DSM-IV-defined inattention and sluggish cognitive tempo: independent and interactive relations to neuropsychological factors and comorbidity.

The aim of the present study was to investigate the independent relations of DSM-IV-defined inattention and behaviors characteristic of sluggish cognitive tempo (SCT) to neuropsychological factors and problem behaviors often comorbid with attention deficit/hyperactivity disorder (ADHD). By controlling for symptoms of DSM-IV-defined inattention, unique relations to SCT could be ascertained. Additionally, interactive relations of DSM-IV-defined inattention and SCT were of interest. A community-based sample of school children (N = 209; the higher end of the ADHD-symptom range was oversampled) completed neuropsychological tasks designed to measure executive function (EF), sustained attention, and state regulation. Behavioral symptoms were measured using parental and teacher ratings of the DSM-IV criteria for ADHD and Oppositional Defiant Disorder (ODD). The results showed that these two domains of inattention, DSM-IV-defined inattention and SCT, have neuropsychological processes and comorbid behavioral problems in common. However, when controlling for the overlap, DSM-IV-defined inattention was uniquely related to EF and state regulation, while SCT was uniquely related to sustained attention. In addition, the results showed an interactive relation of DSM-IV-defined inattention and SCT to ODD. Findings from the present study support the notion that DSM-IV-defined inattention constitutes a somewhat heterogeneous condition. Such results can further our theoretical understanding of the neuropsychological impairments and comorbid behavioral problems associated with ADHD symptoms.