The Tower of London and neuropsychological assessment of ADHD in adults

Abstract

Executive function refers to a variety of behaviors and abilities related to planning and strategy use, as well as the maintenance of attention and behavior in the pursuit of some goal; these behaviors are generally deficient in individuals with Attention Deficit Hyperactivity Disorder (ADHD). The Tower of London (TOL) is one task used in the assessment of executive function. For adults with ADHD, there is minimal research on the extent to which they demonstrate impaired performance on tower tasks. With a sample of 102 individuals between the ages of 16 and 33 years, the extent to which performance on the TOL–Drexel Edition (TOL DX) was related to performance on other measures of executive function and diagnostic grouping was investigated. Results indicated that TOL DX variables are not correlated significantly with age or Global Assessment of Functioning (GAF). Of the TOL DX variables, only Rule Violations correlated with multiple other executive function variables. Rule Violations correlated minimally, but significantly, with cognitive ability, perceptual skills, Matrix Reasoning, Processing Speed, and immediate memory. As might be expected, Processing Speed also significantly correlated with Total Time and Time Violations. Notably, scores on the TOL DX did not correlate significantly with behavioral self-report; no between-group (ADHD, Clinical Control, No Diagnosis) differences emerged for any of the TOL DX variables. Further, with this sample, mean scores across the TOL DX variables were well within the average range. Taken together, these results suggest that while the TOL DX measures aspects of ability not tapped by other measures, and may therefore provide additional information on individual functioning, results should not be interpreted as indicative of the presence or absence of a disorder.