Abstract
Sluggish cognitive tempo (SCT) is characterized by behavioral symptoms reflecting slowness and lethargy (e.g., sluggishness, appearing sleepy) and inconsistent alertness/mental confusion (e.g., daydreaming, fogginess). SCT is substantially correlated with the inattentive symptoms of attention-deficit/hyperactivity disorder (ADHD) and may be part of that domain, but in cross-sectional data, SCT is also strongly associated with both inattention and depression. To date, no study has examined the prospective associations of SCT symptoms in childhood/adolescence with symptoms of ADHD and internalizing problems in adulthood. Using a sample of 449 twin children and adolescent pairs, prospective multiple regression analyses examined whether self- and parent-reported SCT, depression, and parent-reported symptoms of ADHD predicted symptoms in adulthood 12 years later. SCT and depression at time one were strongly correlated (self-reported SCT and depression r = 0.84; parent-reported SCT and depression r = 0.78). When adult outcomes were separately regressed on each youth symptom dimension, self-reported SCT (β = 0.26, p < 0.0001) and depression (β = 0.13, p < 0.0001) each predicted adult symptoms of depression and self-reported SCT predicted inattention (β = 0.12, p = 0.0026). Parent-reported depression, but not parent-reported SCT, predicted self-reported adult depression symptoms (β = 0.17, p = 0.0003). In contrast, when each adult outcome was regressed simultaneously on youth self-reported SCT and depression, neither predicted adulthood inattention or depression. These findings indicate that SCT in childhood and adolescence is strongly associated concurrently and predictively with both inattention and depression. Theoretical and clinical applications of the construct of SCT must take its robust association with both inattention and depression into account.