Kate Norton

ObjectiveIn neuropsychological assessment estimates of how a client was performing prior to an injury is achieved by using instruments that have been developed to predict premorbid abilities, such as the National Adult Reading Test (NART), the re‐standardised NART (NART‐2), the Wechsler Test of Adult Reading (WTAR), and the Test of Premorbid Functioning (TOPF), and comparing these to scores from tests of current ability, such as the Wechsler Adult Intelligence Scale‐Fourth Edition (WAIS‐IV). These instruments have been criticised, however, due to concerns regarding the accuracy of their predictions.MethodThis study evaluated the ability of the NART, NART‐2, WTAR and TOPF to accurately estimate current full scale intelligence quotient (FSIQ) as measured by the WAIS‐IV in an unimpaired Australian sample.ResultsFor the sample as a whole, the NART significantly over‐estimated FSIQ, whilst the TOPF significantly underestimated FSIQ. In the low average IQ group, scores were over‐estimated by the NART‐2 and WTAR. In the average group, the predicted FSIQ scores produced by each measure were relatively accurate. In the high average group, NART was the best predictor of FSIQ, while the other tests all significantly underestimated IQ.ConclusionsIt was concluded that reading tests may not be the most accurate method for predicting IQ, and that other approaches which include demographic correction the should be further explored.

ObjectiveWhile there is a wealth of research into the Flynn effect, as yet no research exists examining the effect on tests of premorbid functioning. This study investigated the ability of the National Adult Reading Test (NART), the Wechsler Test of Adult Reading (WTAR), and the Test of Premorbid Functioning (TOPF) to predict premorbid IQ. It was hypothesised that the tests of premorbid functioning would produce differing premorbid IQ estimates, with the NART predicting the highest premorbid IQ scores, followed by the NART‐2 and the WTAR, with the TOPF predicting the lowest scores.MethodNinety‐five unimpaired Australian male and female participants aged between 18 and 65 years were administered a comprehensive battery of tests, including each of the tests of premorbid functioning.ResultsResults indicated that premorbid IQ estimates were significantly different (p < .001) from each other, with the NART producing the highest premorbid IQ estimate and the TOPF the lowest estimate.ConclusionsThese findings indicate that premorbid estimates of functioning are subject to the Flynn effect, thus use of estimates produced by tests of premorbid abilities that were designed to predict to earlier editions of the Wechsler scales will tend to inflate the level of premorbid baseline, leading to the possibility of spurious diagnosis of deficit. Clinicians should employ the most recently normed versions of these tests and employ the premorbid estimate which has been validated to predict the edition of the Wechsler scales that the individual will actually be using during any testing.