Distinctions Between Sluggish Cognitive Tempo, ADHD-IN, and Depression Symptom Dimensions in Spanish First-Grade Children

Abstract

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.

Acknowledgments

This research was supported by Ministry of Economy and Competitiveness grant PSI2011-23254 (Spanish Government) and a predoctoral fellowship of the Balearic Government (FPI/1451/2012). We thank Cristina Trias and Cristina Solano for their help in data collection.

Notes

¹The current version of the CADBI also included five anxiety symptoms randomly mixed with the five depression symptoms (i.e., seems nervous or tense; worries about relationships with peers; seems anxious or fearful; worries about academic performance; and worries about performance in games or sports). These five anxiety symptoms along with the item “easily cries or seems tearful” did not load high enough on the anxiety/depression factor to include these six items on the factor in this study. The anxiety/depression factor from the earlier Lee et al. (2013) study thus became the depression factor of the current study.

²We thank Russell Barkley for permission to use his Functional Impairment Scale in this research project.

Note: Confirmatory factor analytic procedures were used to calculate the reliability coefficients (i.e., the amount of true score variance in the measure), interrater reliability coefficients (i.e., the correlations between the same factors for mothers and fathers), and the test–retest reliability coefficients (i.e., the correlations between the same factors across the 6-week test–retest interval). A dash indicates measure not administered a second time. SCT = sluggish cognitive tempo; ADHD-IN = attention-deficit/hyperactivity disorder-inattention; ADHD-HI = hyperactivity/impulsivity; ODD-A = oppositional defiant disorder toward adults; ODD-P = oppositional defiant disorder toward peers.

^a n = 723.

^b n = 603.

^c n = 753.

^d n = 792.

^e n = 695.

Note: All correlations were significant at p < .01. The ADHD-IN factor had a significantly stronger relationship with ADHD-HI, ODD toward adults, and ODD toward peers factor than the SCT factor (ps < .0001). The ADHD-IN and SCT factors were equally related to the depression, academic and social impairment factors (ps > .05). The range for the standard errors was from 0.02 to 0.04. SCT = sluggish cognitive tempo; ADHD-IN = attention-deficit/hyperactivity disorder-inattention; ADHD-HI = hyperactivity/impulsivity; ODD-A = oppositional defiant disorder toward adults; ODD-P = oppositional defiant disorder toward peers; DEP = depression; AI = academic impairment; SC = social impairment.

Note: ODD-A = oppositional defiant disorder toward adults; ODD-P = oppositional defiant disorder toward peers; ADHD-IN = attention-deficit hyperactivity disorder–inattention; ADHD-HI = attention-deficit hyperactivity disorder–hyperactivity/impulsivity.

*p < .05. **p < .001.

³This regression analysis was repeated with ADHD-HI as a control variable (i.e., ODD toward adults, ODD toward children, depression, academic, and social impairment regressed on SCT, ADHD-IN, and ADHD-HI). The partial standardized regression coefficients for SCT from this analysis were almost identical to the values reported for SCT in Table 4.