Sluggish Cognitive Tempo Dimension and ADHD-IN Dimension: Distinct Constructs?
The purpose of this study was to develop a teacher rating scale of Sluggish Cognitive Tempo (SCT) and to use this new measure to better understand the relation of the SCT to ADHD-inattention (IN) subtype. Ten SCT items with a good content validity were developed. A series of exploratory factor analyses with teachers' ratings of elementary students showed that eight of the ten SCT symptoms (i.e., daydreams, alertness fluctuates, absent-minded, loses train of thought, easily confused, seems drowsy, thinking is slow, and slow-moving) have the good convergent and discriminant validity with ADHD-IN and Anxiety-Depression. The correlation between SCT and ADHD-IN was stronger than the one between SCT and anxiety-depression. A confirmatory factor analysis supported a SCT, ADHD-IN, and ADHD-HI three-factor model with an adequate overall model fit. The correlation between SCT and ADHD-IN was stronger than one between SCT and ADHD-HI. Multiple regression analyses were conducted in order to examine the external validity of SCT and ADHD-IN on oppositional defiant disorder (ODD), Anxiety-Depression, Verbal-Physical Aggression, Callous-Unemotional Behaviors (CU), and Academic and Social Competence and the results were consistent with previous literature. Specifically, higher levels of SCT predicted higher levels of Anxiety-Depression after controlling for IN and HI, while higher levels of SCT predicted lower levels of externalizing behaviors (e.g., ODD, Verbal-Physical Aggression, CU) as well as lower levels of Academic Competence when IN and HI were controlled for. With regard to ADHD-IN, after controlling for SCT and HI, higher levels of IN predicted higher levels of ODD, Verbal-Physical Aggression, and CU, while higher levels of IN predicted lower levels of Academic and Social Competence. This would indicate that SCT and ADHD-IN have different external correlates, thus providing an initial support for the external validity for the SCT construct. The results from these analyses are expected to increase our understanding of the usefulness of the SCT construct.