Objective: Although internalizing and externalizing disorders have received considerable attention among young population, the mechanisms that explain the relationships of internalization and externalization symptoms with attention deficit/hyperactivity disorder (ADHD) in children and adolescents are not well understood. Since sluggish cognitive tempo (SCT) symptoms had significant associations with ADHD, and internalization/externalization disorders, we examined whether SCT may mediate between ADHD symptoms and internalizing/externalizing problems during childhood.Methods: We performed a retrospective chart-review of 95 children and adolescents (76 boys and 19 girls, aged 6-16) with ADHD. The severity of ADHD was evaluated by Turgay DSM-IV-Based Disruptive Behavioral Disorders Screening and Rating Scale (T-DSMIV-S) completed by teachers. Measures of SCT, internalisation and externalisation symptoms, social, thought, and attentional problems were based on the Teacher Report Form (TRF) that was completed by subjects' primary teachers.Results: The withdrawn scores were significantly correlated with SCT scores, social problems, and ADHD-inattention. There was an inverse correlation between withdrawn and ADHD-hyperactivity/impulsivity scores. The mediation test using bootstrapping method showed that the indirect coefficient for SCT was significant, after controlling of ADHD-inattention and social problems covariates, consistent with partial mediation.Conclusion: Our results may demonstrate that while externalization symptoms were associated with hyperactivity/impulsivity symptoms of ADHD, the internalization symptoms were significantly related to SCT in youngs with ADHD. Specifically, although social withdrawal was significantly related to ADHD-inattention, this relationship was mediated by the severity of SCT.
Keywords: ADHD; SCT; externalization; internalization.