About breaking barriers, the risk paradox, and other twists.

Abstract

Acquiring new knowledge requires many times to break through old barriers and disregard conventional perspectives. Thus, the old classification scheme of attention-deficit/hyperactivity disorder (ADHD) in the DSM-IV stipulated that the symptoms of ADHD might not occur exclusively during the course of pervasive developmental disorder (PDD). Although understandable from a point of view to maximally differentiate ADHD from PDD or autism spectrum disorder (ASD), the classification rule simply ignored clinical reality of the large clinical overlap between ADHD and ASD and has blocked research into the neurobiological underpinnings thereof for many years [7, 8]. In a similar vein, the DSM-IV prohibited to classify oppositional defiant disorder (ODD) when also criteria for conduct disorder (CD) were met. This DSM-IV rule was in marked contrast with the classification of ODD and CD in the ICD-10 nomenclature, where both ODD and CD symptoms were lumped together into one overall category of CD. As a consequence, the DSM-IV system blocked the refined study of the relationships between ODD and CD and did also impediment the study of the added clinical value of diagnosing ODD symptoms in patients with CD. In their carefully conducted longitudinal study of the developmental relations between ODD and CD, Diamantopoulou et al. [2] assessed symptoms of ODD and CD in a community-based sample. They found that ODD and CD symptoms developed rather independently over time, and that ODD symptoms did not increase the risk for later developing CD, except for when already subthreshold CD symptoms were present. The findings did not support the idea that ODD symptoms are a milder or earlier form of CD. Further, the presence of ADHD did not make a difference in increasing the transition rate from ODD to CD, at least in this community sample. What is our next research step? This should further renew and bolster our interest in the study of the phenomenology, aetiology and neurobiology of ODD as separate from CD, as has already been started [9, 10].