ABSTRACT
The study of the psychopathophysiology of attention deficit hyperactivity disorder (ADHD) is at a wonderfully exciting phase in its development. Established ways of thinking about the condition are giving way to new ones: A paradigm shift is underway. We call it a paradigm shift because these changes relate to more than just a replacement of just one theory with another, but rather a fundamental shift in perspective-with one way of thinking about ADHD as a disorder giving way to another. Traditionally, ADHD researchers, influenced by assumptions within the classical disease model of psychiatric disorders (1), have attempted to isolate a common core deficit at the heart of ADHD. More recently there has been a growing acceptance that ADHD is a psychopathopsychologically heterogeneous disorder; with no particular pattern of impairment representing a necessary condition for the presence of the condition and with subgroups of children recognized each with a distinctive pattern of impairment (2). This has been a response to the inconclusive pattern found in studies of ADHD psychopathophysiology which are often contradictory and inconsistent and where replicated results are found, meta-analyses give pooled effect sizes in only the moderate range (i.e., Cohen’s d .4-.6) (3). This shift in perspective has led to a different set of research questions being asked. Rather than asking; where is the core deficit responsible for ADHD? The question becomes: How many different profiles of impairment can be dissociated within the broader ADHD syndrome (4)?
