Improving Clinical Interpretation of Performance on a Neuropsychological Concussion Battery by Utilizing Premorbid IQ

Research indicates that premorbid IQ impacts the rate of impairment across neuropsychological domains. This study explored whether premorbid IQ is a factor in assessing cognitive impairment utilizing a concussion battery and whether a clinical algorithm should be updated based on premorbid IQ. Seven hundred seventy-one student athletes (572 male, 199 female) completed a comprehensive baseline concussion battery. Individuals were grouped as low (<= 99), mid (100-107), and high (108 thorn ) based on the Wechsler Test of Adult Reading full-scale IQ quartiles. A oneway analysis of variance determined whether the three groups differed on the number of scores falling below the 10th percentile (borderline) and at or below the second percentile (impaired). The groups differed significantly on number of borderline scores. Individuals in the low group had more borderline impaired scores than the mid group and the high group. The mid group also had significantly more borderline impaired scores than the high group. Additionally, there was a significant difference between groups on number of impaired scores. Individuals in the low group had significantly more impaired scores than the mid and high groups. The mid and high groups did not significantly differ. These results indicate that college athletes at baseline are likely to have different base rates of borderline and impaired scores based on their premorbid IQ. Different cutoffs are thus needed to classify athletes as recovered or not recovered following concussion, which is reflected in the updated clinical algorithm. This work helps to ensure that the normative data used to make clinical decisions in concussion evaluations are accurate.