The Other Side of the Bell Curve: Multivariate Base Rates of High Scores on the Delis-Kaplan Executive Function System.

OBJECTIVE: Previous researchers have examined the frequency at which healthy participants obtain one or more low scores on neuropsychological test batteries, proposing five psychometric principles of multivariate base rates: (a) low scores are common, with their frequency contingent on (b) the low score cutoff used, (c) the number of tests administered/interpreted, and (d) the demographic characteristics and (e) intelligence of participants. The current study explored whether these principles applied to high scores as well, using the Delis-Kaplan Executive Function System (D-KEFS). METHOD: Multivariate base rates of high scores (≥75th, ≥84th, ≥91st, ≥95th, and ≥98th percentiles) were derived for a three-test, four-test, and full D-KEFS battery, using the adult portion of the normative sample (aged 16-89 years; N = 1050) stratified by education and intelligence. The full D-KEFS battery provides 16 total achievement scores (primary indicators of executive function). RESULTS: High scores occurred commonly for all batteries. For the three-test battery, 24.1% and 12.4% had 1 or more scores ≥95th percentile and ≥98th percentile, respectively. High scores occurred more often for longer batteries: 61.6%, 72.9%, and 87.8% obtained 1 or more scores ≥84th percentile for the three-test, four-test, and full batteries, respectively. The frequency of high scores increased with more education and higher intelligence. CONCLUSIONS: The principles of multivariate base rates also applied to high D-KEFS scores: high scores were common and contingent on the cutoff used, number of tests administered/interpreted, and education/intelligence of examinees. Base rates of high scores may help clinicians identify true cognitive strengths and detect cognitive deficits in high functioning people.

Usability and Effectiveness of Immersive Virtual Grocery Shopping for Assessing Cognitive Fatigue in Healthy Controls: Protocol for a Randomized Controlled Trial.

BACKGROUND: Cognitive fatigue (CF) is a human response to stimulation and stress and is a common comorbidity in many medical conditions that can result in serious consequences; however, studying CF under controlled conditions is difficult. Immersive virtual reality provides an experimental environment that enables the precise measurement of the response of an individual to complex stimuli in a controlled environment. OBJECTIVE: We aim to examine the development of an immersive virtual shopping experience to measure subjective and objective indicators of CF induced by instrumental activities of daily living. METHODS: We will recruit 84 healthy participants (aged 18-75 years) for a 2-phase study. Phase 1 is a user experience study for testing the software functionality, user interface, and realism of the virtual shopping environment. Phase 2 uses a 3-arm randomized controlled trial to determine the effect that the immersive environment has on fatigue. Participants will be randomized into 1 of 3 conditions exploring fatigue response during a typical human activity (grocery shopping). The level of cognitive and emotional challenges will change during each activity. The primary outcome of phase 1 is the experience of user interface difficulties. The primary outcome of phase 2 is self-reported CF. The core secondary phase 2 outcomes include subjective cognitive load, change in task performance behavior, and eye tracking. Phase 2 uses within-subject repeated measures analysis of variance to compare pre- and postfatigue measures under 3 conditions (control, cognitive challenge, and emotional challenge). RESULTS: This study was approved by the scientific review committee of the National Institute of Nursing Research and was identified as an exempt study by the institutional review board of the National Institutes of Health. Data collection will begin in spring 2021. CONCLUSIONS: Immersive virtual reality may be a useful research platform for simulating the induction of CF associated with the cognitive and emotional challenges of instrumental activities of daily living. TRIAL REGISTRATION: ClinicalTrials.gov NCT04883359; http://clinicaltrials.gov/ct2/show/NCT04883359. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/28073.

Developing an Executive Functioning Composite Score for Research and Clinical Trials.

OBJECTIVE: Executive functioning encompasses interactive cognitive processes such as planning, organization, set-shifting, inhibition, self-monitoring, working memory, and initiating and sustaining motor and mental activity. Researchers therefore typically assess executive functioning with multiple tests, each yielding multiple scores. A single composite score of executive functioning, which summarizes deficits across a battery of tests, would be useful in research and clinical trials. This study examines multiple candidate composite scores of executive functioning using tests from the Delis-Kaplan Executive Function System (D-KEFS). METHOD: Participants were 875 adults between the ages of 20 and 89 years from the D-KEFS standardization sample. Seven Total Achievement scores were used from three tests (i.e., Trail Making, Verbal Fluency, and Color-Word Interference) to form eight composite scores that were compared based on their psychometric properties and association with intelligence (IQ). RESULTS: The distributions of most composite scores were mildly to severely skewed, and some had a pronounced ceiling effect. The composite scores all showed a medium positive correlation with IQ. The composite scores were highly intercorrelated in the total sample and in four IQ subgroups (i.e., IQ <89, 90-99, 100-109, 110+), with some being so highly correlated that they appear redundant. CONCLUSIONS: This study is part of a larger research program developing a cognition endpoint for research and clinical trials with sound psychometric properties and utility across discrepant test batteries. Future research is needed to examine the reliability and ecological validity of these composite scores.

Minimizing misdiagnosis: psychometric criteria for possible or probable memory impairment.

BACKGROUND/AIMS: Memory impairment can be easily misdiagnosed in older adults because obtaining some low scores is common. The objective of the present study is to present new psychometric criteria for determining 'possible' and 'probable' memory impairment. METHODS: We propose criteria based on an analysis of performance from 450 healthy older adults (55-87 years old) on 3 measures from the WMS-III: Logical Memory, Word List, and Visual Reproduction. These measures yield 8 age-adjusted scores for learning, recall, and recognition. The proposed criteria for memory impairment are based on the prevalence of low scores when simultaneously examining all 8 scores and are stratified by current intelligence, estimated premorbid intelligence, and education. The criteria are subsequently validated on 100 healthy older adults and 34 patients with 'possible' or 'probable' Alzheimer's Disease (AD). RESULTS: Tables with cutoffs and false-positive rates are presented for clinical use. In the validation cohort there were no misclassifications in AD patients. CONCLUSION: This study presents steps in the development of proposed psychometric criteria that, in conjunction with clinical judgment, could minimize the misdiagnosis of memory impairment. It is important to reduce misdiagnosis in order to (a) optimize patient care, (b) provide an accurate foundation for identifying biological and neurological markers, and (c) successfully develop disease-modifying treatments. Further validation in a sample of older adults with lesser degrees of cognitive impairment is needed.

Healthy children and adolescents obtain some low scores across a battery of memory tests.

Obtaining some low memory scores across a battery of tests is common. The purpose of this study was to examine the prevalence of low scores on the Children's Memory Scale (CMS). Participants were 1000 children and adolescents between 5 and 16 years of age from the CMS standardization sample. Consistent with research on other batteries, having some low memory scores is common in healthy children and adolescents. The prevalence of low memory scores also increases with lower intelligence. Clinicians should be cautious when interpreting isolated low memory scores as sole evidence of memory impairment. Knowing the prevalence of low scores as a supplement to clinical judgment should reduce the likelihood of misdiagnosing memory problems.

Multivariate base rates for the assessment of executive functioning among children and adolescents.

This study provides observed base rates of low executive functioning test scores among healthy children and adolescents, stratifies those base rates by narrow intellectual functioning and age groupings, and provides normative classification ranges to aid the interpretation of performances on the Delis-Kaplan Executive Function System (D-KEFS) in clinical practice and research. Participants included 875 children and adolescents between 8 and 19 years old from the D-KEFS normative sample (48% male; 52% female). Among these participants, 838 had complete data and were included in the current study. The racial/ethnic composition of the sample was: White (73.7%), African American (12.4%), Hispanic (11.1%), and other racial/ethnic backgrounds (2.7%). The Overall Test Battery Mean (OTBM) and the prevalence of low scores at various clinical cut-offs were calculated for the 13 primary scores from the D-KEFS Trail Making Test, Verbal Fluency Test, and Color-Word Interference Test. The OTBM and base rates were also calculated separately for those scores reflecting executive functioning (n = 7) and processing speed (n = 6). Healthy children and adolescents commonly obtained low scores on the D-KEFS tests considered here. Younger age, lower estimated full-scale intelligence quotient, and more test scores interpreted were associated with a greater frequency of low scores. Clinicians and researchers are encouraged to consider these multivariate base rates when assessing and attempting to identify executive functioning impairment among children and adolescents with the D-KEFS.

Potential for misclassification of mild cognitive impairment: a study of memory scores on the Wechsler Memory Scale-III in healthy older adults.

The psychometric criterion of mild cognitive impairment (MCI) generally involves having an unusually low score on memory testing (i.e., -1.5 SDs). However, healthy older adults can obtain low scores, particularly when multiple memory measures are administered. In turn, there is a substantial risk of psychometrically misclassifying MCI in healthy older adults. This study examined the base rates of low memory scores in older adults (55-87 years; n = 550) from the Wechsler Memory Scale-Third Edition (WMS-III; Wechsler, 1997b) standardization sample. The WMS-III consists of four co-normed episodic memory tests (i.e., Logical Memory, Faces, Verbal Paired Associates, and Family Pictures) that yield eight age- and demographically-adjusted standard scores (Auditory Recognition and Working Memory tests not included). When the eight age-adjusted scores were examined simultaneously, 26% of older adults had one or more scores at or below the 5th percentile (i.e., -1.5 SDs). On the eight demographically- adjusted scores, 39% had at least one score at or below the 5th percentile. There was an inverse relationship between intellectual abilities and prevalence of low memory scores, particularly with the age-adjusted WMS-III scores. Understanding the base rates of low scores can reduce the overinterpretation of low memory scores and minimize false-positive misclassification.

Equivalence of a measurement model of cognitive abilities in U.S. standardization and Australian neuroscience samples.

A psychological measurement model provides an explicit definition of (a) the theoretical and (b) the numerical relationships between observed scores and the latent variables that underlie the observed scores. Examination of the metric invariance of a measurement model involves testing the hypothesis that all components of the model relating observed scores to latent variables are equal across groups. The assumption of metric invariance is necessary for simple interpretation of scores. Establishing metric invariance also has implications for interpretation of convergent and divergent validity and patterns of deficit or disability. In this study the equivalence of the measurement model derived from the U.S. Wechsler Adult Intelligence Scale-III standardization sample was compared with a heterogeneous neurosciences sample in Australia. A pattern of strict metric invariance was observed across samples. These results provide evidence of the generality of the model underlying measurement of cognitive abilities.

Advanced clinical interpretation of the Delis-Kaplan Executive Function System: multivariate base rates of low scores.

OBJECTIVE: Multivariate base rates allow for the simultaneous statistical interpretation of multiple test scores, quantifying the normal frequency of low scores on a test battery. This study provides multivariate base rates for the Delis-Kaplan Executive Function System (D-KEFS). METHOD: The D-KEFS consists of 9 tests with 16 Total Achievement scores (i.e. primary indicators of executive function ability). Stratified by education and intelligence, multivariate base rates were derived for the full D-KEFS and an abbreviated four-test battery (i.e. Trail Making, Color-Word Interference, Verbal Fluency, and Tower Test) using the adult portion of the normative sample (ages 16-89). RESULTS: Multivariate base rates are provided for the full and four-test D-KEFS batteries, calculated using five low score cutoffs (i.e. ≤25th, 16th, 9th, 5th, and 2nd percentiles). Low scores occurred commonly among the D-KEFS normative sample, with 82.6 and 71.8% of participants obtaining at least one score ≤16th percentile for the full and four-test batteries, respectively. Intelligence and education were inversely related to low score frequency. CONCLUSIONS: The base rates provided herein allow clinicians to interpret multiple D-KEFS scores simultaneously for the full D-KEFS and an abbreviated battery of commonly administered tests. The use of these base rates will support clinicians when differentiating between normal variations in cognitive performance and true executive function deficits.

A comparison of PHQ-9 and TBI-QOL depression measures among individuals with traumatic brain injury.

PURPOSE/OBJECTIVE: To compare and contrast how individuals with traumatic brain injury (TBI) are classified (positive or negative screen) by different cut-offs on two self-report measures of depressive symptoms: the PHQ-9, which assesses somatic symptoms, and the TBI-QOL Depression item bank, which does not. Research Method/Design: Three hundred eighty-five individuals with TBI were recruited from six rehabilitation hospitals in the U.S. as part of the calibration data collection for the TBI-QOL patient-reported outcome measurement system. RESULTS: The TBI-QOL and PHQ-9 total scores correlated strongly (disattenuated r = .83). The correlation was even stronger (disattenuated r = .92) when the four PHQ-9 somatic items were removed from the total score. When the PHQ-9 was scored traditionally, the rate of agreement was approximately 80-85% using standard cut-offs for each scale. Depending on the cut-off score, 23-26% of participants screened positive on the PHQ-9, whereas 9-38% screened positive on the TBI-QOL Depression. Individuals who screened positive on the PHQ-9 alone reported more somatic symptoms than those who screened positive on the TBI-QOL alone. Individuals who screened positive on the TBI-QOL alone were at slightly greater risk for other negative psychological functioning than individuals who screened positive on the PHQ-9 alone. CONCLUSIONS/IMPLICATIONS: The PHQ-9 and TBI-QOL Depression performed similarly in screening for depressive symptoms among individuals with TBI. The PHQ-9 identified more individuals with somatic symptoms, which may overlap with other medical issues, whereas the TBI-QOL Depression instrument identified more individuals who reported other forms of emotional distress. (PsycINFO Database Record

Reliable Change on Memory Tests is Common in Healthy Children and Adolescents.

OBJECTIVE: Neuropsychologists interpret a large number of scores in their assessments, including numerous retest scores to determine change over time. The rate at which healthy children and adolescents obtain reliably improved or declined memory scores when retested has yet to be explored. The purpose of this study was to illustrate the prevalence of reliable change scores on memory test batteries in healthy children and adolescents. METHODS: Participants were children and adolescents from test-retest samples from two published memory test batteries (ChAMP and CMS). Reliable change scores (RCI with 90% confidence interval and practice effects) were calculated for the indexes and subtests of each battery. Multivariate base rates involved considering all change scores simultaneously within each battery and calculating the frequencies of healthy children obtaining one or more reliably declined or one or more reliably improved scores. RESULTS: Across both memory batteries, one or more reliably changed index or subtest score was common; however, reliable change on three or more scores was uncommon (i.e., found in <5% of the samples). Base rates of change scores did not differ by parent education. CONCLUSIONS: Having a single reliably changed score on retest is common when interpreting these memory batteries. Multivariate interpretation is necessary when determining cognitive decline and cognitive recovery. Further research is warranted with other measures, other samples, and different retest intervals.

Using Multivariate Base Rates to Interpret Low Scores on an Abbreviated Battery of the Delis-Kaplan Executive Function System.

OBJECTIVE: Executive function consists of multiple cognitive processes that operate as an interactive system to produce volitional goal-oriented behavior, governed in large part by frontal microstructural and physiological networks. Identification of deficits in executive function in those with neurological or psychiatric conditions can be difficult because the normal variation in executive function test scores, in healthy adults when multiple tests are used, is largely unknown. This study addresses that gap in the literature by examining the prevalence of low scores on a brief battery of executive function tests. METHOD: The sample consisted of 1,050 healthy individuals (ages 16-89) from the standardization sample for the Delis-Kaplan Executive Function System (D-KEFS). Seven individual test scores from the Trail Making Test, Color-Word Interference Test, and Verbal Fluency Test were analyzed. RESULTS: Low test scores, as defined by commonly used clinical cut-offs (i.e., ≤25th, 16th, 9th, 5th, and 2nd percentiles), occurred commonly among the adult portion of the D-KEFS normative sample (e.g., 62.8% of the sample had one or more scores ≤16th percentile, 36.1% had one or more scores ≤5th percentile), and the prevalence of low scores increased with lower intelligence and fewer years of education. CONCLUSIONS: The multivariate base rates (BR) in this article allow clinicians to understand the normal frequency of low scores in the general population. By use of these BRs, clinicians and researchers can improve the accuracy with which they identify executive dysfunction in clinical groups, such as those with traumatic brain injury or neurodegenerative diseases.

NIH toolbox cognition tests following traumatic brain injury: Frequency of low scores.

PURPOSE/OBJECTIVE: To apply multivariate base rate analyses to the National Institutes of Health Toolbox Cognition Battery (NIHTB-CB) to facilitate the identification of cognitive impairment in individuals with traumatic brain injury (TBI). Research Method/Design: In a multisite cross-sectional design, 158 participants who sustained a complicated mild or moderate TBI (n = 74) or severe TBI (n = 84) at least 1 year earlier were administered the NIHTB-CB. The NIHTB-CB is comprised of 2 crystallized cognition tests (reflecting premorbid ability) and 5 fluid cognition tests, measuring processing speed, memory, and executive functioning. Base rates for obtaining 0 to 5 low fluid cognition scores were calculated across a range of cutoffs for defining a low test score (≤25th to 5th percentiles). Base rates of low scores in the TBI sample were compared to the NIHTB-CB normative sample using diagnostic accuracy statistics. RESULTS: The proportion of the TBI sample obtaining low scores decreased as the cutoff for defining a low score decreased. Individuals with lower premorbid cognitive ability, as measured by NIHTB-CB Crystallized Composite score, tended to produce more low scores on the NIHTB-CB fluid cognition tests, even when using fully demographically adjusted scores. Certain patterns of low scores were associated with TBI (defined as likelihood ratio >2.0), whereas others were nonspecific, occurring almost as often in participants without TBI. CONCLUSIONS/IMPLICATIONS: Premorbid ability stratified base rate tables provided in this article can guide researchers and clinicians in the interpretation of NIHTB-CB performance in adults with TBI. (PsycINFO Database Record

Factor structure of the NIH Toolbox Cognition Battery in individuals with acquired brain injury.

OBJECTIVE: The National Institutes of Health Toolbox Cognition Battery (NIHTB-CB) measures reading, vocabulary, episodic memory, working memory, executive functioning, and processing speed. While previous research has validated the factor structure in healthy adults, the factor structure has not been examined in adults with neurological impairments. Thus, this study evaluated the NIHTB-CB factor structure in individuals with acquired brain injury. METHOD: A sample of 392 individuals (ages 18-84) with acquired brain injury (n = 182 TBI, n = 210 stroke) completed the NIHTB-CB along with neuropsychological tests as part of a larger, multisite research project. RESULTS: Confirmatory factor analyses supported a 5-factor solution that included reading, vocabulary, episodic memory, working memory, and processing speed/executive functioning. This structure generally held in TBI and stroke subsamples as well as in subsamples of those with severe TBI and stroke injuries. CONCLUSIONS: The factor structure of the NIHTB-CB is similar in adults with acquired brain injury to adults from the general population. We discuss the implications of these findings for clinical practice and clinical research. (PsycINFO Database Record

Cognition among community-dwelling individuals with spinal cord injury.

PURPOSE/OBJECTIVE: To compare the cognitive profiles of a well-characterized sample of adults with and without spinal cord injury (SCI) using the NIH Toolbox Cognition Battery NIHTB-CB. Research Method/Design: Participants were 156 community-dwelling individuals with SCI recruited from 3 academic medical centers, and 156 individuals without SCI selected from the NIHTB-CB normative database (N = 312). The main outcome measures were the demographically adjusted NIHTB-CB subtest and composite scores. RESULTS: Individuals with and without SCI performed equivalently on the NIHTB-CB crystallized composite score, suggesting comparable premorbid functioning. Individuals with SCI produced lower scores on the NIHTB-CB fluid composite score by an average of 4.5 T-score points (Cohen's d = 0.50; a medium effect size). As a group, individuals with SCI had the most difficulty on tests of processing speed and executive functions, and some difficulty on a test of episodic memory, although effect sizes were small. These differences remained even after accounting for fine motor speed and dexterity. Individuals with tetraplegia produced lower scores than individuals with paraplegia on tests of processing speed and executive functioning. CONCLUSION/IMPLICATIONS: Community-dwelling individuals with SCI are at elevated risk of mild cognitive difficulties, particularly on tasks that rely on processing speed and executive functions. The NIHTB-CB is relatively brief, samples important cognitive domains, has good normative data, and is appropriate for some individuals with SCI (those who have functional use of one hand). The battery has standardized accommodations for individuals with minor motor limitations, but timed tests are inaccessible for individuals who are unable to perform rapid button presses. (PsycINFO Database Record

Nih toolbox premorbid ability adjustments: Application in a traumatic brain injury sample.

PURPOSE/OBJECTIVE: Metrics to estimate premorbid cognitive ability, such as word reading tests, are important for clinical determination of cognitive changes following brain injury. In the present study, reading adjusted scores for the National Institutes of Health Toolbox Cognition Battery (NIHTB-CB) fluid tests were developed and validated with a sample of individuals with traumatic brain injury (TBI), to evaluate the clinical utility of reading-adjusted scores. Research Method/Design: The development sample included 843 adult participants, ages 20-85, from the NIHTB-CB standardization sample. A sample of 158 participants with complicated mild or moderate TBI (n = 74) or severe TBI (n = 84) were administered the NIHTB-CB, and comprised the validation sample. Scores were derived for the five fluid tests using four adjustment models: age-only, demographic-only, age-and-reading, and demographic-and-reading referenced scores. RESULTS: Estimated premorbid ability varies depending on the reference model. Scores from each of the four reference models differentiated the comparison and TBI samples at the group level. However, performance varied by premorbid ability. CONCLUSIONS/IMPLICATIONS: Premorbid ability affects identification of cognitive difficulties after TBI. Reading referenced scores provide an individualized estimate of the effects of premorbid ability than demographic characteristics alone. Each model identified a similar number of individuals as having cognitive difficulties; however, the models differed on which individuals had cognitive difficulties. The models had higher disagreement rates in the clinical compared with the comparison sample, particularly for individuals with lower premorbid ability. Clinical use and caveats are discussed. (PsycINFO Database Record

Interpreting Patterns of Low Scores on the NIH Toolbox Cognition Battery.

INTRODUCTION: The National Institutes of Health Toolbox for Assessment of Neurological and Behavioral Function Cognition Battery is comprised of seven cognitive tests, including two tests measuring crystallized cognitive ability (i.e., vocabulary and reading) and five tests measuring fluid cognitive functioning (i.e., working memory, memory, speed of processing, and executive functioning). This study presents comprehensive base rate tables for the frequency of low scores in adults and older adults from the normative sample. METHODS: Participants were 843 adults, ages 20-85, from the NIH Toolbox standardization sample who completed all seven cognition tests. Rates of low scores were derived for standard age-adjusted and fully-demographically-adjusted scores at multiple cut-scores. Base rates were stratified by education, crystallized intellectual ability, and cognitive domain. RESULTS: Using the five demographically-adjusted fluid cognitive test scores, 45.9% of adults obtained one or more scores at or below the 16th percentile, and 16.8% obtained one or more score at or below the 5th percentile, which is consistent with findings from other neurocognitive test batteries. DISCUSSION: Based on the study findings, nearly 50% of adults in the general population would meet psychometric criteria for a diagnosis of the Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (DSM-5) Mild Neurocognitive Disorder (MND). We developed new psychometric criteria for identifying MND using the NIH Toolbox Cognition Battery that reduce the false positive rate. Knowing these multivariate normative base rates will help researchers and clinicians interpret NIH Toolbox scores in people with neurodevelopmental, psychiatric, medical, neurological, and neurodegenerative disorders that affect cognitive functioning.

The California Verbal Learning Test--second edition: test-retest reliability, practice effects, and reliable change indices for the standard and alternate forms.

The California Verbal Learning Test - second edition (CVLT-II) is one of the most widely used neuropsychological tests in North America. The present study evaluated the 1-month test-retest reliability and practice effects associated with the standard and alternate forms of the CVLT-II in a sample of 195 healthy adults. Eighty participants underwent repeat assessment using the standard form of the CVLT-II on both occasions, whereas the remaining 115 individuals received the standard form at baseline and the alternate form at follow-up. Consistent with prior research, results revealed generally large test-retest correlation coefficients for the primary CVLT-II measures in both the standard/standard (range=0.80-0.84) and standard/alternate (range=0.61-0.73) cohorts. Despite exhibiting slightly lower test-retest reliability coefficients, participants in the alternate form group displayed notably smaller practice effects (Cohen's d range=-0.01 to 0.18) on the primary indices relative to individuals who received the standard form on both occasions (Cohen's d range=0.27-0.61). Reliable change indices were also generated and applied to primary CVLT-II variables to determine the base rates of significant improvements (range=2-10%), declines (range=0-7%), and stability (range=85-97%) in performance over time. Overall, findings from this study support the test-retest reliability of the standard and alternate forms of the CVLT-II in healthy adults and may enhance the usefulness of this test in longitudinal neuropsychological evaluations.

Age-related invariance of abilities measured with the Wechsler Adult Intelligence Scale--III.

Examination of measurement invariance tests the assumption that the model underlying a set of test scores is directly comparable across groups. The observation of measurement invariance provides fundamental evidence for the inference that scores on a test afford equivalent measurement of the same psychological traits among diverse groups. Groups may be derived from different psychosocial backgrounds or different clinical presentations. In the Wechsler Adult Intelligence Scale-III (WAIS-III)/Wechsler Memory Scale-III (WMS-III) Technical Manual (Psychological Corporation, 2002), there appears to be a breakdown in factor structure among the standardization cases in older adults. In this study, the authors evaluated the invariance of the measurement model of the WAIS-III across 5 age bands. All components of the measurement model were examined. Overall, the evidence pointed to invariance across age of a modified 4-factor model that included cross-loadings for the Similarities and Arithmetic subtests. These results support the utility of the WAIS-III as a measure of stable intelligence traits across a wide age range.

To Change is Human: "Abnormal" Reliable Change Memory Scores are Common in Healthy Adults and Older Adults.

OBJECTIVE: The rate at which people obtain reliably improved or declined cognitive test scores when retested, in the absence of a change in clinical condition, is largely unknown. The purpose of this study was to illustrate the prevalence of statistically reliable change scores on memory test batteries in healthy adults and older adults. METHOD: Participants included three adult and older adult test-retest samples from memory test batteries. Reliable change scores (reliable change index with 90% confidence interval and practice effects) were calculated for the indexes and subtests of each battery. Multivariate analyses involved calculating the frequencies of healthy people obtaining one or more reliably declined or one or more reliably improved scores when considering all change scores simultaneously within each battery. RESULTS: Across all batteries, having one or more reliably changed index or subtest score on retest was common. With most batteries, having two or more reliably changed scores was uncommon. Those with higher intellectual abilities were more likely to have a change on retest; however, no significant differences in base rates were found based on education level, sex, or ethnic minority status. Those older adults who did not have any low memory scores were more likely to improve than decline on retest. CONCLUSIONS: Having a single reliably changed score on retest is common when interpreting a battery of memory measures. This has implications for determining cognitive decline and cognitive recovery, suggesting that multivariate interpretation is necessary.