OBJECTIVE: Since some symptoms are shared by both attention deficit
hyperactivity disorder (ADHD) and comorbid psychiatric conditions, it is
possible that a diagnosis of ADHD is an artifact of the overlapping
symptoms. This article focuses on the assessment of the influence of
overlapping symptoms on the diagnosis of ADHD. METHOD: Three groups of
subjects were studied: a group of clinically referred children and
adolescents, a group of nonreferred adults who were the parents of these
children and adolescents, and a group of clinically referred adults with
ADHD. The authors assessed the extent of symptom overlap between ADHD and
the disorders that frequently co-occur with ADHD; major depression, bipolar
disorder, and generalized anxiety disorder. To determine the degree to
which this symptom overlap influences these diagnoses, each individual was
rediagnosed on the basis of two different techniques that corrected for the
overlapping symptoms, a subtraction method and a proportion method.
RESULTS: The majority of subjects who had both ADHD and a comorbid
psychiatric disorder maintained their diagnosis of ADHD when the
overlapping symptoms were subtracted. Moreover, when overlapping ADHD
symptoms were subtracted, on average, 79% maintained their diagnosis of
major depression, 56% maintained their diagnosis of bipolar disorder, and
75% maintained their diagnosis of generalized anxiety disorder.
CONCLUSIONS: These findings show that ADHD is not an artifact of symptoms
shared with other psychiatric disorders and that the comorbid conditions
themselves are not an artifact of overlapping ADHD symptoms.