An investigation of individual typologies of attention-deficit hyperactivity disorder using cluster analysis of DSM–IV criteria

Cluster analysis was used to investigate empirical typologies of inattention and hyperactivity-impulsivity traits and whether these traits would correspond to DSM–IV ADHD typologies. Parents rated 104 male and female children, aged 5 to 14.7 years, on a scale developed to operationalise DSM-IV (American Psychiatric Association, 1994) criteria. Cluster analysis revealed four ADHD typologies with possible developmental changes in hyperactive-impulsive behavior as children mature as well as two ‘normal’ subgroups. Results indicated that DSM–IV defined ADHD characteristics where present in a cross section of individuals including nonpsychiatric controls. The structure of ADHD characteristics reflected the DSM-IV Combined and Inattentive types but failed to support a robust hyperactivity-impulsivity subgroup. Post hoc analysis suggested this may be a result of developmental factors; wherein hyperactivity-impulsivity traits decrease with age and inattention remains relatively stable. Cluster analysis also suggests that ADHD symptoms are normal personality traits that become pathological at relatively high levels.