Mini-Mental State Examination item scores as predictors of Alzheimer's disease: incidence data from the Kungsholmen Project, Stockholm

BACKGROUND: The present study examined the power of individual Mini-Mental State Examination (MMSE) items in predicting incidence of Alzheimer's disease (AD). In addition, 3-year longitudinal changes in MMSE items were contrasted between incident AD and nondemented persons. METHODS: A population-based group of very old adults, 75-95 years of age, were followed longitudinally. Of the original 327 participants, 32 were diagnosed with probable or possible AD after a 3-year follow-up interval and 189 remained nondemented. Cognitive performance was indexed by the individual item scores from the MMSE. These sample from multiple domains of cognitive functioning, including visuospatial skill, recent memory, orientation to time and place, language, and the ability to sustain attention. RESULTS: Items dealing with delayed episodic memory and orientation to time were significant predictors of AD incidence, independent of age, gender, and years of education, as determined by logistic regression analyses. Longitudinally, changes in performance were largest among individuals diagnosed as incident AD, although the magnitude of change across items was highly variable. In particular, decline was relatively small for the delayed memory item, whereas most other measures showed dramatic decline in performance among individuals with incident AD. CONCLUSIONS: Individual MMSE items, especially those with some type of episodic memory referent, were the best predictors of incident cases of AD. Moreover, MMSE items displayed differential rates of changes, particularly for the incident AD participants.     

Cognitive predictors of incident Alzheimer's disease: A prospective longitudinal study.

The present study examined whether cognitive variables measured at baseline could predict incident cases of Alzheimer's disease (AD) after a 3-year follow-up period. Twenty-six incident AD adults and 179 very old (M?=?83.5 years) adults without dementia participated in a population-based study. Cognitive performance was indexed by the Mini-Mental State Examination (MMSE) and multiple indices of memory and visuospatial and verbal performance. A logistic regression analysis that controlled for age, gender, and education indicated that MMSE scores were reliable indicators of who would develop AD. In addition, recall of organizable words, recognition of faces, and letter fluency were reliable predictors of subsequent dementia status after differences in MMSE performance were partialed out. Thus, although the MMSE is useful in predicting dementia, there is an additional advantage of assessing specific indices of cognitive functioning. Further, supportive episodic memory tasks may be more salient predictors of incident AD than tasks that offer less supportive encoding or retrieval conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mediators of long-term memory performance across the life span.

An individual-differences approach was used to examine the component processes that predict episodic long-term memory performance. A total of 301 participants ages 20-90 received a 7-hr cognitive battery across 3 days. Key constructs hypothesized to affect long-term memory function were assessed, including multiple measures of working memory and perceptual speed. Latent-construct, structural equation modeling was used to examine the relationship of these measures and age to different types of long-term memory tasks. Speed was a key construct for all 3 types of memory tasks, mediating substantial age-related variance; working memory was a fundamental construct for free and cued recall but not spatial memory. The data suggest that both speed and working memory are fundamental to explaining age-related changes in cognitive aging but that the relative contributions of these constructs vary as a function of the type of memory task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive correlates of mortality: Evidence from a population-based sample of very old adults.

The authors examined performance on memory, visuospatial, and verbal tasks and subsequent mortality in adults 75–95 years. The sample consisted of 178 living and 44 deceased participants. Mean-level analyses revealed mortality group differences for all domains of cognitive functioning. A Cox regression analysis, independent of age, gender, education, functional ability, and chronic illness, indicated that measures of word recognition and category fluency were significant predictors of mortality status. The results indicate a relationship between cognitive performance and subsequent mortality status in very old age and suggest that episodic memory and verbal skill may be particularly sensitive in predicting such effects. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Cultural variation in verbal versus spatial neuropsychological function across the life span.

Established culture-invariant measures are needed for cross-cultural assessment of verbal and visuospatial speed of processing and working memory across the life span. In this study, 32 younger and 32 older adults from China and from the United States were administered numerically based and spatially based measures of speed of processing and working memory. Chinese superiority on the numerically based tasks was found for younger adults. Age and increasing task demands diminished this cultural effect, as predicted by the framework proposed by D. C. Park, R. Nisbett, and T. Hedden (1999). However, the visuospatial measures of both working memory and speed of processing did not differ cross-culturally for either age group. The authors concluded that these visuospatial measures provide culture-invariant estimates of cognitive processes in East Asian and Western cultures, but that numerically based tasks show evidence of cultural and linguistic biases in performance levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual and spatial working memory are not that dissociated after all: A time-based resource-sharing account.

Examinations of interference between visual and spatial materials in working memory have suggested domain- and process-based fractionations of visuo-spatial working memory. The present study examined the role of central time-based resource sharing in visuo-spatial working memory and assessed its role in obtained interference patterns. Visual and spatial storage were combined with both visual and spatial on-line processing components in computer-paced working memory span tasks (Experiment 1) and in a selective interference paradigm (Experiment 2). The cognitive load of the processing components was manipulated to investigate its impact on concurrent maintenance for both within-domain and between-domain combinations of processing and storage components. In contrast to both domain- and process-based fractionations of visuo-spatial working memory, the results revealed that recall performance was determined by the cognitive load induced by the processing of items, rather than by the domain to which those items pertained. These findings are interpreted as evidence for a time-based resource-sharing mechanism in visuo-spatial working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of implicit and explicit knowledge in a case of psychogenic retrograde amnesia

There have been few studies of psychogenic amnesia based on a cognitive or neuropsychological framework. In the present study, a patient with acute onset of profound psychogenic retrograde amnesia was examined. Although her performance on neuropsychological tasks revealed intact anterograde memory, language functioning, visuospatial and constructional skills, and mental speed and flexibility, she displayed severe impairments on a variety of retrograde memory tasks. Furthermore, initial observations revealed inconsistencies between the patient's recall of semantic knowledge on direct questioning and her ability to demonstrate the use of this knowledge on indirect tasks. To test this formally, we devised an indirect remote knowledge task to examine a possible dissociation between explicit and implicit memory. Two healthy subjects matched for age, gender, education, occupation, and estimated IQ were also tested. As predicted, the findings demonstrate implicit knowledge despite impaired explicit recall for the same material.     

Influences of preclinical dementia and impending death on the magnitude of age-related cognitive deficits.

The authors examined the influence of preclinical dementia and impending death on the cross-sectional relationship between age and performance in tasks assessing episodic memory, visuospatial skill, and verbal fluency. Increasing age was associated with a general decrease in cognitive performance. In addition, those who were to be diagnosed with dementia had died by a 3-year follow-up, were older, and performed at a lower level than the remaining sample across all cognitive tasks at baseline. Nevertheless, removal of the preclinical dementia and impending death groups from the original sample affected the cross-sectional age-cognition relations relatively little. This pattern of findings suggests that the biological aging process exerts negative influences on cognitive functioning beyond those resulting from disease and mortality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting episodic memory performance in dementia: Is severity all there is?

Whether individual differences in demographic, psychometric, and biological domains can predict episodic memory in dementia was investigated. Mildly to moderately demented very old persons performed episodic memory tasks (free recall and recognition of slowly and rapidly presented random words, free and cued recall of organizable words, and recognition of dated and contemporary famous faces). A factor analysis of the memory measures yielded 2 factors, 1 indexing recall and 1 recognition. Controlling for severity of dementia, only 2 predictors contributed to performance: (a) Block Design (a marker of fluid intelligence) was positively related to recall, and (b) age was negatively related to recognition. Although these results are similar to data reported on predictors of episodic memory in normal aging, (a) the number of predictive variables appears to be reduced in dementia, and (b) age seems to affect recall and recognition differentially in normal aging and dementia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental change in working memory strategies: From passive maintenance to active refreshing.

Change in strategies is often mentioned as a source of memory development. However, though performance in working memory tasks steadily improves during childhood, theories differ in linking this development to strategy changes. Whereas some theories, such as the time-based resource-sharing model, invoke the age-related increase in use and efficiency of a strategy of active maintenance of memory traces, other theories, such as the task-switching model, do not mention strategy change. According to these models, either the cognitive load of the task or the duration of maintenance would account for recall performance. In the present study, we varied orthogonally these 2 factors. The results revealed that a different and unique factor affected recall performance at different ages: the duration of maintenance at age 6 and the cognitive load at age 7. As described by the task-switching model, younger children would not implement any maintenance activities while performing a concurrent task, their memory traces suffering from a time-based decay. This suggests that an increasing capacity of cognitive monitoring allows children to shift from this passive maintenance of memory traces to the active refreshing thereof at around the age of 7, reunifying the 2 current accounts of working memory development as 2 developmental stages. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

How are visuospatial working memory, executive functioning, and spatial abilities related? A latent-variable analysis.

This study examined the relationships among visuospatial working memory (WM) executive functioning, and spatial abilities. One hundred sixty-seven participants performed visuospatial short-term memory (STM) and WM span tasks, executive functioning tasks, and a set of paper-and-pencil tests of spatial abilities that load on 3 correlated but distinguishable factors (Spatial Visualization, Spatial Relations, and Perceptual Speed). Confirmatory factor analysis results indicated that, in the visuospatial domain, processing-and-storage WM tasks and storage-oriented STM tasks equally implicate executive functioning and are not clearly distinguishable. These results provide a contrast with existing evidence from the verbal domain and support the proposal that the visuospatial sketchpad may be closely tied to the central executive. Further, structural equation modeling results supported the prediction that, whereas they all implicate some degree of visuospatial storage, the 3 spatial ability factors differ in the degree of executive involvement (highest for Spatial Visualization and lowest for Perceptual Speed). Such results highlight the usefulness of a WM perspective in characterizing the nature of cognitive abilities and, more generally, human intelligence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of aging and IQ on item and associative memory.

The effects of aging and IQ on performance were examined in 4 memory tasks: item recognition, associative recognition, cued recall, and free recall. For item and associative recognition, accuracy and the response time (RT) distributions for correct and error responses were explained by Ratcliff's (1978) diffusion model at the level of individual participants. The values of the components of processing identified by the model for the recognition tasks, as well as accuracy for cued and free recall, were compared across levels of IQ (ranging from 85 to 140) and age (college age, 60–74 years old, and 75–90 years old). IQ had large effects on drift rate in recognition and recall performance, except for the oldest participants with some measures near floor. Drift rates in the recognition tasks, accuracy in recall, and IQ all correlated strongly. However, there was a small decline in drift rates for item recognition and a large decline for associative recognition and cued recall accuracy (70%). In contrast, there were large effects of age on boundary separation and nondecision time (which correlated across tasks) but small effects of IQ. The implications of these results for single- and dual-process models of item recognition are discussed, and it is concluded that models that deal with both RTs and accuracy are subject to many more constraints than are models that deal with only one of these measures. Overall, the results of the study show a complicated but interpretable pattern of interactions that present important targets for modeling. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Severity of cognitive impairment in Alzheimer's disease affects list learning using the California Verbal Learning Test (CVLT)

Impairment in list learning is considered a primary symptom of Alzheimer's disease (AD), yet there are no published reports examining the relationship between list learning and severity of cognitive impairment. We gave nine-item and 16-item versions of the California Verbal Learning Test (CVLT; Delis et al., 1987), a standardized shopping list assessment of memory, to 24 AD patients (mean age = 76.2 +/- 8.1; mean years of education = 13.8 +/- 2.4), who were stratified into four groups based on MMSE scores (mean = 16.0 +/- 5.6). ANOVAs revealed severity effects for total list learning (p < 0.001), the first trial (p < 0.001), the last trial (p < 0.001) and short- and long-delay recall measures. Most of these differences seemed due to floor effects. For example, the modal number of words recalled after a delay was 0 by subjects with MMSE scores below 21. Severity of cognitive impairment was associated with the proportion of intrusions such that the most severely demented subjects gave almost entirely intrusion responses. Surprisingly, list length did not significantly affect any of the free recall measures. Our results suggest that list learning and recall seem to be lost relatively early in AD. Measures of list recall like the CVLT may not be useful in tracking severity of cognitive impairment over time.     

The Generality of Working Memory Capacity: A Latent-Variable Approach to Verbal and Visuospatial Memory Span and Reasoning.

A latent-variable study examined whether verbal and visuospatial working memory (WM) capacity measures reflect a primarily domain-general construct by testing 236 participants in 3 span tests each of verbal WM. visuospatial WM, verbal short-term memory (STM), and visuospatial STM. as well as in tests of verbal and spatial reasoning and general fluid intelligence (Gf). Confirmatory' factor analyses and structural equation models indicated that the WM tasks largely reflected a domain-general factor, whereas STM tasks, based on the same stimuli as the WM tasks, were much more domain specific. The WM construct was a strong predictor of Gf and a weaker predictor of domain-specific reasoning, and the reverse was true for the STM construct. The findings support a domain-general view of WM capacity, in which executive-attention processes drive the broad predictive utility of WM span measures, and domain-specific storage and rehearsal processes relate more strongly to domain-specific aspects of complex cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The subcortical dementia of Huntington's disease

An effect size analysis incorporating meta-analytic principles was used to review neuropsychological findings in patients with Huntington's disease (HD). Studies dating back to 1980 were gathered and the neuropsychological test results from a total of 760 patients with HD, and 943 healthy controls were synthesized using effect size analyses. The results indicate that patients with HD are most deficient on tests of delayed recall, followed by performance on measures of memory acquisition, cognitive flexibility and abstraction, manual dexterity, attention/concentration, performance skill, and, finally, verbal skill. However, patients with HD display core deficits in fronto-subcortical circuits that give rise to a multitude of cognitive deficits. A rank-order list of specific neuropsychological tasks and test variables in order of sensitivity to HD is also provided to aid in the interpretation of the quantitative results.     

Examining the relationships among item recognition, source recognition, and recall from an individual differences perspective.

The authors of the current study examined the relationships among item-recognition, source-recognition, free recall, and other memory and cognitive ability tasks via an individual differences analysis. Two independent sources of variance contributed to item-recognition and source-recognition performance, and these two constructs related differentially to other memory and cognitive ability constructs. The results are in accordance with a dual-process theory of memory retrieval in which a familiarity process can support judgments of previous occurrence and a more strategic recollection process is needed for controlled search of long-term memory. Furthermore, the authors offer additional evidence in favor of a dual-process model by showing validity for these two unique sources of variance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of contextual organization on spatial memory of middle-aged and older women.

Examined the memory performance of 20 women aged 31–59 yrs and 20 aged 65–85. Ss reconstructed spatial arrays, replacing miniature objects in either a contextually organized panorama or a noncontextually organized bank of cubicles. Performance of the middle-aged Ss did not differ between the 2 tasks. Older Ss performed as well as middle-aged Ss in the panorama task, but in the cubicles task their scores were lower than in the panorama task and lower than those of the younger Ss in the cubicles task. Results support the conclusion that in a task that allows the use of existing contextual organization as a memory aid, age differences in memory performance disappear. Age differences may be limited to tasks that remove previously learned relationships between items (as in recall of lists of unrelated words), requiring Ss to invent an organizational structure to facilitate recall. Though such tasks predominate in research, they probably do not represent the memory problems met in everyday life, especially by older adults. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and memory for action events: The role of familiarity.

Two experiments with young and elderly adults explored age-related memory differences for performed action events varying in familiarity. Memory for similar items encoded verbally was also assessed. The findings demonstrated that type of encoding and item-familiarity influenced immediate as well as delayed free recall in both age groups. Highest recall performances were found for familiar performed items. Both factors affected memory performance separately and did not compensate for each other, either in immediate or in delayed free recall. These findings held true regardless of age. Performed actions were especially resistant against forgetting, indicating that, besides the amount of items encoded, performing while encoding especially enhances the retention of knowledge. Recognition memory also varied with type of encoding. Age-related memory differences were found in all free recall tests irrespective of item familiarity and type of encoding, favoring young adults. No age-related memory differences were found in the recognition test. Because of possible ceiling effects, this finding must be treated with care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic architecture of learning and delayed recall: A twin study of episodic memory.

Objective: Although episodic memory is often conceptualized as consisting of multiple component processes, there is a lack of understanding as to whether these processes are influenced by the same or different genetic determinants. The aim of the present study was to utilize multivariate twin analyses to elucidate the degree to which learning and delayed recall, two critical measures of episodic memory performance, have common or different genetic and environmental influences. Method: Participants from the Vietnam Era Twin Study of Aging (314 monozygotic twin pairs, 259 dizygotic twin pairs, and 47 unpaired twins) were assessed using the second edition of the California Verbal Learning Test. Mean age at the time of the evaluation was 55.4 years (SD = 2.5). Results: Model fitting revealed the presence of a higher-order latent factor influencing learning, short- and long-delay free recall, with a heritability of .36. The best-fitting model also indicated specific genetic influences on learning, which accounted for 10% of the overall variance. Given that learning involves the acquisition and retrieval of information, whereas delayed recall involves only retrieval, we conclude that these specific effects are likely to reflect genes that are specific to acquisition processes. Conclusion: These results demonstrate that even in nonclinical populations, it is possible to differentiate component processes in episodic memory. These different genetic influences may have implications for gene association studies, as well as other genetic studies of cognitive aging and disorders of episodic memory such as Alzheimer's disease or mild cognitive impairment. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Can training in a real-time strategy video game attenuate cognitive decline in older adults?

Declines in various cognitive abilities, particularly executive control functions, are observed in older adults. An important goal of cognitive training is to slow or reverse these age-related declines. However, opinion is divided in the literature regarding whether cognitive training can engender transfer to a variety of cognitive skills in older adults. In the current study, the authors trained older adults in a real-time strategy video game for 23.5 hr in an effort to improve their executive functions. A battery of cognitive tasks, including tasks of executive control and visuospatial skills, were assessed before, during, and after video-game training. The trainees improved significantly in the measures of game performance. They also improved significantly more than the control participants in executive control functions, such as task switching, working memory, visual short-term memory, and reasoning. Individual differences in changes in game performance were correlated with improvements in task switching. The study has implications for the enhancement of executive control processes of older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)