Validity of the sluggish cognitive tempo symptom dimension in children: sluggish cognitive tempo and ADHD-inattention as distinct symptom dimensions.

This study examined the validity of the sluggish cognitive tempo (SCT) symptom dimension in children. Ten symptom domains were used to define SCT (i.e., (1) daydreams; (2) attention fluctuates; (3) absent-minded; (4) loses train of thought; (5) easily confused; (6) seems drowsy; (7) thinking is slow; (8) slow-moving; (9) low initiative; and (10) easily bored, needs stimulation). Teacher ratings of 366 children (ages 5 to 13 with 56 % girls) along with parent ratings of 703 children (ages 5 to 13 with 55 % girls) indicated that SCT symptom domains one to eight showed convergent validity (i.e., substantial loadings on the SCT factor) and discriminant validity with the ADHD-IN dimension (i.e., higher loadings on the SCT factor than the ADHD-IN factor). Higher scores on this eight-symptom measure of SCT predicted lower levels of academic and social competence even after controlling for ADHD-IN and ADHD-HI. In addition, higher SCT scores still predicted higher anxiety/depression scores after controlling for ADHD-IN and ADHD-HI. Higher SCT scores also predicted lower ADHD-HI scores after controlling for ADHD-IN and anxiety/depression while higher ADHD-IN and anxiety/depression scores predicted higher ADHD-HI scores after controlling for SCT and anxiety/depression or ADHD-IN. SCT also showed a unique negative relationship with ODD while ADHD-IN and anxiety/depression showed unique positive relationships with ODD. This new measure of the SCT dimension was meaningfully independent from the ADHD-IN and anxiety/depression dimensions and suggests that such an SCT dimension may signify a distinct presentation of ADHD or a different (if highly comorbid) disorder altogether.