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.