Global clinical dementia rating of 0.5 in MCI masks variability related to level of function

Longitudinal declines in instrumental activities of daily living in stable and progressive mild cognitive impairment

BACKGROUND

Previous cross-sectional studies suggest that assessments of instrumental activities of daily living (IADLs) may be useful for operationalizing the differences in functional deficits seen in mild cognitive impairment (MCI) and dementia. However, their utility for longitudinal changes in IADLs in the transition between MCI and dementia remains unclear.

METHODS

We analyzed longitudinal IADL data with the Functional Activities Questionnaire (FAQ) in stable (MCI-S; n = 1,318) or progressive (MCI-P; n = 1,108) MCI patients.

RESULTS

Larger increases in FAQ scores were seen in the MCI-P group across a 14.5-month interval, but overlapping distributions in the two groups yielded poorer discriminatory power than prior cross-sectional reports.

CONCLUSION

Our findings emphasize the difficulties in operationalizing the criterion of 'essentially intact' IADLs in MCI, which may complicate the interpretation of disease progression in MCI treatment trials.

Assessing cognition and function in Alzheimer's disease clinical trials: do we have the right tools?

Several lines of evidence from Alzheimer's disease (AD) research continue to support the notion that the biological changes associated with AD are occurring possibly several decades before an individual will experience the cognitive and functional changes associated with the disease. The National Institute on Aging-Alzheimer's Association revised criteria for AD provided a framework for this new thinking. As a result of this growing understanding, several research efforts have launched or will be launching large secondary prevention trials in AD. These and other efforts have clearly demonstrated a need for better measures of cognitive and functional change in people with the earliest changes associated with AD. Recent draft guidance from the US Food and Drug Administration further elevated the importance of cognitive and functional assessments in early stage clinical trials by proposing that even in the pre-symptomatic stages of the disease, approval will be contingent on demonstrating clinical meaningfulness. The Alzheimer's Association's Research Roundtable addressed these issues at its fall meeting October 28-29, 2013, in Washington, D.C. The focus of the discussion included the need for improved cognitive and functional outcome measures for clinical of participants with preclinical AD and those diagnosed with Mild Cognitive Impairment due to AD.

Telephone screening for mild cognitive impairment in hispanics using the Alzheimer's questionnaire

BACKGROUND/STUDY CONTEXT: There is a need for a simple and reliable screening test to detect individuals with mild cognitive impairment (MCI). The authors analyzed the relationship between performance of the Alzheimer's Questionnaire (AQ), an informant-rated measure of dementia-related behaviors, relative to the Telephone Interview for Cognitive Status-modified (TICS-m), Memory Impairment Scale-telephone version (MIS-t), and the Telephone Executive Assessment (TEXAS) as predictors of MCI.

METHODS

Comparative cross-sectional design, with data collected from participants in the Texas Alzheimer's Research and Care Consortium's (TARCC) San Antonio site. One-hundred percent of our sample was Hispanic. The San Antonio subset of TARCC sample is highly enriched with Mexican Americans (MAs). Fifty-five percent of the interviews were conducted in Spanish. Of the 184 persons enrolled, 124 were normal controls (NCs), and 60 participants had MCI. MCI status and Clinical Dementia Rating Scale Sum of Boxes (CDR-SOB) were determined through clinical consensus and performed blind to telephone assessments. Controlling for age, gender, education, and language of interview, the association between telephone measures and CDR-SOB was evaluated by multivariate regression.

RESULTS

AQ scores were not affected by education, gender, and language of interview, but subject's age did show a positive correlation with informant AQ ratings. The AQ predicted CDR-SOB independently of the cognitive measures, adding variance above and beyond demographics. The TICS-m and the TEXAS appear to have additive value in improving the detection of cognitively impaired patients. The MIS-t failed to contribute significantly to CDR-SOB, independent of the other measures.

CONCLUSION

The AQ may have utility as a culture-fair telephone screening for MCI. The AQ was able to modestly distinguish MCI from NCs. The TEXAS adds variance to a model of dementia severity independent of the AQ, suggesting that the latter may weakly assess that cognitive domain (executive control function). On the other hand, the AQ attenuates the MIS-t effect. This suggests a prominent AQ bias in favor of detecting memory impairment. Additional studies are required to determine if the AQ can distinguish between amnestic and dysexecutive MCI subtypes, or between MCI and Alzheimer's disease in Hispanics.

A qualitative review of instrumental activities of daily living in dementia: what's cooking?

SUMMARY 

The measurement of instrumental activities of daily living (IADL) is common in clinical practice and research into dementia. IADL are cognitively complex daily activities, such as cooking and doing finances. Their measurement is required for the diagnostic process of dementia, and also useful for the monitoring of disease progression. Since problems in IADL contribute to the disease burden of both patient and caregiver, it is a relevant outcome measure for disease-modifying and non-pharmacological interventions. Despite the widespread use of IADL instruments, an overview of its theoretical background, measurement methods, and potential sources of bias is lacking. In the current manuscript, we therefore aim to provide a selective overview of these topics.

Cognitive reserve moderates relation between global cognition and functional status in older adults

The ability to perform instrumental activities of daily living (IADLs) is necessary for independent living. Research suggests that community-dwelling older adults are at risk for experiencing subtle decrements in the performance of IADLs. Neuropsychological tests have been used to account for differences in IADL status. Studies of the relationship between cognitive ability and functional status have produced variable results, however, and cognitive ability appears to be only a moderate predictor. Several studies of normal aging have revealed cognitive and functional benefits of higher cognitive reserve (CR) in healthy, nondemented older adults. The purposes of the present study were to: (a) examine the relationship between global cognitive ability and IADL performance among 53 community-dwelling older adults, and (b) determine whether formal education, as a proxy of CR, significantly moderates this relationship. Consistent with previous findings, global cognitive ability accounted for a considerable portion of variance in IADL performance [ΔR(2) = .54; ΔF(2, 53) = 67.96; p < .001]. Additionally, CR modestly but significantly attenuated this relationship [ΔR(2) = .044; ΔF(4, 53) = 5.98; p = .018; total R(2) = .65]. This finding suggests that community-dwelling older adults with lower levels of formal education may be at greater risk for functional decrements associated with age-related cognitive decline.

Mild cognitive impairment: a concept and diagnostic entity in need of input from neuropsychology

This virtual issue consists of studies previously published in the Journal of the International Neuropsychological Society and selected on the basis of their content related to one of the most highly researched concepts in behavioral neurology and neuropsychology over the past decade: mild cognitive impairment (MCI). The reliance on cognitive screening measures, staging-based rating scales, and limited neuropsychological testing in diagnosing MCI across most research studies may miss individuals with subtle cognitive declines or mis-diagnose MCI in those who are otherwise cognitively normal on a broader neuropsychological battery of tests. The assembled articles highlight the perils of relying on these conventional criteria for MCI diagnosis and reveal how the reliability of diagnosis is improved when sound neuropsychological approaches are adopted. When these requirements are met, we illustrate with a second series of articles that neuropsychological measures associate strongly with biomarkers and often reflect pathology beyond or instead of typical AD distributions. The final set of articles reveal that people with MCI demonstrate mild but identifiable functional difficulties, and a challenge for neuropsychology is how to incorporate this information to better define MCI and distinguish it from early dementia. Neuropsychology is uniquely positioned to improve upon the state of the science in MCI research and practice by providing critically important empirical information on the specific cognitive domains affected by the predominant neurodegenerative disorders of late life as well as on the diagnostic decision-making strategies used in studies. When such efforts to more comprehensively assess neuropsychological functions are undertaken, better characterizations of spared and impaired cognitive and functional abilities result and lead to more convincing associations with other biomarkers as well as to prediction of clinical outcomes.

Assessment of instrumental activities of daily living in dementia: diagnostic value of the Amsterdam Instrumental Activities of Daily Living Questionnaire

BACKGROUND

Measuring impairments in "instrumental activities of daily living" (IADL) is important in dementia, but challenging due to the lack of reliable and valid instruments. We recently developed the Amsterdam Instrumental Activities of Daily Living Questionnaire (A-IADL-Q; note 1). We aim to investigate the diagnostic accuracy of the A-IADL-Q for dementia in a memory clinic setting.

METHODS

Patients visiting the Alzheimer Center of the VU University Medical Center with their informants between 2009 and 2011 were included (N = 278). Diagnoses were established in a multidisciplinary consensus meeting, independent of the A-IADL-Q scores. An optimal A-IADL-Q cutoff point was determined, and sensitivity and specificity were calculated. Area under the curves (AUCs) were compared between A-IADL-Q and "disability assessment of dementia" (DAD). The additional diagnostic value of the A-IADL-Q to Mini-Mental State Examination (MMSE) was examined using logistic regression analyses.

RESULTS

Dementia prevalence was 50.5%. Overall diagnostic accuracy based on the AUC was 0.75 (95% confidence interval [CI]: 0.70-0.81) for the A-IADL-Q and 0.70 (95% CI: 0.63-0.77) for the DAD, which did not differ significantly. The optimal cutoff score for the A-IADL-Q was 51.4, resulting in sensitivity of 0.74 and specificity of 0.64. Combining the A-IADL-Q with the MMSE improved specificity (0.94), with a decline in sensitivity (0.55). Logistic regression models showed that adding A-IADL-Q improved the diagnostic accuracy (Z = 2.55, P = .011), whereas the DAD did not.

CONCLUSIONS

In this study, we showed a fair diagnostic accuracy for A-IADL-Q and an additional value in the diagnosis of dementia. These results support the role of A-IADL-Q as a valuable diagnostic tool.

Cognitive declines precede and predict functional declines in aging and Alzheimer's disease

OBJECTIVE

To investigate the temporal ordering of cognitive and functional declines separately in older adults with or without Alzheimer's disease (AD).

DESIGN AND SETTING

A community-based longitudinal study of aging and dementia in Northern Manhattan (Washington Heights/Hamilton Heights Inwood Columbia Aging Project) and a multicenter, clinic-based longitudinal study of prevalent AD at Columbia University Medical Center, Johns Hopkins School of Medicine, Massachusetts General Hospital, and the Hôpital de la Salpêtrière in Paris, France (the Predictors Study).

PARTICIPANTS

3,443 initially non-demented older adults (612 with eventual incident dementia) and 517 patients with AD.

MAIN OUTCOME MEASURES

Cognitive measures included the modified Mini-Mental State Exam and composite scores of memory and language derived from a standardized neuropsychological battery. Function was measured with the Blessed Dementia Rating Scale, completed by the participant (in the sample of non-demented older adults) or an informant (in the sample of prevalent AD patients). Data were analyzed with autoregressive cross-lagged panel analysis.

RESULTS

Cognitive scores more consistently predicted subsequent functional abilities than vice versa in non-demented older adults, participants with eventual incident dementia, and patients with prevalent AD.

CONCLUSIONS

Cognitive declines appear to precede and cause functional declines prior to and following dementia diagnosis. Standardized neuropsychological tests are valid predictors of later functional changes in both non-demented and demented older adults.

Lateral temporal hyper-activation as a novel biomarker of mild cognitive impairment

Memory dysfunction in mild cognitive impairment (MCI) due to Alzheimer's pathology is primarily associated with episodic memory deficits linked to deterioration of the medial temporal lobes (MTLs). Currently, there is a call to discover novel biomarkers of MCI in order to improve research criteria. Functional activation differences in MCI during episodic memory-task performance are often evidenced in the MTLs, and frontal and parietal lobes, but it has been suggested that examination of working memory (WM) differences may be more useful in detecting MCI. In the current study, MCI and control participants performed a complex WM span (CWMS) task while functional magnetic resonance imaging (fMRI) data were acquired. Results indicated hyper-activation of the lateral temporal lobes, MTLs, and frontal and parietal regions during encoding and maintenance, and hyper-activation of the lateral temporal, frontal, and parietal lobes during CWMS recall for the MCI participants. Medial and lateral temporal differences during encoding and maintenance are consistent with previous findings, but lateral temporal differences are often not elaborated upon. Hyper-activation of the lateral temporal lobes during WM encoding and maintenance, and also during recall, suggests that this region may provide valuable information regarding WM impairment in MCI and Alzheimer's. Given that whole-brain functional imaging of the MTLs is often limited due to artifact and partial voluming of sub-fields, examination of lateral temporal differences may provide a novel biomarker related to WM impairment in MCI.

The default mode network and related right hemisphere structures may be the key substrates of dementia

We have employed structural equation models to explicitly distinguish dementia-relevant variance in cognitive task performance (i.e., δ) from the variance that is unrelated to a dementing process (i.e., g'). Together g' and d comprise Spearman's "g". Although d represents only a minor fraction of the total variance in cognitive task performance, it is more strongly associated with dementia severity than is g'. In this analysis, we replicate δ in a new dataspace, the University of Kansas Brain Aging Project, and associate it specifically with regional grey matter atrophy by voxel-based morphometry of magnetic resonance imaging data. The latent variable d localizes to elements of the default mode network and related structures in the R hemisphere.

The Informant Questionnaire on Cognitive Decline in the Elderly individuals in screening mild cognitive impairment with or without functional impairment

The Informant Questionnaire on Cognitive Decline in the Elderly individuals (IQCODE) is a reliable, validated informant-based instrument. Most of the studies well support the validity of the IQCODE in dementia screening, but the sensitivity of the rating scale at the early stage during the course of dementia is limited. In this study, we investigate the utility of the IQCODE for patients with mild cognitive impairment (MCI) and the discriminative power of the IQCODE in patients having MCI with and without functional impairment. The samples included mild Alzheimer disease (AD, N=280), MCI ([N=657], further divided into 2 subgroups: patients with MCI having functional impairment [MCI-fi, N=357] and patients having MCI without functional impairment [MCI-fn, N=300]), and normal cognition (NC, N=274). The IQCODE, Mini-Mental State Examination (MMSE), and other neuropsychological tests were administered to all participants. Logistic regression and receiver-operating characteristic (ROC) curves were used to evaluate the diagnostic ability of the IQCODE, compared to the MMSE. The optimal cutoff scores of the IQCODE were 3.19 for the MCI (sensitivity/specificity: 0.979/0.714) and MCI-fn (0.900/0.817), 3.25 for the MCI-fi (0.978/0.701), and 3.31 for mild AD (0.893/0.779), while the MMSE was identical, that is 26, for both MCI and its functional normal and functional impaired subgroups (0.892/0.755, 0.867/0.745, and 0.913/0.745, respectively) and 24 for mild AD (0.807/0.836). The discriminating accuracy of the IQCODE was slightly superior to that of the MMSE but did not reach statistical significance. Our study suggests that the IQCODE might be useful in screening for MCI, with hierarchical scores indicating functional normal or impaired.

Revised criteria for mild cognitive impairment may compromise the diagnosis of Alzheimer disease dementia

OBJECTIVE

To evaluate the potential impact of revised criteria for mild cognitive impairment (MCI), developed by a work group sponsored by the National Institute on Aging and the Alzheimer's Association, on the diagnosis of very mild and mild Alzheimer disease (AD)dementia.

DESIGN

Retrospective review of ratings of functional impairment across diagnostic categories.

SETTING

Alzheimer's Disease Centers and the National Alzheimer's Coordinating Center.

PARTICIPANTS

Individuals (N=17 535) with normal cognition,MCI, or AD dementia.

MAIN OUTCOME MEASURES

The functional ratings of individuals with normal cognition, MCI, or AD dementia who were evaluated at Alzheimer's Disease Centers and submitted to the National Alzheimer's Coordinating Center were assessed in accordance with the definition of "functional independence" allowed by the revised criteria. Pairwise demographic differences between the 3 diagnostic groups were tested using t tests for continuous variables and 2 for categorical variables.

RESULTS

Almost all (99.8%) individuals currently diagnosed with very mild AD dementia and the large majority(92.7%) of those diagnosed with mild AD dementia could be reclassified as having MCI with the revised criteria,based on their level of impairment in the Clinical Dementia Rating domains for performance of instrumental activities of daily living in the community and at home.Large percentages of these individuals with AD dementia also meet the revised "functional independence" criterion for MCI as measured by the Functional Assessment Questionnaire.

CONCLUSIONS

The categorical distinction between MCI and milder stages of AD dementia has been compromised by the revised criteria. The resulting diagnostic overlap supports the premise that "MCI due to AD" represents the earliest symptomatic stage of AD.

Item response theory reveals variability of functional impairment within clinical dementia rating scale stages

BACKGROUND/AIMS

To investigate whether an item response theory (IRT) approach to measuring variations of dementia severity within Clinical Dementia Rating (CDR) stages is associated with activities of daily living (ADLs).

METHODS

IRT estimates of dementia severity within CDR stages in 1,181 patients were correlated with ADLs and analyzed.

RESULTS

IRT-determined dementia severity was significantly correlated with ADLs in three of four impaired dementia stages.

CONCLUSION

An IRT approach shows considerable advantages over traditional scoring practices of the CDR not only because it increases precision in dementia measurement, but also because it enables one to discover more precise associations with functional outcomes such as ADLs.

Greater precision when measuring dementia severity: establishing item parameters for the Clinical Dementia Rating Scale

BACKGROUND/AIMS

An item response theory (IRT)-based scoring approach to the Clinical Dementia Rating Scale (CDR) can account for the pattern of scores across the CDR items (domains) and their differential abilities to indicate dementia severity. In doing so, an IRT-based approach can provide greater precision than other CDR scoring algorithms. However, neither a good set of item parameters nor an easily digestible set of instructions needed to implement this approach is readily available.

METHODS

Participants were 1,326 patients at the Baylor College of Medicine Alzheimer's Disease and Memory Disorders Clinic.

RESULTS

The item parameters necessary for an IRT-based scoring approach were identified (a parameters ranged from 3.01 to 6.22; b parameters ranged from -2.46 to 2.07).

CONCLUSION

This study provides, and demonstrates how to easily apply, IRT-based item parameters for the CDR

Verbal serial list learning in mild cognitive impairment: a profile analysis of interference, forgetting, and errors

Using cluster analysis Libon et al. (2010) found three verbal serial list-learning profiles involving delay memory test performance in patients with mild cognitive impairment (MCI). Amnesic MCI (aMCI) patients presented with low scores on delay free recall and recognition tests; mixed MCI (mxMCI) patients scored higher on recognition compared to delay free recall tests; and dysexecutive MCI (dMCI) patients generated relatively intact scores on both delay test conditions. The aim of the current research was to further characterize memory impairment in MCI by examining forgetting/savings, interference from a competing word list, intrusion errors/perseverations, intrusion word frequency, and recognition foils in these three statistically determined MCI groups compared to normal control (NC) participants. The aMCI patients exhibited little savings, generated more highly prototypic intrusion errors, and displayed indiscriminate responding to delayed recognition foils. The mxMCI patients exhibited higher saving scores, fewer and less prototypic intrusion errors, and selectively endorsed recognition foils from the interference list. dMCI patients also selectively endorsed recognition foils from the interference list but performed similarly compared to NC participants. These data suggest the existence of distinct memory impairments in MCI and caution against the routine use of a single memory test score to operationally define MCI.

The role of neuropsychology in prodromal dementia

SUMMARY Before dementia becomes manifest, it is preceded by a long period during which neuropathology exists without clinical symptoms, termed the prodromal stage of dementia (ProD). Owing to its relevance for clinical and research aspects, many efforts are being made to define, diagnose and investigate ProD in greater detail. The ProD state has often been studied in Alzheimer’s disease (AD), whereas less is known about the prodromes of the vascular, extrapyramidal and frontotemporal dementias. Since the operational criteria of ProD are unclear, many studies act on the assumption that ProD and mild cognitive impairment are equivalent concepts. However, owing to several methodological problems with the mild cognitive impairment construct, the viewpoint taken here is that ProD can be understood more profoundly in cohorts of normal elderly subjects. This article discusses the neuropsychological findings of longitudinal, population-based studies, which included elderly, normal subjects, who were followed for years, and made case–control comparisons. Neuropsychological findings clearly revealed deficits in cases (subjects who developed dementia later, mostly AD), which were present already at baseline. Cognitive abnormalities were apparent in the domains of episodic memory, but also in tasks tapping executive, psychomotor and visuospatial functions, attention and naming. Although subtle, these impairments were significant at the group level and often demonstrated deterioration to dementia. Early cognitive deficits of the ProD stage therefore represent markers for the identification of incident AD. It is concluded that neuropsychology is a useful method to screen subjects for ProD at an early time point, when individuals are still normally functioning.