Clinical differentiation of sluggish cognitive tempo and attention-deficit/hyperactivity disorder in children.

This study (a) determined whether clinical elevations of sluggish cognitive tempo (SCT) and attention-deficit/hyperactivity disorder (ADHD) symptom distributions in a large community sample of children would allow for identifying SCT-only, ADHD-only, and SCT + ADHD clinical groups; (b) examined co-occurrence of clinically elevated SCT and ADHD; (c) evaluated whether these clinical groups differed in their gender distribution, co-occurring mental health symptoms, or impairment in academic and social functioning; and (d) explored patterns of independence and overlap when clinically elevated depressive symptoms were considered in tandem with SCT and ADHD. Participants were mothers, fathers, and teachers of 2,142 children (50.51% boys, ages 8-13 years) from 32 schools in Spain. All three groups of informants completed measures of SCT, ADHD, oppositional defiant disorder (ODD), anxiety, depression, shyness, social impairment, and academic impairment. Cut-off scores for the top 5% of the sample were used to create SCT-only, ADHD-only, SCT + ADHD, and comparison groups. Across informants, 4.97%-5.53% met criteria for clinically elevated ADHD-only, and 2.30%-2.80% met criteria for clinically elevated SCT-only; 27%-35% of the ADHD group also met the criteria for the SCT group, whereas 44%-54% of the SCT group met the criteria for the ADHD group (primarily based on inattentive symptoms). The ADHD-only group had higher ODD scores than the SCT-only group, whereas the SCT-only group generally had higher shyness and internalizing scores (particularly depression) than the ADHD-only group. Additional analyses that also included clinically elevated depression revealed that 28-46% of the children with elevated SCT had elevations in neither ADHD nor depression. This study moves the field toward examining both the empirical and clinical differentiation of SCT and ADHD. Findings are discussed regarding how SCT may fit in diagnostic nosologies and models of psychopathology. (PsycINFO Database Record (c) 2018 APA, all rights reserved).