I recently began reading a Continuing Medical Education (CME) course by Dr. Russell Barkley. This course was updated by Dr. Barkley in 2007 so I believe that the information there is fairly current. In the CME Dr Barkley proposes that when the new DSM V is published in 2012, the classification of the Predominantly Inattentive Subtype of ADHD (ADHD-I) will be different. Dr. Barkley has long proposed that patients with ADHD-I have different responses to treatment, have different life outcomes, and are a separate clinically entity from the hyperactive/impulsive subtype
If I am reading the CME correctly what he is saying is that he now believes that people with ADHD-I are either ADHD Combined Type missing a few of the hyperactive symptoms or that they actually have a Sluggish Cognitive Tempo (SCT). People with SCT are described as slow, passive, daydreamy, shy, and HYPO-active. These are the folks that are most like Winnie the Pooh.
There have been studies done that indicate that patients with SCT are definitely inattentive. The problem comes here. Most inattentives cannot be classified as having SCT. It is believed by some researchers that 40% of people with ADHD-I also have symptoms of SCT. That would mean that 60% of us would, using this new criteria, be lumped into the category of ADHD-C. I am not convinced that most people with ADHD-I are sub-clinical combined types or of Sluggish Cognitive Tempo. If your remove 1-2 hyperactive symptoms from the ADHD-C type don't you then get a person who is normally active. How do you perform a controlled study using that classification??
A recently published study done by
evaluated the utility of using the symptoms of SCT for discriminating among DSM-IV subtypes of ADHD. Their conclusion was “that the inclusion of SCT symptoms in the ADHD diagnostic criteria has limited utility for isolating diagnostically meaningful subgroups of the Inattentive type…” A study done by the Emory University in 2001 where 700 children with inattention were evaluated found that symptoms of SCT positively predicted inattention but that inattention did not predict SCT. University of Chicago
As a child, I might have fit the criteria for a diagnosis of SCT. I do not fit those criteria now. I can hold a great many numbers in my head and have no trouble with speech or reading. My son has a great deal of trouble with organization, distractibility, and inattentiveness but absolutely no problem with sluggish cognition. He is a 5th grader doing 6th grade math and he has always been a better reader than a mathematician. Does he have some symptoms of Hyperactivity? Does he occasionally fidget? Does he occasionally leave his seat at the dinner table? Yes, but no one who knows him would ever classify him as "almost hyperactive" and he has absolutely no impulsive symptoms. Someone may need to explain all this to me more thoroughly but I do not believe that you can wedge all people with ADHD-I into the categories of ADHD Combined type and Sluggish Cognitive Tempo. Winnie does not fit into his honey pot and we do not all fit into the SCT pot.