In a very current article on Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD), Stewart (1994) examined the evidence for the external validity of ADD as separate from ADHD. Based on his discussion of the history of association between the diagnoses as well as research on behavioral characteristics, family history, psychiatric comorbidity, test performance, treatment response, and physiological and neuroanatomical correlates, Stewart concluded that the evidence supporting the external validity of ADHD as a distinct clinical entity was lacking. On the other hand, Stavinoha (1993) has noted that there is a rapidly increasing body of research supporting the validity of different subtypes of ADD in terms of ADD with and without hyperactivity.
It seems reasonable to state here that the conflicting conclusions about the general state of the literature on ADD and ADHD make it difficult to accurately characterize the conditions.
Given this, perhaps the most correct characterization has been offered by Sue, Sue and Sue (1994) who state that there is yet to be a consensus on whether the two conditions are in fact essentially the same or different and that more research needs to be conducted before a definitive evaluation can be made.
The purpose of this paper is to bring some perspective to the issue of whether ADD and ADHD represent one or two clinical conditions. Specifically, the paper examines the current literature on ADD and ADHD toward the objective of determining areas of difference and areas of similarity.
ADD and ADHD: Similarities and Differences
ADD and ADHD are childhood disorders characterized by:
(1) Inattention (often fails to finish things he or she starts, often doesn't seem to listen, easily distracted, has difficulty concentrating on schoolwork or other tasks requiring sustained attention) and
(2) Impulsivity (often acts before thinking, shifts excessively...