Appraisal of Memory Functioning and Memory Performance in Healthy Ageing and Early-Stage Alzheimer's Disease

ABSTRACT

Background/Aims: To compare memory evaluations in healthy older people and people with Alzheimer's disease (AD) and present standardised individual and dyadic methods for classifying degree of memory awareness in the participants with dementia. Methods: Cross-sectional study evaluating awareness of memory functioning and performance and providing normative data for healthy individuals and couples, together with comparison data from people with AD. Results: As a group, older people are reasonably accurate raters of their own memory functioning and performance, although considerable individual differences can be observed, and control dyads show good comparative accuracy. Comparing normative data from the control group to data from participants with AD confirms that significant overestimation is a frequent feature among people with dementia, with approximately two-thirds showing this pattern, although significant under-estimation is also reliably observed in a small proportion of people with dementia. Different types of measure elicit different profiles of memory awareness in participants with dementia. Conclusion: Normative data from older individuals and couples provides useful percentile-based indices for determining level of memory awareness in people with dementia.     

Lack of awareness of neuropsychological deficit in cerebral small vessel disease: The relationship with executive and episodic memory functions

A common cause of neuropsychological impairment in older adults is cerebral small vessel disease (SVD), but little is known as to whether lack of awareness of neuropsychological impairment is a feature of this clinical condition. In this study, we investigated awareness deficits in a well‐phenotyped population of patients with SVD (n= 45; 21 with defined concomitant neuropsychological impairment) and made comparisons with 24 Alzheimer's disease (AD) patients and a further 80 control participants. Awareness of performance on a range of neuropsychological measures was examined based on the Brief Memory and Executive Test Battery (BMET) (Brookes, Hannesdottir, Lawrence, Morris, & Markus, 2012 ), exploring the relationship between awareness and memory and executive function. The results revealed significant awareness deficits in both the SVD and AD groups. When splitting the SVD group into those with or without concomitant neuropsychological impairment, only those with neuropsychological impairment showed reduced awareness. For the SVD group, executive function was significantly correlated with awareness but memory was not. By comparison, memory was significantly correlated with awareness in the AD group, with executive function showing a trend but remaining non‐significant. The results show that lack of awareness of deficit is a clinical feature of SVD and indicate that there are distinct neuropsychological associations with awareness deficit for SVD and AD.     

Everyday‐like memory for objects in ageing and Alzheimer's disease assessed in a visually complex environment: The role of executive functioning and episodic memory

To investigate everyday memory, more and more studies rely on virtual‐reality applications to bridge the gap between in situ approaches and laboratory settings. In this vein, the present study was designed to assess everyday‐like memory from the virtual reality‐based Human Object Memory for Everyday Scenes (HOMES) test (Sauzéon et al., 2012 , Exp. Psychol., 59, 99) in ageing and in Alzheimer's disease (AD). Two aims motivated this study: the first was to assess multiple processes of episodic memory (EM) functioning embedded within contexts closely related to real life in ageing and AD using the multi‐trial free‐recall paradigm, and the second aim was to evaluate the mediating effects of executive functioning (EF), EM, and subjective memory complaints (SMCs) on age differences in the HOMES measures and in AD. To this end, the HOMES test and neurocognitive tests of EF and EM were administered to 23 younger adults, 23 older adults, and 16 patients with AD. The results were: firstly, compared to young adults, elderly adults presented only free‐recall decline that almost disappeared in recognition condition whereas AD patients exhibited a poor clustering, learning, and recognition performance, and also a high amount of false recognition; secondly, age differences as well as AD related deficits on the HOMES test were mediated by both memory and EF measure while those observed on false memory indices were only mediated by EM measure; thirdly, the HOMES indices are related to SMCs even when episodic or EF measures are controlled. Overall, the results supported the fact that the VR‐based memory test is an appropriate device to capture age‐related differences as well as the AD effect with respect to both in situ and laboratory settings.     

Cognitive impairment in dementia: correlations with atrophy and cerebrovascular disease quantified by magnetic resonance imaging

This project assessed the contributions of atrophy and cerebrovascular disease (CVD) to cognitive impairment in dementia. Ten individuals with clinically diagnosed pure VaD were age-, sex-, and education-matched to individuals with AD. All participants underwent neuropsychological testing and MRI which were processed to generate quantitative indices of atrophy and CVD. A linear regression, including thalamic lesion and vCSF volumes, predicted cognitive status (R2 = .74; p < .0005). Three VaD subgroups were identified: thalamic lesion (n = 4), hippocampal infarcts (n = 3), and other (n = 3). In participants without thalamic lesion, vCSF predicted general cognition (R2 = .48), hippocampal atrophy predicted memory impairment (R2 = .33), and white matter lesions predicted executive dysfunction (R2 = .48). Both atrophy and CVD burden correlated highly with cognitive impairment and should be simultaneously assessed in studies of brain-behaviour relations in dementia.     

Relationship of cognitive strategy use to prospective memory performance in a diverse sample of nondemented older adults with varying degrees of cognitive complaints and impairment

Although older adults typically have better performance on prospective memory (PM) tasks carried out in naturalistic settings, a paucity of research directly assesses older adults’ use of compensatory strategies on such tasks. The current study investigates external memory strategy use during performance of a clinical PM test that features both short-term (in laboratory) and long-term (out of laboratory) subtasks (i.e., the Royal Prince Alfred Prospective Memory Test – RPA-ProMem. Nondemented, community-dwelling older adults (n = 214; mean age = 80.5; 68.2% female; 39.7% non-white) with mild cognitive impairment, subjective cognitive decline, and healthy controls completed the RPA-ProMem while external strategy use was permitted and recorded. Overall, participants utilized external strategies 41% of the time on the RPA-ProMem. Increased utilization of external memory strategies was significantly associated with better PM performance. Additionally, better performance on executive functioning tasks was associated with increased use of external memory strategies. Results are discussed in relation to how memory strategy use can be enhanced to improve everyday memory ability in older adults at risk for dementia.     

Metacognitive awareness of event-based prospective memory

This study examined people’s ability to predict and postdict their performance on an event-based prospective memory task. Using nonfocal cues, one group of participants predicted their success at finding animal words and a different group predicted their ability to find words with a particular syllable in it. The authors also administered a self-report questionnaire on everyday prospective and retrospective memory failures. Based on the different strategies adopted by the two groups and correlations among the dependent variables, the authors concluded that people do have a basic awareness of their prospective memory abilities, but that this awareness is far from accurate. The importance of metamemory concerning one’s prospective memory is discussed in terms of how it influences the strategies that people might choose for actually completing their various everyday intentions.     

Episodic and semantic memory in early versus late onset Alzheimer's disease.

The aim of this study was to replicate and extend previous work demonstrating selective impairment of semantic, but not episodic, memory in late versus early onset Alzheimer's disease (AD). Measures of episodic and semantic memory were administered to 12 pairs of patients; early (less than or equal to 62) and late (greater than or equal to 68) onset pairs were matched on dementia severity and education. As hypothesized, the groups did not differ on the three episodic memory measures but did on two of three semantic memory measures. In conjunction with prior research, these findings indicate that late onset AD is characterized by more profound impairment on measures of semantic processing.     

Can cognitive and behavioural disorders differentiate frontal variant-frontotemporal dementia from Alzheimer's disease at early stages?

Frontal variant-Frontotemporal dementia (fvFTD) and Alzheimer's disease (AD) patients matched for severity of dementia at the Clinical Dementia Rating (CDR) received neuropsychological testing in order to explore if the dysexecutive disorder might characterise fvFTD at early stage, when AD is dominated by the episodic memory defect. We also determined if the behavioural syndrome was more severe in fvFTD than AD, and if specific patterns of behavioural symptoms could differentiate the two types of dementia, using the Neuropsychiatry Inventory (NPI). AD patients performed worse than fvFTD not only in memory but also in executive tasks. Apathy and eating disorders proved to be more severe or frequent in fvFTD even if the two groups did not differ in the total NPI score. CDR score significantly correlated with the NPI score in fvFTD and with the MMSE in AD. Our data confirm that the memory disorders may differentiate the two types of dementia; however, the dysexecutive syndrome is as severe, and even more severe in AD. The severity of the behavioural syndrome is comparable in the two groups but the nature of the behavioural disorders may vary to some extent. We conclude that AD dementia at early stage is a behavioural-cognitive syndrome, while in fvFTD the behavioural disorders appear when the cognitive deficit is still relatively mild.     

主观记忆减退老年人情节记忆的行为表现及其脑机制

情节记忆是个体对特定时间,特定地点所经历的特定事件的记忆.主观报告情节记忆下降是主观记忆减退老年人最典型的表现.与健康对照组老年人相比, 主观记忆减退老年人情节记忆下降的速率更快, 罹患老年性痴呆的风险更高, 但其情节记忆加工的脑机制尚不明确.前人研究提示, 主观记忆减退老年人在外在记忆行为尚未出现损伤的情况下, 其大脑情节记忆相关脑区的神经活动已经出现异常.探究主观记忆减退的记忆神经环路关键节点和路径的异常, 揭示神经环路在老年痴呆发生发展中的变化规律, 对深入理解老年痴呆的发病机制有重要的科学意义.同时, 主观记忆减退老年人作为特殊的记忆损伤群体, 对其神经环路的深入探究, 也必将为揭示人类记忆的神经机制做出独特的贡献.     

Exploring mechanisms that affect retrograde memory for public events in amnestic mild cognitive impairment: A longitudinal update

Here, we examined mechanisms that affect retrograde memory in amnestic mild cognitive impairment (a-MCI) as a function of longitudinal clinical outcome. 8 a-MCI who converted to Alzheimer's dementia (AD) during the subsequent 3-year follow-up (converter a-MCI) and 10 a-MCI who remained clinically stable during the same period (stable a-MCI) were compared at the baseline evaluation (i.e., when they were diagnosed as a-MCI) using a remote memory questionnaire for public events that allows disentangling the differential contribution of storage and retrieval mechanisms to performance accuracy. Results suggest that deficits in remote memory are primarily explained by impaired retrieval abilities in stable a-MCI and by impaired storage in converter-to-AD a-MCI. This distinction between retrograde amnesia due to defective trace utilisation in stable a-MCI and trace storage in converter a-MCI is consistent with the temporal unfolding of declining anterograde memory over the course of disease progression to AD.     

Discrepancy processes in prospective memory retrieval

Discrepancy processes may be helpful in noticing prospective memory targets (McDaniel, Guynn, Einstein, & Breneiser, 2004). We manipulated the discrepancy of prospective memory targets from the processing coherence established by the ongoing task by preexposing nontarget items in the ongoing task either five times (high discrepancy) or two times (low discrepancy). Prospective memory performance was significantly better in the high-discrepancy group than in the low-discrepancy group. These results support a discrepancy view of prospective remembering.     

Efficacy of a group memory training method for older adults based on visualization and association techniques: A randomized,controlled trial with a placebo group

The aim of this trial has been to determine the efficacy of a group memory training method. The experimental group was compared to a placebo group (health education) or to a control group (waiting list). Forty‐five adults between the ages of 60 and 70 years (M = 66.9) were recruited by placing notices in senior citizen community centres, which encouraged people with memory problems to participate in the study. Data were collected at baseline, 1 week, and 6 months after the intervention. The efficacy of the training was evaluated by measures of objective and subjective everyday memory performance. After intervention, the experimental group participants showed an increase in objective memory performance (d = 1.95). The effect size was even higher at 6 months after intervention (d = 2.88). Further, their subjective experience related to everyday memory slips decreased (d = ?0.52). The memory training method was effective in improving everyday memory in older people with some cognitive decline. Copyright © 2009 John Wiley & Sons, Ltd.     

The usefulness of the story recall test in patients with mild cognitive impairment and Alzheimer's disease

ABSTRACT

Background: The story recall test (SRT) is one of the most reliable neuropsychological assessments for evaluating verbal memory function in order to distinguish between individuals with normal aging, mild cognitive impairment (MCI), and Alzheimer's disease (AD). The SRT is analogous to the logical memory test in Wechsler Memory Scale-III, which has recently been developed and standardized to apply to older adults in Korea. The purpose of this study was to examine the usefulness of the SRT and its ability to discriminate between normal cognitive aging and patients with MCI or AD. Methods: One hundred and twelve patients with MCI, 97 patients with AD, and 53 healthy elderly adults participated in this study. The SRT was compared with the Clinical Dementia Rating (CDR), Global Deterioration Scale (GDS), Korean version of the Mini Mental State Examination (K-MMSE), and the Korean version of the Hopkins Verbal Learning Test (K-HVLT). Results: The SRT was well-correlated with the dementia rating scales and the K-HVLT. However, the sensitivity and specificity of the SRT was greatly influenced by the level of education of the subjects. Conclusions: The SRT is a sensitive measurement of verbal memory function that can be used in clinical settings to discriminate between normal memory functioning and the very early and moderate stages of AD in a Korean population. Moreover, it is important to recognize that the SRT is more appropriate for subjects with a high level of education rather than a low level of education to differentiate normal cognitive aging from MCI or AD.     

The occurrence of different intrusive errors in patients with Alzheimer's disease, multiple cerebral infarctions, and major depression.

Recent evidence suggests that specific types of intrusive errors may occur more often in the protocols of Alzheimer's disease (AD) patients than in those of patients diagnosed with other types of dementia. Using the FULD Object Memory Evaluation, we documented the occurrence of five qualitatively different types of intrusive errors for mildly and moderately impaired patients with AD and multiple cerebral infarctions (MCI). Depressed and normal elderly controls were also studied. Despite an equivalent degree of impairment on a broad array of neuropsychological measures, mildly impaired AD patients evidenced greater deficits on a measure tapping retrieval from semantic memory and demonstrated a higher occurrence of specific types of intrusive errors relative to their mildly impaired MCI counterparts. Further, both of these measures were highly correlated, suggesting that these indices may be particularly sensitive to semantic dysfunction associated with early AD.     

Impaired Consonant Trigrams Test (CTT) performance relates to everyday working memory difficulties in children with Autism Spectrum Disorders

Individuals with Autism Spectrum Disorders (ASD) often struggle with complex tasks, such as those requiring divided attention (simultaneously completing two independent tasks) that also place high demands on working memory. Prior research shows that divided attention is impaired in adults and children with ASD and is related to ASD and comorbid attention deficit/hyperactivity disorder (ADHD) symptoms, but the impact on everyday functioning is unclear. Because ADHD symptoms are associated with poor divided attention and working memory performance in children with ASD, we also examined ADHD symptoms as moderators of divided attention performance. We examined performance on the Consonant Trigrams Test (CTT) between high-functioning 8- to 13-year-olds with ASD (n?=?28) and typically developing controls (n?=?18) matched on age and IQ. In the ASD group, we also correlated performance with ADHD symptoms and behavior ratings of everyday working memory. CTT performance in children with ASD was significantly worse than in matched controls. A significant correlation between CTT performance and everyday working memory was observed, but CTT performance was not related to comorbid ADHD symptoms in the ASD group. Divided attention with high working-memory demands is a relative weakness in children with high-functioning ASD; this weakness relates to everyday functioning, and it is independent from ADHD symptoms. That ADHD symptoms are not associated with divided attention performance is inconsistent with one prior investigation, which likely results from using different divided attention tasks in the two studies.     

Strategic value-directed learning and memory in Alzheimer's disease and behavioural-variant frontotemporal dementia

In healthy adults, the ability to prioritize learning of highly valued information is supported by executive functions and enhances subsequent memory retrieval for this information. In Alzheimer's disease (AD) and behavioural-variant frontotemporal dementia (bvFTD), marked deficits are evident in learning and memory, presenting in the context of executive dysfunction. It is unclear whether these patients show a typical memory bias for higher valued stimuli. We administered a value-directed word-list learning task to AD (n = 10) and bvFTD (n = 21) patients and age-matched healthy controls (n = 22). Each word was assigned a low, medium or high point value, and participants were instructed to maximize the number of points earned across three learning trials. Participants’ memory for the words was assessed on a delayed recall trial, followed by a recognition test for the words and corresponding point values. Relative to controls, both patient groups showed poorer overall learning, delayed recall and recognition. Despite these impairments, patients with AD preferentially recalled high-value words on learning trials and showed significant value-directed enhancement of recognition memory for the words and points. Conversely, bvFTD patients did not prioritize recall of high-value words during learning trials, and this reduced selectivity was related to inhibitory dysfunction. Nonetheless, bvFTD patients showed value-directed enhancement of recognition memory for the point values, suggesting a mismatch between memory of high-value information and the ability to apply this in a motivationally salient context. Our findings demonstrate that value-directed enhancement of memory may persist to some degree in patients with dementia, despite pronounced deficits in learning and memory.     

Word List Generation Performancein Alzheimer's Disease and Vascular Dementia

Word list generation (WLG) was examined among clinical samples of individuals with Alzheimer's disease (AD) (n = 73) or ischemic vascular dementia (IVD) (n = 85), equivalent in age, education, current and estimated premorbid intellectual functioning, and proportion of men and women. The AD group performed significantly better than did the IVD group on lexical WLG, and a trend was observed indicating superior performance among the IVD group on categorical WLG. Within-groups, comparisons of group means, and profile analyses of individual performance patterns all indicated that persons with AD demonstrated a lexical > categorical pattern significantly more often than did IVD participants. The absolute difference in average performance between the AD and IVD groups on lexical and categorical WLG was small; the findings, however, generally support the clinical utility of the lexical > categorical WLG pattern in the differential diagnosis of AD and IVD. The patterns of performance support the presence of relative impairment in semantic processing among the individuals with AD and global deficits in retrieval and processing speed in individuals with IVD.     

The cholinergic neurotransmitter system in human memory and dementia: A review

The present paper reviews three types of evidence implicating the role of acetylcholine in human memory and dementia: (1) neuropathological evidence that the cholinergic transmitter system is depleted in Alzheimer-type dementia; (2) psychopharmacological studies that have employed “cholinergic blockade” as a model of cholinergic depletion; and (3) clinical studies of cholinergic “replacement” therapy in Alzheimer-type dementia. The evidence that the cholinergic system is depleted in Alzheimer-type dementia has been complemented by the finding that cholinergic blockade in healthy subjects causes a substantial learning (or “acquisition”) deficit in episodic memory. The overall results of studies of replacement therapy have generally been disappointing, but a few have reported benefits in recall and recognition tests. The role of the cholinergic system in many aspects of memory remains to be elucidated; but it seems unlikely that cholinergic depletion accounts for all aspects of the memory disorder in Alzheimer-type dementia, and possibly the depletions of other neurotransmitters also contribute to the memory impairment.     

The free and cued selective reminding test for predicting progression to Alzheimer's disease in patients with mild cognitive impairment: A prospective longitudinal study

Amnestic mild cognitive impairment (aMCI) patients carry a greater risk of conversion to Alzheimer's disease (AD). Therefore, the International Working Group (IWG) on AD aims to consider some cases of aMCI as symptomatic prodromal AD. The core diagnostic marker of AD is a significant and progressive memory deficit, and the Free and Cued Selective Reminding Test (FCSRT) was recommended by the IWG to test memory in cases of possible prodromal AD. This study aims to investigate whether the performance on the FCSRT would enhance the ability to predict conversion to AD in an aMCI group. A longitudinal study was conducted on 88 aMCI patients, and neuropsychological tests were analysed on the relative risk of conversion to AD. During follow‐up (23.82 months), 33% of the aMCI population converted to AD. An impaired FCSRT TR was significantly associated with the risk of conversion to dementia, with a mean time to conversion of 25 months. The FCSRT demonstrates utility for detecting AD at its prodromal stage, thus supporting its use as a valid clinical marker.