Improving test interpretation for detecting executive dysfunction in adults and older adults: prevalence of low scores on the test of verbal conceptualization and fluency.

Knowing the prevalence of low scores on a battery of executive-functioning tests supplements clinical interpretation and can reduce the likelihood of misdiagnosing deficits in executive functioning. The purpose of this study is to examine the base rates of low scores on the Test of Verbal Conceptualization and Fluency (TVCF; Reynolds & Horton, 2006 ) in healthy adults (n = 332; M (age) = 33.0 years, SD = 10.5, range = 20-59) and older adults (n = 138; M (age) = 74.9 years, SD = 7.8, range = 60-89) from the TVCF standardization sample. The TVCF consists of four tests of executive functioning (i.e., Category Fluency, Letter Naming, Classification, and Trails C) that provide five age-adjusted T-scores. The prevalence of low scores was examined in the total sample and was stratified by educational level. When the five T-scores were considered simultaneously, having one or more scores that were 1 standard deviation (SD) below the mean was found in 28% of healthy adults and 38% of older adults. Education-based differences were also present with more lenient cutoff scores (e.g., 1 SD) but not with more conservative cutoffs. Consistent with the existing literature on other test batteries, at least one low subtest score on the TVCF is common in healthy adults and older adults.