Studies on the Comorbidity of
Disorder with Other Disorders
We must not cease from exploration and the end of all our exploring will be to arrive where we began and to know the place for the first time.
-- T. S. Eliot
There appear to be specific "subtypes" of Attention Deficit/Hyperactivity Disorder (AD/HD) that are defined by the co-occurrence or comorbidity with other disorders. These comorbid "subtypes" are not the same as the subtypes defined in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) under AD/HD (see Appendix A). The apparent variety of subtypes contributes to the heterogeneity of the disorder, making it difficult to approach as a single entity. As educators we are accustomed to differentiating instruction to meet the individual needs of students based on learning styles. Therefore, information about subtypes is essential for educators if we are to truly understand the disorder and be able to modify our instruction accordingly, as we are already doing to accommodate the diverse styles of all learners. We must move beyond the misconception that AD/HD is a simple, homogeneous disorder; the research indicates that it is otherwise in many cases.
This chapter is a review of the research on the co-occurrence of AD/HD and other disorders, including: Conduct Disorder (CD), Oppositional Defiant Disorder (ODD), Learning Disabilities, Bipolar Disorder, Major Depressive Disorder, Anxiety Disorder, and Tourette's Syndrome. The frequency of co-occurrence of other disorders with AD/HD influenced the selection of comorbidity studies. The frequency of co-occurrence is highest