IntroductionWhen evaluating individuals for acquired neurological disorder, premorbid functioning data is crucial for determining the degree of impairment, which is invaluable in clinical, legal, and research settings. One of the most widely used measures of premorbid cognitive functioning is word reading (Bright, Jaldow, & Kopelman, 2002) due to evidence that it is resistant to effects of neurological injury. Research has demonstrated that word reading correlates highly with both prior assessments of cognitive functioning (Smith, Bohac, Ivnik, & Malec, 1997; Berry et al., 1994) and current assessments of healthy individuals (Bright et al., 2002).

A number of connections between reading abilities and executive functioning skills have been identified. Reading automaticity was found to play a role in the performance of executive functioning tasks (Leon-Carrion, Garcia-Orza, & Perez-Santamaria, 2004). Associations between executive functions and word reading accuracy were identified in children with ADHD (Bental & Tirosh, 2007). Also, impaired executive functions were found in children with reading difficulty (Helland & Asbjornsen, 2000).

If a measure resistant to impairment by acquired neurological dysfunction were a strong predictor of executive functioning, it may have utility in assessing premorbid executive functioning skills. However, little research has investigated the predictive ability of word reading to estimate premorbid executive functioning.

The Delis-Kaplan Executive Function System (D-KEFS; Delis, Kaplan, & Kramer, 2001) is a battery of nine tests which can be administered in isolation or as a battery to assess executive functioning skills. The purpose of this study was to investigate the predictive relationship between word reading and three widely used tasks of executive functioning, the D-KEFS Trail Making Test, Color Word Interference Test, and Tower Test.

Results and SummaryCorrelations among the Word Reading test of the WIAT-II and the scores from the D-KEFS Tower Test, Color-Word Interference Test, and Trail Making Test ranged from -.234 to .329. The Word Reading Test was positively correlated at the .01 level with FSIQ, VIQ, and PIQ. Linear regression results indicated that Word Reading predicted a significant proportion of the variance in performance on the Inhibition task from the Color Word Interference Test (R2=.108; p=.036) but no other primary executive function task. Although word reading was a very strong predictor of crystallized, fluid, and global intelligence, it was a generally weak predictor of executive functions aside from a measure of inhibition.

Most premorbid functioning research has focused on the prediction of IQ, particularly global IQ. This makes sense given that g tends to be the most stable and reliable cognitive measure. However, research has consistently identified a strong relationship between global intelligence and measures of executive functioning. The lack of research on estimation of premorbid executive functions is a significant oversight given that the anterior cortical areas are susceptible to injury in TBI. This study suggests that word reading tasks have mixed effectiveness in predicting executive functioning and thus extreme caution should be used when attempting to extrapolate this ability from word reading tasks.

The strong relationship demonstrated between word reading and measures of cognitive functioning is consistent with earlier research. Although the WIAT-II Word Reading task was not designed as a measure of premorbid functioning, the relationship found in this study is consistent with results found using the Wechsler Test of Adult Reading (Pearson, 2001), a measure of premorbid functioning, and WAIS-II scores for the 18-19 sample (FSIQ=.70; VIQ=.74; PIQ=.55). Similar to this study, the correlations were higher for VIQ which is to be expected given the larger role of language and acquired knowledge inherent in VIQ.

ReferencesBental, B., & Tirosh, E. (2007). The relationship between attention, executive functions and reading domain abilities in attention deficit hyperactivity disorder and reading disorder: A comparative study. Journal of Child Psychology and Psychiatry 48(5), 455–463.

Berry, D. T. R., Carpenter, G. S., Campbell, D. A., Schmitt, F. A., Helton, K., & Lipke-Molby, T. (1994). The New Adult Reading Test – Revised: Accuracy in estimating WAIS-R IQ scores obtained 3.5 years earlier from normal older persons. Archives of Clinical Neuropsychology, 9(3), 239-250.

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Bright, P., Jaldow, E., & Kopelman, M. D. (2002). The National Adult Reading Test as a measure of premorbid intelligence: A comparison with estimates derived from demographic variables. Journal of the International Neuropsychological Society, 8(6), 847-854.

Delis, D. C., Kaplan, E., & Kramer, J. H. (2001). Delis-Kaplan Executive Function System: Examiner’s manual. San Antonio, TX: The Psychological Corporation.

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Presented at the 29th Annual Conference of the National Academy of NeuropsychologyContact for Correspondence: davis@bsu.edu

MethodologyParticipants were 64 healthy college students (mean age 19.89 years, SD = 3.63 years). The mean number of years of education was 13.77 with a standard deviation of 1.19. All participants completed the Delis-Kaplan Executive Function System (D-KEFS), the WAIS-III, and the WIAT-II as part of a validity study.

Correlation Results

WIAT-II Word Reading

D-KEFS Trail Making Test Condition 4

-.171

D-KEFS Color Word Interference Inhibition

.329*

D-KEFS Color Word Interference Inhibition/Switching

-.003

D-KEFS Tower Test

Achievement

-.234

WAIS-III FSIQ .586**

WAIS-III VIQ .570**

WAIS-III PIQ .425**

*Significant at the .05 level

**Significant at the .01 level