Even though the American Psychiatric Association did not include Sluggish Cognitive Tempo (SCT) as a separated disorder in the recently revised DSM-V, the diagnosis manual that psychiatrists use to identify disorders, there is still considerable confusion surrounding the question of whether SCT is Inattentive ADHD (ADHD-PI) or if SCT is not ADHD at all and another condition altogether. The American Psychiatric Association has had a difficult time concluding that SCT is not a subtype of ADHD as the symptoms of ADHD-PI and SCT overlap considerably.
The condition that we now refer to as SCT was first examined In the early 1990s, Thomas Brown, Assistant Clinical Professor of Psychiatry at Yale and Russell Barkley both noticed that there was a group of kids with attention disorders that were no hyperactive at all. These kids seemed to have the opposite problem, they were sleepy, dreamy, slow and sluggish. It seemed that these kids had executive functioning problems just like ADHD kids but their problems were related to the executive functions that controlled effort, motivation, arousal and alertness. Brown described the kids with this condition as "day dreamy", "spacey", and "drowsy".
Many people studying this group concluded that the sleepy kids belonged in the the primarily inattentive sub-type, but when researchers looked a bit closer they discovered that the problems with their arousal and alertness levels were more severe and were different from the arousal and levels of kids with the inattentive ADHD subtype. Barkley hypothesized that ADHD-PI kids were really children that had almost all the symptoms of combined type ADHD but missed being labeled as ADHD-C because they lacked one or two hyperactive symptoms and that SCT kids were part of another disorder altogether.
Psychiatrists and psychologists are still working on this question and they have not quite figured it out but there have been several medical articles published on this topic this month that are interesting. In this months Journal of Clinical Child and Adolescent Psychology there is a published study by Russell Barkley looking at the executive function scores , co-conditions, and impairments of 1800 kids with ADHD and SCT. Barkley found that kids with ADHD had more executive function deficits when compared with kids with SCT, kids with ADHD were more likely to have more co-existing conditions and that ADHD kids were more impaired in school. He found that kids with SCT had high rates of depression but not of other co-conditions that are common in ADHD. He found that SCT kids were more impaired socially but less impaired academically especially in a home school environment.
Perhaps the most interesting finding from his study was that there was a dramatic overlap between the two conditions. He found that almost 40% to 60% of kids with ADHD and SCT also met the diagnostic criteria for the other condition. I believe that this means that 40% of the ADHD kids had SCT symptoms and 60% of the SCT kids had ADHD symptoms. This would certainly explain why separating these conditions has proved so difficult.
Understanding Executive functions (EF) and executive skills is important to understanding the problems of ADHD and SCT. I have written several posts on the EFs but different researchers have different ideas about how these skills relate to ADHD or SCT impairments. Some researchers have found it useful to divide the EFs into two categories that they refer to as the "Hot and Cold executive functions". The "hot" executive function involve emotional control, response inhibition, and impulsive behavior. The "cold" executive functions involve organization, working memory, sustained attention, alertness and arousal. All the executive skills are managed by the brain's pre-frontal cortex and from brain imaging studies we know that appropriate brain activation in these areas are amiss in both SCT and ADHD.
Barkley concluded from this recent study that kids with ADHD had various "hot" and "cold" executive functioning problems, while kids with SCT mostly had "cold" executive function problems and this recent study seems to confirm what Barkley first suspected. Kids with SCT are different from the rest of the ADHD sub-types. If you read what Barkley has written about the ADHD group without emotional control or response inhibition problems, you will learn that he believes that people who primarily have 'cold' executive function problems, are fundamentally and clinically different from the kids with ADHD. Because of this, Barkley believes, they should be treated and managed differently from the way that Hyperactive-Impusive or combined type ADHD (ADHD-C) is managed and treated.
In the end, it may be Russell Barkley who leads people with SCT and with "cold" executive function problems into the daylight. All of this is important because finding the best treatment for people with primarily inattentive symptoms, depends on it. Luckily, for us, he has help. I will report on several other SCT studies in my next post.
I would love to know your thoughts on Barkley's most recent findings. Drop me a note!
Barkley RA .Distinguishing sluggish cognitive tempo from ADHD in children and adolescents: executive functioning, impairment, and comorbidity. J Clin Child Adolesc Psychol. 2013 Mar;42(2):161-73. doi: 10.1080/15374416.2012.734259. Epub 2012 Oct 24.