A model of attention and its relation to ADHD

We present a neuropsychological model of attention in normal and disordered states, including attention deficit hyperactivity disorder (ADHD). The model is based on a factor analysis of data derived from more than 600 children and adults. The robustness of the model is supported by its replication in a number of studies and its application in numerous investigations. It divides attention into a number of elements or factors including the capacities of encoding, focusing, and executing responses, sustaining attention, shifting attention, as well as a measure of response stability. The factors are assessed by measures derived from neuropsychological tests; we have posited a system of brain structures that maintains the elements of attention, each of which may be supported by a distinct cerebral region. We illustrate the use of the model in an investigation in progress of children referred to an inner-city family clinic for evaluation of ADHD. The ADHD study indicates that a number of aspects of attention are impaired in children diagnosed with ADHD, and that the deficient attention is probably not attributable to learning disorders. We also speculate on the possible role of immaturity of brain development in ADHD. MRDD Research Reviews 1999;5:169–176. Published 1999 Wiley-Liss, Inc.