Using the Delis–Kaplan Executive Function System Tower Test to Examine ADHD Sensitivity in Children: Expanding Analysis Beyond the Summary Score

Abstract

Attention-deficit/hyperactivity disorder (ADHD) affects many children and is commonly regarded as a disorder of executive function (EF; Willcutt et al. Journal of Biological Psychiatry, 57, 1336–1346, 2005). EF is thought to be housed primarily within the brain’s prefrontal cortex (PFC), with different areas of the PFC orchestrating different EF components (Jurado and Rosselli Neuropsychology Review, 17, 213–233, 2007). Key PFC areas for this study included the dorsolateral PFC and orbitofrontal cortex. A measure on the Delis–Kaplan Executive Function System (D-KEFS), the Tower Test, has been infrequently studied with child populations, particularly those with ADHD. The limited research that does exist has primarily focused on the Tower’s summary score, overlooking available optional scores. The current study involved investigation of Tower performance in children ages 8 to 18 with ADHD (n = 252) to look for impaired scores, examine correlations with common ADHD measures, and compare Tower scores to clinical (n = 49) and normative controls (n = 110). Children with ADHD showed deficits on multiple Tower scores. Notably, more than half of the children with ADHD scored more than 1 standard deviation below the norm on the Move Accuracy Ratio (MAR) score, and children younger than 14 completed the Tower less efficiently than older children (i.e., lower MAR). Lower MAR scores were also correlated with higher parent ratings of inhibition on the Behavior Rating Inventory of Executive Function (BRIEF) and more errors of impulsivity on the Conners’ Continuous Performance Test, second edition (CPT II). Normative controls significantly outperformed children with ADHD on five of six Tower measures. The sensitivity of these optional measures was evident even while the total score was not sensitive to group differences, which highlights the importance of analyzing Tower optional scores and underscores the need for future research applying similar methods.