Potential of and problems with new measures of psychometric intelligence after traumatic brain injury

Objective: Examination of the concurrent and criterion validities of the General Ability Measure for Adults (GAMA) and the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) in patients with traumatic brain injury (TBI). Study Design: Correlational methods and multivariate analyses of variance. Setting: Regional rehabilitation center. Participants: Prospective series of consecutive rehabilitation referrals, including 60 adults with TBI and no confounding premorbid histories. Main Outcome Measures: GAMA and WAIS-III IQ and factor index scores were obtained within 1 year after injury and were compared with each other and with measures of injury severity. Results: GAMA and WAIS-III summary IQ scores demonstrated substantial covariance (supporting concurrent validity), but neither was sufficiently sensitive to injury severity. The WAIS-III Processing Speed (PS) index was the only measure that clearly demonstrated criterion validity. Conclusions: GAMA and WAIS-III summary IQ scores measure similar abilities but may not be sensitive to degree of injury severity in individuals with TBI. In contrast, the WAIS-III PS index appears to have promise in the evaluation of sequelae of TBI.