Estimation of premorbid intelligence and executive cognitive functions with lexical reading tasks.

Abstract

Objective: Estimation of premorbid function is essential to accurate identification of cognitive impairments. We explored how lexical tasks can be used to estimate various cognitive functions. Method: Adults with cognitive impairment due to neurological illness (n = 15) and a nonclinical sample of adults (n = 143) completed tests of word pronunciation, lexical decision, and stem-completion naming. In three studies lexical-task performance associations with intelligence Wechsler Adult Intelligence Scale 4th edition (WAIS-IV), episodic memory, executive functioning, and theory of mind were explored. Results: At the group level, word pronunciation was robust in the presence of cognitive impairment. However, as a case series, patients showed idiosyncratic patterns of preservation of lexical skills. All of the lexical tasks were highly correlated with intelligence quotient (IQ) scores in the nonclinical sample, suggesting that they may function well as estimators of premorbid intelligence. Simulated impairments in nonclinical adults revealed that the median score from the three different tasks had the highest correlation with, and provided the most accurate and precise estimates of, measured IQ, and was also the least sensitive to impairment. We also show that these methods predict executive functions, in particular, proverb interpretation, phonemic/semantic alternating verbal fluency, and working memory span performance. Conclusions: Several lexical tasks are potentially useful in predication of preillness cognitive ability. However, due to the heterogeneity of impairments between patients, estimation of premorbid levels could be improved by the use of average estimated values from multiple tests. This could potentially improve diagnostic accuracy and quantification of neuropsychological impairments. Public Significance StatementUnderstanding a patient's cognitive impairments following brain illness is better if their abilities before the illness can be estimated. Reading that requires preexisting knowledge of the words, such as how to pronounce them, can be used for this purpose. Word pronunciation, particularly when combined with other tests of word knowledge, appears to be not much affected by cognitive impairment and gives a good indication of a patient's preillness ability.

Using External Information for More Precise Inferences in General Regression Models

“…To illustrate the possible benefits of using external information in a linear model, we reanalyze a dataset of Pluck and Ruales-Chieruzzi ( 2021 ), who investigated the estimation of premorbid intelligence based on lexical reading tasks in Ecuador. We will focus on their Study 2.…”

“…Since the purpose of this analysis is to illustrate the proposed use of external information, we will only shortly sketch the theoretical background of the study. For a more detailed description, see Pluck and Ruales-Chieruzzi ( 2021 ). The dataset was downloaded from PsychArchives (Pluck, 2020a ).…”

“…To quantify the cognitive impairment of patients, it is necessary to have an accurate baseline estimate observed in the premorbid state (Pluck & Ruales-Chieruzzi, 2021 ). As psychometric intelligence tests can be too long or cumbersome for elderly people with emerging cognitive impairments, it is important to have short, yet reliable tests for general intelligence.…”

“…5 . An application to a real data set analyzing the relation of premorbid (general) intelligence and performance in lexical tasks (Pluck & Ruales-Chieruzzi, 2021 ) is presented in Sect. 6 .…”

The Misguided Veneration of Averageness in Clinical Neuroscience: A Call to Value Diversity over Typicality

“…Those scores can then be compared to the current IQ and memory performance without any need to compare them to ‘typically’ performing individuals. Furthermore, word pronunciation and other lexical reading tasks can be used to predict a range of cognitive functions [ 125 ], not just memory and IQ, and so could be extended to a wider range of cognitive tests.…”