Objective: To determine the effect of age and vocabulary as predictors of performance on neuropsychological tests in children with and without traumatic brain injury (TBI).
Setting and participants: In the first study, 213 school-age children were evaluated in their public school environment. In the second study, 65 children with a history of TBI were examined in a medical centre.
Major outcome measures: Age of the child and two estimates of intellectual functioning (Vocabulary and Block Design) were used to predict performance on the Barrow Neurological Institute Screen for Higher Cerebral Functions in School-Age Children (BNIS-C), a verbal fluency task and the Halstead Finger Tapping Test (HFTT).
Results: In study 1, the exact age of the child was the strongest predictor of performance (e.g. 47.5% of the variability on the BNIS-C) in normal school-age children. Vocabulary level accounted for less than 10% of the variability across the three measures. In children with TBI (study 2; n = 65) age effects remained strong, but a greater vocabulary effect was observed on two of the three measures (i.e. 29.2% on the BNIS-C and 18.8% on verbal fluency).
Conclusions: While age is an important predictor of neuropsychological test performance in children, post-injury vocabulary level appears to be an important moderator variable.