Examining the comorbidity of language disorders and ADHD.

In the companion papers this issue we presented the value of research on comorbidity, particularly in complex developmental disorders where the identification of etiology is challenging. As we will document below, Language Impairment (SLI) and Attention Deficit Hyperactivity Disorder (ADHD) have been shown to co-occur in a number of studies, and this phenomenon is commonplace in the experience of many clinicians. Given this, we must ask whether the overlap between SLI and ADHD can aid our understanding of these disorders, particularly with regard to the basis for comorbidity. As we review the literature, we will consider the models of comorbidity that were outlined in the Introduction to this issue. Finally, we present original data on SLI and ADHD from a population-based sample of children that have studied over the last two decades in the State of Iowa.