Relationship between sluggish cognitive tempo and sleep, psychological, somatic, and cognitive problems and impairment in children with autism and children with ADHD

Sluggish cognitive tempo (SCT) is a topic of renewed interest. Much remains to be learned about its association with symptoms and diagnoses that have received little research attention, particularly sleep disturbance, somatic complaints, and autism. Our study is the first to explore the relationship between SCT and sleep, internalizing, externalizing, somatic, and cognitive problems, impairment, and demographics in large samples of children with autism, ADHD-Combined, and ADHD-Inattentive. Mothers rated 1,436 children with autism and 1,056 with ADHD without autism, 2 to 17 years, on the Pediatric Behavior Scale (PBS). Factor analysis yielded a 6-item SCT factor (sluggish/slow moving/low energy, stares/preoccupied/in own world, tires easily, in a fog/confused, drowsy/sleepy/not alert, and apathetic) plus 10 additional factors. SCT was distinct from but related to several factors and was associated with social and academic impairment. The strongest independent predictors of SCT were depression, sleeping more than normal, cognitive problems, autism, and somatic complaints. Scores on the remaining factors (sleep disturbance, attention deficit, impulsivity, hyperactivity, oppositional defiant disorder, conduct disorder, and anxiety) increased explained variance by less than 2%. Findings suggest that SCT is not simply sluggish cognitive tempo, as the name implies, and is a complex construct with behavioral, affective, emotional, cognitive, and somatic components and associations. Given that 49% of children with autism had SCT, SCT symptoms should be considered in all children being evaluated for autism, as well as for ADHD-C and ADHD-I (with SCT percentages of 31% and 40%). Assessing and treating SCT is especially important because of its association with impairment.