The case for DSM-IV subtypes in ADHD

This article selectively reviews research that has examined the three DSM-IV attention deficit-hyperactivity disorder (ADHD) subtypes. Data relevant to the validity of the subtyping system, including demographic, comorbidity, cognitive/attentional, and social correlates of the three subtypes are presented. The majority of relevant research has examined the ADHD/C and ADHD/IA subtypes, with less information available for the newly identified ADHD/HI subtype. Findings support the existence of the ADHD/IA subtype; children so diagnosed show impairment and patterns of dysfunction unique from those with the ADHD/C subtype. Further research on many aspects of ADHD/IA is needed to clarify whether it is best considered a separate disorder or an ADHD subtype, however, and to determine the most appropriate diagnostic criteria. Although the scant existing data also suggest that the ADHD/HI subtype is associated with impairment and a different pattern of deficits relative to the other two subtypes, further elucidation of its developmental course is needed to clearly determine its validity. MRDD Research Reviews 1999;5:199–206 © 1999 Wiley-Liss, Inc.