Memory and metamemory performance in Alzheimer's disease and healthy elderly: the Contextual Memory Test (CMT)

Online awareness: a concept analysis and review of assessment approaches for adults with neurological conditions

PURPOSE

Self-awareness is a multifaceted phenomenon that comprises two main concepts: general awareness and online awareness. The latter is an emerging concept that requires further consensus on its definition. The aim of this paper is to define the key components of online awareness and identify approaches for measuring this concept for adults with neurological conditions.

MATERIALS AND METHODS

Concept analysis using Rodgers' evolutionary method was used to systematically review and summarise relevant literature. Papers were included if they provided a definition of online awareness or method for assessing online awareness for an adult neurological population.

RESULTS

Fifty-six papers were included in this review, with 21 online awareness assessment approaches identified. Online awareness was described to occur within the context of task performance, with the definition framework comprising four main aspects: 1/appraisal; 2/anticipation and prediction; 3/monitoring; and 4/self-evaluation. Self-regulation is a related concept that is considered to sit outside the conceptual boundaries of online awareness.

CONCLUSIONS

The findings of this analysis highlight the complexity of online awareness and its importance in rehabilitation. Psychometrically robust measures of online awareness that are inclusive of the essential elements of this concept are needed to advance practice in this area.

Awareness of Cognitive Decline in Patients With Alzheimer's Disease: A Systematic Review and Meta-Analysis

Background: Identifying a poor degree of awareness of cognitive decline (ACD) could represent an early indicator of Alzheimer's disease (AD). Objectives: (1) to understand whether there is evidence of poor ACD in the pre-dementia stages of AD; (2) to summarize the main findings obtained investigating ACD in AD; (3) to propose a conceptual framework. Data Sources: We searched Scopus, Pubmed, and the reference lists for studies published up to August 2020. Original research articles must report a measure of ACD and included individuals with AD dementia, or prodromal AD (or MCI), or being at risk for AD. Data Synthesis: All studies covering preclinical, prodromal, and AD dementia were systematically reviewed. We intended to perform a meta-analysis of empirical studies on preclinical AD or prodromal AD (or MCI), to compare ACD between clinical groups. Due to the paucity of literature on preclinical AD, meta-analysis was only possible for prodromal AD (or MCI) studies. Results: We systematically reviewed 283 articles, and conducted a meta-analysis of 18 articles on prodromal AD (or MCI), showing that ACD was not significantly different between patients with amnestic and non-amnestic MCI (SMD = 0.09, p = 0.574); ACD was significantly poorer in amnestic MCI (SMD = -0.56, p = 0.001) and mild AD (SMD = -1.39, p < 0.001) than in controls; ACD was also significantly poorer in mild AD than in amnestic MCI (SMD = -0.75, p < 0.001), as well as poorer than in non-amnestic MCI (SMD = -1.00, p < 0.001). We also discuss key findings on ACD in AD, such as its neural and cognitive correlates. Conclusions and Implications: We propose that patients may be complaining of their initial subtle cognitive changes, but ACD would soon start to decrease. The individual would show mild anosognosia in the MCI stage, and severe anosognosia in dementia. The evaluation of ACD (comparing self-report to cognitive scores or to informant-report) could be useful to guide the clinician toward a timely diagnosis, and in trials targeting early-stage AD.

Test-retest reliability and minimal detectable change of the Contextual Memory Test in older adults with and without mild cognitive impairment

BACKGROUND

The ability to detect one's own memory capacity and develop strategies based on daily contexts is important for daily activities. The Contextual Memory Test (CMT) assesses self-awareness, self-efficacy, self-perception/evaluation of performance, recall, and strategy use that are associated with daily contexts, and could be a potentially suitable measurement for assessing memory and meta-memory in older adults with and without cognitive impairment. Nevertheless, the test-retest reliability and minimal detectable change (MDC) remain unknown in these individuals.

OBJECTIVE

The purpose of this study was to examine test-retest reliability and calculate MDC of the CMT in healthy older adults and those with mild cognitive impairment (MCI).

METHODS

Eighty-three participants completed the CMT twice with a one-month interval. Test-retest reliability was examined using intraclass correlation coefficient (ICC) in all seven domains of the CMT and the recognition subtest. The standard error of measurement (SEM) and MDC were calculated. The Bland-Altman analysis was performed to evaluate the degree of agreement between measurements.

RESULTS

The ICC of five domains (self-awareness, self-perception/evaluation of performance, immediate/delayed/total recall) and the recognition subtest were good to excellent (ICC = 0.63-0.94) in healthy and MCI participants and the MDC% were less than 30% The ICC of the other two domains (self-efficacy and total strategy use, TSS) were low (ICC = 0.07-0.59) and the MDC% exceeded 30%. The Bland-Altman analysis showed generally better performance in the 2nd than the 1st measurement in most CMT domains.

CONCLUSIONS

Our results revealed sufficient test-retest reliability and acceptable MDC in most CMT domains in healthy and MCI participants. Only the self-efficacy and TSS domains demonstrated low ICC and large MDC. Possible practice effects were found between repeated measurements. Clinicians should be cautious when evaluating self-efficacy and strategy use using the CMT in older adults. Further improvements are needed for these two domains.

Altered synaptic structure in the hippocampus in a mouse model of Alzheimer's disease with soluble amyloid-β oligomers and no plaque pathology

Background

Mounting evidence suggests that soluble oligomers of amyloid-β (oAβ) represent the pertinent synaptotoxic form of Aβ in sporadic Alzheimer’s disease (AD); however, the mechanistic links between oAβ and synaptic degeneration remain elusive. Most in vivo experiments to date have been limited to examining the toxicity of oAβ in mouse models that also possess insoluble fibrillar Aβ (fAβ), and data generated from these models can lead to ambiguous interpretations. Our goal in the present study was to examine the effects of soluble oAβ on neuronal and synaptic structure in the amyloid precursor protein (APP) E693Q (“Dutch”) mouse model of AD, which develops intraneuronal accumulation of soluble oAβ with no detectable plaques in AD-relevant brain regions. We performed quantitative analyses of neuronal pathology, including dendrite morphology, spine density, and synapse ultrastructure in individual hippocampal CA1 neurons.

Results

When assessing neuronal morphology and complexity we observed significant alterations in apical but not in basal dendritic arbor length in Dutch mice compared to wild type. Moreover, Dutch mice exhibited a significant decrease in dendritic arborization with a decrease in dendritic length and number of intersections at 120 μm and 150 μm from the soma, respectively. We next examined synaptic parameters and found that while there were no differences in overall synaptic structure, Dutch mice displayed a significant reduction in the post-synaptic density (PSD) length of synapses on mushroom spines, in comparison to wild type littermates.

Conclusion

The structural alterations to individual neurons in Dutch mice along with the changes in larger dendritic spines support the Aβ oligomer hypothesis, which postulates that the early cognitive impairments that occur in AD are attributed to the accumulation of soluble oAβ first affecting at the synaptic level with subsequent structural disturbances and cellular degeneration.

Electronic supplementary material

The online version of this article (doi:10.1186/1750-1326-9-41) contains supplementary material, which is available to authorized users.

Comparing memory and meta-memory abilities between children with acquired brain injury and healthy peers

This study compared visual memory and meta-memory abilities of children with ABI to that of healthy peers. Participants included 16 children (aged 13.55 ± 3.29 years) with moderate or severe ABI and 16 healthy children (aged 12.44 ± 3.24 years) with typical development. Children completed the Contextual Memory Test for Children (CMT-CH). The study group showed significantly lower immediate and delayed recall abilities. While the controls used the context for better memorizing, most of the children with ABI used rehearsals. In both groups better delayed recall correlated with the use of a more efficient strategy. Meta-memory should be an integral part of the assessment for children with ABI. Therapists should enhance child's self-awareness to his/her abilities and encourage the use of strategies (e.g. context) for memorizing in daily life.

Metacognitive deficits in frontotemporal dementia

OBJECTIVES

To investigate whether metacognitive impairments in self-awareness and self-monitoring occur in patients with frontotemporal dementia (FTD), particularly among those with prominent social and dysexecutive impairments.

METHODS

Patients diagnosed with FTD were divided by clinical subtype (social-dysexecutive (n = 12) aphasic (n = 15), and constituent subgroups of progressive non-fluent aphasia and semantic dementia) and compared with subjects with probable Alzheimer's disease (AD, n = 11) and age-matched healthy controls (n = 11). All subjects completed comprehensive behavioural ratings scales, which were compared with caregiver ratings. Subjects also rated their test performances in verbal associative fluency, word list learning, and memory task with comparisons made between actual and judged performance levels.

RESULTS

The FTD sample as a whole showed significantly less behavioural self-awareness and self-knowledge than the AD and healthy control samples. FTD patients with prominent social and dysexecutive impairments demonstrated the most extensive loss of self-awareness and self-knowledge, significantly overrating themselves in multiple social, emotional, and cognitive domains, and failing to acknowledge that any behavioural change had occurred in most areas. The remaining clinical samples showed select and minimal discrepancies. All clinical groups were significantly unaware of their apathy levels. Most FTD patients judged episodic cognitive test performance adequately, with partial difficulties observed in the socially impaired and progressive non-fluent aphasia subgroups.

CONCLUSIONS

FTD patients, particularly those with prominent social and dysexecutive impairments, exhibit profound metacognitive anosognosia that may represent a loss of self-awareness, self-monitoring, and self-knowledge, likely related to significant prefrontal pathophysiology. Other FTD clinical groups and AD patients showed less pervasive and more select metacognitive deficiencies.