically, already three months post-training, the CG began to show a decline in training-related gains. In contrast, the EG's performance consistently improved, highlighting the superior efficacy of the MTP. Gains attributed to the MTP were detected in cognitive measures: cognitive flexibility and immediate visual recall, as well as in metacognitive measures: metacognitive control, improved metacognitive beliefs of attention, and an increased use of cognitive strategies. In conclusion, the results demonstrated the sustained effects of the MTP in cognitive and metacognitive measures over a period of six months, providing novel insight into the application and efficacy of the MTP in individuals with MCI.

Metacognitive beliefs of efficacy about daily life situations and use of cognitive strategies in amnestic mild cognitive impairment: a cross-sectional study

Metacognition, the ability to monitor and regulate cognitive processes, is essential for individuals with Mild Cognitive Impairment (MCI) to accurately identify their deficits and effectively manage them. However, previous studies primarily focused on memory awareness in MCI, neglecting other domains affected in daily life. This study aimed to investigate how individuals with MCI perceive their abilities to handle various cognitively challenging situations representing real-life scenarios and their use of compensatory strategies. Thus 100 participants were recruited, including 50 with amnestic MCI with multiple deficits (aMCI) and 50 cognitively healthy controls (HC) matched in age and education. Participants completed three metacognitive scales assessing self-perceived efficacy in everyday life scenarios and one scale evaluating use of cognitive strategies. Results indicated that aMCI participants reported significantly lower self-efficacy in memory and divided-shifted attention scenarios compared to HC. Surprisingly, no significant group differences were found in the self-reports about the use of cognitive strategies. This suggests a potential gap in understanding or applying effective strategies for compensating cognitive deficits. These findings emphasize the importance of cognitive training programs targeting metacognitive knowledge enhancement and practical use of cognitive strategies that could enhance the quality of life for individuals with MCI.

Metacognitive Differences in Amnestic Mild Cognitive Impairment and Healthy Cognition: A Cross-Sectional Study Employing Online Measures

This study aimed to examine metacognitive abilities in individuals diagnosed with amnestic mild cognitive impairment (aMCI) by using online metacognitive measures during cognitive tasks. A total of 100 participants were enrolled, all aged 50 or older (mean age = 61.98; SD = 6.27), and with a minimum of six years of education (mean = 14.95; SD = 2.94). The sample included 50 individuals with aMCI (34 females) and 50 healthy controls (HC) (33 females). Both groups underwent metacognitive versions of memory tasks (Doors and People) and executive functions tasks (Wisconsin Card Sorting Test). Metacognition was assessed through confidence ratings given after each answer (referred to as metacognitive monitoring) and the accuracy of the participants' decisions to include or exclude answers from their final scores (known as metacognitive control). The results showed that although individuals with aMCI were aware of their cognitive limitations-evidenced by their lower confidence ratings across all tasks-they still exhibited overconfidence relative to their actual performance. Moreover, they included a greater number of incorrect answers in their final scores compared to the healthy control group. These findings suggest that while individuals with aMCI retain some level of awareness, their self-evaluations appear to lack precision. This observation was consistent across both types of cognitive tasks. The results underscore the need for additional research to better understand metacognition in MCI as well as the interplay between metacognitive monitoring and control.

The effects of combined cognitive training on prospective memory in older adults with mild cognitive impairment

This study aimed to assess the effects of combined cognitive training on prospective memory ability of older adults with mild cognitive impairment (MCI). A total of 113 participants were divided into a control group and three intervention groups. Over three months, the control group received only community education without any training, whereas for the first six weeks, an executive function training group received executive function training, a memory strategy training group received semantic encoding strategy training, and the combined cognitive training group received executive function training twice a week for the first six weeks, and semantic encoding strategy training twice a week for the next six weeks. The combined cognitive training group showed improvement on the objective neuropsychological testing (Montreal Cognitive Assessment scale). The memory strategy training group showed improvement on the self-evaluation scales (PRMQ-PM). Combined cognitive training improved the prospective memory and cognitive function of older adults with MCI.

Anosognosia in Mild Cognitive Impairment: Lack of Awareness of Memory Difficulties Characterizes Prodromal Alzheimer's Disease

While anosognosia is often present in Alzheimer's disease, the degree of awareness of cognitive difficulties in the earlier stages, such as Mild Cognitive Impairment (MCI), is less clear. Using a questionnaire and Feeling-of-Knowing tasks, the aims of this study were (1) to test the hypothesis that anosognosia is present specifically in prodromal AD stage in patients that, owing to a more severe AD neuropathology, will rapidly progress to overt dementia and (2) to assess the neural bases of self-awareness for memory functioning. A group of 44 patients with amnestic MCI and a group of 29 healthy older participants (CTRL) performed two Feeling-of-Knowing tasks (episodic and semantic FOK) and responded to the Functional Memory Scale (MARS), also completed by one of their relatives. They underwent FDG-PET and structural MRI. The participants were followed clinically for 4 years. At the end of follow-up, 23 patients with MCI developed Alzheimer's disease (converters) and 21 patients still presented symptoms of MCI without progression (non-converters). The analyses focused on the data from inclusion stratified according to clinical status 4 years later (converters, non-converters, CTRL). On the episodic FOK task, converters patients overestimated their ability to later recognize unrecalled words and they showed prediction accuracy (Hamann coefficient) at the level of chance. No difficulty was observed in any group with the semantic FOK task. On the MARS, converters patients had a higher anosognosia score than non-converters patients and CTRL, which did not differ from each other. Correlations between self-awareness scores and neuroimaging data using small volume correction analyses in a priori regions of interest in converters indicated that inaccurate episodic FOK judgments was related to changes in brain areas that might support interpretation of retrieved content for judging the likelihood of recognition. For the MARS, the association between anosognosia and decreased gray matter density of the left inferior prefrontal cortex in converters might indicate poor inhibition over outdated personal knowledge. In amnestic MCI, anosognosia could be an early sign of neurodegeneration in brain areas that would support control mechanisms over memory representations.

Retrospective metamemory monitoring of semantic memory in community-dwelling older adults with subjective cognitive decline and mild cognitive impairment

In neurodegenerative conditions, better memory/cognitive awareness, indexed by greater "metamemory monitoring accuracy", is linked to stronger cognitive remediation outcomes. Differences in metamemory monitoring accuracy in predementia conditions, which could inform treatment effectiveness, have not been systematically investigated. We utilized a retrospective confidence judgment (RCJ) task for general knowledge recognition in community-dwelling older adults: 106 cognitively healthy (HC), 68 subjective cognitive decline (SCD) despite intact neuropsychological function, 14 amnestic mild cognitive impairment (aMCI), and 31 non-amnestic mild cognitive impairment (naMCI). Participants gave confidence ratings after making recognition responses to general knowledge questions. Recognition accuracy, confidence levels, and absolute and relative RCJ accuracy (i.e., metamemory monitoring accuracy) were analysed. Compared to HC and SCD, absolute RCJ accuracy was significantly poorer in both MCI groups but relative RCJ accuracy was significantly poorer in naMCI, but not aMCI. This novel result may be driven by lower confidence for correct recognition responses in naMCI and suggests that poorer RCJ accuracy in naMCI may be attributable to poorer performance monitoring. We discuss results in relation to the possibility that individuals in distinct preclinical dementia conditions, who have different levels of memory/cognitive awareness, may differentially benefit from cognitive remediation strategies tailored to their levels of memory/cognitive awareness.

Investigations of Memory Monitoring in Individuals With Subjective Cognitive Decline and Amnestic Mild Cognitive Impairment

BACKGROUND

Subjective cognitive decline (SCD) has been called the prodromal stage of amnestic mild cognitive impairment (aMCI); however, further investigation is needed to confirm this observation.

OBJECTIVE

To define the relationship between SCD and aMCI.

METHOD

In this case-control study, we used the feeling-of-knowing in episodic memory (FOK-EM) test to measure the memory-monitoring function of 40 adults with aMCI, 60 with SCD, and 55 healthy controls.

RESULTS

The recognition rates of FOK-EM (53.53% ± 7.82%; 55.12% ± 6.08%) and judgment accuracy of the aMCI and SCD groups (γ values 0.21 ± 0.11; 0.30 ± 0.16) were significantly lower than those of the control group (72.32% ± 5.14%; 0.57 ± 0.16) (F = 116.24, P < 0.01; F = 128.57, P < 0.01; F = 73.33, P < 0.01). The scores for correct decision/correct recognition (RR; 27.2 ± 6.43; 29.36 ± 5.16) and correct decision/false recognition (RF; 30.41 ± 5.06; 27.26 ± 4.37) of the aMCI and SCD groups were also significantly lower than those of the control group (49.35 ± 7.13; 11.16 ± 4.35) (FRR = 132.67, P < 0.01; FRF = 131.8, P < 0.01).

CONCLUSION

Mild clinical impairments in memory-monitoring function may precede clinically confirmed objective memory impairment in individuals with SCD.

Sources of Response Bias in Cognitive Self-Report Items: "Which Memory Are You Talking About?"

BACKGROUND AND OBJECTIVES

Self-reported cognitive difficulties are common in the years before an Alzheimer's disease (AD) diagnosis. Understanding how older adults interpret and respond to questions about their cognition is critical to recognize response biases that may limit the accuracy of cognitive self-reports in identifying AD risk. Cognitive interviewing is a systematic approach for examining sources of response bias that influence individuals' answers to specific questions. The purpose of this study was to identify features of common cognitive self-report items that contribute to (a) differing interpretations among respondents and (b) older adults' decisional processes when responding.

RESEARCH DESIGN AND METHODS

A convenience sample of community-dwelling older adults (n = 49; Mage = 74.5 years; 36.7% male) without dementia completed a demographic questionnaire, the Montreal Cognitive Assessment, and an audio-recorded cognitive interview. Twenty commonly used cognitive self-report items were evaluated using cognitive interviewing techniques. The Question Appraisal System was used to guide the analysis of interview data and identify sources of response bias within and across cognitive self-report items.

RESULTS

The most common sources of inconsistency in item interpretation and decisional processes were vague item wording, incorrect assumptions regarding consistency of cognitive problems across situations, and provocation of an emotional reaction that influenced responses.

DISCUSSION AND IMPLICATIONS

Assessment of self-reported cognition is critical to facilitate research on early AD symptoms. Findings from this study identify modifiable sources of response bias that may influence the measurement properties of currently used cognitive self-report items and can inform refinement of measures.

Decreased meta-memory is associated with early tauopathy in cognitively unimpaired older adults

The ability to accurately judge memory efficiency (meta-memory monitoring) for newly learned (episodic) information, is decreased in older adults and even worse in Alzheimer's disease (AD), whereas no differences have been found for semantic meta-memory. The pathological substrates of this phenomenon are poorly understood. Here, we examine the association between meta-memory monitoring for episodic and semantic information to the two major proteinopathies in AD: amyloid (Aβ) and tau pathology in a group of cognitively unimpaired older adults. All participants underwent multi-tracer PET and meta-memory monitoring was assessed using a feeling-of-knowing (FOK) task for non-famous (episodic) and famous (semantic) face-name pairs. Whole brain voxel-wise correlations between meta-memory and PET data were conducted (controlling for memory), as well as confirmatory region-of-interest analyses. Participants had reduced episodic FOK compared to semantic FOK. Decreased episodic FOK was related to tauopathy in the medial temporal lobe regions, including the entorhinal cortex and temporal pole, whereas decreased semantic FOK was related to increased tau in regions associated with the semantic knowledge network. No association was found with Aβ-pathology. Alterations in the ability to accurately judge memory efficiency (in the absence of memory decline) may be a sensitive clinical indicator of AD pathophysiology in the pre-symptomatic phase.

Memory awareness disruptions in amnestic mild cognitive impairment: comparison of multiple awareness types for verbal and visuospatial material

Successful memory is normally accompanied by explicit awareness of retrieval and confidence in the accuracy of the retrieval product. Prior findings suggest that these features of metamemory can be dissociated from retrieval accuracy in Amnestic Mild Cognitive Impairment (aMCI). However, the literature on this question contains variable and conflicting results, likely because of differences in experimental conditions. We sought to systematically evaluate memory awareness disruptions in aMCI using multiple measures and stimulus formats within the same individuals. Memory awareness was tested with global predictions and postdictions, judgments of learning, confidence level ratings, and modified feeling-of-knowing ratings in tasks of visuospatial and verbal memory. These tests were administered to 14 individuals with aMCI and 15 healthy, age-matched controls. Memory awareness accuracy was calculated as the correspondence between subjective judgments and memory performance.Individuals with aMCI demonstrated impaired global and trial-level retrospective task awareness for visuospatial and verbal stimuli. Additionally, modified feeling-of-knowing awareness was impaired selectively for verbal stimuli. Statistical effect sizes for global awareness impairments were comparable to impairments in several objective neuropsychological memory assessments.Memory awareness (metamemory) disruptions in aMCI were most evident for a subset of subjective judgment types and task input modalities. These findings advance understanding of the nature of memory impairments in aMCI and support the utility of incorporating memory awareness testing to better characterize memory integrity in older adults.

Self and informant memory concerns align in healthy memory complainers and in early stages of mild cognitive impairment but separate with increasing cognitive impairment

BACKGROUND

Information provided by an informant about a patient with cognitive change is an essential component of clinical history taking. How an informant's report relates to the patient's phenomenological experience of memory loss is yet to be understood. The aim was to examine patterns of relationships between self and informant reports from a phenomenological perspective.

METHODS

Forty-three healthy non-memory complainers (HC-NMC), 37 healthy subjective memory complainers (HC-SMC) and 43 individuals with mild cognitive impairment (MCI) were administered a semi-structured interview, which measured their concerns of frequency of memory lapses and impact on mood. Informants responded to questionnaires.

RESULTS

Self-reported concerns of increasing frequency and impacted mood related to informant concerns in HC-SMCs. MCI with lower informant concern showed a similar pattern to HC-SMCs on complaints of increasing frequency. In those with higher informant concern, self-reports markedly separated from informant concern. The MCI group with greater informant concern performed comparatively poor on verbal and non-verbal memory measures.

CONCLUSIONS

Our results suggest that the association between self-reported and informant memory concerns is moderated by MCI severity. Self and informant reports of increasing memory lapse frequency aligned in HC-SMC and MCIs with low informant concern, suggesting a similar dyadic experience of memory change. In MCIs with greater informant concern, the pattern changed exposing a changing insight with advancing memory impairment. These individuals are potentially reflecting a 'forgetting that they forget' phenomenon in elements of their concern.

Self-awareness and traumatic brain injury outcome

PRIMARY OBJECTIVE

Impaired self-awareness following a traumatic brain injury (TBI) can reduce the effectiveness of rehabilitation, resulting in poorer outcomes. However, little is understood about how the multi-dimensional aspects of self-awareness may differentially change with recovery and impact outcome. Thus, this study examined four self-awareness variables represented in the Dynamic Comprehensive Model of Awareness: metacognitive awareness, anticipatory awareness, error-monitoring and self-regulation.

RESEARCH DESIGN

This study evaluated change of the self-awareness measures with recovery from TBI and whether the self-awareness measures predicted community re-integration at follow-up.

METHODS AND PROCEDURES

Participants were 90 individuals with moderate-to-severe TBI who were tested acutely following injury and 90 age-matched controls. Forty-nine of the TBI participants and 49 controls were re-tested after 6 months.

MAIN OUTCOME AND RESULTS

Results revealed that the TBI group's error-monitoring performance was significantly poorer than controls at both baseline and follow-up. Regression analyses revealed that the self-awareness variables at follow-up were predictive of community re-integration, with error-monitoring being a unique predictor.

CONCLUSIONS

The results highlight the importance of error-monitoring and suggest that interventions targeted at improving error-monitoring may be particularly beneficial. Understanding the multi-dimensional nature of self-awareness will further improve rehabilitation efforts and understanding of the theoretical basis of self-awareness.

The apolipoprotein E genotype predicts longitudinal transitions to mild cognitive impairment but not to Alzheimer's dementia: findings from a nationally representative study

OBJECTIVE

The ε4 allele of the apolipoprotein E (APOE) genotype is the most widely accepted genetic risk factor for Alzheimer's dementia (AD), but findings on whether it is a risk factor for the AD prodrome, mild cognitive impairment (MCI), have been inconsistent. In a prospective longitudinal design, we investigated (a) whether transitions to MCI and other forms of neurocognitive impairment without dementia (CIND) are more frequent among normal ε4 carriers than among noncarriers and (b) whether subsequent transitions to AD from MCI and from other forms of CIND are more frequent among ε4 carriers than among noncarriers.

METHOD

The frequency of the ε4 allele was studied in older adults (mean age > 70), who had participated in two or more waves of neuropsychological testing and diagnosis in the Aging, Demographics, and Memory Study (ADAMS) of the United States Department of Health and Human Services, National Institutes of Health, National Institute on Aging's Health and Retirement Study, conducted by the University of Michigan. The association between ε4 and longitudinal transitions to specific types of CIND and dementia can be determined with this data set.

RESULTS

Epsilon 4 increased the rate of progression from normal functioning to MCI (58% of new diagnoses were carriers) but not to other forms of CIND. The rate of progression to AD from MCI or from other forms of CIND was not increased by ε4.

CONCLUSIONS

The results support the hypothesis that ε4 is a risk factor for transitions from normal functioning to MCI but not for subsequent transitions to AD. In the ADAMS sample, the reason ε4 is elevated in AD individuals is because it is already elevated in MCI individuals, who are the primary source of new AD diagnoses.

Remember to buy milk on the way home! A meta-analytic review of prospective memory in mild cognitive impairment and dementia

Prospective memory (PM) is the ability to remember to execute delayed intentions. Previous studies indicate that PM is impaired in persons with mild cognitive impairment (MCI) and dementia, but the extent, nature, and cognitive correlates are unclear. A meta-analytic review was, therefore, performed (literature search 1990 to July 2011) on case-control studies on PM in dementia (10 studies, 336 patients, 505 controls) and MCI (7 studies, 225 patients, 253 controls). Differences between event-based and time-based PM and between measures of prospective and retrospective memory were examined, as well as correlations with other cognitive functions. Results showed that patients with dementia or MCI exhibit large deficits in PM (Hedges' d -1.62 [95% confidence interval -1.98 to -1.27; p < .0001] for dementia; -1.24 [-1.51 to -0.995; p < .0001] for MCI; difference dementia vs. MCI: QM = 1.94, p = .16). Impairments were comparable in size for event-based and time-based PM (p > .05), as well as for prospective and retrospective memory (p > .05). PM showed modest correlations with measures of retrospective memory (median r = 0.27) and executive functioning (median r = 0.30). PM appears a valid construct in neuropsychological assessment in patients with dementia or MCI, but more insight is needed in the optimal characteristics of PM tasks to be used in clinical practice.

Promising Genetic Biomarkers of Preclinical Alzheimer's Disease: The Influence of APOE and TOMM40 on Brain Integrity

Finding biomarkers constitutes a crucial step for early detection of Alzheimer's disease (AD). Brain imaging techniques have revealed structural alterations in the brain that may be phenotypic in preclinical AD. The most prominent polymorphism that has been associated with AD and related neural changes is the Apolipoprotein E (APOE) ε4. The translocase of outer mitochondrial membrane 40 (TOMM40), which is in linkage disequilibrium with APOE, has received increasing attention as a promising gene in AD. TOMM40 also impacts brain areas vulnerable in AD, by downstream apoptotic processes that forego extracellular amyloid beta aggregation. The present paper aims to extend on the mitochondrial influence in AD pathogenesis and we propose a TOMM40-induced disconnection of the medial temporal lobe. Finally, we discuss the possibility of mitochondrial dysfunction being the earliest pathophysiological event in AD, which indeed is supported by recent findings.

Neuropsychological features of mild cognitive impairment and preclinical Alzheimer's disease

Detectable cognitive decline occurs in patients with Alzheimer's disease (AD) well before the clinical diagnosis can be made with any certainty. Studies examining this preclinical period identify decline in episodic memory as the earliest manifestation of the disease (i.e., a condition of amnestic Mild Cognitive Impairment). The episodic memory impairment is characterized by deficits in a number of processes including delayed recall, the recollective aspect of recognition memory, associative memory necessary for "binding" representations of two or more stimuli, pattern separation necessary to distinguish between two similar memory representations, prospective memory required to remember a delayed intention to act at a certain time in the future, and autobiographical memory for specific episodes that occurred in one's past. A growing body of evidence suggests that cognitive changes in preclinical AD may be more global in nature. Deterioration of semantic knowledge is evident on demanding naming and category fluency tasks, and "executive" dysfunction is apparent on tasks that require concurrent mental manipulation of information (e.g., working memory) or cue-directed behavior (e.g., set-shifting). Asymmetric cognitive test performance may also be apparent prior to significant decline in cognitive ability. The pattern and progression of these neuropsychological changes fit well with the proposed distribution and spread of AD pathology and serve as important cognitive markers of early disease.