The objective was to determine if the external correlates of sluggish cognitive tempo (SCT) and ADHD-inattention (IN) dimensions were the same in cross-sectional and longitudinal analyses. Teachers and aides rated SCT, ADHD-IN, ADHD-hyperactivity/impulsivity (HI), oppositional defiant disorder (ODD), and depression along with academic impairment in 758 Spanish children (55 % boys) on three occasions (twice at the end of the first grade year [6-week separation] and then again 12-months later at the end of the second grade year). Three of eight SCT symptoms showed substantial loadings on the SCT factor and substantially higher loadings on the SCT factor than the ADHD-IN factor for teachers and aides at each assessment (seems drowsy, thinking is slow, and slow moving). Cross-sectional and longitudinal analyses yielded similar results with SCT and ADHD-IN factors having different and unique external correlates (higher scores on SCT predicted lower scores on ADHD-HI and ODD while higher scores on ADHD-IN predicted higher scores on ADHD-HI and ODD with SCT and ADHD-IN both uniquely predicting academic impairment and depression). Developmental and methodological reasons are discussed for the failure to find an inconsistent alertness SCT factor (daydreams, alertness fluctuates, absent-minded, loses train of though, and confused).

The objective was to examine the longitudinal correlates of sluggish cognitive tempo (SCT) and attention deficit/hyperactivity disorder (ADHD)-Inattention (IN) dimensions with mothers' and fathers' ratings of Spanish children. Mothers and fathers rated SCT, ADHD-IN, ADHD-hyperactivity/impulsivity (HI), oppositional defiant disorder (ODD), depression, academic impairment, and social impairment on 3 occasions (twice in first-grade year [6-week separation] and once in the second-grade year [12 months after the first assessment]) in Spanish children (758, 746, and 718 children at the 3 time-points with approximately 55% boys). The results showed that (a) higher levels of SCT from earlier assessments predicted higher levels of depression, academic impairment, and social impairment at Assessment 3 after controlling for ADHD-IN at earlier assessments; (b) higher levels of ADHD-IN from earlier assessments predicted higher levels of depression, academic impairment, and social impairment at Assessment 3 after controlling for SCT at earlier assessments; (c) higher levels of ADHD-IN from earlier assessments predicted higher levels of ADHD-HI and ODD at Assessment 3 after controlling for SCT from earlier assessments; and (d) higher levels of SCT from earlier assessments either showed no unique relationship with ADHD-HI and ODD or predicted lower levels of ADHD-HI and ODD at Assessment 3 after controlling for ADHD-IN from earlier assessments. Initial evidence is provided of SCT's unique longitudinal relationships with depression and academic/social impairment and different longitudinal relationships with ADHD-HI and ODD relative to ADHD-IN, thus adding to a growing body of research underscoring the importance of SCT as distinct from ADHD-IN.

The objective of this study was to evaluate the validity of a new parent rating scale of Sluggish Cognitive Tempo (SCT). SCT was defined with 10 symptom domains--daydreams; attention fluctuates; absentminded; loses train of thought; easily confused; seems drowsy; thinking is slow; slow-moving; low initiative; and easily bored, needs stimulation--with each domain represented by multiple examples. Mothers' and fathers' ratings of SCT, ADHD-IN, ADHD-HI, oppositional defiant disorder (ODD), and depression symptoms along with ratings of academic and social impairment were obtained for a sample of 802 Spanish first-grade children (54% boys). SCT Symptom Domains 4 to 8 showed substantial loadings on the SCT factor (i.e., convergent validity) and substantially higher loadings on the SCT factor than the ADHD-IN factor (i.e., discriminant validity). This 5-domain measure of SCT showed good interrater and test-retest reliability for a 6-week interval. Higher scores on the 5-domain measure of SCT predicted higher levels of academic and social impairment even after controlling for ADHD-IN and depression. In contrast, higher levels of SCT were not uniquely related (or uniquely negatively related) to ADHD-HI and ODD, whereas ADHD-IN and depression were uniquely positively related to ADHD-HI and ODD. The new measure of SCT more clearly establishes that SCT, ADHD-IN, and depression represent independent symptom dimensions, thus providing a measurement tool to help determine if SCT and ADHD-IN dimensions have unique biological correlates and if SCT and ADHD meet the criteria for different disorders.