Repeatable battery for the assessment of neuropsychological status and its relationship to biomarkers of Alzheimer's disease

Classification of Mild Cognitive Impairment and Alzheimer's Disease Using Manual Motor Measures

INTRODUCTION

Manual motor problems have been reported in mild cognitive impairment (MCI) and Alzheimer's disease (AD), but the specific aspects that are affected, their neuropathology, and potential value for classification modeling is unknown. The current study examined if multiple measures of motor strength, dexterity, and speed are affected in MCI and AD, related to AD biomarkers, and are able to classify MCI or AD.

METHODS

Fifty-three cognitively normal (CN), 33 amnestic MCI, and 28 AD subjects completed five manual motor measures: grip force, Trail Making Test A, spiral tracing, finger tapping, and a simulated feeding task. Analyses included (1) group differences in manual performance; (2) associations between manual function and AD biomarkers (PET amyloid β, hippocampal volume, and APOE ε4 alleles); and (3) group classification accuracy of manual motor function using machine learning.

RESULTS

Amnestic MCI and AD subjects exhibited slower psychomotor speed and AD subjects had weaker dominant hand grip strength than CN subjects. Performance on these measures was related to amyloid β deposition (both) and hippocampal volume (psychomotor speed only). Support vector classification well-discriminated control and AD subjects (area under the curve of 0.73 and 0.77, respectively) but poorly discriminated MCI from controls or AD.

CONCLUSION

Grip strength and spiral tracing appear preserved, while psychomotor speed is affected in amnestic MCI and AD. The association of motor performance with amyloid β deposition and atrophy could indicate that this is due to amyloid deposition in and atrophy of motor brain regions, which generally occurs later in the disease process. The promising discriminatory abilities of manual motor measures for AD emphasize their value alongside other cognitive and motor assessment outcomes in classification and prediction models, as well as potential enrichment of outcome variables in AD clinical trials.

Revisiting reliable change with Iverson (2001)

Objective: Iverson (2001) expanded on reliable change methodology by accounting for the variability in scores at Time 2 in the calculation of change scores. However, due to limitations in available data, an incomplete picture of variables affecting change was presented. The current paper sought to address some of these limitations and clarify the methodology for assessing reliable change. Method: Using one-year test-retest data on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) in older adults who were cognitively intact or had mild Alzheimer's disease (AD), change scores were calculated, and various models, consistent with or divergent from Iverson, were presented. Results: Across the RBANS, individuals with intact cognition tended to show less variable scores, especially at Time 2, which resulted in larger change scores than those with AD. When applied to an independent sample, different patterns of change were observed, with: (1) models that used intact data showed more cognitive change than those using AD data; (2) the model that corrected for practice effects and used intact data showed the most decline; and (3) the model that corrected for practice effects and used AD data showed the most improvement. The models that showed the strongest association in classifying independent cases as decline/stable/improve were those that used intact data and were discordant on the use of practice effects. Conclusions: Overall, findings highlight the complexity of calculating reliable change, and they lend additional caution to Iverson's original limitations. However, the use of data from individuals classified as cognitively intact and a correction for practice effects seems warranted.

A Closer Look at Practice Effects in Mild Cognitive Impairment and Alzheimer's Disease

Practice effects have become a potentially important variable regarding the diagnosis, prognosis, and treatment recommendations in mild cognitive impairment (MCI) and Alzheimer's disease (AD). However, the understanding of these short-term changes in test scores remains unclear. The current observational study sought to examine variables that influence the magnitude of short-term practice effects in MCI and AD, including demographic information, cognitive performance, daily functioning, and medical comorbidities. One hundred sixty-six older adults classified as cognitively intact, amnestic MCI, or mild AD were tested twice across 1 week with a brief battery of neuropsychological tests. Correlational and regression analyses examined the relationship of practice effects with demographic and clinical variables. Results indicated that practice effects were minimally related to demographic variables and medical comorbidities, but they were significantly related to cognitive variables, depressive symptoms, and daily functioning. These findings expand our understanding of practice effects in MCI and AD, and they may allow a better appreciation of how they could affect clinical care and research.

Diagnostic accuracy of BASIC-Q for detection of cognitive impairment in a primary care setting - a cross-validation study

OBJECTIVES

This study aims to evaluate the diagnostic accuracy and reliability of a new, brief questionnaire, 'Brief Assessment of Impaired Cognition- Questionnaire' (BASIC-Q) for detection of cognitive impairment, primarily developed for use in primary care. BASIC-Q has three components: Self-report, Informant report, and Orientation. Self-report and Orientation are completed by the individual and Informant report is answered by a close relative.

METHODS

We included 275 participants ≥ 70 years, without a prior diagnosis of dementia, and with a close relative who agreed to participate as an informant. Participants were included prospectively in 14 general practices in urban and rural Denmark using a convenience sampling method. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), the informant-completed Functional Activities Questionnaire (FAQ) and reported memory concern were used as a reference standard for the classification of the participants' cognitive function.

RESULTS

BASIC-Q demonstrated a fair to good diagnostic accuracy to differentiate between people with cognitive impairment and normal cognition with an area under the ROC curve (AUC) of 0.84 (95% CI 0.79-0.89) and a sensitivity and specificity of 0.80 (95% CI 0.72-0.87) and 0.71 (95% CI 0.63-0.78). A prorated BASIC-Q score derived from BASIC-Q without Informant report had significantly lower classification accuracy than the full BASIC-Q. The test-retest reliability of BASIC-Q was good with an intraclass correlation coefficient of 0.84.

CONCLUSION

BASIC-Q is a brief, easy-to-use questionnaire for identification of cognitive impairment in older adults. It demonstrated fair to good classification accuracy in a general practice setting and can be a useful case-finding tool when suspecting dementia in primary health care.

Recall and recognition subtests of the repeatable battery for the assessment of neuropsychological status and their relationship to biomarkers of Alzheimer's disease

Recently, two new recognition subtests for the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) were developed and initially validated in a cohort of older adults who were cognitively intact or classified as amnestic Mild Cognitive Impairment (MCI) or mild Alzheimer's disease (AD). The current paper extends that validation by comparing the recall and recognition subtests of the RBANS, including the existing and recently developed scores, to three commonly used biomarkers in AD in an expanded sample from the initial validation. One hundred fifty-four older adults (65 intact, 46 MCI, 43 AD) were administered the RBANS, which included the recently developed subtests for Story Recognition and Figure Recognition (hits, false positives, total correct), as part of a study on memory and biomarkers. Participants also completed magnetic resonance imaging to obtain hippocampal volumes, positron emission tomography to obtain amyloid plaque deposition, and a blood draw to obtain APOE ε4 status. Whereas correlations between recall scores and biomarkers tended to be moderate (average r = ±0.48), these correlations were comparable across the three recognition total scores (average r = ±0.42), but tended to be lower for recognition hits (average r = ±0.28) and false positives (average r = ±0.38). These results further validate the existing and recently developed recognition scores on the RBANS as providing useful information about brain and genetic pathology in older adults with intact and impaired cognitive functioning.

Change on the Repeatable Battery for the Assessment of Neuropsychological Status and its relationship to brain amyloid

BACKGROUND

The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) has been associated with commonly used biomarkers of Alzheimer's disease (AD), including brain amyloid plaque density. However, less is known about if changes in the RBANS across time are also related to brain amyloid deposition. The current study sought to expand on prior work by examining the relationship between changes over time on the RBANS and amyloid deposition via positron emission tomography (PET).

METHOD

One-hundred twenty-six older adults with intact or impaired cognition and daily functioning underwent repeat assessment with the RBANS across nearly 16 months, as well as had a baseline amyloid PET scan.

RESULTS

In the entire sample, amyloid deposition was significantly related to change on all five Indexes and the Total Scale score of the RBANS, with greater amyloid being associated with worsening cognition. This pattern was also observed in 11 of 12 subtests.

CONCLUSIONS

Whereas prior studies have identified a relationship between baseline RBANS and amyloid status, the current findings support that changes in the RBANS are also indicative of AD brain pathology, even if these findings are mediated by cognitive status. Although replication in a more diverse sample is needed, these results continue to support the use of the RBANS in AD clinical trials.

Repeatable Battery for the Assessment of Neuropsychological Status: Italian Normative Data for Older Adults

OBJECTIVE

The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), widely used for detecting cognitive impairment in different neuropsychiatric conditions, is increasingly applied for measuring cognitive functioning in older individuals. Available normative data for RBANS Italian version suffer from under-representation of the older ages (>60 years) and are not corrected for education. Moreover, normative data are provided only for Indexes and Total scores. We thus administered RBANS Italian version in a larger sample of older adults, taking into account the effect of age, education and gender on all scores.

METHOD

We used a regression-based model to assess the effect of age, education, and gender on RBANS Subtests, Indexes and Total scores in a consecutive series of healthy cognitively normal volunteers aged 60-79 years (N = 158). The obtained norms were compared with the Italian original normative data by means of Wilcoxon rank-sum test.

RESULTS

Multiple linear regression analyses showed that age and educational level significantly influence performances on most RBANS scores. A free-to-use Excel to calculate subject's percentiles for any single score was developed. When compared with original normative values, our percentiles distribution of Indexes and Total scores did not reveal significant differences (p > .05).

CONCLUSION

The obtained normative data show good concordance with previous norms. The instrument seems not significantly affected by educational level. The possibility to correct for any single score could make RBANS a more precise measure for capturing subtle cognitive deficits in prevention studies.

Delayed and More Variable Unimanual and Bimanual Finger Tapping in Alzheimer's Disease: Associations with Biomarkers and Applications for Classification

BACKGROUND

Despite reports of gross motor problems in mild cognitive impairment (MCI) and Alzheimer's disease (AD), fine motor function has been relatively understudied.

OBJECTIVE

We examined if finger tapping is affected in AD, related to AD biomarkers, and able to classify MCI or AD.

METHODS

Forty-seven cognitively normal, 27 amnestic MCI, and 26 AD subjects completed unimanual and bimanual computerized tapping tests. We tested 1) group differences in tapping with permutation models; 2) associations between tapping and biomarkers (PET amyloid-β, hippocampal volume, and APOEɛ4 alleles) with linear regression; and 3) the predictive value of tapping for group classification using machine learning.

RESULTS

AD subjects had slower reaction time and larger speed variability than controls during all tapping conditions, except for dual tapping. MCI subjects performed worse than controls on reaction time and speed variability for dual and non-dominant hand tapping. Tapping speed and variability were related to hippocampal volume, but not to amyloid-β deposition or APOEɛ4 alleles. Random forest classification (overall accuracy = 70%) discriminated control and AD subjects, but poorly discriminated MCI from controls or AD.

CONCLUSIONS

MCI and AD are linked to more variable finger tapping with slower reaction time. Associations between finger tapping and hippocampal volume, but not amyloidosis, suggest that tapping deficits are related to neuropathology that presents later during the disease. Considering that tapping performance is able to differentiate between control and AD subjects, it can offer a cost-efficient tool for augmenting existing AD biomarkers.