Dimensions and Types of Attention Deficit Disorder

An empirically derived cluster analysis of three factors derived from factor analyses of teacher ratings of ADD symptoms produced three distinct clusters: patients without ADD, those with both inatt attention and hyperactivity, and a group that exhibited inattention and sluggish tempo but not hyperactivity.

Abstract

DSM-III-R provides a unidimensional definition of attention deficit-hyperactivity disorder (ADHD), based on the assumption that inattention, impulsivity, and motor hyperactivity are unitary aspects of the same dimension. The definition of undifferentiated attention deficit disorder (UADD), however, contradicts this assumption by treating inattention as a separate dimension. The present study evaluated these assumptions empirically. A cluster analysis of three factors derived from factor analyses of teacher ratings of ADD symptoms and a broader list of ADD symptoms produced three distinct clusters: patients without ADD, those with both inattention and hyperactivity, and a group that exhibited inattention and sluggish tempo but not hyperactivity. The association was very strong between the empirically derived clusters and clinical DSM-III diagnoses of ADD with and without hyperactivity. These findings do not support the DSM-III-R unidimensional definition of ADHD.