This is an invited commentary, not a new study. The author summarizes other research on sluggish cognitive tempo (SCT) and ADHD, with no stated search method. He notes that all but two studies of SCT have focused on children, so most of the evidence is about children, not adults. In one U.S. adult survey, a small share met criteria for high SCT symptoms.
He concludes SCT is likely a distinct attention problem from ADHD that overlaps with it in about half of all cases. He calls the split between SCT and ADHD symptoms well established. Compared with ADHD, SCT showed no link or a negative link with oppositional defiant disorder, while ADHD carries a much higher risk of it. It had a stronger link with anxiety and depression. SCT was tied to social withdrawal even after allowing for ADHD. Its link with organization and problem solving was very modest. The author proposes renaming SCT "Concentration Deficit Disorder," saying the current name is premature and patients find it offensive.
Links with school performance are emerging. Findings on who has SCT, its causes and its treatment need much more research. Atomoxetine reduced SCT symptoms in one study. When he used his own survey to argue that most children with SCT lack anxiety or depression diagnoses, he noted it relied on parent reports of past diagnoses.
He suggests that ADHD medicines cannot be assumed to work for SCT until tested directly in people with SCT.
The numbers Stats and what the terms mean
The statistics behind the plain-language claims above.
- Barkley, 2013: share of U.S. children with SCT who also had ADHD, 59 %.
- Barkley, 2013: share of children qualifying for ADHD (any type) who also qualified for SCT, 39 %.
- Barkley, 2012: share of U.S. adults who met criteria for high SCT symptoms, 5.8 %.
- Barkley, 2012: share of those adults with high SCT symptoms who had ADHD, 54 %.
- Barkley, 2012: share of adults with ADHD who also met criteria for SCT, 46 %.
- Angold, 1999: how much more likely oppositional defiant disorder was with ADHD, 11 times higher risk (comparator not stated).
- Barkley's samples of adults and children (cited in Barkley, 2013): overlap between SCT and an organization and problem solving rating after controlling for ADHD, 5 % of variance shared. What the terms mean:
- Variance shared is how much of the differences between people on one measure line up with differences on another; the author calls 5 % very modest.
Source: Barkley R. Sluggish Cognitive Tempo (Concentration Deficit Disorder?): Current Status, Future Directions, and a Plea to Change the Name. Journal of Abnormal Child Psychology (2013). doi:10.1007/s10802-013-9824-y