Using multivariate base rates of low scores to understand early cognitive declines on the uniform data set 3.0 Neuropsychological Battery

Does neuropsychological intraindividual variability index cognitive dysfunction, an invalid presentation, or both? Preliminary findings from a mixed clinical older adult veteran sample

INTRODUCTION

Intraindividual variability across a battery of neuropsychological tests (IIV-dispersion) can reflect normal variation in scores or arise from cognitive impairment. An alternate interpretation is IIV-dispersion reflects reduced engagement/invalid test data, although extant research addressing this interpretation is significantly limited.

METHOD

We used a sample of 97 older adult (mean age: 69.92), predominantly White (57%) or Black/African American (34%), and predominantly cis-gender male (87%) veterans. Examinees completed a comprehensive neuropsychological battery, including measures of reduced engagement/invalid test data (a symptom validity test [SVT], multiple performance validity tests [PVTs]), as part of a clinical evaluation. IIV-dispersion was indexed using the coefficient of variance (CoV). We tested 1) the relationships of raw scores and "failures" on SVT/PVTs with IIV-dispersion, 2) the relationship between IIV-dispersion and validity/neurocognitive disorder status, and 3) whether IIV-dispersion discriminated the validity/neurocognitive disorder groups using receiver operating characteristic (ROC) curves.

RESULTS

IIV-dispersion was significantly and independently associated with a selection of PVTs, with small to very large effect sizes. Participants with invalid profiles and cognitively impaired participants with valid profiles exhibited medium to large (d = .55-1.09) elevations in IIV-dispersion compared to cognitively unimpaired participants with valid profiles. A non-significant but small to medium (d = .35-.60) elevation in IIV-dispersion was observed for participants with invalid profiles compared to those with a neurocognitive disorder. IIV-dispersion was largely accurate at differentiating participants without a neurocognitive disorder from invalid participants and those with a neurocognitive disorder (areas under the Curve [AUCs]=.69-.83), while accuracy was low for differentiating invalid participants from those with a neurocognitive disorder (AUCs=.58-.65).

CONCLUSIONS

These preliminary data suggest IIV-dispersion may be sensitive to both neurocognitive disorders and compromised engagement. Clinicians and researchers should exercise due diligence and consider test validity (e.g. PVTs, behavioral signs of engagement) as an alternate explanation prior to interpretation of intraindividual variability as an indicator of cognitive impairment.

Self-perceived cognitive fluctuations and their relationship to everyday functioning in older adults with and without HIV disease

Objective: HIV is associated with elevated performance-based cognitive intra-individual variability (IIV) in the laboratory that can reflect difficulty regulating cognitive resources over time (i.e., cognitive fluctuations) and disrupt everyday functioning. Whether persons living with HIV (PLWH) experience appreciable cognitive fluctuations in their daily lives is unclear. This study examined the presence of cognitive fluctuations and their relationship to everyday functioning in PLWH. Methods: Participants were 145 PLWH and 61 seronegative individuals age ≥ 50 years who completed a self-report version of the Mayo Fluctuations Scale (MFS), structured psychiatric interview, medical evaluation, and well-validated measures of mood, cognitive symptoms, and activities of daily living (ADLs). A confirmatory factor analysis of the MFS yielded three factors, including a 7-item cognitive fluctuations scale. Results: Univariable analyses showed that HIV was associated with moderately higher MFS Cognitive Fluctuation subscale scores (d = 0.46), but this effect was no longer significant a multiple regression model that included medical comorbidities and affective disorders, which emerged as unique predictors. Of clinical relevance, higher MFS Cognitive Fluctuation subscale scores were independently associated with more frequent cognitive symptoms and dependence in ADLs in the full sample. Conclusions: Higher frequency of self-perceived cognitive fluctuations disrupts management of ADLs among middle-aged and older adults independent of HIV status and general cognitive symptoms. Future studies are needed to understand the full clinical significance of self-perceived cognitive fluctuations among PLWH and their impact on daily life.

Recent Advances in Neuropsychological Test Interpretation for Clinical Practice

Much attention in the field of clinical neuropsychology has focused on adapting to the modern healthcare environment by advancing telehealth and promoting technological innovation in assessment. Perhaps as important (but less discussed) are advances in the development and interpretation of normative neuropsychological test data. These techniques can yield improvement in diagnostic decision-making and treatment planning with little additional cost. Brooks and colleagues (Can Psychol 50: 196-209, 2009) eloquently summarized best practices in normative data creation and interpretation, providing a practical overview of norm development, measurement error, the base rates of low scores, and methods for assessing change. Since the publication of this seminal work, there have been several important advances in research on development and interpretation of normative neuropsychological test data, which may be less familiar to the practicing clinician. Specifically, we provide a review of the literature on regression-based normed scores, item response theory, multivariate base rates, summary/factor scores, cognitive intraindividual variability, and measuring change over time. For each topic, we include (1) an overview of the method, (2) a rapid review of the recent literature, (3) a relevant case example, and (4) a discussion of limitations and controversies. Our goal was to provide a primer for use of normative neuropsychological test data in neuropsychological practice.

Multivariate base rates of potentially problematic scores on the NIH Toolbox Emotion Battery

OBJECTIVE

To examine the normal frequency of obtaining one or more scores considered potentially problematic based on normative comparisons when completing the NIH Toolbox Emotion Battery (NIHTB-EB).

METHOD

Participants (N = 753; ages 18-85, 62.4% women, 66.4% non-Hispanic White) from the NIHTB norming study completed 17 scales of emotional functioning fitting into three subdomains (i.e., Negative Affect, Psychological Well-being, Social Satisfaction). Scores were considered potentially problematic if they were 1 SD above/below the mean, depending on the orientation of the scale, and cutoffs for 1.5 and 2 SD were also included for reference. Multivariate base rates quantified the rate at which participants obtained one or more potentially problematic scale or subdomain scores.

RESULTS

The portion of participants obtaining one or more potentially problematic scores on the NIHTB-EB scales and subdomains was 61.2 and 23.2%, respectively. Participants who were younger (i.e., 18-49) or had less education had higher rates of potentially problematic scores within specific subdomains. There were no significant differences by sex or race/ethnicity.

CONCLUSIONS

Elevated scores on the NIHTB-EB were common in the normative sample and related to education/age. The multivariate base rates provided indicate obtaining one or more potentially problematic scores on the NIHTB-EB is broadly normal among adults, which may guard against overinterpreting a single score as clinically significant. These base rates should be considered in the context of other assessment findings, such as interviews, medical history or informant reports, to ensure that true emotional problems are not dismissed, and normal variation in emotional functioning is not pathologized.

Development and Validity of Norms for Cognitive Dispersion on the Uniform Data Set 3.0 Neuropsychological Battery

OBJECTIVE

Cognitive dispersion indexes intraindividual variability in performance across a battery of neuropsychological tests. Measures of dispersion show promise as markers of cognitive dyscontrol and everyday functioning difficulties; however, they have limited practical applicability due to a lack of normative data. This study aimed to develop and evaluate normed scores for cognitive dispersion among older adults.

METHOD

We analyzed data from 4,283 cognitively normal participants aged ≥50 years from the Uniform Data Set (UDS) 3.0. We describe methods for calculating intraindividual standard deviation (ISD) and coefficient of variation (CoV), as well as associated unadjusted scaled scores and demographically adjusted z-scores. We also examined the ability of ISD and CoV scores to differentiate between cognitively normal individuals (n = 4,283) and those with cognitive impairment due to Lewy body disease (n = 282).

RESULTS

We generated normative tables to map raw ISD and CoV scores onto a normal distribution of scaled scores. Cognitive dispersion indices were associated with age, education, and race/ethnicity but not sex. Regression equations were used to develop a freely accessible Excel calculator for deriving demographically adjusted normed scores for ISD and CoV. All measures of dispersion demonstrated excellent diagnostic utility when evaluated by the area under the curve produced from receiver operating characteristic curves.

CONCLUSIONS

Results of this study provide evidence for the clinical utility of sample-based and demographically adjusted normative standards for cognitive dispersion on the UDS 3.0. These standards can be used to guide interpretation of intraindividual variability among older adults in clinical and research settings.

Ecological validity of cognitive fluctuations in dementia with Lewy bodies

OBJECTIVES

Cognitive fluctuations are a core clinical feature of dementia with Lewy bodies (DLB), but their contribution to the everyday functioning difficulties evident DLB are not well understood. The current study evaluated whether intraindividual variability across a battery of neurocognitive tests (intraindividual variability-dispersion) and daily cognitive fluctuations as measured by informant report are associated with worse daily functioning in DLB.

METHODS

The study sample included 97 participants with consensus-defined DLB from the National Alzheimer's Coordinating Center (NACC). Intraindividual variability-dispersion was measured using the coefficient of variation, which divides the standard deviation of an individual's performance scores across 12 normed neurocognitive indices from the NACC neuropsychological battery by that individual's performance mean. Informants reported on daily cognitive fluctuations using the Mayo Fluctuations Scale (MFS) and on daily functioning using the functional activities questionnaire (FAQ).

RESULTS

Logistic regression identified a large univariate association of intraindividual variability-dispersion and presence of daily cognitive fluctuations on the MFS (Odds Ratio = 73.27, 95% Confidence Interval = 1.38, 3,895.05). Multiple linear regression demonstrated that higher intraindividual variability-dispersion and presence of daily cognitive fluctuations as assessed by the MFS were significantly and independently related to worse daily functioning (FAQ scores).

CONCLUSIONS

Among those with DLB, informant-rated daily cognitive fluctuations and cognitive fluctuations measured in the clinic (as indexed by intraindividual variability-dispersion across a battery of tests) were independently associated with poorer everyday functioning. These data demonstrate ecological validity in measures of cognitive fluctuations in DLB.

Examining racial disparities in the diagnosis of mild cognitive impairment

Black individuals are less likely to receive an accurate diagnosis of mild cognitive impairment (MCI) than their White counterparts, possibly because diagnoses are typically made by a physician, often without reference to objective neuropsychological test data. We examined racial differences in actuarial MCI diagnoses among individuals diagnosed with MCI via semi-structured clinical interview (the Clinical Dementia Rating) to examine for possible biases in the diagnostic process. Participants were drawn from the National Alzheimer's Coordinating Center Uniform Data Set and included 491 individuals self-identifying as Black and 2,818 individuals self-identifying as White. Chi-square tests were used to examine racial differences in rates of low scores for each cognitive test (domains assessed included attention, processing speed/executive functioning, memory, language, and visual skills). Next, we tested for racial differences in probability of meeting actuarial criteria for MCI by race. Compared to Black participants diagnosed with MCI via clinical interview, White individuals diagnosed with MCI via clinical interview demonstrated significantly higher rates of low demographically-adjusted z-scores on tests of memory, attention, processing speed, and verbal fluency. Furthermore, White individuals were significantly more likely to meet actuarial criteria for MCI (71.60%) than Black individuals (57.90%). Results suggest there may be bias in MCI classification based on semi-structured interview, leading to over diagnosis among Black individuals and/or under diagnosis among White individuals. Examination of neuropsychological test data and use of actuarial approaches may reduce racial disparities in the diagnosis of MCI. Nonetheless, issues related to race-based norming and differential symptom presentations complicate interpretation of results.

Cognitive impairment indicator for the neuropsychological test batteries in the Canadian Longitudinal Study on Aging: definition and evidence for validity

BACKGROUND

Prevalence of overall cognitive impairment based on each participant's performance across a neuropsychological battery is challenging; consequently, we define and validate a dichotomous cognitive impairment/no cognitive indicator (CII) using a neuropsychological battery administered in a population-based study. This CII approximates the clinical practice of interpretation across a neuropsychological battery and can be applied to any neuropsychological dataset.

METHODS

Using data from participants aged 45-85 in the Canadian Longitudinal Study on Aging receiving a telephone-administered neuropsychological battery (Tracking, N = 21,241) or a longer in-person battery (Comprehensive, N = 30,097), impairment was determined for each neuropsychological test based on comparison with normative data. We adjusted for the joint probability of abnormally low scores on multiple neuropsychological tests using baserates of low scores demonstrated in the normative samples and created a dichotomous CII (i.e., cognitive impairment vs no cognitive impairment). Convergent and discriminant validity of the CII were assessed with logistic regression analyses.

RESULTS

Using the CII, the prevalence of cognitive impairment was 4.3% in the Tracking and 5.0% in the Comprehensive cohorts. The CII demonstrated strong convergent and discriminant validity.

CONCLUSIONS

The approach for the CII is a feasible method to identify participants who demonstrate cognitive impairment on a battery of tests. These methods can be applied in other epidemiological studies that use neuropsychological batteries.

Base rates of low neuropsychological test scores in older adults with subjective cognitive impairment: Findings from a tertiary memory clinic

Base rates of low scores are typically determined from normative samples, which differ from clinical samples. We examined base rates of spuriously low scores for 93 older adults with subjective cognitive impairment presenting to a memory clinic. Crawford's Monte Carlo simulation algorithm was used to estimate multivariate base rates by calculating the percentage of cognitively intact memory clinic patients who produced normed scores at or below the 5th percentile. Neuropsychological tests included: Weschler Adult Intelligence Scale block design, digit span backwards, coding, Weschler Memory Scale logical memory immediate/delayed; California Verbal Learning Test immediate/delayed memory; Brief Visuospatial Memory Test immediate/delayed; and Delis-Kaplan Executive Functioning category switching, letter number sequencing, and inhibition/switching. An estimated 33.58% of the cognitively intact memory clinic population would have one or more low scores, 14.7% two or more, 6.55% three or more, 2.94% four or more, and 1.31% 5 or more due to chance. Base rates were then applied to a subset of clinical data: all with dementia and most with MCI had low scores that exceeded the base rates. Determining base rates of spuriously low scores on a neuropsychological battery in clinical samples could reduce false positives by using empirical adjustments for expected low scores.

The impact of conventional versus robust norming on cognitive characterization and clinical classification of MCI and dementia

We examined the impact of conventional versus robust normative approaches on cognitive characterization and clinical classification of MCI versus dementia. The sample included participants from the National Alzheimer's Coordinating Center Uniform Data Set. Separate demographically adjusted z-scores for cognitive tests were derived from conventional (n = 4273) and robust (n = 602) normative groups. To assess the impact of deriving scores from a conventional versus robust normative group on cognitive characterization, we examined likelihood of having a low score on each neuropsychological test. Next, we created receiver operating characteristic (ROC) curves for the ability of normed scores derived from each normative group to differentiate between MCI (n = 3570) and dementia (n = 1564). We examined the impact of choice of normative group on classification accuracy by comparing sensitivity and specificity values and areas under the curves (AUC). Compared with using a conventional normative group, using a robust normative group resulted in a higher likelihood of low cognitive scores for individuals classified with MCI and dementia. Comparison of the classification accuracy for distinguishing MCI from dementia did not suggest a statistically significant advantage for either normative approach (Z = -0.29, p = .77; AUC = 0.86 for conventional and AUC = 0.86 for robust). In summary, these results indicate that using a robust normative group increases the likelihood of characterizing cognitive performance as low. However, there is not a clear advantage of using a robust over a conventional normative group when differentiating between MCI and dementia.

Dispersion-based cognitive intra-individual variability in dementia with Lewy bodies

OBJECTIVE

Cognitive fluctuations are characteristic of dementia with Lewy bodies (DLB) but challenging to measure. Dispersion-based intra-individual variability (IIV-d) captures neurocognitive performance fluctuations across a test battery and may be sensitive to cognitive fluctuations but has not been studied in DLB.

METHOD

We report on 5,976 participants that completed the uniform data set 3.0 neuropsychological battery (UDS3NB). IIV-d was calculated via the intra-individual standard deviation across 12 primary UDS3NB indicators. Separate models using mean USD3NB score and the Montreal cognitive assessment (MoCA) total score tested the reproducibility of the incremental value of IIV-d over-and-above global cognition. Binary logistic regressions tested whether IIV-d could classify individuals with and without clinician-rated cognitive fluctuations. Multinomial logistic regressions tested whether IIV-d could differentiate participants with DLB, participants with Alzheimer's disease (AD), and participants with healthy cognition (CH), as well as the incremental diagnostic utility of IIV-d over-and-above clinician-rated cognitive fluctuations.

RESULTS

IIV-d exhibited large univariate associations with clinician-rated and non-clinician-informant reported cognitive fluctuations, which persisted when adjusting for MoCA but not the full battery mean. Of diagnostic relevance, greater IIV-d was consistently associated with DLB and AD relative to CH over-and-above global cognition and clinician-rated cognitive fluctuations. Greater IIV-d was less consistently associated with an increased probability of DLB relative to AD when controlling for global cognition.

CONCLUSIONS

IIV-d accurately differentiates DLB from CH over-and-above global cognition and clinician-rated cognitive fluctuations. IIV-d may supplement a thorough clinical interview of cognitive fluctuations and serve as a standardized performance-based indicator of this transdiagnostic phenomenon. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The ecological validity of the Uniform Data Set 3.0 neuropsychological battery in individuals with mild cognitive impairment and dementia

Objective: Ecological validity refers to the ability of neuropsychological measures to predict real world performance. Questions remain as to the ecological validity of commonly used measures, particularly regarding their relationships to global versus specific activities of daily living among those with neurodegenerative disease. We explored these issues through the lens of the Uniform Data Set 3.0 Neuropsychological battery (UDS3NB) in individuals with mild cognitive impairment and dementia. Method: UDS3NB and informant rated Functional Activities Questionnaire scales were evaluated from 2,253 individuals with mild cognitive impairment and dementia. Ordinal regression equations were used to explore the relationships of demographic and cognitive variables with overall and specific instrumental activities of daily living. Results: Delayed recall for visual and verbal material, and performance on trail making tests were consistent predictors of global and specific functions. Specific skills (i.e. naming or figure copy) showed differential relationships with specific activities, while phonemic fluency was not related to any particular activity. Conclusions: Measures in the UDS3NB predicted activities of daily living in individuals with MCI and dementia, providing initial support for the ecological validity of these tests. Specifically, measures that tap core deficits of Alzheimer's disease, such as delayed recall and sequencing/shifting, are consistent predictors of performance in daily tasks.

Multivariate Base Rates of Low Neuropsychological Test Scores in Cognitively Intact Older Adults with Subjective Cognitive Decline from a Specialist Memory Clinic

OBJECTIVE

To avoid misdiagnosing mild cognitive impairment (MCI), knowledge of the multivariate base rates (MVBRs) of low scores on neuropsychological tests is crucial. Base rates have typically been determined from normative population samples, which may differ from clinically referred samples. The current study addresses this limitation by calculating the MVBR of low or high cognitive scores in older adults who presented to a memory clinic experiencing subjective cognitive decline but were not diagnosed with MCI.

METHOD

We determined the MVBRs on the Kaplan-Baycrest Neurocognitive Assessment for 107 cognitively healthy older adults (M age = 75.81), by calculating the frequency of patients producing n scores below or above different cut-off values (i.e., 1, 1.5, 2.0, 2.5 SD from the mean), stratifying by education and gender.

RESULTS

Performing below or above cut-off was common, with more stringent cut-offs leading to lower base rates (≥1 low scores occurred in 84.1% of older adults at -1 SD, 55.1% at -1.5 SD, and 39.3% at -2 SD below the mean; ≥1 high scores occurred in 80.4% of older adults at +1 SD, 35.5% at +1.5 SD, and 16.8% at +2 SD above the mean). Higher education was associated with varying base rates. Overall, the MVBR of obtaining a low cognitive test score was higher in this clinic sample, compared with prior studies of normative samples.

CONCLUSIONS

MVBRs for clinically referred older adults experiencing memory complaints provide a diagnostic benefit, helping to prevent attributing normal variability to cognitive impairment and limiting false positive diagnoses.

A Comparison of Operational Definitions for Mild Cognitive Impairment

Background: Consideration of many tests from different cognitive domains in defining mild cognitive impairment (MCI) is clinical routine, but guidelines for a neuropsychological operationalization of MCI are lacking. Objective: Among different operational MCI criteria, to identify those which are best in predicting either conversion to dementia, or a biomarker profile indicative for Alzheimer’s disease (AD). Methods: Memory-clinic patients without dementia (N = 558; mean age = 66; up to 3 years of follow-up; n = 360 with baseline CSF biomarkers) were included in an observational study using most liberal criteria of cognitive impairment. Four operational definitions of MCI were retrospectively applied: 1) amnestic MCI (word list delayed recall), 2) CERAD total score, 3) comprehensive criteria and 4) base rate corrected CERAD. We compared their accuracy in predicting incident all-cause dementia or AD dementia within three years, or a concurrent CSF Aβ42/tau-ratio indicative of AD. Results: The four definitions overlapped considerably, classified 35–58% of the original sample as impaired and were associated with markedly increased PPVs regarding incident all-cause dementia (39–46% versus 26% of the original sample), AD dementia and AD biomarker positivity. The base-rate corrected MCI definition had the highest prognostic accuracy. Conclusion: he operational criteria examined seem suitable to specify MCI in memory clinic settings, as they identify subjects at high risk of clinical progression. Depending on the neuropsychological battery in use, one or several of these criteria could help to calibrate the clinical judgment of test results, reduce false-positive decisions, and define risk-enriched groups for clinical trials.

Reducing misclassification of mild cognitive impairment based on base rate information from the Uniform data set

The current study aimed to define and validate the criteria for characterizing possible and probable cognitive deficits based on the psychometric approach using the Uniform data set Czech version (UDS-CZ 2.0) to reduce the rate of misdiagnosis. We computed the prevalence of low scores on the 14 subtests of UDS-CZ 2.0 in a normative sample of healthy older adults and validated criteria for possible and probable cognitive impairment on the sample of amnestic Mild Cognitive Impairment (MCI) patients. The misclassification rate of the validation sample using psychometrically derived criteria remained low: for classification as possible impairment, we found 66-76% correct classification in the clinical sample and only 2-8% false positives in the healthy control validation sample, similar results were obtained for probable cognitive impairment. Our findings offer a psychometric approach and a computational tool to minimize the misdiagnosis of mild cognitive impairment compared to traditional criteria for MCI.

Enhanced interpretation of the BRIEF2: multivariate base rates of elevated scores in the standardization samples

The Behavior Rating Inventory of Executive Function, Second Edition (BRIEF2) is a standardized rating (self, parent, and teacher) scale of executive functioning in children and adolescents. Here, we provide multivariate base rate (MBR) information (for the Self, Parent, and Teacher forms), which is not included in the BRIEF2 Professional Manual. Participants were children and adolescents for the BRIEF2 Self-Report (ages = 11-18; N = 803), Parent-Report (ages = 5-18; N = 1,400), and Teacher-Report (ages = 5-18; N = 1,400) standardization samples. We focused on cumulative (e.g., % of sample with oneor more elevated scores) MBRs across scales, which were examined at three elevation levels on each form: T≥ 60, ≥65, and ≥70. Across forms, MBRs predictably decreased with increasing number of elevated scores and at higher cutoffs. The cumulative MBR of having at least one score at T≥ 60 was common (37.5-42.2%), but less frequent at T≥ 70 (15.4-17.4%). The probability of having elevated scores on all scales was very low, irrespective of form, age, or elevation threshold (T≥ 60 = 2.4-4.4%; T≥ 65 = 1.0-1.4%; T≥ 70 = 0.0-0.7%). There was no clinically meaningful relation between demographic factors (age, gender, race, and parental education) and MBRs. These data provide clinicians and researchers with an enhanced way of concurrently interpreting multiple BRIEF2 scales.

An initial exploration of the convergent and ecological validity of the UDS 3.0 neuropsychological battery in Parkinson's Disease

OBJECTIVE

The Uniform Data Set 3.0 neuropsychological battery (UDS3NB) is well developed for research with Alzheimer's disease and related dementias, and may serve as a common set of measures of cognitive decline across neurodegenerative diseases. However, the battery has not been formally assessed in persons with Parkinson's disease (PD). The current research provides initial information on the convergent and ecological validity of the UDS3NB in individuals with PD.

METHODS

Participants included 75 individuals diagnosed with PD from the Arizona Study of Aging and Neurodegenerative Disorders. Clinical dementia ratings, administered independently from the cognitive measures, identified individuals as having normal cognition (n = 38), Mild Cognitive Impairment (MCI; n = 25) and dementia (n = 12). UDS3NB measures were compared between these groups, and correlations between UDS3NB measures, gold standard neuropsychological measures, and informant rated activities of daily living ability (ADL) were evaluated.

RESULTS

At the group-level, UDS3NB scores followed the expected pattern with higher scores in participants with PD but no cognitive diagnosis and lower in those with dementia; scores in the MCI group were between these extremes. Convergent validity was suggested by moderate correlations between UDS specific measures (i.e., Craft story) and measures such as the RAVLT. Ecological validity was suggested by statistically significant correlations between UDS3NB performance and caregiver ratings of ADLs, with speed and executive functioning measures (Trailmaking A; r = -.51, p < .01; Trailmaking B; r = -.51, p < .01) most strongly related to reported daily functioning.

CONCLUSIONS

Findings provide initial support for the convergent and ecological validity of the UDS3NB in individuals with PD. Implications and future directions for this battery are discussed.

Empirically defining the preclinical stages of the Alzheimer's continuum in the Alzheimer's Disease Neuroimaging Initiative

AIM

The National Institute on Aging and the Alzheimer's Association published new research criteria defining the Alzheimer's continuum (AC) by the presence of positive amyloid-β biomarkers. Symptom severity of those on the AC is staged across six levels, including two preclinical stages (stages 1 and 2). AC stage 2 is defined by the presence of at least one of the following: (i) transitional cognitive decline; (ii) subjective cognitive decline; or (iii) neurobehavioural symptoms. In contrast, AC stage 1 is defined by the absence of symptoms.

METHODS

Initial empirical definitions for each symptom class were developed. These empirical criteria were then applied in a sample of 285 cognitively normal, amyloid-positive individuals from the Alzheimer's Disease Neuroimaging Initiative for purposes of AC stage 1 and 2 classification.

RESULTS

In this sample, 56.10% of participants were asymptomatic and classified as AC stage 1. In contrast, 42.46% of individuals were positive for at least one symptom class: 22.11% for transitional cognitive decline, 20.35% for subjective cognitive decline, and 14.74% for neurobehavioural symptoms. AC stage was a predictor of cognitive/functional decline over 4 years of follow up in a longitudinal growth model (B = 0.33, P < 0.001).

CONCLUSIONS

Results provide a methodology to operationalize the National Institute on Aging and the Alzheimer's Association AC stage 1 and 2 criteria and include preliminary evidence of the validity of this approach. The methods outlined in this manuscript can be used to test hypotheses regarding prodromal Alzheimer's disease, as well as implemented in clinical trial selection procedures.

How impaired is too impaired? Exploring futile neuropsychological test patterns as a function of dementia severity and cognitive screening scores

Some older adults cannot meaningfully participate in the testing portion of a neuropsychological evaluation due to significant cognitive impairments. There are limited empirical data on this topic. Thus, the current study sought to provide an operational definition for a futile testing profile and examine cognitive severity status and cognitive screening scores as predictors of testing futility at both baseline and first follow-up evaluations. We analysed data from 9,263 older adults from the National Alzheimer's Coordinating Center Uniform Data Set. Futile testing profiles occurred rarely at baseline (7.40%). There was a strong relationship between cognitive severity status and the prevalence of futile testing profiles, χ² (4) = 3559.77, p < .001. Over 90% of individuals with severe dementia were unable to participate meaningfully in testing. Severity range on the Montreal Cognitive Assessment (MoCA) also demonstrated a strong relationship with testing futility, χ² (3) = 3962.35, p < .001. The rate of futile testing profiles was similar at follow-up (7.90%). There was a strong association between baseline dementia severity and likelihood of demonstrating a futile testing profile at follow-up, χ² (4) = 1513.40, p < .001. Over 90% of individuals with severe dementia, who were initially able to participate meaningfully testing, no longer could at follow-up. Similarly, there was a strong relationship between baseline MoCA score band and likelihood of demonstrating a futile testing profile at follow-up, χ² (3) = 1627.37, p < .001. Results can help to guide decisions about optimizing use of limited neuropsychological assessment resources.

An Initial Empirical Operationalization of the Earliest Stages of the Alzheimer's Continuum

PURPOSE

The Alzheimer's Continuum (AC) includes 2 preclinical stages defined by subjective cognitive complaints, transitional cognitive declines, and neurobehavioral symptoms. Operationalization of these stages is necessary for them to be applied in research.

METHODS

Cognitively normal individuals with known amyloid biomarker status were selected from the National Alzheimer's Coordinating Center Uniform Data Set. Participants and their caregivers provided information on subjective cognitive complaints, neurobehavioral features, and objective cognitive functioning.

PATIENTS

The sample included 101 amyloid positive (A+) and 447 amyloid negative (A-) individuals.

RESULTS

Rates of subjective cognitive complaints (A+: 34.90%, A-: 29.90%) and neurobehavioral symptoms (A+: 22.40%, A-: 22.40%) did not significantly differ between A+/- individuals. However, the frequency of transitional cognitive decline was significantly higher among A+ (38.00%) than A- participants (24.90%). We explored various empirical definitions for defining the early stages of the AC among A+ participants. Rates of classification into AC stage 1 versus AC stage 2 varied depending on the number of symptoms required: 57.40% versus 42.60% (1 symptom), 28.70% versus 71.30% (2 symptoms), and 6.90% versus 93.10% (all 3 symptoms).

CONCLUSION

The presence of 2 of the proposed symptom classes to separate AC stage 2 from stage 1 seems to provide a good empirical balance.

Development and Preliminary Validation of Standardized Regression-Based Change Scores as Measures of Transitional Cognitive Decline

OBJECTIVE

An increasing focus in Alzheimer's disease and aging research is to identify transitional cognitive decline. One means of indexing change over time in serial cognitive evaluations is to calculate standardized regression-based (SRB) change indices. This paper includes the development and preliminary validation of SRB indices for the Uniform Data Set 3.0 Neuropsychological Battery, as well as base rate data to aid in their interpretation.

METHOD

The sample included 1,341 cognitively intact older adults with serial assessments over 0.5-2 years in the National Alzheimer's Coordinating Center Database. SRB change scores were calculated in half of the sample and then validated in the other half of the sample. Base rates of SRB decline were evaluated at z-score cut-points, corresponding to two-tailed p-values of .20 (z = -1.282), .10 (z = -1.645), and .05 (z = -1.96). We examined convergent associations of SRB indices for each cognitive measure with each other as well as concurrent associations of SRB indices with clinical dementia rating sum of box scores (CDR-SB).

RESULTS

SRB equations were able to significantly predict the selected cognitive variables. The base rate of at least one significant SRB decline across the entire battery ranged from 26.70% to 58.10%. SRB indices for cognitive measures demonstrated theoretically expected significant positive associations with each other. Additionally, CDR-SB impairment was associated with an increasing number of significantly declined test scores.

CONCLUSIONS

This paper provides preliminary validation of SRB indices in a large sample, and we present a user-friendly tool for calculating SRB values.