The “Dutch Reading Test for Adults” has Been Used for 29 Years to Estimate the Premorbid Performance Level, does it Still Meet the Expectations?

Abstract

To detect cognitive change after brain damage, it is important to know the level of premorbid intellectual functioning. A popular instrument in this context is the “Nederlandse Leestest voor Volwassenen” (NLV; Schmand et al., 1992). In this test, 50 words with irregular pronunciation must be read out loud. The score on this test used to be considered as a good estimate of someone's premorbid IQ, due to high correlations with the Verbal and Full-Scale IQ estimates of the WAIS (Verbal IQ: r = .85, Full Scale IQ: r = .74; Schmand et al., 1992). Despite some updates of the normative data (e.g., Bouma et al., 2012), the validity of the test has not been re-evaluated since. The aim of the current study was to evaluate whether the NLV still correlates sufficiently with the WAIS-IV to warrant its proper use as a psychodiagnostic tool. In Study 1, 30 participants (age range: 20-29 year) were tested, and in Study 2, 51 participants (age range: 45-65 year). We checked whether the NLV-generated IQ-score estimates correlated with the different IQ indices of the WAIS-IV. In the younger group, no correlations were found between the NLV-generated IQ-score estimate and any of the WAIS-IV indices nor the Full-Scale IQ. In the older group, the NLV-generated IQ-score estimate correlated with Full scale IQ and the indices of Verbal Comprehension, Working Memory and Processing Speed. These correlations were all < .46 which is far below the typically hold standard in test development of > .70. Based on these findings we conclude the NLV in its current form is not appropriate anymore to estimate premorbid IQ in both young and older adults.