Estimating premorbid intelligence in people living with dementia: a systematic review

Methodological quality of 100 recent systematic reviews of health-related outcome measurement instruments: an overview of reviews

PURPOSE

Systematic reviews evaluating and comparing the measurement properties of outcome measurement instruments (OMIs) play an important role in OMI selection. Earlier overviews of review quality (2007, 2014) evidenced substantial concerns with regards to alignment to scientific standards. This overview aimed to investigate whether the quality of recent systematic reviews of OMIs lives up to the current scientific standards.

METHODS

One hundred systematic reviews of OMIs published from June 1, 2021 onwards were randomly selected through a systematic literature search performed on March 17, 2022 in MEDLINE and EMBASE. The quality of systematic reviews was appraised by two independent reviewers. An updated data extraction form was informed by the earlier studies, and results were compared to these earlier studies' findings.

RESULTS

A quarter of the reviews had an unclear research question or aim, and in 22% of the reviews the search strategy did not match the aim. Half of the reviews had an incomprehensive search strategy, because relevant search terms were not included. In 63% of the reviews (compared to 41% in 2014 and 30% in 2007) a risk of bias assessment was conducted. In 73% of the reviews (some) measurement properties were evaluated (58% in 2014 and 55% in 2007). In 60% of the reviews the data were (partly) synthesized (42% in 2014 and 7% in 2007); evaluation of measurement properties and data syntheses was not conducted separately for subscales in the majority. Certainty assessments of the quality of the total body of evidence were conducted in only 33% of reviews (not assessed in 2014 and 2007). The majority (58%) did not make any recommendations on which OMI (not) to use.

CONCLUSION

Despite clear improvements in risk of bias assessments, measurement property evaluation and data synthesis, specifying the research question, conducting the search strategy and performing a certainty assessment remain poor. To ensure that systematic reviews of OMIs meet current scientific standards, more consistent conduct and reporting of systematic reviews of OMIs is needed.

A Potential Measure of Premorbid Functioning: Evaluating the Construct Validity of the Author and Magazine Recognition Tests

OBJECTIVE

To establish convergent and discriminant validity for a combined measure of print exposure (i.e., Author Recognition Test and Magazine Recognition Test [ART/MRT]) and assess its potential utility for estimating premorbid cognitive functioning.

METHOD

Community-dwelling older adults (N = 84; 95% non-Hispanic White) completed the ART/MRT, Test of Premorbid Functioning (ToPF), Dementia Rating Scale - 2nd Edition (DRS-2), Hopkins Verbal Learning Test - Revised (HVLT-R-DR), and select subtests from the Delis-Kaplan Executive Functioning System (D-KEFS) as measures of executive functioning (i.e., D-KEFS-EF) and processing speed (i.e., D-KEFS-PS). Pearson correlations and linear regressions were used to examine the relationships between the ART/MRT, cognition, and demographics.

RESULTS

Cognitive scores, with the exception of HVLT-R-DR, were positively correlated with ART/MRT score such that better cognitive performance was associated with greater print exposure (range r = 0.39-0.49). ART/MRT score was positively correlated with years of education and negatively correlated with age. ToPF and DRS-2 differentially and uniquely predicted ART/MRT score beyond the other cognitive and demographic variables and beyond each other.

CONCLUSIONS

Findings indicate that measures of print exposure reflect crystallized knowledge but may also capture fluid abilities that may be more vulnerable to age-related decline or neurodegeneration. Assessment of print exposure may offer an alternative to word reading measures that may be inappropriate for translation into other languages and for use with individuals with certain language difficulties.

Construct validation of NIH Toolbox Cognition Battery premorbid cognitive functioning scores in Black and White older Americans with and without mild cognitive impairment

OBJECTIVE

Valid estimates of premorbid cognitive functioning (PMIQ) are crucial for the assessment of older adults at risk for Alzheimer's disease. We investigated the relationship between the NIH Toolbox-Cognition Battery's (NIHTB-CB) Oral Reading Recognition (ORR) subtest and Wechsler Test of Adult Reading scores (WTAR, convergent validity). We also compared ORR to NIHTB-CB Flanker scores, where null relationships were expected (discriminant validity).

METHODS

The WTAR and NIHTB-CB were administered to 130 cognitively normal (CN) and 113 participants with mild cognitive impairment (MCI). Participants were community-dwelling, older Black and White adults, ages 55-88 years. Data analysis used uncorrected standard scores and Bayesian bivariate correlations. Supplemental materials include intraclass correlations.

RESULTS

ORR and WTAR scores were strongly positively associated, while ORR and Flanker scores were unrelated. This pattern held when restricting analyses to the two cognitive status groups, the two racial groups, and the four race-by-diagnosis subgroups.

CONCLUSION

The findings demonstrate convergent and discriminant validity and support NIHTB-CB ORR scores as valid estimates of scores on a PMIQ measure in older Black and White adults with and without MCI.

Vocabulary changes in adulthood: Main findings and methodological considerations

BACKGROUND

Vocabulary scores increase until approximately age 65 years and then remain stable or decrease slightly, unlike scores on tests of other cognitive abilities that decline significantly with age.

AIMS

To review the findings on ageing-related changes in vocabulary, and to discuss four methodological issues: research design; test type; measurement; and vocabulary ability as a proxy for general intelligence.

MAIN CONTRIBUTION

A discussion of cross-sectional and longitudinal research designs shows that cohort membership accounts for some but not all ageing-related changes in vocabulary, and that drop-out and test-retest effects do not alter conclusions regarding these changes. Test type affects age trends in vocabulary, and if researchers use only one test, they should choose a multiple-choice synonym test. While some authors suggest that vocabulary tests do not measure the same underlying ability in younger and older adults, more research of this suggestion is needed. A brief examination of the use of vocabulary ability as a proxy for general intelligence in healthy ageing and for premorbid abilities in dementia indicates that such practice is often questionable.

CONCLUSIONS

Vocabulary knowledge increases through the mid-60s regardless of measurement method. However, there is little information on how word knowledge serves other verbal skills in old age, how and when adults learn new words, or how much exposure is necessary for meanings to remain in storage for a lifetime. Research of these issues may require new methodologies, as well as novel theoretical accounts of ageing-related effects on vocabulary.

WHAT THIS PAPER ADDS

What is already known on this subject Unlike many cognitive abilities that decline with ageing, vocabulary knowledge continues to increase until approximately age 65, and then remains stable or decreases slightly. These findings have been replicated in different research designs and across languages. What this paper adds to existing knowledge The article presents a summary of findings on changes in vocabulary across adulthood, and a discussion of four key methodological issues: research design, test type, measurement, and the use of vocabulary ability as a proxy for general intelligence. What are the potential or actual clinical implications of this work? To better understand changes in vocabulary knowledge across adulthood, clinicians must be aware of methodological considerations that affect the field. Such considerations have direct clinical implications regarding the choice of vocabulary tests and their use as a proxy for other abilities in both healthy older adults and in individuals with dementia.

Intelligence, cognition, and major neurocognitive disorders: From constructs to measures

The study of intelligence's role in development of major neurocognitive disorders (MND) is influenced by the approaches used to conceptualize and measure these constructs. In the field of cognitive impairment, the use of single 'intelligence' tests is a common approach to estimate intelligence. Despite being a practical compromise between feasibility and constructs, variance of these tests is only partially explained by general intelligence, and some tools (e.g., lexical tasks for premorbid intelligence) presented inherent limitations. Alternatively, factorial models allow an actual measure of intelligence as a latent factor superintending all mental abilities. Royall and colleagues used structural equation modeling to decompose the Spearman's general intelligence factor g in δ (shared variance across cognitive and functional measures) and g' (shared variance across cognitive measures only). Authors defined δ as the 'cognitive correlates of functional status', and thus a 'phenotype for all cause dementia'. Compared to g', δ explained a little rate of cognitive measures' variance, but it demonstrated a higher accuracy in dementia case-finding. From the methodological perspective, given g 'indifference' to its indicators, further studies are needed to identify the minimal set of tools necessary to extract g, and to test also non-cognitive variables as measures of δ. From the clinical perspective, general intelligence seems to influence MND presence and severity more than domain specific cognitive abilities. Giving δ 'blindness' to etiology, its association with biomarkers and contribution to differential diagnosis might be limited. Classical neuropsychological approaches based on patterns of performances at cognitive tests remained fundamental for differential diagnosis.

Normative Reference Values for Crystallized-Fluid Discrepancy Scores for the NIH Toolbox Cognition Battery

INTRODUCTION

The purpose of this study was to translate NIH Toolbox Cognition Battery (NIHTB-CB) Crystallized-Fluid discrepancy scores into research and clinical practice with adults by providing normative data for discrepancy scores for both age-adjusted standard scores (SSs) and demographically adjusted T-scores.

METHOD

We included adult participants from the NIHTB-CB standardization sample who denied having neurodevelopmental, medical, psychiatric, or neurological conditions (n = 730; M = 47.4 years old, SD = 17.6, range: 18-85; 64.4% women; 63.1% White). Descriptive statistics were calculated for the Fluid and Crystallized composite scores and Crystallized-Fluid discrepancy score, along with correlations between the composite scores and reliability estimates of the discrepancy score. Percentiles were calculated for the discrepancy score, with stratifications by the gender, education, and Crystallized composite for the age-adjusted SSs and demographically adjusted T-scores (T).

RESULTS

Crystallized-Fluid discrepancy scores ranged from -40 to 44 (M = -0.63, SD = 14.89, Mdn = -1, interquartile range [IQR]: -11 to 10) for age-adjusted SSs and from -29 to 27 (M = -0.39, SD = 10.49, Mdn = -1, IQR = -8 to 7) for demographically adjusted T-scores. Crystallized-Fluid discrepancy scores of SS = 15 and T = 11 were at the 16th percentile (1 SD below the mean) and discrepancy scores of SS = 21 and T = 15 were at the 7th percentile (1.5 SD below the mean).

CONCLUSIONS

Crystallized-Fluid discrepancy scores may be, with future research, a useful within-person interpretive approach for detecting a decline from pre-injury or pre-disease levels of cognitive functioning. These normative reference values assist clinicians and researchers in determining the frequency at which given Crystallized-Fluid discrepancy scores occurred among healthy adults in the normative sample.