Estimation of premorbid general cognitive abilities in children

Abstract

This paper aims to review currently available methods of estimating premorbid cognitive abilities in children of school age, and to discuss the potential usage of the CAT-3 to provide estimates of premorbid general cognitive abilities or IQ. Data were collected on a sample of 60 pupils who completed the Cognitive Abilities Test (third ed.) (CAT-3) either in year 5 (age 9+), year 7 (age 11+) or year 9 (age 13+). Children completed the Wechsler Intelligence Scale for ChildrenUK(third ed.) (WISC-IIIUK) within nine months of having undertaken routine CAT-3 testing in school. Correlation coefficients between CAT-3 and WISC-IIIUKindices are presented alongside other comparable data that might be used to estimate premorbid intellectual abilities. The results show that correlation coefficients between CAT-3 scales and WISC-IIIUKindex scores are strong and significant, accounting for 50–75 per cent of the variance in WISC IQ. Other methods of estimating premorbid abilities in children show poorer correlations accounting for 50–75 per cent of the variance in actual IQ. The current results reveal high correlations between CAT-3 scores and WISC-IIIUKindex scores, which are superior to other published methods that may be employed to estimate premorbid abilities. These results, coupled with evidence of the high stability of CAT-3 scores over time, highlights their superior utility in providing estimates of premorbid ability in children. Simple regression equations are provided for the estimation of premorbid intellectual ability.