Correlation between functional mobility and cognitive performance in older adults with cognitive impairment

Association between cognitive impairment and gait performance occurs in mild cognitive impairment (MCI) and Alzheimer‘s disease (AD), particularly under “divided attention” conditions, leading to a greater risk of falls. We studied 36 controls, 42 MCI, and 26 mild AD patients, using the Timed Up-and-Go test (TUG) under four conditions: TUG single – TUG1; TUG cognitive – TUG2; TUG manual –TUG3; TUG cognitive and manual – TUG4. Cognition was assessed using the MMSE, SKT, Exit25, and TMT (A and B). We found significant correlations between cognitive scores and TUG2 [r values (MMSE: –0.383, TMT-A: 0.430, TMT-B: 0.386, Exit25: 0.455, SKT: 0.563)] and TUG4 [(MMSE: –0.398, TMT-A: 0.384, TMT-B: 0.352,Exit25: 0.466, SKT: 0.525)] in the AD group, and between all TUG modalities and SKT in MCI and AD. Our results revealed that functional mobility impairment in cognitive dual tasks correlated to cognitive decline in AD patients and to attention and memory impairment in MCI.     

Dissociations in Visual Attention Deficits among Persons with Mild Cognitive Impairment

ABSTRACT

Impairments in visual attention and visual information processing have been identified as part of the neuropsychological features of Alzheimer's disease (AD), even in its earliest stages. There is increasing recognition that these deficits may be selective rather than global, with some attentional subtypes being more vulnerable than others. The few studies that have investigated attentional deficits in mild cognitive impairment (MCI), a putatively prodromal phase of AD, have not satisfactorily addressed the possible selectivity in attentional deficits in MCI. This study examined potential dissociations in visual attention deficits in MCI using a measure that assesses simple, divided, and selective attention. The results indicated a hierarchy of attentional impairments, with divided attention being the most affected and simple attention the least. Among participants with MCI, 53% showed evidence of impairment in divided attention compared to 19% of controls (OR = 4.81, p < .001). Poorer visual attention was also associated with poorer overall cognitive status. The implications of these findings for early identification of MCI, prevention of functional decline in MCI, and delay/reversal of cognitive degradation in MCI are discussed.     

A computerized test for the assessment of mild cognitive impairment subtypes in sentence processing

This study examines thesentence processing ability of mild cognitive impairment (MCI) subtypes. In addition to standard MCI neuropsychological tests, an experimental approach was applied to assess language. 133 people (93 MCI/40 controls) participated in novel computerized sentence processing tasks. Results presented statistically significant differences between MCI/controls andMCI subtypes (ANOVA):(a) duration F(2,92) = 19.259,p < .001) in sentence construction; (b) correct answers (F(2, 89) = 8.560,p < .001) and duration (F2,89) = 15.525,p < .001)in text comprehension; (c) correct answers (F(2, 92) = 8.975,p < .001) andduration (F(2, 92) = 4.360,p = .016) in metaphoric sentences comprehension; (d) correct answers (F(2, 92) = 12.836,p < .001) andduration (F(2, 92) = 10.974,p < .001) in verb form generation. Subtle changes in MCIsubtypes could affect sentence processing and provide useful information for cognitive decline risk estimation and screening purposes.     

The free and cued selective reminding test: Validation for mild cognitive impairment and Alzheimer's disease

The International Working Group on Alzheimer's disease (AD) suggested the free and cued selective reminding test (FCSRT) to assess memory, as it showed high sensitivity and specificity in the differentiation of AD from healthy controls and other dementias. The FCSRT involves the use of selective reminding with semantic cueing in memory assessment. This study aims to validate the FCSRT for mild cognitive impairment (MCI) and AD through the analysis of the diagnostic accuracy and the suggestion of cut‐off scores. Patients were classified into two groups according to standard criteria: MCI (n = 100) and AD (n = 70). A matched control group (n = 101) of cognitively healthy subjects was included. The reliability and the validity of the FCSRT were analysed on the immediate (IR) and delayed (DR) recalls. The Cronbach's alpha was 0.915 for the IR and 0.879 for the DR. The total recall measures revealed good areas under the curve for MCI (IR: .818; DR: .828) and excellent for AD (IR: .987; DR: .991). Furthermore, the MCI group was subdivided with respect to a non‐similar/similar AD pattern of impairment, with almost half of the subjects showing an AD‐like decline. This analysis represents a novel contribution regarding the properties of the FCSRT in illustrating the heterogeneity of MCI at baseline. The FCSRT has proved to be a very useful tool in the characterization of the memory impairment of the AD spectrum.     

A comparison of the diagnostic accuracy of the AD8 and BCAT-SF in identifying dementia and mild cognitive impairment in long-term care residents

We compared the accuracy of the Brief Cognitive Assessment Tool—Short Form (BCAT-SF) and AD8 in identifying mild cognitive impairment (MCI) and dementia among long-term care residents. Psychometric analyses of 357 long-term care residents (n = 228, nursing home; n = 129, assisted living) in Maryland referred for neuropsychological evaluation evidenced robust internal consistency reliability and construct validity for the BCAT-SF. Furthermore, hierarchical logistic regression and receiver operating characteristic curve analyses demonstrated superior predictive validity for the BCAT-SF in identifying MCI and dementia relative to the AD8. In contrast, previously reported psychometric properties or cut scores for the AD8 could not be cross-validated in this long-term care sample. Based on these findings, the BCAT-SF appears to be a more reliable and valid screening instrument than the AD8 for rapidly identifying MCI and dementia in long-term care residents.     

Investigating the influence of an effort–reward interaction on cognitive fatigue in individuals with multiple sclerosis

This study examined whether an alteration in the effort–reward relationship, a theoretical framework based on cognitive neuroscience, could explain cognitive fatigue. Forty persons with MS and 40 healthy age- and education-matched cognitively healthy controls (HC) participated in a computerized switching task with orthogonal high- and low-demand (effort) and reward manipulations. We used the Visual Analog Scale of Fatigue (VAS-F) to assess subjective state fatigue before and after each condition during the task. We used mixed-effects models to estimate the association and interaction between effort and reward and their relationship to subjective fatigue and task performance. We found the high-demand condition was associated with increased VAS-F scores (p < .001), longer response times (RT) (p < .001) and lower accuracy (p < .001). The high-reward condition was associated with faster RT (p = .006) and higher accuracy (p = .03). There was no interaction effect between effort and reward on VAS-F scores or performance. Participants with MS reported higher VAS-F scores (p = .02). Across all conditions, participants with MS were slower (p < .001) and slower as a function of condition demand compared with HC (p < .001). This behavioural study did not find evidence that an effort–reward interaction is associated with cognitive fatigue. However, our findings support the role of effort in subjective cognitive fatigue and both effort and reward on task performance. In future studies, more salient reward manipulations could be necessary to identify effort–reward interactions on subjective cognitive fatigue.     

Transcranial direct-current stimulation enhances implicit motor sequence learning in persons with Parkinson's disease with mild cognitive impairment

Implicit motor sequence learning (IMSL) is affected in Parkinson's disease (PD). Research in healthy young participants shows the potential for transcranial direct-current stimulation (tDCS) over the primary motor cortex (M1) to enhance IMSL. In PD, only null effects have been reported to date. We determined concurrent, short-term, and long-term effects of anodal tDCS over M1 on IMSL, as measured by the serial reaction time (SRT) task, in persons with PD with mild cognitive impairment (MCI). Concurrent (anodal/sham tDCS intervention during the SRT task), short-term (5 min post-intervention), and long-term (1 week post-intervention) effects on IMSL were evaluated in persons with idiopathic PD (Hoehn and Yahr stage II-III) with MCI. Results of 11 persons with PD (8 men and 3 women; mean age = 77.1 years; mean disease duration = 7.7 years) showed significant IMSL in the anodal (p = .016), but not in the sham tDCS condition (p = .937). Post-hoc analyses showed that IMSL reached statistical significance at 1 week post-intervention (p < .001). Anodal tDCS over M1 exerted beneficial effects on IMSL in persons with PD with MCI, in particular one week post-intervention. Our study is the first to report a positive effect of tDCS on IMSL in PD. Further research should include a larger, more cognitively diverse sample and additional follow-up periods.     

Association Between Gait and Dual Task With Cognitive Domains in Older People With Cognitive Impairment

The authors investigated whether impaired gait and dual-task performances are associated with specific cognitive domains among older people with preserved cognition (PC), mild cognitive impairment (MCI), and mild Alzheimer's disease (AD). The sample comprised 40 older adults with PC, 40 with MCI, and 38 with mild AD. The assessment consisted of gait (measured by 10-m walk test and Timed Up and Go Test [TUGT]), dual task (measured by TUGT associated with a cognitive-motor task of calling a phone number), and cognition (domains of the Addenbrooke Cognitive Examination–Revised and Frontal Assessment Battery [FAB]). For data analysis, the Pearson product-moment correlation and the backward stepwise linear regression were conducted. Language, fluency, and visuospatial domains predicted the 10-m walk test measure specifically in PC, MCI, and AD groups. Only the visuospatial domain was independently associated with the TUGT measure in the MCI and AD groups. FAB score, language domain, and FAB score and fluency domain were the strongest predictors for the isolated cognitive-motor task measure in the PC, MCI, and AD groups, respectively. The visuospatial domain was independently associated with the dual-task test measure in all 3 groups. The study findings demonstrate the influence of specific cognitive domains in daily mobility tasks in people with different cognitive profiles.     

Differential Memory Test Sensitivity for Diagnosing Amnestic Mild Cognitive Impairment and Predicting Conversion to Alzheimer's Disease

ABSTRACT

Episodic memory is the first and most severely affected cognitive domain in Alzheimer's disease (AD), and it is also the key early marker in prodromal stages including amnestic mild cognitive impairment (MCI). The relative ability of memory tests to discriminate between MCI and normal aging has not been well characterized. We compared the classification value of widely used verbal memory tests in distinguishing healthy older adults (n = 51) from those with MCI (n = 38). Univariate logistic regression indicated that the total learning score from the California Verbal Learning Test-II (CVLT-II) ranked highest in terms of distinguishing MCI from normal aging (sensitivity = 90.2; specificity = 84.2). Inclusion of the delayed recall condition of a story memory task (i.e., WMS-III Logical Memory, Story A) enhanced the overall accuracy of classification (sensitivity = 92.2; specificity = 94.7). Combining Logical Memory recognition and CVLT-II long delay best predicted progression from MCI to AD over a 4-year period (accurate classification = 87.5%). Learning across multiple trials may provide the most sensitive index for initial diagnosis of MCI, but inclusion of additional variables may enhance overall accuracy and may represent the optimal strategy for identifying individuals most likely to progress to dementia.     

Performance of an Adapted Version of the Timed Up-and-Go Test in People with Cognitive Impairments

In clinical practice, older people with cognitive impairment may have difficulties to understand the instructions of the Timed Up-and-Go (TUGT) test and present a bad performance. The purpose of this study was to identify differences in the TUGT performance, in an adapted version, between older adults with preserved cognition (PC), mild cognitive impairment (MCI) and Alzheimer's disease (AD), and to identify the association between the adapted TUGT performance and cognition among groups. A cross-sectional study was conducted with 118 community-dwelling older adults divided in three groups: PC (n?=?40), MCI (n?=?40) and AD (n?=?38). The evaluation was composed by the adapted TUGT and cognitive assessment (Addenbrooke's Cognitive Examination and Frontal Assessment Battery). Only the cadence of TUGT presented significant difference between groups, specifically between AD versus MCI and PC groups. The main correlations were found between time of TUGT with fluency domain and global cognitive function, especially in the AD Group. The findings contribute to the understanding of how cognition interferes on functional mobility in older people with MCI and AD. The adapted TUGT is easy to perform in clinical practice and can be useful when assessing mobility in people with cognitive impairment.     

Dissociations in visual attention deficits among persons with mild cognitive impairment

Impairments in visual attention and visual information processing have been identified as part of the neuropsychological features of Alzheimer's disease (AD), even in its earliest stages. There is increasing recognition that these deficits may be selective rather than global, with some attentional subtypes being more vulnerable than others. The few studies that have investigated attentional deficits in mild cognitive impairment (MCI), a putatively prodromal phase of AD, have not satisfactorily addressed the possible selectivity in attentional deficits in MCI. This study examined potential dissociations in visual attention deficits in MCI using a measure that assesses simple, divided, and selective attention. The results indicated a hierarchy of attentional impairments, with divided attention being the most affected and simple attention the least. Among participants with MCI, 53% showed evidence of impairment in divided attention compared to 19% of controls (OR = 4.81, p < .001). Poorer visual attention was also associated with poorer overall cognitive status. The implications of these findings for early identification of MCI, prevention of functional decline in MCI, and delay/reversal of cognitive degradation in MCI are discussed.     

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.     

Recognition memory deficits in mild cognitive impairment

ABSTRACT

There is no agreement on the pattern of recognition memory deficits characteristic of patients diagnosed with mild cognitive impairment (MCI). Whereas lower performance in recollection is the hallmark of MCI, there is a strong controversy about possible deficits in familiarity estimates when using recognition memory tasks. The aim of this research is to shed light on the pattern of responding in recollection and familiarity in MCI. Five groups of participants were tested. The main participant samples were those formed by two MCI groups differing in age and an Alzheimer's disease group (AD), which were compared with two control groups. Whereas one of the control groups served to assess the performance of the MCI and AD people, the other one, composed of young healthy participants, served the purpose of evaluating the adequacy of the experimental tasks used in the evaluation of the different components of recognition memory. We used an associative recognition task as a direct index of recollection and a choice task on a pair of stimuli, one of which was perceptually similar to those studied in the associative recognition phase, as an index of familiarity. Our results indicate that recollection decreases with age and neurological status, and familiarity remains stable in the elderly control sample but it is deficient in MCI. This research shows that a unique encoding situation generated deficits in recollective and familiarity mechanisms in mild cognitive impaired individuals, providing evidence for the existence of deficits in both retrieval processes in recognition memory in a MCI stage.     

Slow gait as a motor marker of mild cognitive impairment? the relationships between functional mobility and mild cognitive impairment

The purpose of this study was to evaluate the association between functional mobility and mild cognitive impairment in older adults. A total of 800 older adults were recruited (653 controls and 147 subjects with MCI [88 subjects with aMCI and 59 subjects with naMCI]). Motor performance was measured with the Timed Up and Go test (TUG). The demographic factors associated with MCI were: age (OR = 1.05; 95% CI: 1.01–1.09) and the level of education (OR = 0.73; 95% CI: 0.68–0.79). An independent clinical factor associated with MCI was the TUG (OR = 1.14; 95% CI: 1.03–1.27). In the aMCI group, the relation between the TUG and cognitive status occurred (OR = 1.15; 95% CI: 1.02–1.31), whereas in the naMCI group this relationship was not observed. There is an association between cognitive dysfunction and impaired motor performance in older adults with MCI.     

Influence of mild cognitive impairment on visual word recognition

The present study examined the effects of normal aging and mild cognitive impairment (MCI) on visual word recognition. Madden et al. (1999) reported evidence of general slowing of cognitive processes in Alzheimer's disease (AD) patients relative to younger adults and healthy older adults using a lexical decision task. It was of interest to determine whether similar effects would be observed in MCI patients relative to healthy younger and older adults. We extended the lexical decision task paradigm developed by Allen et al. (2004b) on younger adults to an examination of the effect(s) of MCI on visual word recognition. Results from the present study showed that healthy older adults and MCI patients performed similarly. That is, both groups took longer than younger adults to process words presented in mixed-case than in consistent-case letters. Mild cognitive impairment patients, however, responded significantly more slowly than healthy older adults across all lexical decision task conditions and showed a trend toward larger case-mixing effects than healthy older adults, which suggests that MCI may result in poorer analytic processing ability. Based on the current findings, evidence of a generalized slowing of cognitive processes using a standard lexical decision task can be expanded to include not only AD patients, but also the preclinical stages of the disease as well.     

Memory profiling in mild cognitive impairment: Can we determine risk for Alzheimer's disease?

Mild cognitive impairment (MCI) is considered a transitional stage between normal ageing and Alzheimer's disease (AD), but not all MCI cases progress to AD and there has been limited focus on how to identify who will progress. Given claims for a characteristic kind of memory impairment in AD involving deficits in encoding and consolidation of information, we propose that ‘memory profiling’ of individuals with MCI may help identify which individuals will progress. We initially set out to establish whether the same characteristic memory profile was present prior to the onset of AD (preAD). Very few studies provided data that allowed us to examine this, but results tentatively supported an encoding/consolidation profile in preAD. A single study tested the clinically important contrast of preAD versus non‐preAD MCI cases and found no difference under any condition or in memory profiles, but interpretation of the findings is limited by short duration of follow‐up, ceiling effects, and task limitations in assessing more complex and qualitative aspects of memory. Although existing data lead to equivocal conclusions, we believe that memory profiling is an endeavour worth pursuing, particularly given the increasing number of people with MCI presenting for clinical assessment. We propose that tests designed specifically to measure memory processes should be sensitive to preAD and are required in prospective longitudinal designs to identify these clinically crucial MCI cases.     

Contribution of temporal preparation and processing speed to simple reaction time in persons with Alzheimer’s disease and mild cognitive impairment

Temporal preparation was assessed in 15 Alzheimer’s disease (AD) patients, 20 persons with mild cognitive impairment (MCI) and 28 healthy older adults. Participants completed a simple reaction time task in which the preparatory interval duration varied randomly within two blocks (short versus long temporal window). Results indicated that AD and MCI patients had difficulty preparing for the shortest preparatory interval of the short temporal window. AD and MCI patients also had difficulty maintaining an optimal level of preparation up to 5 s within the short temporal window. These results suggest that AD and MCI patients might show difficulty preparing for rapidly occurring events and maintaining preparation over time. This phenomenon should be considered when using reaction time measures with such patients.     

False memory,attentional bias and future thinking among people living with HIV with posttraumatic stress disorder

People living with HIV can experience posttraumatic stress disorder (PTSD). Complex relationships exist between HIV, PTSD and cognitive impairments. This cross-sectional study compared three cognitive impairments (false memory, attentional bias, deficits in future thinking) among people living with HIV with and without PTSD in Iran. People living with HIV with PTSD (n = 20) and without PTSD (n = 20) completed measures of psychological symptomatology, dot-probe task, Deese Roediger McDermott paradigm and future thinking task at Razavi Khorasan Health Center. The PTSD group, when compared to the non-PTSD group, recognised a significantly greater number of false memories (p < .001; η² = .58), had an attentional bias toward threat-related words (p < .001; η² = .35) and imagined fewer specific future events (p < .001; η² = .31). People living with HIV with PTSD may have difficulties with false memory, attentional biases, and generating future events. Since psychological treatments are limited in Iran, this research highlighted some potential cognitive targets for people living with HIV.     

Factor Structure of Patient and Caregiver Ratings on the Dementia Quality of Life Instrument

ABSTRACT

Preliminary evidence suggests that quality of life reports from patients diagnosed with mild cognitive impairment (MCI) and mild Alzheimer's disease (AD) are as reliable and valid as data provided by caregivers. To date, no studies compared the factor structure of data provided by caregivers and patients. Factor analyses are important to conduct because they are an indicator of validity. This study compared the factor structure of patient and caregiver reports on the Dementia Quality of Life scale (DQoL). Participants (N?=?67) were patients diagnosed with amnestic MCI or mild AD and their caregivers. Principal axis factor analyses were run separately on patient and caregiver report data. The three-factor solutions for patient and caregiver data were nearly identical. Three factors corresponding to positive affect, negative affect, and aesthetics emerged reliably from analyses. Thus, data from patients demonstrated a factor structure that was highly consistent with caregiver report data and conformed to meaningful psychological constructs.     

Practice Effects on Motor Control in Healthy Seniors and Patients with Mild Cognitive Impairment and Alzheimer's Disease

ABSTRACT

This research was designed to test the hypothesis that motor practice can enhance the capabilities of motor control in healthy controls (NC) and patients with a diagnosis of probable Alzheimer's disease (AD) and mild cognitive impairment (MCI), and consequently results in better motor performance. Approximately half of the subjects in the NC (n = 31), AD (n = 28), and MCI (n = 29) either received or did not receive practice on a task of fast and accurate arm movement with a digitizer. Changes in movement time (MT), movement smoothness (jerk), and percentage of primary submovement (PPS) were recorded and compared among the three groups across six blocks of trials (baseline and five training sessions). For all subjects, practice improved motor functions as reflected by faster and smoother motor execution, as well as a greater proportion of programming control. Compared to unaffected matched controls, AD and MCI subjects exhibited a greater reduction in movement jerk due to practice. Movement time and PPS data revealed that motor practice appeared to reduce the use of “on-line” correction adopted by the AD or MCI patients while performing the aiming movements. Evidently, their arm movements were quicker, smoother, and temporally more consistent than their untrained peers. The findings of this study shed light on how MCI and AD may affect motor control mechanisms, and suggest possible therapeutic interventions aimed at improving motor functioning in these impaired individuals.