DIAGNOSING ODD IN CHILDREN WITH ADHD
Although some of the criteria for the diagnosis of ODD were established somewhat arbitrarily, the current ODD diagnostic criteria (Table 1) are the best method we have for identifying children who have additional difficulty with self-regulation. Between 40% and 70% of children with ADHD also meet the diagnostic criteria for ODD or CD.4-6 In a study of preschoolers with ADHD, just over 50% were found to also have a diagnosis of ODD.7 To put these figures in perspective, consider that in a group of school-aged children who may or may not have ADHD, the prevalence of ODD may be between 1% and 16%,8 or with strict application of diagnostic criteria, between 2% and 3%.9
The comorbidity of ODD and ADHD seems to be bidirectional.
The clear overlap of symptoms blurs somewhat the lines of distinction between the 2 disorders and raises a number of questions for the clinician. Where does one disorder begin and the other end? Is it possible that ODD is a by-product of severe ADHD? Is there a common pathway to the evolution of disruptive behavior diagnoses? Is it possible to improve ODD symptoms simply by treating a child's ADHD?
For primary care clinicians, the importance of identifying co-occurring disorders, such as ODD and ADHD, lies in the possibility of earlier intervention, which has a greater likelihood of having an impact than does the treatment of a more enduring pathology, which may develop if intervention is not timely.
Criteria for an ODD diagnosis.
The diagnosis of ODD requires that a child display several symptoms of antagonism and hostility, have impairment in daily function, and have symptoms/behaviors in excess of what would be expected for a developmentally matched peer—all for more than 6 months.3
The symptoms should not be better accounted for by another mental illness (eg, psychotic disorder in a paranoid child who refuses to eat, or separation anxiety disorder in a child who refuses to attend school)—nor should oppositionality and defiance be symptoms of a biologically mediated illness (eg, autism, schizophrenia).10
The ODD diagnosis from a developmental perspective.
Consideration of how children acquire self-regulation in the course of normal development can help one to better understand how disruptive behavior evolves. Toddlers, in an effort to develop some independence, display expected poor self-regulation at times (hence the expression "terrible twos"). This is a normal developmental process that assists with the acquisition of new skills for self-soothing and managing unpleasant mood states. We do not consider a diagnosis of ODD in a child who is in this developmental phase. However, if, as the child ages, he or she fails to assimilate new skills and continues to have tantrums and external expressions of emotional instability, defiance, and hostility, then it is appropriate for the family to seek assistance.
RISK FACTORS FOR ODD
A multitude of factors may affect the development of certain disorders. A child may have certain vulnerabilities that contribute to the development of a disorder—or strengths that protect against it. The risk factors and protective factors associated with ODD are summarized in Table 2.