Premorbid intelligence and brain injury.

Objectives: To determine whether NART scores are associated with severity of brain injury and therefore presumably affected by brain injury. In addition, to compare the Cambridge Contextual Reading Test (CCRT) with injury severity in head-injured individuals.

Design And Methods: Participants were 55 survivors of traumatic head injury, who completed the NART and the CCRT. The scores on these premorbid measures were then compared with indices of injury severity from their initial neurosurgical admission.

Results: The NART was significantly correlated with Glasgow coma scale, with greater severity of injury associated with poorer performance. Poorer NART performance was also significantly more likely amongst those whose injury resulted in coma. The CCRT was preferred by patients, though it was also significantly associated with Glasgow coma scale and presence of coma.

Conclusions: The data suggest that performance on both the NART and the CCRT are affected by brain injury severity and thus may underestimate true premorbid ability in these individuals. Similar findings would be likely with the conceptually identical WTAR measure. These measures should be used with appropriate caution and may be usefully supplemented by predictions based on demographic information.